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Building 72V Battery: Moped Build - Which Battery Type?

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    Building 72V Battery: Moped Build - Which Battery Type?


    After much consideration. I've decided that I want to build a 72V 40Ah Battery and use a 4000kW motor.

    If I use 21700 cells at 5000mAh. I would need 20S and 8P which is 160 21700 total. I would need to ensure each weld correct and there are many cells to go through. Then I thought to myself, if down the road the BMS reported for example Series connection 5 is reporting an error, I would have to look through those 8 Cells. Meaning I'll have to remove the nickel, inspect each cell and so on. This is very hard and tedious to do generally from my experience because you can easily short cells, damage them trying to remove the bad cell and such.

    Then I came across these so called Eig C020B which contain a massive 20Ah capacity and can fit in my Enduro Bike frame. But they aren't in production anymore. I would just need 20S and 2P which is far easier maintenance and these contain much longer cycles before dropping to 80%.

    I was thinking these type of cells NMC would be great. But my only concern is safety. These type of cells seem like they could be punctured so much easier and explode into a ball of flame when punctured as I saw on YouTube. See video here: I was reading and people say you need to ensure that you keep them secured together tightly and such

    I saw these LiitoKala Lii-70A 3.2V 32700 7000mAh LiFePO4 Battery 35A Continuous Discharge Maximum 55A High power battery. They're LiFePO4 and contain around 7000mah. I would just need 20S and 6P and these cells seem so much safer looking on YouYube and I was thinking with it's 35A continuous Discharge this would be great and it would be cheaper too. These are the cells: ... 5616%23723 With these ones I will only need 120 Cells and that isn't much at all to spot weld. I think these are great.

    I see the positives and negatives of them all, but these LiFePO4 cells seem like the ones to pick. I would like any advice, especially from anyone that has had to maintenance their batteries and what you wished you had done before if you could go back. I would like to use those LiFePO4 but I'm open to any suggestions. Thanks everyone.