Because of the higher internal resistance more of the capacity is converted to heat, so with higher C rates the useable capacity drops depending on that internal resistance values. Your 45° measurement is an evidence for that. The "missing" capacity warms up your rainy day ;) (greetings from Austria)
Thanks for the insight testing the sodium batteries Andy! LiFePo4 really is kinda magical in that nice flat discharge curve. Provides nice stable voltage thru almost the entire capacity. Loving mine so far! (1 100Ah rack battery on a cart and a 12.8v 304ah one in the garage) Again thanks for all your work, it's nice to see someone else as entertained with and geeking out on the graphs data like I am! The wife could care less....until the power goes out....
Can someone explain to me? Is it because the voltage drop increases the amps flow when discharging with a steady wattage? So when the soc goes down we could potentially over discharge the max C rate? I am not sure what the disadvantages are besides the heat. (Did I fall asleep during the video?)
@@camielkottethe disadvantage is the battery performs worse as you increase the rate of discharge. They do fine at 0.5C or less but get exponentially worse at 1C. I don’t know the cost of these batteries but if they are low cost they are best used in low amp requirements. In that scenario they excel (if inexpensive)
Hi Andy I have a comment unrelated to this videos content, I am new to the channel and looking at all your older videos, I strongly recommend getting yourself a set of 1000V electrical screw drivers. Safety for just in case I am thoroughly enjoying all videos Gavin 😁
Thanks Andy- great job, love your work, and as always, very educational 👍👍 (I don’t think I’ll be switching to Sodium batteries any time soon.) Stay charged!
From those curves you can easily calculate the DCir for the cell at the various SoC's and temperatures. Then you can apply a terminal voltage correction based on that DCir to "see" an approximation of the electropotential of the cell at its current chemical state 🙂 One nice test for DCir is to write a little scripted function that does a pulse discharge followed by a pulse charge at the same current and for the same duration, so the overal SoC is not changed. If you run that test at say 0.1v steps through the discharge from the response you can calculate both the DCir and ACir as well, and even build a model of the cell from that data which becomes very useful in terms of any openloop corrections for a BMS system etc
Good ol' battery testing! You can't beat a good graph. It's amazing how plotting something into a picture on a computer screen can really tell a good story. Excellent information Andy! Have you discuss the results with Andy 2?
There is now a version 0.7 for the Seplos V3 bms. This update fixes a big calculation and display problem for SOC. While they were at around 60% SOC, the bms displayed 98.5% and remained at this value until a cell passed the UVP. In addition, the SOC display increased or decreased twice as much as in reality. We made, with Cyrille from the UA-cam channel "Lemoult'e Batteries", a request for rectification to Seplos, and they have just released the new firmware
Yes, thank you. I'm in contact with Cyrille. I tested as well with 0.5 and 0.6 and could not see any jumping in SOC. But the V3.0 has lots of other issues. All around it's not a great BMS and even worse is the software.
Hej Andy Thanks for great test. The difference in energy is actually around 15%. 614 wh out of 4090 wh. This because of greater difference in voltage-curve with greater C-rate, than LiFePo4. Best regards Brian
True The energy is about 13% less but the curve is considerably less flat so in real world the inverter cutoff is 30% sooner. Also discharge for Na+ is .5C up to 113f rather than lithium 1C up to 150f. Further testing in real world conditions is needed. Lithium costs considerably more and I haven't seen Na+ to be considerably less yet.
one of the problems to take into account is the problem of intensity. If you have a fixed load of 10W, at 3.8V you will have a discharge current of 2.63A, but arriving at 1.8V for the same load, the current will be 5.55A, which will make the discharge will be outside the datasheet parameters
Great test, thanks! Next up could be bigger, prismatic cells (if they're available...?) and also puncture and other mishandling tests like overcharging etc!
thanks again for this interesting content. Regarding sodium batteries, their biggest advantage is also their biggest weakness. The large voltage difference between a charged and discharged battery gives a great opportunity to relatively accurately measure capacity as a function of voltage, but at the same time it can be difficult for regulators and inverters to deal with such a large voltage difference. So, if sodium batteries are not significantly more affordable in the future, there will not be much reason to switch to this chemistry. The advantage of being able to charge at low temperatures is already quite easy to solve for lithium cells today.
you could make a weird battery that changes the interal connection from parallel to series between the sub modules to bump the voltage up (when switching from parallel to series) this way you could keep the voltage stable :)
The sodium battery maybe a good backup for below 0°C (32°F) or for use in low demand times, but they really need to be way cheaper than lifepo4 to replace them in my view. I could see if they do get a 1/3 the cost to consider them or as a hybred system for sub freezing weather. That flat discharge voltage, cycle life, safety of lifepo4 is hard to beat.
I believe that idea around Sodium batteries is to be "cheap" (when production/demand volume goes up) and more eco friendly . By all means LiFePO4 are , in my opinion , for the price , the best storage solution at this time , but Sodium batteries have great potential (when price goes down and people start producing them locally) and those aren't "unsafe" (I saw the nail test videos - no flames and not much of explosion - more like a "burst" ). 3C constant discharge rate is pretty nice , even though the battery packs are never designed to perform all the time at max discharge rate and the number of cycles is , also , very good. It is , still (relatively) early days , so , given a couple of years , we may see the improvements (in terms of performance and much lower price) and hardware to catch up.
Great info Andy. The moral of the story is, will your inverter be happy with the discharge range and don’t think about paralleling Lifepo4 with sodium.
I have some here, but why would we use them? With solar, we don't use high c-ratings and they are a lot more expensive than LiFePO4. Just for the sake of testing... OK🤷♂️
@@OffGridGarageAustralia I build electric mopeds, bikes, but I still love your channel, the bms reviews have helped me a lot. I plan to do solar one day. I love LTO, for solar the high c rate is not needed I agree, but having cells that will never need replacing is a positive, and even safer than lifepo4.
@@toriwatson9655 Yes, perfect for that matter. The high C-rate is exactly what you need for that type of application. LTO have a lifespan of 10yrs so are not infinite...
The downside is LTO is bulky, so for mobile uses you need quite a bit of battery space to get good range, and as you say they are expensive. Cycle life should be around 20,000 cycles, in fact the Zenaji Aeon batteries have a warranty for 22,000 cycles, so I would have thought well over a 10 year lifespan. @@OffGridGarageAustralia
At each section of this graph 0 - 137 - 274 - 411 - etc. we have equal mAh but different ammout of energy in the cell, because of different voltage at start and end of each section, so e.g. first section has / 3.94 + 3.65 / === 7.59, 7.59 / 2 === 3.795, 3.795 x 137 === 519.9 Wh of energy, but from 412 - 549 we have / 3.35 + 3.17 / === 6.52, 6.52 / 2 === 3..26, 3.26 x 137 === 446.6 Wh of energy. A lot of BMSs and system for SOC reporting, reports SOC % for mAh or Ah, but this is not equal to SOC % ENERGY. Becuase integral function under voltage curve is different for equal Ah ranges 0 - 10 - 20 - 30 -- etc.
