Some Safety Musts for Giant Lifepo4 Cells (Eve/Lishen)
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- Опубліковано 5 вер 2024
- A few thoughts on safety that I thought I would share now that people are watching the channel.
Affiliate links:
Safety Glasses:
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Resistor:
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Battery Cells:
1. s.click.aliexp... (lishen)
2. s.click.aliexp... (lishen)
3. s.click.aliexp... (eve)
Nice job, but tip number ONE should be to remove your watch or any jewelry that may conduct electricity. Been there.... not pretty.
Great point. I don't wear much jewelry but taking off the watch is 100% correct.
You are correct sir, thank you.
Absolutely. I was an EMT, and I saw plenty of fried ring fingers. Some had to be amputated. And the ring always had to be cut off, destroying it.
My 2 biggest tips is to have a dedicated wrench for your terminals and wrap it up with electrical tape because you will slip and drop the wrench above the terminals, also, use a paint marker and clearly mark your terminal polarity.
Those are great points. Insulating your tools is a great idea, and if there is any ambiguity with your terminals they should be marked, 100%.
Red fingernail polish works well for marking positive terminals.
The aluminum cases are connected to the positive terminal. If the plastic covering is damaged, a case can contact another adjacent case in series-connected battery, and you will then have a short circuit that cannot be controlled by any BMS. I suggest separating the cases with a thin sheet of polycarbonate or mylar. If the battery is sitting in or on a conductive surface, the cell bottoms and sides also need to be insolated from that surface with an abrasion resistant insolating material. This is critical in mobile installations where movement can abrade the plastic coverings.
I agree. I'm going to be doing a video soon where I will be doing just that. But my focus is not as much on mobile installations, where you are 100 % right. In that circumstance, the cells need extra protection and precaution.
I learned that the hard way ..i didn't know that and. Had a lil fireworks show
There's one misconception. Standing upright is the best position, but you can orientate the cells on their sides, just not flat. So never on top of each other, but next to each other is OK. The electrolyte level is below the vents. I explicitly discussed this with the vendor of my 105 Ah aluminium cells before assembly. I had to put them on their sides to make them fit into my battery box. Which I needed to be as small as possible because it had to fit in a confined space in my sailboat.
That is really interesting. Do you know which type of cells you have? I think this issue could vary among different types. If it works for you, that is great. But generally speaking I would strongly advise people to put them upright unless the data sheet explicitly allows otherwise.
@@TheWilltoBuild Upright is always OK. I got my cells from BLS battery store. The brand only has Chinese characters, but I believe they are the only ones who produce 105 Ah cells. I heard you say that some people stack their cells on top of each other, but that's definitely not the way to do it.
Great tips, thanks. I used 1mm silicone project mats (cut to size) to act as an isolator between cells. This is an added non-conductive and heat tolerant safety measure at low cost.
That is what I'll be doing as well.
Excellent tips all around
thanks helpfull specialy since i
just got my batteries Monday
Good tips! Definitely using glasses now
Awesome safety suggestions! Man I'm guilty of being a two handed builder on my 280ah 12v. When I put together the 24v in a few months am going to practice 1 handed building. I was thinking of that working on 12v fasho! Cheers bro 🌞
It happens to all of us. But it is best to try and be careful, the consequences of a mistake are quite real.
@@TheWilltoBuild right on. Is all a part of learning and doing better the next time around. Stay safe and have a great sunny weekend 🌞
Please post a link to some recommendations for installated gloves.
Any work gloves will do, as long as they aren't made of something that will conduct electricity (insulators), and since pretty much no gloves will conduct electricity, almost any pair will do
What gloves are you using? I have had a hard time finding insulated rubber gloves that still have some movement to work in and that come in larger sizes.
I just used the standard ones I got at the local hardware store. Anything with some rubber insulation will work, and they do often have large sizes. I buy the cheap ones though, they tend to be a little thiner and provide a better grip.
I can vouch for molten metal in the eye and had to get my eye cut open to get it out . Make sure the glasses are up against your face. With as little gap as possible .
Please support your cell orientation recommendations with data, as your recommendations don't ring true with others that I have seen.
Also, some calculations regarding current limiting with resistors would be good to share. For example, your recommendation in the video is broad--up to 1 kΩ--and that's pretty high for this application. Assuming that your inverter has 4000 µF of input capacitance (a guess, but in the ballpark), and that it's completely discharged, it will look like a dead short when initially connected to your battery. The RC time constant with these component values is 4 seconds to reach 63% of charge, and 8 seconds to reach about 86% of charge--enough to minimize spark risk. Not many people are going to hold that resistor in place for 8 seconds before thinking they've eliminated the spark risk. The maximum current drawn at 13 V, however, would be limited to a tiny 13 mA. By contrast, a 25-Ω resistor in the same application has an RC time constant of 100 ms (200 ms to 86% of full charge), and would momentarily handle only 520 mA. Even a 10-Ω resistor would be fine, with just 80 ms to 86% of full charge, and 1.3 A maximum current. Here's a tool to use to get a better handle on the RC time constant topic: www.digikey.com/en/resources/conversion-calculators/conversion-calculator-time-constant
Bottom line here: Between 10 and 50 Ω is a good choice for a charging resistor, and it doesn't have to be very big--1 W is plenty since it dissipates peak power for a fraction of a second.
I agree 100% with the commenter who recommended using only insulated wrenches around batteries. The energy stored in these batteries is enormous and a dropped wrench can become red hot in seconds if it shorts the terminals. I see battery builders (even good, well-known ones) all the time in videos using uninsulated wrenches for this work and it makes me cringe! Heat shrink tubing, tool handle compound, or insulated tools would all be a vast improvement. A torque wrench is also a good investment for those building battery banks.
For the cell orientation, you can check the datasheets. I believe at least one (either Lishen or Eve) explicitly says not to put it on its side. Also, Will Prowse has a leak with his cells that were on their side. But this isn't a law, just my opinion,
This is a great point about the resistor. A lower resistance would be better, and you are right many people may not hold them long enough.
Insulated tools is a very good point. I've wrapped my tools recently. And I agree 100% on the torque wrench.
Thank you - great safety tips!
What size of battery do you plan to build and how do you plan to attach BMS - one for entire battery or divide them into 12-24v block with separate BMS on each section?
I'll be building one 48v system - 16s with one BMS. Generally speaking, it's better to put batteries in series rather than parallel. Additionally, the higher the voltage the lower the current, holding power constant, so you can use thinner wires and save money with a higher voltage system.