Homemade Electric Buggy, Ep 5: Lithium Battery Build - LiFePO4
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- Опубліковано 6 вер 2024
- Homemade Electric Buggy, Ep 5: Lithium Battery Build - LiFePO4
In this video I make the LiFePO4 battery modules for my homemade electric buggy and seal them in custom ABS plastic cases that I made with the new vacuum former that I built last month. Check out the module build article for more details about the cells and other components that I used, how I used them and why: www.resystech....
Vacuum former build video:
• Vacuum Former Build - ...
Electric crosskart build series:
• Electric Crosskart
Electric motorbike build:
• Build An Electric Moto...
RST website: www.resystech.com
Follow RST on Facebook:
/ renewablesystemstechno...
That quality is amazing. Out of interest, what amperage are those cells rated at? Is that the reason you went with a pack like that instead of the 100Ah or 275Ah prismatic cells?
edit: Oh, I'm reading your article, so that's a 3C rating. Not bad.
Another thing: Your top cells in each pack will take a little more of the surge current because of the resistance in the wires. I'm sure that won't be a huge issue because these LiFePO4 cells are bulletproof, so that probably won't even matter. Looking forward to the rest of this build.
Thanks. At low current (
I stopped halfway through building them and gave it more thought. I'm moving the neg cables to the bottom of the packs. I'd rather get an extra year or two out of the battery vs save a couple hundred $ on cable. I'll upload a short video showing the change later.
@@JamesBiggar Ahh thats good to know, i posted a comment about that uneven discharge. At high currents even thick copper can show a voltage drop across it.
Here's a post showing the change: ua-cam.com/users/postUgkxVihf18rPzcCzkJKhcvgAfNz-ZPvfOvBP
@@JamesBiggar Great stuff. I think having better info out there for others to use is worth it, even though it's unlikely you'd have had issues. I would be interested to see what voltage droop you get in a single battery pack bus from top to bottom if you leave a pack open for testing (You could solder in some sense wires to each side instead if you prefer).
This is so professional it hurts . Well done
Hi folks! In this video I make the battery modules for the electric crosskart and seal them in custom ABS plastic cases that I made with the new vacuum former that I built last month. Check out the module build article for more details about the parts I used, how I used them and why:
www.resystech.com/project-blog/how-i-made-sealed-lithium-battery-modules
Vacuum former build video:
ua-cam.com/video/hdH8LSn1va8/v-deo.html
Electric crosskart build series:
ua-cam.com/play/PLdO3Wk-XPC_BYIyKzLDE410YO1IWXkHCI.html
RST website: www.resystech.com
Follow RST on Facebook:
facebook.com/RenewableSystemsTechnology
hey, great projects. love them. can you please tell more about where did you buy batteries and they are of which brand? will be very helpful. thanks in advance.
the neatness of your work is extreme, I congratulate you, you are not a technician, you are a craftsman
Great work. You set an awesome example of excellence in manufacturing quality!
I desperately need someone like Batteryhookup but in Europe.
Agree! Anyone know about a good reseller in Europe?
Totally agree!
Nkon is the biggest i know
Expensive though.
They ship to Australia, so maybe to Europe also.
Very nice work! Keep inspiring!! Use this as the "Please build your own electric car button"
you've mastered many arts!
Excellent job on the pos. Neg.
Dude this is super awesome! I built an electric tractor and this looks like a great way to upgrade the batteries in it.
I was waiting for this episode I just won a bet you you would make your own battery cell for the buggy 🤣👍🏾👍🏾
My guy even makes his own battery packs, amazing work dude
Thanks man.
@@JamesBiggar iv been in total amazement every episode with your fabrication skills, you have a talent pal, I would be shocked if no one has asked to buy one of your chassis. Keep working respect from🇬🇧💯🙏
Gustan mucho tus videos, vale la pena esperar tanto para ver el proceso que llevas, da gusto el canal❤️⭐⭐⭐⭐⭐🎉
This work is amazing, I'm feel lucky to find this guy 👏🏻
You are a perfectionist, that is for sure. Amazing work - the buggy is Pro.