Excellent Andy! exactly the comparison test I was hoping for, thank you. Have you considered of doing any life-cycle capacity tests on your little sodium Ion friends, maybe 300 cycles at 1C? Btw, I've been looking into the sustainability of Lithium in meeting projected demands and some estimates by the World Economic Forum claimed 700 years of lithium mining at current rates would be required to meet projected demand over the next 12 to 20 years for lithium batteries, or by my estimate a 100X increase in lithium mining, so it would seem that alternative sustainable chemistries are essential, and your test Andy is a telling preliminary insight into one possible chemistry. Perhaps Sodium ion battery chemistry used in stationary power systems, could free-up lithium for mobile batteries? Also, some promising results using AI to invent new battery chemistries promises to reduce invention and development time of new batteries from 20 years to 80 hours.
Very hard to do long term tests as it occupies the equipment and the computer would need to run for that time too. I'll consider it maybe later when we are done with all the sodium testing. Not sure where the 700yrs number comes from but there is other information out there that we need only to mine for 20yrs if we have a good recycling program for lithium set up... I don't see sodium batteries become a viable solution in the near future.
You gotta remember these are pretty much first generation production sodium batteries... and that they should be able to apply many similar technologies as they adapt them from Lion to get performance and specs up.... old lithium ION batteries weren't as good as they are today when they came out either.
Great test, thanks! Do you have measurement results of the internal resistance of the battery? I would be interested in whether it could be operated in parallel with a LiFePO4 + Sodium battery? There is an overlap in the range 3.6>2.8V. It would be an interesting experiment!
it's so weird that it rained here today too (Uruguay), this makes it feel like the whole southern hemisfere was rainy. (even if we really are just talking abour a few sq km area really) for me the main thing is that sodium batteries have the capacity to be so much cheaper than lithium ones. its as common as sea salt.
QUESTION It's a great video showing the discharge curves of the sodium battery C-Rating. The only question in my mind is, was there any degradation to the cell. Would you get the same results if you repeated the tests again?
Well regarding Ri, IT seems this chemistry is Not for Inverter... IT IS more for DC/DC bucket converter. When i calculate a Bit, IT Points Out that one cell has Ri=0,1 Ohm and this is the rootcause why voltage IS dropping in end of charging and start of discharging. IT means you have to Take down the current, otherwise you do not hit 3.95 in real.
Hi - just a thought..... because you are drawing far more current through your test set up cables, could that contribute to the voltage drop? (perhaps run 1 more test where you double up the thickness of the wires? (obviously, ou cant change the thickness of the cables within the tester itself - but at least reduce the length of the cabling???)
Wouldn't E-rate in watts be more relevant than C-rate in amps for a battery chemistry that has such a wide voltage range? At 3C the battery is providing 15.41W at full and at near empty it's only providing 5.85W. What happens if I drain the battery down at a constant energy of 10W? Would I have to stop discharging at 2.56V to avoid cell damage? Doesn't the C-rate vary drastically with a constant energy throughout the discharge cycle? I apologize in advance if what I am saying is misinformed. :)
C-rates is what batteries are tested with to make them all comparable. Watts are not great as they contain the voltage, which sodium batteries show a very high delta of. C-rates and Ah use only the current and are far better to compare.
you have to calculate your application, so that it will work in every condition. you have to make sure, that your battery can deliver enough power at the lowest SOC you will allow. In your example you have to set your discharge voltage to 2,56V or you have to use bigger cells or 2 or more in parallel. If you want to compare different chemistries, or differently organized batteries than you will go for Wh than for Ah. Ah is only suitable for single cell with the same chemistry. But even there could be diffences in the voltages over time and then Ah isn't accurate anymore. But Ah is easier and Ok enough for tests with a single cell.
For the sake of cycle life, would you recommend setting low voltage cutoff at the plateau? What state of charge does that plateau occur? These discharge curves look very much like Ni-Zn, though with just over twice the voltage.
Another question is whether charging to a lower target voltage such as 3.70V fully charges the sodium battery, or do you have to push it up to 3.95V to fully charge it?
So, what would be the use case for sodium batteries? Inverters don’t like the 50% voltage drop over the discharge curve. I know my BLDC motor controller doesn’t like that either. What about for small solar light applications, where output can run through a joule-thief circuit? If these cells don’t mind draining very far down, then I could see their use there. Or perhaps in power banks. Or emergency lighting? Where do you see their specs as an asset instead of something to be worked around?
@@faustinpippin9208 that’s just working around the problem. There are better suited chemistries for those situations. I am wondering where these batteries naturally make sense. Engineering around the problem is just money and effort best put towards a solution that doesn’t require that money and effort.
@@somebody1869 that workaround will solve the problem and will still end up being cheaper then other chemistries in many situations....and to meet the gov goals we will need all the batteries we can get and we still wont have enough, so this sodium stuff will be used in a lot of places despite the atrocious voltage drop
Why not for inverters, if you only use the batteries above 20 or 30% SOC. Depends on price, finally you get more life-cycle. After all, lead batteries allowed also using only 50%...
I think that low temperature operation is a big plus, everything else being equal. Sodiuum can be sourced everywhere and is not subject to geopolitical forces.
So Andy, What would you say the Power Density of Na+ battery versus LFP battery? So if you built a battery Bank such as Seplos what would the KWHr capacity be versus the LFP Seplos Battery Bank capacity??
You would need a lot more space, that's for sure. We can use only a portion of the available capacity of sodium cells with our inverters so, atm it makes no sense to build any batteries with these cells.
I like the curves :-) from the Sodium batteries cause you can estimate the SOC much better. Next time please compere the same rates for both batterys chemicals, the lifepo4 was only testet with 1C max and the chart was much smaler. 9% less with 3C discharge is a prity good value.
Can you Discharge them with constant watts instead of constant amps? I think you will see they do have a knee a very steep one. As the voltage drops the amps will rise, at the point of intersection of the two graphs I think they will perform badly and possibly heat up incredibly
LTO is not great for solar storage. Super expensive and we would not benefit from the high C rating they can do at all. Pretty much wasted money for solar applications.
