DIY 72v 20AH Battery Build

Ғылым және технология

This was quite the project for me. I built a 72V 20AH battery from used batteries that I had to disassemble and balance myself then rebuild to make a large 72v battery protected with a BMS for a 5000w E-bike build I'm working on. I had a lot of hiccups along the way: My spot welder died, packages got lost in the mail, I got a bunch of parts from Ebay and Ali-express that were not as described. I also learned that nickel plated steel is often used when you have 2p,3p and 4p rolls, even if the seller lists it as something else. Thanks for watching!
Relevant links:
- 20s lithium battery charger (72v nominal 84v max): amzn.to/4apvrf2
- Cycle Satiator I purchased (for 85% and variable charging): amzn.to/3vXlqH2
- Jumper cables for cheap(er) 8awg cable at time of filming: amzn.to/3VNHbUh
- Ebike kit: amzn.to/3vvs1bK
- BMS 72v: amzn.to/4cOwLKk
- Molecel INR 18650A cell used: www.batteryjunction.com/catal...
Dave's KZread Gear:
- GoPro Hero 11 - amzn.to/44tlnyL
- Zoom F2 field recorder - amzn.to/44AoHIc
- Desktop mic: amzn.to/3OGa5k7
Time Stamps:
0:00 - intro
1:54 - Size and configuration
2:47 - spot welding
3:55 - BMS
7:37 - Terminals +
9:30 - Shrink Wrap and sealing
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Пікірлер: 4

  • @imho7250
    @imho7250Ай бұрын

    Did you manually top balance the pack before wrapping it to give that poor little BMS a fighting chance at maintaining that balance? Since you assembled it with harvested cells, unless you manually charged each cell to 4.20v before assembling, it is good to watch it the first charge and use an hobby charger to drain or top off each brick until you see everything in balance, the charger light green, and the BMS bleeding down any slightly high brick. Its good you added a AWG 12 collector on the nickel. Most people overlook that and just attach to one end, effectively making a snake bus with 80a/200a going through one sliver of nickel strip. The only thing I did differently was distribute the 2 B- wires along the collector, which on your battery would be between 2p/3p and 6p7p so that each segment of the AWG12 collector only carries 20a and each B- wire carries 40a/100a. Those look like Molicel 18650’s. Not sure which cell but I don’t think Molicel makes anything weak, so im sure the pack does pretty good. ANT BMS are dirt cheap now and being able to see what’s going on, especially with harvested cells, is really nice. My 80a/200a Bluetooth ANT was only $40 delivered. Its just so nice to open the app, check how the cells are doing, check for sag in each group, check for self discharge, etc. Im currently rebuilding my P42a pack because my BMS told me I had some bleeders. Not surprised because I knew I burned some holes in a few of them when spot welding but figured I would monitor them. After a few weeks when enough electrolyte leaked out the damaged cells began self discharging, progressively more and more. So Im in the process of letting them set so I can see which are bleeders and which I can reuse. Lol

  • @fgbhrl4907
    @fgbhrl49072 ай бұрын

    Length of sense leads doesn't matter. You should really cover up all the areas you're not directly dealing with when welding the nickel strips. I accidently had a strip shift between rows.. insta fireworks. Also, protects against accidently setting it down on a scrap piece of wire / nickel strip / screw etc.

  • @tminustoday

    @tminustoday

    2 ай бұрын

    Thanks for the advice! I'll completely cover any areas not being worked on with my next project, there is no reason not to.

  • @TheMiniRonster
    @TheMiniRonsterАй бұрын

    Hey do you know could you build a 76v 20ah battery that fits in your razor dirt bikes the sx500? Also how much would that cost to make?

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