YES!!!! Was dying for this video to be released!
I should have bought more of those 32650’s while battery hookup had them… such a great buy.
BH got theirs here: www.alibaba.com/product-detail/3-2v-lifepo4-32650-6000mah-battery_1600204982827.html
Same cells. They do custom wraps. I'm getting some for the enduro bike build (coming up after the current e-moto build). I got the very last of BH's stock a couple months ago, but they didn't have enough to fill the order and said they probably won't be getting more. I'm not sure why because they agreed with me when I told them that they're great cells. All tested with higher capacity than they're rated for. I have 0 complaints.
@@JamesBiggar I KNEW I remembered someone giving me the link to these, and I FINALLY FOUND IT!!! Thank you for the link!
amazing work! can't wait to see this thing riding.
on the battery packs. i understand that they need to to be watter resistant but, you might want to think about a venting solution. if any of those batteries wants to vent (electrolyte goes crazy and wants to burst out of the battery), well the other batteries might want to go along and a sealed case is not a good place for them to be. things tend to go boom when that happens. what i've seen done in these cases is, they add vent holes and a thin membrane behind it, with spiky things in between. if the batteries want to vent, the pressure will push the membrane against the spiky things and break, letting the pressure out. but it wont let watter in if the membrane is intact. silicone membrane would be easy to make i guess.
This lifepo4 batteries not pb acid, absolutelly no vents needed
thank you for sharing. i like the way you connect the backbone style to the battery block.👍👍👍👍
Im sooo damn impressed in the detail and tech of this build. RESPECT
Extra marks for abs moulding 👍👍👍👍👍
Great job and I can't wait for part 6 ♥
You should get a patent invention /or/ invention patent 😂🔥
Oh man, the sexyness. If the final specs are 12.8v 30ah, per module - so much versatility to use for 12v appliances as well!!
Max voltage possible is actually only 6.5V, and 60ah with the cables connected in series, given that two rows of cells are paralleled together per cable. If each row had its own bus cable, then they could all be series connected for 12.8V and 30 ah. I'm paralleling the cables for 3.2V and 120ah, and connecting 32 of these modules in series, balanced with a Daly bms. Nominal voltage of the battery when the modules are finally wired up together in the kart will be 102V, for a total ~12.5 kWh.
@@JamesBiggar thanks for replying, looking forward to your next update!
@@JamesBiggar This isn't just going to be able to rip, it's going to be able to rip all day with 12.5 KWH...Awesome....
A couple hundred km at least, hopefully lol
Sir you are really very genius, Lots of love from India, Westbangal Darjeeling district
I'm no genius but thanks for watching!
Wow very professional looks like thos were made in a factory I like how clean a professional everything you do is everything you make looks very high quality I love it and very clever Idea with the vacuum chamber to form the plastic case for the battery's I want to see that on the interior maybe fir the dashboard ?
thanks for sharing this stuff bud, amazing work.
You're welcome!
a master at work
Absolutely love everything about this build! You forethought is clearly well done! as someone who has worked avionics for for long time, it is refreshing to see your attention to detail.
It may help you with your vac former to increase the diameter of your hose, the larger you can go, the better, if that surge tank is 3/4npt, you might plumb it with 3/4 pex, you would see a massive increase in detail. Also, adding another ball valve ahead of the tank attached to your air compressor would help you remove your parts easily.
You can sink two screws through your platten into the buck. A light dusting of baby powder and you will be able to pop them off with nothing but a blast of air. If you want speed up cycles, a fan on a switch will save you a lot of time too. Cycle time may not really be a factor for you and you obviously don't need the help, but i learned a lot from your videos and felt compelled to return something that is hopefully of value.
Look forward to your next upload!
Thanks for the tips!