Interesting. Not just capacity, but the watt-hours will be even worse due to the larger voltage drop. Hard to see the 1C difference in voltage drop but it does look larger than for 1C LiFePO4. That wasn't a complete capacity test though, it the tester stopped earlier because of the voltage drop but there was probably still energy in the cell. We need round-trip efficiency numbers for 0.2C too (watt-hours-out / watt-hours-in). Tried to look that up but I only see the 0.5C tests in the Test2 zip download. Oh, under Test2_C-Rating ... only the 0.2C discharge curve though, I couldn't find a 0.2C charge curve to check mWh against. Color bars at 14:24 aren't right. It's showing green as 1.0C but that's the best curve, not the worst curve. EDIT: Add. 4165mWh for 0.5C charge curve, 4090mWh for 0.2C discharge curve. 98.2% round-trip efficiency (so 0.2C charge curve would almost certainly be at least a bit better). That isn't bad at all. Then 1C discharge curve, 3729mWh ... 89.5% round-trip (vs 0.5C charge curve). Pretty horrid. Same for 3C discharge curve, 3476mWh... 83.5% round-trip. Yuch. But that isn't counting energy left in the cell after the tester stops. -Matt
How different is it to charge these batteries from the LiFEPO4 batteries, I'm just wondering if you have a BMS that supports LiFePO4 can you use it for the sodium batteries or do you need a new BMS
I was doing some reading about Graphene and I stumbled on battery chemistry of Hemp and Lithium I think. As a starting or surge battery. Have you heard of this and what's your opinion?
No I haven't heard about it. There are sooooo many battery chemistries out there and only 0.001% are making it into some sort of production. Even less are available on the market. My personal opinion after testing these hyped sodium batteries: LFP will stay for a very long time.
@@OffGridGarageAustralia cool, please check out the hemp batteries. I'd like to here you report on the chemistry. Very curious from a knowledgeable person opinion.
I can see these being useful in a low power setting using a boost buck converter to stabilise the output voltage to the load but the voltage swing is too great to be used directly in a 12/24/48v system
@@OffGridGarageAustralia I’ll be sticking to my lifepo4 cells for the foreseeable future. Built my first battery over 2 years ago after watching your channel and learning a lot from yourself. Thank you 🙏🏼
16:07 Can Andy or anyone explain to me why anyone would care about capacity in amp-hours and not kilowatt-hours? Those results then come out completely different, e.g. at 3C the usable capacity in kilowatt hours is only 85% as opposed to 92% in amp-hours. But I wonder why I should care about ampere-hours? Thanks for the clarification!
We use Ah and C-rating because it only contains the current only (constant current) and not the voltage. Voltage changes all the time, so makes no sense to use it in such test. Hence, all batteries have Ah stated and not Wh.
@@OffGridGarageAustralia I would just expect that just because the voltage is changing, only the capacity in kWh is important because that is what plays a role in real life operation of a solar inverter...
Most consumers aren't going to notice the difference unless the life expectancy is much different. Self discharge can be a bigger issue. Will my flashlight work as intended, when I need it?
looks like a good buffer storrage, i mean, if you build for example a 100Ah Batttery, with 10% Lifepo4 at beginning, and the end of SOC, lol? can the cells be mixed with lifepo? serious question
They cannot be mixed, no. Due to the flat voltage curves of LiFePO4, we would use only a small amount of the sodium capacity. From 2.5V to 3.65V if we max out LFP. Mor realistic it would be between 3.0V to 3.45V only.
obviously the voltage sag of the load affects the total ah that can be extracted from the battery , i would love to see a test of 3c discharge from full to close to shutdown voltage and just before shutdown happens or lets say 10% from empty reduce the load to 0.2 c and then see ah extracted from battery compared to 0.2c as we can see the battery jumps back up to 1.8v the moment the load dissapears ie a test like we tend to use our batteries in our phones , happy go lucky but the moment it gets closer to empty we tend to conserve in other words is the sag on high load causing us to get the wrong puicture of efficiency
All these tests are done with constant current though. If we change the current during testing, what can we compare the result to? There is no capacity under 2V in these sodium cells. I'll show this in the next test video.
@@OffGridGarageAustralia ok after doing the high drain test and once it shuts down, do a 0.1/0.2c to see how many AH is extracted until a low voltage shutdown This is more a curiosity I don't think there is much to extract Just curious how much the sag affects the efficiency % Example the axpert type inverters will do different low voltage shutdown voltages dependant on load to compensate for sag(naturally this is designed for lead acid only happens on the gel/flooded profiles not USE) On a big cell the difference may be negligible since the test is done on a small cell , .that tiny bit may affect the % more
Interesting test, suggestion since the battery voltage varies so much would not a constant power load test be more useful? The curve would look much flatter the a rapid drop off. Say 1.5V x 3.9A = 5.85W constant power. It would be easy to design a DC/DC converter to supply a constant voltage.
@@davidpenfold To test battery's I use my Rigol electronic load, it can do constant V,I,R,P it's limited to 150Vdc, 40A, 200W, it has a battery test function.
Both ZKE testers also can do a constant load test. But all batteries are tested with constant current. Including the voltage makes no sense as it changes all the time.
@@OffGridGarageAustralia But small battery loads will/can be constant power, with a DC/DC converter creating a constant load voltage, the discharge curve will be much different. These batteries will suit that application easily.
The reason I ask is that watt-hours charging and watt-hours discharging give efficiency to the battery. And what would a typical efficiency be?@@OffGridGarageAustralia
You seem to know alot about battery. I have a 12.8 volt 50amh LifePo4 and its going to be connected to a 1500 inverter. The ebike charger is 54.7 volt ,will the ebike charger damage the LifePo4 battery?
This data is quite interesting. If I define the lower end of usable power as 2.6V (10.4 V for a 4S battery), the different C rates give very different usable capacities: 0.2C - 78% 0.5C - 73% 1C - 66% 3C - 55% These results are rather negative considering that sodium batteries have been touted as a cheaper, easier to source materials, replacement for Lithium ion and lithium iron phosphate batteries. Based on these results and energy density data it looks like sodium batteries will have to be considerably larger and heavier than lithium batteries. That isn't much of a problem for stationery batteries such as in a backup power system, but is a real issue for use of sodium batteries in EVs. They may be an option for short range, low speed EVs, but not much else.
@@pavelsulc2617 If they end up a quarter of the price of LiFePO4 then you could easily just use 3.9 to 2.5V for about 60% capacity and still be ahead. For storage only, I'd imagine, but that could be a huge potential market for inexpensive peak load injection etc.
Even if they would be cheaper, you end up needing more to compensate for the capacity you cannot use. Space is a HUGE factor for EV batteries. LiFePO4 will stay for a very long time and sodium will NOT replace them. That's my take.
hello here, I've been looking for your email for a long time but I can't find it, I'm in Greece and I'm looking for some spare parts for solar panels like noark and I can't find them in Europe and I would like your help
@@OffGridGarageAustralia That's my point. It's good to plot voltage vs state of charge. But what's important (in my opinion is energy. Imagine two batteries. One was constant voltage in constant current discharge and the other dropped linearly. The second batter would have half the energy storage capability. Keep up the good work. It should be easier to balance the sodium batteries.
I was hopeful for sodium batteries, but the wide voltage range is a no-go for me. I'll be leaving so many amphours on the table by the time I hit the lowest voltage my inverter can run on. I may get a low amphour battery to use in an emergency situation such as sub zero temps.
Yes, so far it still seems that it is better to take care of the temperature comfort of LiFePo batteries than to use sodium ones because of the temperature. Because price is definitely not the reason at the moment.
