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Building Custom Brownout Battery

avrojockey

Well Known Member
Patron
Anyone roll with their own Li-Ion brownout battery using 18650 cells and a PCB BMS? Thought this would be a cheap alternative to the $200+ TCW battery for my G3X.

I built bluetooth boomboxes for my kids a few Christmas ago and they're still going strong on their original 18650 cells so the BMS must be doing its job. The box is also made of wood and they have caught on fire yet ;)

The only issue I ran into was finding a local guy to spot-weld the cells in series (can't solder as the heat can damage the cells), and I found someone that rebuilds cordless battery packs that could do it.

Thoughts?
 
I have wondered about that Tim, and already had to replace mine. I was thinking some A123 cells that are the LiFePO formation so the stock TWC charging would match the cell needs.

Is this factor or something I imagined as a problem?
 
You may be able to solder the 18650 cells if you use the same technique I use for NimH or NiCd...

I take a dremel sanding wheel and scuff up the battery ends.

Then pre-tin the battery ends without any connectors (the scuffed-up end really helps).

Then pre-tin the connector.

Then while the solder is molten on the connector (and soldering iron/gun is keeping hot) touch connector to battery and hold long enough until pre-tinned battery solder melts.
 
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