Que canal sensacional! Que trabalho bem feito! Como a plataforma não me indicou esse canal antes!? Acaba de ganhar mais um inscrito aqui do Brasil!
Nice Clean Work..
Dang I knew that vacuum would be use on the project
Hi, I am a young person who thinks this stuff is very interesting. The ABS vacuum process you went through seemed very laborious and extreme. Is it superior to just 3d printing the part?
Sorry if its a rude assumption to make, but my guess is that the technology has a bad rep and you haven't bothered to work with it yet because what you have works. I recently taught one of the older engineering volunteers at my school about 3d printing and reccomended a small printer and he already knows more about it than I do. He used to work on ABS injection molding, so he uses those skills to make ABS prints work properly, with better results than I ever have had.
I have 4 printers - 2 Enders, a Qidi XMax 3, and an FLSun Super Racer. I love them and use them when I think it's appropriate. You could print the enclosures as I'm doing with the current e-moto build, but the vacuum former is actually a lot quicker when you've got 32 modules to make, and the result is a waterproof case. I have a vacuum former, so I used that. Takes less than 2 minutes to form, and another 10 minutes to assemble with cement. A 3d printed enclosure of the same size would take a day or two to print with a typical desktop printer and would require further treatment to match waterproofing, since these were used in an off road buggy where water exposure/submersion is inevitable. That's 1400-2800 minutes, per module. Yes, having a robot do the work frees a person up to do other work, but that doesn't necessarily mean you're being more productive if the job is taking 144 times longer than it would if you did it old school. I would need a lot more printers to make up the difference. Print farms do exist and are profitable, but not for a one-off battery like this, and most mass production of enclosures like this is still done with vac injection and vac forming simply because they're still the quickest and subsequently the most cost efficient means.
3D printers are best for designing and prototyping, but vac forming is better for production.
Awesome job mate!
I can't wait to see this thing rip!
much better than 3d printed
Excellent work
Thank you!
Nicely done
looking forward to the rest of the power train :D
I'm sure you made your research; no BMS will prove to be a mistake. Great work enclosing the batteries 💪.
The BMS isn't connected until the modules are wired up in the kart - I thought that would have been obvious lol.
@@JamesBiggar I thought you would use balance leads, but you are treating the pack as a single cell anyways. My bad.
For a duder in his garage, this is my new DIY standard for building batteries....
Can't wait to see this thing ripping....
professionally built
Великолепная работа! Внутрь ещё селикагель положить, так на всякий случай...
Wow nice job❤️❤️❤️❤️❤️❤️
hey James, it would be good to have a water mark on your videos, so even if people see your videos upload by some1 who's not you, other's will know that's from your channel
Nice work buddy.. great attention to detail 💪👍
Them batteries look cool
ive waited for thus video for a long time
Very clever! Looking good!
Amazing.
Awesome build
I'm surprised u didn't parallel the connections together in the center of the 4 rows. Great job on the build so far!
Thanks. Would need thicker or layered strips to handle double the current that each strip would carry from two cells on either side of a center bus instead of just carrying current from one cell to two busses. My spot welder can only handle 0.25mm and I don't like the idea of layering thin strips on top of each other to build up ampacity. Soldering is easy and the extra cable was cheaper than buying a more powerful spot welder. Two bus cables gives a person the ability to change the configuration and opt for higher voltage/lower capacity modules for smaller projects. I can connect the two positive and negative cables in each module in parallel and use all 32 modules in series for the 55 kW crosskart, or, I can connect the cables in series to double the voltage (see end of video) and use just 16 modules in series in my 24 kW cyber trike - half the capacity, but the trike is half the power and 1/3 the weight and size. I don't plan to swap the batteries, that's just an example. It's just more convenient for me to build and a bit more versatile, that's all.