Look at the specs of these cells. below freezing point, it's only a 0.2C charge and discharge, so not great if you need power. Secondly, even if prices would come down, due to the fact that you cannot use its full capacity, you would need to purchase even more sodium batteries to match LiFePO4 capacity. That also means more storage space for sodium batteries.
I can't say if those sodium batteries are good, if you think about a 16s battery whose terminal voltage fluctuates a lot with the load. And, for example, which inverter can use such an enormously wide voltage range without interference. (example 48V system and battey voltage fluctuates 24V-63V NOT GOOD!) In my opinion lifepo is much better because of the flat voltage curve. The devices survive more easily when the pole voltage does not drift over wide area, and remain almost constant throughout the capacity range.
These curves resemble Lead acid batteries more than LFP or li-ion. Which has upsides and downsides. Most importantly the amps go up when the batteries are going empty and the load is the same. But the upside is I think, no need to balance! That will save a lot of money on hardware.
Balancers are not expensive though (in comparison to other equipment and devices you would buy for a solar battery system). We will get to that point in one of the next videos 😉
@@OffGridGarageAustralia That sounds like a matter of opinion. One good(ish) 16s 200A BMS costs about 200 to 300 euros. For that money you can also get 3 or 4 Grade A 280Ah cells. Let's agree on "significant".
I wonder what would happen if you lowered the discharge rate before the steep drop in voltage. - Is the high discharge rate causing losses (heat) or is it mostly a matter of the test cutting off prematurely because of the lower voltage so the remaining capacity can not be used? It would also be nice to see a discharge test with the cell in a SPAT cooler as LFP typically does not work well at something like 0 degrees celcius and loses about 17% of it's usable capacity if I read the EVE specs right. -This would be a realistic scenario for those of us that don't want to waste energy heating the outside mancave.
These tests are always conducted with constant currents. If you are lowering the current during testing, we cannot compare the results to other battery chemistries anymore. A proper climate chamber costs A$5k+. I have tried using ice and coolers, but results are too inconsistent as the temperature is not constant.
@@OffGridGarageAustralia I understand there are standards for testing, but it would be nice to see if there is some way to get more out of these cells by lowering the current in the lower SoC. 3C seems like a lot for continous use but is very nice for peak loads like cooking. Maybe the low temperature tests are a bit unrealistic in a small fridge as the batteries themselves will change the temperature, even more so at high charge/discharge rates. Maybe someone in a colder climate with the right equipment and experience can do this?
too bad the voltage range is so wide. otherwise it would be great for rv use in north america during colder weather. would be interesting charging and discharging within lifepo4 voltage range and see what the capacity might be.
Even during colder weather, you can only charge and discharge with 0.2C. Is that still an advantage to lithium? Yes, but a very small one. Would you swap lithium for sodium? Certainly not...
@@OffGridGarageAustralia and in the case of more cold resistant electric car(I live in the canadian praries), not going to cut it at .2c And we would need something -30 capable atleast for non climate controled equiptment
Man, we had 3 super cloudy days up here and the battery is so down. Luckily I had all the others charged to 60-70% so can now use that stored sunshine. The battery shelf is not enough for my energy hunger.
Because of the higher internal resistance more of the capacity is converted to heat, so with higher C rates the useable capacity drops depending on that internal resistance values. Your 45° measurement is an evidence for that. The "missing" capacity warms up your rainy day ;)
(greetings from Austria)
That's why I was sweating a lot!😄
Thanks for the insight testing the sodium batteries Andy! LiFePo4 really is kinda magical in that nice flat discharge curve. Provides nice stable voltage thru almost the entire capacity. Loving mine so far! (1 100Ah rack battery on a cart and a 12.8v 304ah one in the garage) Again thanks for all your work, it's nice to see someone else as entertained with and geeking out on the graphs data like I am! The wife could care less....until the power goes out....
Thanks a lot for your feedback and kind words, Chris.
I was so excited when I first heard of these. I quickly changed my mind when I got my hands on a data sheet last year.
LiFePo4's super flat curve is just hard to beat.
@@ChrisEpler agreed.
Can someone explain to me?
Is it because the voltage drop increases the amps flow when discharging with a steady wattage?
So when the soc goes down we could potentially over discharge the max C rate?
I am not sure what the disadvantages are besides the heat.
(Did I fall asleep during the video?)
@@camielkottethe disadvantage is the battery performs worse as you increase the rate of discharge. They do fine at 0.5C or less but get exponentially worse at 1C.
I don’t know the cost of these batteries but if they are low cost they are best used in low amp requirements. In that scenario they excel (if inexpensive)
@@mikebalentine thx.
Congrats on 80K+ subscribers!
Thanks for the vid! Best testing ive seen for sodium batteries.
Very nice information on Sodium Battery C rating test. Fantastic!
Thank you very much!
Hi Andy
I have a comment unrelated to this videos content,
I am new to the channel and looking at all your older videos, I strongly recommend getting yourself a set of 1000V electrical screw drivers.
Safety for just in case
I am thoroughly enjoying all videos
Gavin 😁
Thanks Gavin and welcome to the channel.
Thanks Andy- great job, love your work, and as always, very educational 👍👍
(I don’t think I’ll be switching to Sodium batteries any time soon.)
Stay charged!
Thanks, Dave. Nah, nobody will change to sodium for a very long time...
From those curves you can easily calculate the DCir for the cell at the various SoC's and temperatures. Then you can apply a terminal voltage correction based on that DCir to "see" an approximation of the electropotential of the cell at its current chemical state 🙂
One nice test for DCir is to write a little scripted function that does a pulse discharge followed by a pulse charge at the same current and for the same duration, so the overal SoC is not changed. If you run that test at say 0.1v steps through the discharge from the response you can calculate both the DCir and ACir as well, and even build a model of the cell from that data which becomes very useful in terms of any openloop corrections for a BMS system etc
Good ol' battery testing! You can't beat a good graph. It's amazing how plotting something into a picture on a computer screen can really tell a good story. Excellent information Andy! Have you discuss the results with Andy 2?
There is now a version 0.7 for the Seplos V3 bms. This update fixes a big calculation and display problem for SOC.
While they were at around 60% SOC, the bms displayed 98.5% and remained at this value until a cell passed the UVP. In addition, the SOC display increased or decreased twice as much as in reality.
We made, with Cyrille from the UA-cam channel "Lemoult'e Batteries", a request for rectification to Seplos, and they have just released the new firmware
Yes, thank you. I'm in contact with Cyrille.
I tested as well with 0.5 and 0.6 and could not see any jumping in SOC. But the V3.0 has lots of other issues. All around it's not a great BMS and even worse is the software.
Brilliant test.
Thank you.
Hej Andy
Thanks for great test.
The difference in energy is actually around 15%. 614 wh out of 4090 wh. This because of greater difference in voltage-curve with greater C-rate, than LiFePo4.
