Li+ battery conversion

Maker, DIY
1

Hi, this is my first post on this forum.

I found a golfcart battery 72v Lithium ion left outside a shop for to be taken. Most of the cells are good. I plan to disassemble it down to the cells, test the cells, and repack the good ones into 1 or 2 large AH 12v battery packs that can be connected up to my vehicles. One is a van for work, another is a Tacoma for personal use.

But first, to discharge it to safe levels to properly disassemble and test.

  1. what is the preferred method to discharge via load? I have heard using a “load resistor” and suggestions to use incandescent lightbulb if I can find one.
    b) second part of this question, why can certain appliances take DC current for power sources if normally designed for AC current? Ie. Directly woring a lightbulb with alligator clips to a 12v pack when it’s designed to screw into a socket plugged to a wall outlet.)
  2. any suggestions on battery resistance testers for this application?
  3. any suggestions on designs(shapes) of cell packs, and materials used to reconnect/solder newly cleaned working cells?
  4. What is the best method to remove the soldering from the individual cells to create a clean surface finish to solder to again in a different layout?

Thank you for any suggestions advice.

20250322_120728
20250322_1207284080×3060 3.72 MB

2

Oh and any suggedtions for battery management system boards? And battery isolator setups to connect the final product via a red 0awg wire from behind driver seat to starter battery+ alternator?

Thank you.

3

Hello,
Welcome to the DigiKey TechForum. This is beyond my experience but it’s a public forum so hopefully someone can jump in and offer some suggestions.

4

Greetings,

Such activity is politely discouraged. In a best case, one will likely end up spending an amount of time/money to get a cobbled-together mishmash of largely-used-up cells that could have otherwise bought something new, purpose-built, and having a manufacturer warranty/guarantee.