@@JamesBiggar that's awesome man, it would be nice having the versatility of being able to change pack sizes and configurations. I like the way you did it to be honest and I asked the question before I got the end of the video like I normally do lol but once I seen why u went that route it makes perfect sense! I just put together 2 6.4ah modules from battery hookup for my electric gokart
@@JamesBiggar unfortunately right after I put those on I overheated my motor. I'm running a 48v 1500watt brushless controller on a 48v 1000watt brushless motor but now that I fried the motor I'm looking into a 96v system so I can run the batteries in series and really get to moving but as of right now I can't find a motor for it just the 96v controller so I may just live with the 32mph 48v system again lol look forward to the rest of this build!
Wow. Just wow.
very professional looking! good job
All your work is amazing! I'd work for you for free for a chance to learn a fraction of what you know! Amazing content!
Thanks!
Respect...!!!
Thanks for share brother
Amazing Job
Great job, as always!
The last bit of your video you showed 6.25 volts and 60 A/hr. This is in error, you will have 6.25 volts and 120 A/hr. This is a very interesting and informative video, great job.
Voltage increases in series and AH increases in Parallel.
the real error is that in series he said that there are 120 A/hr and there are really 60 A/hr 5000 mah x 12 so in parallel still being 60
they look skookum as FRIG BUDS
I have the same batteries but 6000mah in 8s3p configuration for big RC buggy, it rips :)))
Really neat James!! I like! :)
Love it bro
Always pumped to see you've released a new video! Vicarious welding projects and EV hacking!!
even this battery works could be a product
Wow!
Great job! But a bit overkill with casing, if you ask me. Makes sense if it is all about the process though =)
Thanks, but they're going into an off road crosskart. They need to be waterproof. The typical DIY PVC shrink wrap method will not suffice. Protecting a $3K investment from water damage in a very wet environment is not overkill ;)
@@JamesBiggar usually people make battery boxes for weather proofing, but considering size of your tiny car, that makes sense.
Yep, and that's technically what I did lol. The ABS cases serve the same purpose, just better for a racing 'kart' with cabin space and weight limitations. I've made metal batt boxes for past projects, like the streetfighter motorcycle, vented wooden batt boxes for my off grid bank, and have sealed batteries inside of DIY monocoque e-bikes as well. Whether the boxes are formed in plastic or screwed/bolted together with gaskets or welded/cast depends as much on a person's skill and resources as it does the application. I recommend that people do what's convenient and cost effective for them and their circumstances, but at the end of the day you get back what you put into it. Waterproofing was just one factor in my decision. The ABS is cheaper than aluminum and since I have a vacuum former that I built for
Awsome work my friend .
Can you make a video on how to make karbonfiber parts .
Лучший!!! Спасибо за видео!!!
A lot of work in that! I saw on a picture that it looked like you tried to draw the abs the whole length of the battery but it failed? I see you went with gluing them together, do you think the length way draw is possible?
Lol, it may seem that way. But 30-40 min of the easiest work I've ever done to build a sealed battery module is a small price to pay compared to replacing a flooded bank or paying at the pump. I doubt the cases can be cast in one piece though. As mentioned in the article, the side surfaces are too vertical/sharp. Even if the ABS didn't tear, the excess created at the corners after pre-stretching bunches up into a mess. I've got more pics on Facebook showing that. Vac injection would be a better option, but machined aluminum molds to do it would probably cost a few grand to have made. Two pieces works fine, just an extra step. It's actually not glue that I used - it's solvent cement. Glue just binds to surfaces, solvent cement chemically welds the plastics into one. Known as 'solvent welding'. Like welding metal, just a different process. Impossible to separate or leak without damaging. They're as robust as the ABS drain pipes in a new home - that component assembly uses the same method.
What kind of spot welder yous use... give details about welder
fantastycznie 👍👍
Awesome! What if the housing allowed the battery pack to be slipped in and the cover could be snapped it place? Wouldn't it make the unit more serviceable?