Best regards Brian
True The energy is about 13% less but the curve is considerably less flat so in real world the inverter cutoff is 30% sooner. Also discharge for Na+ is .5C up to 113f rather than lithium 1C up to 150f. Further testing in real world conditions is needed. Lithium costs considerably more and I haven't seen Na+ to be considerably less yet.
Thanks again Andy
No problem, thank you.
Morning Andy, send some of that rain down here. I need to order 2 of the Peters soon.
Raining again, battery was down to 14% this morning...
thank you for the peter comparison
one of the problems to take into account is the problem of intensity. If you have a fixed load of 10W, at 3.8V you will have a discharge current of 2.63A, but arriving at 1.8V for the same load, the current will be 5.55A, which will make the discharge will be outside the datasheet parameters
Yes, correct. We are pretty spoiled with our LiFePO4 chemistry.
(change in voltage) divided by (change in current) = internal resistance of the cell
(3.65V - 3.35V) / (3.90A - 0.26A) = 0.082 Ohm
Great test, thanks! Next up could be bigger, prismatic cells (if they're available...?) and also puncture and other mishandling tests like overcharging etc!
As discussed in the last video... 😉
Дякую, дідо, цікава інформація.
thanks again for this interesting content. Regarding sodium batteries, their biggest advantage is also their biggest weakness. The large voltage difference between a charged and discharged battery gives a great opportunity to relatively accurately measure capacity as a function of voltage, but at the same time it can be difficult for regulators and inverters to deal with such a large voltage difference. So, if sodium batteries are not significantly more affordable in the future, there will not be much reason to switch to this chemistry. The advantage of being able to charge at low temperatures is already quite easy to solve for lithium cells today.
you could make a weird battery that changes the interal connection from parallel to series between the sub modules to bump the voltage up (when switching from parallel to series) this way you could keep the voltage stable :)
If sodium batteries are really cheap, it could be possible to let them only go down to 20-30% or so. In return Lifecycle is longer...
Yep, that's what we discussed in the last video.
The sodium battery maybe a good backup for below 0°C (32°F) or for use in low demand times, but they really need to be way cheaper than lifepo4 to replace them in my view. I could see if they do get a 1/3 the cost to consider them or as a hybred system for sub freezing weather. That flat discharge voltage, cycle life, safety of lifepo4 is hard to beat.
I believe that idea around Sodium batteries is to be "cheap" (when production/demand volume goes up) and more eco friendly . By all means LiFePO4 are , in my opinion , for the price , the best storage solution at this time , but Sodium batteries have great potential (when price goes down and people start producing them locally) and those aren't "unsafe" (I saw the nail test videos - no flames and not much of explosion - more like a "burst" ). 3C constant discharge rate is pretty nice , even though the battery packs are never designed to perform all the time at max discharge rate and the number of cycles is , also , very good. It is , still (relatively) early days , so , given a couple of years , we may see the improvements (in terms of performance and much lower price) and hardware to catch up.
maybe it will be a hybrid system with both in advantage.
Charge and discharge is only 0.2C below freezing point, so not THAT great either.
It'll keep your Ham radio going!@@OffGridGarageAustralia
Thanks Andy!
Any time!
I've got them in my scooter and they're great. Fast charge time -40/50 minutes-. No more 8 hours or 4 hours charge time. Pretty good in 2 years time.
I think Kevin also knew the answer to the 1C question ;-)
eyeglasses changed at 6:03... Hey, the video is so much easier to watch!
9:03 the suspense is killing me - the show must go on! 😁 Nice guy
I do this to confuse people and get more comments about my glasses 😄
Great info Andy. The moral of the story is, will your inverter be happy with the discharge range and don’t think about paralleling Lifepo4 with sodium.
No and No is my answer😉
Thanks Andy
Thank you, Wayne!
Inverter makers have to figure out how to use such voltages differnces. DC to DC converter then inverter? Andy thanks for your job.
Yes, as we discussed int he last video. The huge voltage delta is a challenge!
thanks Andy
Thank you!
You deserve a pay raise //// salt batteries not so good. I am still waiting for a pepper ion battery 🙂
Love to see some tests of lithium titanate cells.
I have some here, but why would we use them? With solar, we don't use high c-ratings and they are a lot more expensive than LiFePO4.
Just for the sake of testing... OK🤷♂️
@@OffGridGarageAustralia I build electric mopeds, bikes, but I still love your channel, the bms reviews have helped me a lot. I plan to do solar one day. I love LTO, for solar the high c rate is not needed I agree, but having cells that will never need replacing is a positive, and even safer than lifepo4.
@@toriwatson9655 Yes, perfect for that matter. The high C-rate is exactly what you need for that type of application.
LTO have a lifespan of 10yrs so are not infinite...
The downside is LTO is bulky, so for mobile uses you need quite a bit of battery space to get good range, and as you say they are expensive. Cycle life should be around 20,000 cycles, in fact the Zenaji Aeon batteries have a warranty for 22,000 cycles, so I would have thought well over a 10 year lifespan. @@OffGridGarageAustralia
At each section of this graph 0 - 137 - 274 - 411 - etc. we have equal mAh but different ammout of energy in the cell, because of different voltage at start and end of each section, so e.g. first section has / 3.94 + 3.65 / === 7.59, 7.59 / 2 === 3.795, 3.795 x 137 === 519.9 Wh of energy, but from 412 - 549 we have / 3.35 + 3.17 / === 6.52, 6.52 / 2 === 3..26, 3.26 x 137 === 446.6 Wh of energy. A lot of BMSs and system for SOC reporting, reports SOC % for mAh or Ah, but this is not equal to SOC % ENERGY. Becuase integral function under voltage curve is different for equal Ah ranges 0 - 10 - 20 - 30 -- etc.
Thanks Andy. Great testing to set the base of the current state technologie. Im curious how the new versions with the higher 200Wh/kg will turn out.
Thanks so much for your support. Much appreciated!
U. R. the man!
Great work!
I would like to know the expected lifespan (number of cycles) and the cost per discharge cycle
Excellent Andy! exactly the comparison test I was hoping for, thank you. Have you considered of doing any life-cycle capacity tests on your little sodium Ion friends, maybe 300 cycles at 1C?
Btw, I've been looking into the sustainability of Lithium in meeting projected demands and some estimates by the World Economic Forum claimed 700 years of lithium mining at current rates would be required to meet projected demand over the next 12 to 20 years for lithium batteries, or by my estimate a 100X increase in lithium mining, so it would seem that alternative sustainable chemistries are essential, and your test Andy is a telling preliminary insight into one possible chemistry.
Perhaps Sodium ion battery chemistry used in stationary power systems, could free-up lithium for mobile batteries?
Also, some promising results using AI to invent new battery chemistries promises to reduce invention and development time of new batteries from 20 years to 80 hours.
