Hello guys. I’m buying the parts now. I’m starting with the battery cells. Since it’s going to be 20s8p, that’ll be 160 cells. My friend told me to buy 200 cells just in case there’s bad cells. Do I really need to order 40 extra cells or is he just telling me to buy extra so he has some for himself for a range extender or to add an external power booster? LOL. I would understand 170 or even 180 but 200? LOL.
This is my first time buying cells so I’m not sure how much of the cells are usually DOA. So yeah. Thanks.
Some of those, I already have. The ones I don’t have are the BMS and the Cells. Let me know what you guys think of the BMS and how much cells I should be buying.
I forgot about the shrink wrap and the fish paper. I’ll look for it some other time but when I find them, I’ll leave the link here for future people who are planning on building their own batteries.
I agree, I usually buy 2-5 extra cells and base it off of how close i am to the threshold for lower price per cell by quantity. If going up a few gets enough of a discount to pay for the extra that just makes good sense.
I dont get many doa cells, mostly i want a few to test and mess up. Weld settings and tear off tests on separate non important cells is a nice little peace of mind.
My current battery is started cutting off at 73v. Recently, it started cutting of at 76v.
I planned on upgrading to a better battery in the past but I’ve put it off for so long since my reasoning was “I got a working battery. Why bother?” but now, since it’s broken, I finally got the push to build it.
You don’t need a 250a bms. You aren’t going to use the discharge port anyway.
Save your money and get a much smaller bms. I have a 40a jbd in my 20s board. It’s quite small.
Cells DOA? Probably extremely rare that happens. I wouldnt buy an extras. If you need 160 buy 160. 40 extra cells is nonsense. Someone’s trying to rip you off if they’re telling you that.
. If you get unlucky and have a few cells under voltage, just buy a cheap charger. Or if they’re over voltage throw them in a 21700 flashlight for a few minutes.
I built a pack out of only low cells purchased from a battery builder, and it’s stayed perfectly balanced. I’ve also used those cells in in regular packs and also saw no imbalance. Ymmv ofc, I just buy +1 cell in case I drop one like a dumbass
I’m not suggesting putting questionable cells in a new battery. I said buy a battery charger so you can charge up any low voltage cell before assembly.
Imo it’s just wasteful to order extra cells if you only have plans to build 1 pack. More likely than not those cells will be unneeded. Just order a few more cells if you end up in the unlikely scenario that you need them.
Op is talking about ordering 40 extra cells and that is ridiculous.
When i get a batch of a 100 or so cells and every one is at 3.52v but one is at 3.47 im not gonna use it other than for testing welds.
Personal preference of risk mitigation of having to repair a pack down the line.