Thanks. Would need vac injection molds to make a cover like that I think, and would lose the seal if one isn't built into the cap somehow. They shouldn't need to be serviced anyway, but in case I'm wrong then it would be pretty simple to just cut the cap off the problem module and pull the cells out - there's not a whole lot of slack inside but the cases aren't tight, either. The cells will fall right out if the pack is turned upside down. Do the fix, put it back in the case, clamp a piece of ABS in the former and 4.5 min later I've got a new cap. It'll be a little taller than the other caps to compensate for cutting off the old one, but that's just aesthetics. I could make an entirely new case in less than 15 min if I felt the need. But everything being cemented and technically chemically welded together ensures that I don't have to worry about water holes when I've got the buggy in the trail. That's my bottom line in this case. If these were going in my house or somewhere they would have better protection, then I would just friction fit the caps or use PVC shrink wrap instead of ABS.
I'd like to replace my six 6 volt Trojan lead acid batteries in my 36 Volt ego golf cart. Would you have any work ups or suggestions for something like that ? Great video ! Thanks, - M
Thanks. Check out my latest battery build video for an ongoing e-moto project. I modified some 36V M50LT modules from Battery Hookup that you might be interested in ua-cam.com/video/1KXRtSAv37A/v-deo.html
Solid 👍
Really I like ur all works sir handsoff to u sir can I work with you a small request
Great job do you have a link for that spot welder? Than you...
Nice 👌
Top 👌
Just curious where you found that spot welder? The one I have can’t weld over .15mm pure nickel and all others I see that can are >500$
On Ebay. It's barely powerful enough for the job but it worked fine for the price. Made strong welds that don't break. But it's just another cheap sub $100 welder that slightly outperforms the rest in its class. I would need a kWeld or something else if I used anything thicker for strips. The battery also doesn't last long. I think I could only do 1 module per charge. The kWeld isn't cheap but it's a much better rig to invest in if you plan on building more than one battery or need to weld thick strips. I'll be upgrading because I'm not sure how many welds the cheap one has left in it. 14 kWh was a lot of work.
gridrewired.com/products/kweld-spot-welder-kit
Your patience is legendary… That would take a very long time. Thank you for the link! I had heard of kweld but wasn’t able to find a state side option to purchase and looks like these are from Canada. Maybe They have an open source of the pcb somewhere… Also your battery balancing between packs looks like you discharge to a particular voltage before connection to avoid one battery charging another battery. Does the Bms somewhere protect if one battery shuts off and then when you plug it back in reconnects at a lower voltage? Something I’m worried about with connecting batteries in parallel.
Amazing!!
Will it owerheat on full power? Tesla uses water battery cooling for example.
No. The battery for the kart is relatively small compared to what's in a Tesla. It's the same size as an air cooled Zero battery. The cells and conductors in the P groups are sized to handle much more current than what the motor is rated for (110A more continuous current and 500A more peak current to be exact), they won't get any warmer than 40-50°C with passive cooling on a warm summer day. I incorporated forced air cooling just to help increase efficiency while driving. Tesla uses a liquid based TMS because when you get into building packs as large as theirs, it becomes more economical and practical to push the cells to their limit and invest in more complicated cooling systems to provide higher cooling rates to counter the increased heat generation, than it is to install more cells to lighten the load on the battery - especially with space and weight constraints being big prohibitive factors for large EV batteries. Bottom line, increased heat generation is caused by increased resistance which is caused by increased current in the cells and/or conductors. Size accordingly.
I've enjoyed following this build. one question though: why did you choose cylindrical cells? you can get a similar form factor in prismatic cells without any extra work
Glad to know you're enjoying it. Prismatic cells make things super simple for the avg DIY'er as long as they're not trying to fit them into a confined, irregular space, but are less reliable because they're more prone to internal shorts, overheating and swelling like lead acid batteries due to the electrodes being stacked tightly together, particularly with the higher capacity cells. The higher the capacity, the greater the risk and the harder it is to automate, leading to more inconsistencies and a higher retail cost in the end. The extra cost to eliminate a bit of soldering and welding isn't worth it. Neither cylindrical or prismatic cells are waterproof, and I would still need to make sealed cases for the latter if I expect to drive off road with them and survive the waterholes.