Very hard to do long term tests as it occupies the equipment and the computer would need to run for that time too. I'll consider it maybe later when we are done with all the sodium testing.
Not sure where the 700yrs number comes from but there is other information out there that we need only to mine for 20yrs if we have a good recycling program for lithium set up...
I don't see sodium batteries become a viable solution in the near future.
You gotta remember these are pretty much first generation production sodium batteries... and that they should be able to apply many similar technologies as they adapt them from Lion to get performance and specs up.... old lithium ION batteries weren't as good as they are today when they came out either.
super interesting thanks lot
Thank you.
Thanks!
Thank you.
Bells Beer =) keep it up brother =)
Cheers!
Great test, thanks!
Do you have measurement results of the internal resistance of the battery?
I would be interested in whether it could be operated in parallel with a LiFePO4 + Sodium battery? There is an overlap in the range 3.6>2.8V. It would be an interesting experiment!
it's so weird that it rained here today too (Uruguay), this makes it feel like the whole southern hemisfere was rainy. (even if we really are just talking abour a few sq km area really)
for me the main thing is that sodium batteries have the capacity to be so much cheaper than lithium ones. its as common as sea salt.
Raining here in Hampton Roads Virginia (Chesapeake) also. 😂
Even if they were cheaper, you would need more of them to match the capacity of lithium. So, more space to store and connect them.
Heya, oke 1 plus point they have you can tell the SOC of these batteries by looking at the voltisch
Very nice testing but would like to see it compared to AGM battery ?
QUESTION
It's a great video showing the discharge curves of the sodium battery C-Rating.
The only question in my mind is, was there any degradation to the cell.
Would you get the same results if you repeated the tests again?
I have cycled this battery cell for 40+ times now and still get the same results. If we cycle it 1000 times maybe...
Hallo Andy, danke für das Video. Mich würden noch die Ruhespannungen bei verschiedenen Ladezuständen interessieren. Viele Grüße aus DE.
OK, thanks for your suggestion.
Well regarding Ri, IT seems this chemistry is Not for Inverter... IT IS more for DC/DC bucket converter.
When i calculate a Bit, IT Points Out that one cell has Ri=0,1 Ohm and this is the rootcause why voltage IS dropping in end of charging and start of discharging.
IT means you have to Take down the current, otherwise you do not hit 3.95 in real.
👍👍👍
Please make test for the leoch pure lead carbon battery
Hi - just a thought..... because you are drawing far more current through your test set up cables, could that contribute to the voltage drop? (perhaps run 1 more test where you double up the thickness of the wires? (obviously, ou cant change the thickness of the cables within the tester itself - but at least reduce the length of the cabling???)
The EBC-A20 uses 4 wire measurement, so current does not matter. We would have the same result with 20m long wires. I'll show this in a video soon😉
Wouldn't E-rate in watts be more relevant than C-rate in amps for a battery chemistry that has such a wide voltage range? At 3C the battery is providing 15.41W at full and at near empty it's only providing 5.85W. What happens if I drain the battery down at a constant energy of 10W? Would I have to stop discharging at 2.56V to avoid cell damage? Doesn't the C-rate vary drastically with a constant energy throughout the discharge cycle?
I apologize in advance if what I am saying is misinformed. :)
C-rates is what batteries are tested with to make them all comparable.
Watts are not great as they contain the voltage, which sodium batteries show a very high delta of.
C-rates and Ah use only the current and are far better to compare.
you have to calculate your application, so that it will work in every condition. you have to make sure, that your battery can deliver enough power at the lowest SOC you will allow. In your example you have to set your discharge voltage to 2,56V or you have to use bigger cells or 2 or more in parallel.
If you want to compare different chemistries, or differently organized batteries than you will go for Wh than for Ah. Ah is only suitable for single cell with the same chemistry. But even there could be diffences in the voltages over time and then Ah isn't accurate anymore. But Ah is easier and Ok enough for tests with a single cell.
For the sake of cycle life, would you recommend setting low voltage cutoff at the plateau? What state of charge does that plateau occur? These discharge curves look very much like Ni-Zn, though with just over twice the voltage.
Another question is whether charging to a lower target voltage such as 3.70V fully charges the sodium battery, or do you have to push it up to 3.95V to fully charge it?
This will be in the next video!
❤❤❤
Thank you.
So, what would be the use case for sodium batteries? Inverters don’t like the 50% voltage drop over the discharge curve.
I know my BLDC motor controller doesn’t like that either.
What about for small solar light applications, where output can run through a joule-thief circuit? If these cells don’t mind draining very far down, then I could see their use there. Or perhaps in power banks.
Or emergency lighting?
Where do you see their specs as an asset instead of something to be worked around?
Inverters and associated equipment will need to be redesigned for the new discharge/charge curve to be useful..
you could make a weird battery bank that changes internal connection from parallel to series to bump the voltage
@@faustinpippin9208 that’s just working around the problem. There are better suited chemistries for those situations. I am wondering where these batteries naturally make sense. Engineering around the problem is just money and effort best put towards a solution that doesn’t require that money and effort.
@@somebody1869 that workaround will solve the problem and will still end up being cheaper then other chemistries in many situations....and to meet the gov goals we will need all the batteries we can get and we still wont have enough, so this sodium stuff will be used in a lot of places despite the atrocious voltage drop
Why not for inverters, if you only use the batteries above 20 or 30% SOC. Depends on price, finally you get more life-cycle. After all, lead batteries allowed also using only 50%...
hello is it possible to parellel LIFEPO4 pack and Lithium iron NMC battery pack together with solar inverter?
I think that low temperature operation is a big plus, everything else being equal. Sodiuum can be sourced everywhere and is not subject to geopolitical forces.
So Andy, What would you say the Power Density of Na+ battery versus LFP battery? So if you built a battery Bank such as Seplos what would the KWHr capacity be versus the LFP Seplos Battery Bank capacity??
It seems that 210 ah prismatic is about equal to 280 ah lfp by size and weight
You would need a lot more space, that's for sure. We can use only a portion of the available capacity of sodium cells with our inverters so, atm it makes no sense to build any batteries with these cells.
I like the curves :-) from the Sodium batteries cause you can estimate the SOC much better. Next time please compere the same rates for both batterys chemicals, the lifepo4 was only testet with 1C max and the chart was much smaler. 9% less with 3C discharge is a prity good value.
Seems to be very little voltage sag still at 3C, would've been interesting to see peak discharge tested, it could've likely done a lot more.
Can you Discharge them with constant watts instead of constant amps? I think you will see they do have a knee a very steep one. As the voltage drops the amps will rise, at the point of intersection of the two graphs I think they will perform badly and possibly heat up incredibly
Liquid Sunshine, Andy. It still makes Power.
Looks promising. What's the current price of a sodium cell ?
Lto vs sodium vs lifepo4 please. Specially very cold cell and sub optimal solar yield
LTO is not great for solar storage. Super expensive and we would not benefit from the high C rating they can do at all. Pretty much wasted money for solar applications.
Interesting. Not just capacity, but the watt-hours will be even worse due to the larger voltage drop. Hard to see the 1C difference in voltage drop but it does look larger than for 1C LiFePO4. That wasn't a complete capacity test though, it the tester stopped earlier because of the voltage drop but there was probably still energy in the cell.
We need round-trip efficiency numbers for 0.2C too (watt-hours-out / watt-hours-in). Tried to look that up but I only see the 0.5C tests in the Test2 zip download. Oh, under Test2_C-Rating ... only the 0.2C discharge curve though, I couldn't find a 0.2C charge curve to check mWh against.
Color bars at 14:24 aren't right. It's showing green as 1.0C but that's the best curve, not the worst curve.
EDIT: Add.
4165mWh for 0.5C charge curve, 4090mWh for 0.2C discharge curve. 98.2% round-trip efficiency (so 0.2C charge curve would almost certainly be at least a bit better). That isn't bad at all.
Then 1C discharge curve, 3729mWh ... 89.5% round-trip (vs 0.5C charge curve). Pretty horrid. Same for 3C discharge curve, 3476mWh... 83.5% round-trip. Yuch. But that isn't counting energy left in the cell after the tester stops.
-Matt
Thanks Matt, all curves and data is in the folder. Even the 0.2C test...
How different is it to charge these batteries from the LiFEPO4 batteries, I'm just wondering if you have a BMS that supports LiFePO4 can you use it for the sodium batteries or do you need a new BMS
I was doing some reading about Graphene and I stumbled on battery chemistry of Hemp and Lithium I think. As a starting or surge battery. Have you heard of this and what's your opinion?
No I haven't heard about it. There are sooooo many battery chemistries out there and only 0.001% are making it into some sort of production. Even less are available on the market.
My personal opinion after testing these hyped sodium batteries: LFP will stay for a very long time.
@@OffGridGarageAustralia cool, please check out the hemp batteries. I'd like to here you report on the chemistry. Very curious from a knowledgeable person opinion.
That's worth a beer even if I don't care for those ole salty batteries. Prolly rust your terminals off. :)
I can see these being useful in a low power setting using a boost buck converter to stabilise the output voltage to the load but the voltage swing is too great to be used directly in a 12/24/48v system
Yeah, that would technically work, but the energy density is still lower than with lithium, so makes no sense using sodium batteries atm.
@@OffGridGarageAustralia I’ll be sticking to my lifepo4 cells for the foreseeable future. Built my first battery over 2 years ago after watching your channel and learning a lot from yourself. Thank you 🙏🏼
What software and probe are you using for your graphs?
Shown here in this past video: ua-cam.com/video/bx7Df_nbv0A/v-deo.html
16:07 Can Andy or anyone explain to me why anyone would care about capacity in amp-hours and not kilowatt-hours? Those results then come out completely different, e.g. at 3C the usable capacity in kilowatt hours is only 85% as opposed to 92% in amp-hours. But I wonder why I should care about ampere-hours? Thanks for the clarification!
We use Ah and C-rating because it only contains the current only (constant current) and not the voltage. Voltage changes all the time, so makes no sense to use it in such test. Hence, all batteries have Ah stated and not Wh.
@@OffGridGarageAustralia I would just expect that just because the voltage is changing, only the capacity in kWh is important because that is what plays a role in real life operation of a solar inverter...
Most consumers aren't going to notice the difference unless the life expectancy is much different. Self discharge can be a bigger issue. Will my flashlight work as intended, when I need it?
looks like a good buffer storrage, i mean, if you build for example a 100Ah Batttery, with 10% Lifepo4 at beginning, and the end of SOC, lol?
can the cells be mixed with lifepo? serious question
They cannot be mixed, no. Due to the flat voltage curves of LiFePO4, we would use only a small amount of the sodium capacity. From 2.5V to 3.65V if we max out LFP. Mor realistic it would be between 3.0V to 3.45V only.
Hello. Can do a 30days continuous 3C charge/discharge with a DIY heat cooling on 1 cell ? :)
That means ~1000 cycles.
obviously the voltage sag of the load affects the total ah that can be extracted from the battery , i would love to see a test of 3c discharge from full to close to shutdown voltage and just before shutdown happens or lets say 10% from empty reduce the load to 0.2 c and then see ah extracted from battery compared to 0.2c
as we can see the battery jumps back up to 1.8v the moment the load dissapears
ie a test like we tend to use our batteries in our phones , happy go lucky but the moment it gets closer to empty we tend to conserve
in other words is the sag on high load causing us to get the wrong puicture of efficiency
All these tests are done with constant current though. If we change the current during testing, what can we compare the result to?
There is no capacity under 2V in these sodium cells. I'll show this in the next test video.
@@OffGridGarageAustralia ok after doing the high drain test and once it shuts down, do a 0.1/0.2c to see how many AH is extracted until a low voltage shutdown
This is more a curiosity
I don't think there is much to extract
Just curious how much the sag affects the efficiency %
Example the axpert type inverters will do different low voltage shutdown voltages dependant on load to compensate for sag(naturally this is designed for lead acid only happens on the gel/flooded profiles not USE)
On a big cell the difference may be negligible
since the test is done on a small cell , .that tiny bit may affect the % more
Interesting test, suggestion since the battery voltage varies so much would not a constant power load test be more useful? The curve would look much flatter the a rapid drop off. Say 1.5V x 3.9A = 5.85W constant power. It would be easy to design a DC/DC converter to supply a constant voltage.
The ZKEtech testers can only do constant current or constant voltage (at least, that's the case for the 40A one, and it uses the same software).
@@davidpenfold
To test battery's I use my Rigol electronic load, it can do constant V,I,R,P it's limited to 150Vdc, 40A, 200W, it has a battery test function.
@@universeisundernoobligatio3283 That sounds rather good, but I'm not buying another tester!
Both ZKE testers also can do a constant load test.
But all batteries are tested with constant current. Including the voltage makes no sense as it changes all the time.
@@OffGridGarageAustralia
But small battery loads will/can be constant power, with a DC/DC converter creating a constant load voltage, the discharge curve will be much different. These batteries will suit that application easily.
What are watt-hours when charging, and what are watt-hours when discharging?
Depends on the voltage. Hence, we use constant current.
The reason I ask is that watt-hours charging and watt-hours discharging give efficiency to the battery. And what would a typical efficiency be?@@OffGridGarageAustralia
how can i read cycle count in lifepo4 battery.?
What do you mean by 'read cycle count'?
Does this mean you wouldn't need a shunt to know the SOC for sodium-ion batteries?
sodium power 💪💪💪💪
Well, I don't know if they are THAT great!
New chemistrys takes a long time to replace the older ones. And not for technical but bussines matters.
Here, more for technical reasons than ever. Sodium seems to be far worse than LiFePO4. I cannot see it replacing lithium for a very long time.
You seem to know alot about battery.