Correction: the extra cost isn't worth it if you can solder and spot weld. If a person doesn't have those skills already and doesn't plan on building enough batteries to justify learning, then the cost may be worth it for them to avoid noob mistakes.
Looks like Batteryhookup is selling prismatic now, too. The price actually reflects their value now, ~15¢/wh vs the 17¢/wh that I paid for 32650's. Not sure if they're new or used, though (they sell both of various types of batteries). Would have to contact them to find out. I might consider them for a smaller project, but still prefer cylindrical for reliability/longevity for a big project like this:
www.ufo-battery.com/cylindrical-cells-vs-prismatic-cells-what-is-the-right-one-for-your-device
batteryhookup.com/products/calb-3-2v-72ah-230wh-prismatic-battery-l135f72-fully-tested
How about the stl for the battery
Wow I was waiting for your video
Great work James, is there a reason you chose to seal the batteries inside the cases vs. complete the case around the wooden template, remove that, and make the batteries easier to swap out? It seems with this method the ABS concrete could leak onto the batteries and seal them into the case, and the silicon being pressed right into the cases could make them more permanent...
Permanent (and waterproofing) is the idea. Keep in mind these are going into an off road buggy - being sealed is of utmost importance, but that doesn't mean inaccessible/unserviceable. The cases are oversized ~1/16" for the modules - I installed the modules during assembly simply to help hold things together and set them in place at the same time. Get two birds stoned at once instead of trying to match the OG buck with another wooden template, which would be next to impossible without automation or a duplicator. If, by chance, I effed something up and need to fix a module, it's just a matter of cutting the cap off the case with a utility knife and turning the module upside. They fall right out. Make the fix, set a sheet in the former for a new cap and 5 minutes later it's back together. The ABS 'cement' doesn't leak into the module. It tacks up long before the pieces are even assembled, by nature of being a solvent cement. The solvent immediately begins evaporating the moment it's exposed to air, so a person has to be quick when assembling. That's the only downside. The upside is that solvent cement isn't glue - it actually chemically welds the ABS together, and ONLY the ABS. It doesn't work on other plastics. Different plastics use solvent cements specific to their chemistries. If I do happen to get sloppy with the cement, it'll just touch the tape and stick to the surface. It's not going to fix the module in place permanently. Neither will the silicone. Silicone literally sticks to nothing unless the surface is roughed up really well. I can caulk a window at work tomorrow with window and door specific 100% silicone caulk, then go back the next day, grab an end of the bead and peel it off in one piece. That's why my company doesn't use 100% window and door silicone for windows and doors - I've spent too much time recaulking other people's work. Silicone works much better as a gasket under slight pressure, such as in these battery cases, not as an adhesive sealant.
@@JamesBiggar makes perfect sense, thanks for the reply!
Is there any concern about heat buildup from the cells while charging/discharging affecting the ABS?
No. ABS glass transition point is 110C, melting point is 200C - if a person's cells get that hot, they've got much bigger problems than melted ABS. The pack will probably die. If they're running hotter than 40-50C, then they weren't built properly. The pack should NEVER get hotter than 60C, otherwise it risks being damaged internally. A person needs to pay attention to the cell specs and use an ampacity chart to size conductors larger than what's needed, and there won't be heat issues. Guaranteed :) Most batteries - whether they're powering an off grid home or an e-bike - are passive cooled because they're sized accordingly. There are no heat pipes running through my home bank, for ex. Almost all commercial lithium batteries are encased in plastic, polypropylene to be exact, which has a melting point 40C lower than ABS. Some batteries are almost entirely plastic right down to the polymeric electrolytes. Active cooling isn't a requirement unless the builder is pushing the limits of the battery design, and his/her luck. Like Tesla does. Bottom line - size the cells and conductors to handle at least 25% more continuous current than what the battery is expected to deliver and IR will be low enough to keep heat under control without having to pump fluids through it.