I have a 12.8 volt 50amh LifePo4 and its going to be connected to a 1500 inverter.
The ebike charger is 54.7 volt ,will the ebike charger damage the LifePo4 battery?
Why is my inverter beeping, lol. Thanks for the testing. LFP is still king. For the time being.
LFP will stay for a long time. Sodium will be for special applications maybe. Not sure which ones though😄
This data is quite interesting. If I define the lower end of usable power as 2.6V (10.4 V for a 4S battery), the different C rates give very different usable capacities:
0.2C - 78%
0.5C - 73%
1C - 66%
3C - 55%
These results are rather negative considering that sodium batteries have been touted as a cheaper, easier to source materials, replacement for Lithium ion and lithium iron phosphate batteries. Based on these results and energy density data it looks like sodium batteries will have to be considerably larger and heavier than lithium batteries. That isn't much of a problem for stationery batteries such as in a backup power system, but is a real issue for use of sodium batteries in EVs. They may be an option for short range, low speed EVs, but not much else.
If they end up a lot less expensive they do become viable for storage with existing battery inverters.
I don't think anyone in their right mind would consider using this chemistry for an EV
@@pavelsulc2617 If they end up a quarter of the price of LiFePO4 then you could easily just use 3.9 to 2.5V for about 60% capacity and still be ahead. For storage only, I'd imagine, but that could be a huge potential market for inexpensive peak load injection etc.
@@pavelsulc2617 I have read that the first EVs with sodium batteries are coming out already in China via a VW-Chinese joint venture.
Even if they would be cheaper, you end up needing more to compensate for the capacity you cannot use. Space is a HUGE factor for EV batteries. LiFePO4 will stay for a very long time and sodium will NOT replace them. That's my take.
hello here, I've been looking for your email for a long time but I can't find it, I'm in Greece and I'm looking for some spare parts for solar panels like noark and I can't find them in Europe and I would like your help
Plot power and energy. that's what matters from an economic point of view. Note the slope on the voltage curve means you don't have to top balance.
All batteries are tested with constant current for C-rating. Voltage changes too much with sodium batteries...
@@OffGridGarageAustralia That's my point. It's good to plot voltage vs state of charge. But what's important (in my opinion is energy. Imagine two batteries. One was constant voltage in constant current discharge and the other dropped linearly. The second batter would have half the energy storage capability. Keep up the good work.
It should be easier to balance the sodium batteries.
if you get a better cycle duty
with using a 10% margin
it actually evens out
I was hopeful for sodium batteries, but the wide voltage range is a no-go for me. I'll be leaving so many amphours on the table by the time I hit the lowest voltage my inverter can run on. I may get a low amphour battery to use in an emergency situation such as sub zero temps.
Yes, so far it still seems that it is better to take care of the temperature comfort of LiFePo batteries than to use sodium ones because of the temperature. Because price is definitely not the reason at the moment.
@pavelsulc2617 at the moment correct but I can see this becoming cheaper as the manufacturing process gets better as sodium is more available
Look at the specs of these cells. below freezing point, it's only a 0.2C charge and discharge, so not great if you need power.
Secondly, even if prices would come down, due to the fact that you cannot use its full capacity, you would need to purchase even more sodium batteries to match LiFePO4 capacity. That also means more storage space for sodium batteries.
digeree doo in the fan motor lol
Hahaha, yeah...
I can't say if those sodium batteries are good, if you think about a 16s battery whose terminal voltage fluctuates a lot with the load.
And, for example, which inverter can use such an enormously wide voltage range without interference. (example 48V system and battey voltage fluctuates 24V-63V NOT GOOD!)
In my opinion lifepo is much better because of the flat voltage curve. The devices survive more easily when the pole voltage does not drift over wide area, and remain almost constant throughout the capacity range.
Yeah, that's what we discussed in the last video: ua-cam.com/video/H5iTZ_0WT9w/v-deo.html
Wow that's a wide voltage range
As we have seen in the last video 😉
So what’s the price of salt 🧂 compared with a battery 🔋?
Look it up and tell us what you found. Helps me out and save me time.
If you measure Capacity in Wh you will See also differnences with LFP
Energy, energy .... , Watt-Hour.., Inverters with a constant load see this. Voltage is very elastic.
These curves resemble Lead acid batteries more than LFP or li-ion.
Which has upsides and downsides. Most importantly the amps go up when the batteries are going empty and the load is the same.
But the upside is I think, no need to balance!
That will save a lot of money on hardware.
Balancers are not expensive though (in comparison to other equipment and devices you would buy for a solar battery system). We will get to that point in one of the next videos 😉
@@OffGridGarageAustralia That sounds like a matter of opinion. One good(ish) 16s 200A BMS costs about 200 to 300 euros. For that money you can also get 3 or 4 Grade A 280Ah cells. Let's agree on "significant".
You should get a few LTO, Lithium titanate batteries to play with
I have 6 here. But they are not good for solar applications where we have low C rates. Far too expensive for that.
I wonder what would happen if you lowered the discharge rate before the steep drop in voltage.
- Is the high discharge rate causing losses (heat) or is it mostly a matter of the test cutting off prematurely because of the lower voltage so the remaining capacity can not be used?
It would also be nice to see a discharge test with the cell in a SPAT cooler as LFP typically does not work well at something like 0 degrees celcius and loses about 17% of it's usable capacity if I read the EVE specs right.
-This would be a realistic scenario for those of us that don't want to waste energy heating the outside mancave.
These tests are always conducted with constant currents. If you are lowering the current during testing, we cannot compare the results to other battery chemistries anymore.
A proper climate chamber costs A$5k+. I have tried using ice and coolers, but results are too inconsistent as the temperature is not constant.
@@OffGridGarageAustralia I understand there are standards for testing, but it would be nice to see if there is some way to get more out of these cells by lowering the current in the lower SoC. 3C seems like a lot for continous use but is very nice for peak loads like cooking.
Maybe the low temperature tests are a bit unrealistic in a small fridge as the batteries themselves will change the temperature, even more so at high charge/discharge rates. Maybe someone in a colder climate with the right equipment and experience can do this?
So what are my chances on my ebike?
too bad the voltage range is so wide. otherwise it would be great for rv use in north america during colder weather. would be interesting charging and discharging within lifepo4 voltage range and see what the capacity might be.
Even during colder weather, you can only charge and discharge with 0.2C. Is that still an advantage to lithium? Yes, but a very small one. Would you swap lithium for sodium? Certainly not...
@@OffGridGarageAustralia and in the case of more cold resistant electric car(I live in the canadian praries), not going to cut it at .2c And we would need something -30 capable atleast for non climate controled equiptment
In Melbourne we need more sun, night time should be reserved for rain and clouds.
Man, we had 3 super cloudy days up here and the battery is so down. Luckily I had all the others charged to 60-70% so can now use that stored sunshine.
The battery shelf is not enough for my energy hunger.