wow (again)
This is an interesting approach. I usually just build the full series in a single pack of cells. However I suppose with such a massive pack size this would make things easier if a single 3.2v block went bad. Did you ever get to charge those cells and see if they hold 3.6v? Charging my pack on a BMS, even after doing a 3.6v balance charge on all cells prior to building my series they still sag back to 3.35v (80.4v 24s) after a full charge to BMS cutoff. I ordered a new set of the 6aH cells to see if there is any difference, and I'm going to use the 5aH ones to build an electric dirtbike project.
Haven't charged any yet, but have a few that need to be so we'll see near the end of the build. I'll update you here.
@@JamesBiggar Yes please update us on this. I've heard all kinds of good and bad about these cells. I'd be curious to hears your experience with them
I think we need to keep in mind that charge voltage and resting voltage are two different things. Do you have 32650 LFP's from another manufacturer to hook up to a power supply and test/compare with BH's cells using CC/CV charging? Are you charging the cells at 1C or lower? I only have BH's cells to investigate atm. After hours of searching, I'm finding that ~3.4-3.5V seems to be the resting voltage for most 3.2V nominal LFP cells - how far they 'sag' depends as much on charging methods and voltage/current settings as it does IR and cell health. All cells will drop voltage to a degree depending on conditions for up to 24 hrs after charging. No battery will ever maintain the full charge voltage after charging. If you're charging to 3.6V (as you should be), then you should expect the resting voltage to drop to around 3.4-3.5V depending on your charge settings - this is normal behaviour. Typically, fast charging at a higher voltage and current will result in a higher voltage drop after charging than charging at a slightly lower current, for example. During charging, particularly at high currents, the ions will stack up in higher concentrations in different parts of a cell, leading to a larger imbalance across the cell's storage medium and a higher reading at the terminals. When charging stops, the ions settle and level out in the anode's carbon material, causing a voltage drop at the terminals. That doesn't mean a loss of charge, it's just balancing the charge it has but because the higher current causes a higher concentration of ions near the terminals, the terminals have a higher voltage and the charging is stopped based on said voltage before the cell is 'technically' 100% SOC. Any factors that affect how the ions stack up during charging will affect how they settle. That's my best guess as to what's going on. If you're charging near the max rating for the cells, try 20-30% less current and see if anything changes. Regardless, as I mentioned in an earlier post, trying to maintain an LFP cell above 3.4-3.5V will do more harm than good. Less than 1% of the cells capacity exists above 3.4V - a person will burn that off in the first mile or two of driving at the expense of degrading the cells sooner.
It also wouldn't hurt to contact BH to get their opinion on your experience with their cells to see what they have to say about it. No one would know their charging specs better.
@@JamesBiggar Historically, I've worked mostly with NCA chemistry, but I have built LFP packs. My resting cell voltage on previous packs were closer to 3.5v, charging voltage being 3.65v/cell @ ~.2C. I'm under the assumption that these cells are new, and fully functional, were intended to be 6AH, but are a bad batch. 3.35v resting on a new cell is rather poor, yet still meets or exceeds the 5AH rating these have if they were built intended as 6AH cells. LFP chem tends to store most of its capacity near the nominal voltage, so being 3.4-3.5v is near/full charge.
It would explain why they claim many are getting capacity over 5AH, and not giving a strict capacity rating. I now have my 6AH cells in, and I'm building the replacement pack tonight. 80.4v was the other packs resting voltage, and I'll see what the new pack tells when it's done.
These 6AH cells came with the white insulators, and were manufactured 11-20.
@@JamesBiggar Also, my 5Ah cells, as well as these new 6AH cells were all parallel balanced charged as a 96p group prior to spot welding using CC/CV 3.65v at 10a. It took over 24hr to complete, being 576AH for these 6AH cells. So the charging current would have been well below any issues, like .04c. Once I build the packs I put them on a typical charger through the bms before cycling them to ensure I get a good starting balance.
Like I said, I don't think these 5AH cells are a scam, or bad buy. It just itches me that my ebike display says 90% charge when the pack is "full" at BMS cutoff. Either way, bumping up ~10% greater capacity on my bike won't hurt with the 6AH cells. Money's not a concern in the least, so I'll just convert one of my old dirtbikes and order another batch of 96 5AH cells and go for a ~45AH 72v setup, perhaps with a liquid cooled 30kW peak motor.
No cooling for the batteries?
Passive. Resistance = heat. No active cooling required when cells and conductors are sized adequately for the load.
How much you charge for a 52v 20ah triangular battery pack?
What are your thoughts about cooling the battery when in use?
Not required. See previous responses.
Great job, I like the spot welder. Price list?
Thanks. Links are in the build article.
Real life tony stark
...without all the $ 🤣
When you put them in series, if they're 120Ah in a single cell, 2S they are still 120Ah. Not 60Ah.
Parallel = increasing cap, series = increasing volts. Electricity basics 101. Each cell is 5 Ah. There are 12 cells connected in parallel per set of cables. 12*5 = 60Ah. Connect each set of cables (ie each p group) in series and that = 6.4V nominal and still 60Ah. Connect the cables in parallel and it's 24*5 = 120Ah @ 3,2V nominal. Grade school math. I even provided a link with test results. Fact check before criticizing/correcting, bro, don't assume anything. It's kind of an important habit to practice.
@@JamesBiggar Cool. So each cell is 60ah. I miss interpreted that bit in the video.
How come the spot welder not be damaging for the batteries?
Because the current just travels through the terminal caps - not into the cells. Soldering generates too much heat on the terminals which conducts into the cells, that's why I soldered the strips to the cable first.
How are you dealing with any excess heat these give off?
They don't. LFP behave differently than the NCM tech that most people think of when they think "li-ion". Cells with higher energy density have higher resistances, so they generate more heat as a result. Some a lot more than others. The M50lt's that I'm using in the bike can reach 70C. These LFP's never reach above 45C on a hot summer day. See the end of the test drive video for temps.
That said, I did build forced air intake ports in the buggy, but they're more for looks until I decide to upgrade to a higher density for more play time.
Make a boober electric bike
Professional work right there! Super well built, one question: no BMS?
Not until they're series connected in the kart later.
I will be interested to see how each individual cell is balanced to make sure none are lagging in voltage. Awesome craftsmanship!
Thanks. Lithium cells connected in parallel equalize their capacity and thus voltage, ie 'balance' themselves automatically and become one cell, called a 'P group' (ie module in my case). Each P group is effectively the same as one large cylinder cell now - they have no choice but to equalize naturally on their own when paralleled, unless a cell goes bad and doesn't want to play ball or a person is attempting to connect P groups made up of cells with mismatch capacity ratings, but that's another discussion. When charged or under load, the cells within each P group still act as one large cell and share the charge or load current in the same way they equalize when resting. That's why the voltage between each cell needs to be
@@JamesBiggar Right... I realized my mistake after I commented. These are really cool batteries. Love the vacuum former and I noted that ABS plastic you used.
@@JamesBiggarHeck no... Not a bit of that. :)
Молодец, хорошая работа. Не лучше был бы металлический корпус?
Спасибо. Нет, если я не хочу увеличить вес и риск закоротить клеммы внутри коробки. Металл не представляет никакой ценности, когда они уже окружены металлом в картинге.
I feel the pain of doing this
Lol. Pain is 20+ years blowing out your knees and back working as a journeyman carpenter. This was a welcome change from the daily grind :)