3s7p 18650 in nice little box

[DThames]

I found this box with cell holders on Ebay. I put some salvaged cells in it (about 2300mah ea). It tested 16.5ah. The third image shows my build (1170grams) beside a lead acid 7ah (2490 grams). More than twice the power and less than half the weight.

 

[schmism]

what are you useing for a tab welder and BMS?

 

[DThames]

This is the welder. It was a huge disappointment. It blew up. I think the transformer was shorted coil to coil and overloaded the power switching Triac. I replace it and it blew up again, this time taking out the control board. I replace the control board with one for DIY builds. By that time I was sure the transformer was the root of the problem. Working up the power level it would blow a fuse before it had power to weld. So I rewound a microwave transformer and managed to get all of the new stuff inside the same box. It welds good now but I can't weld really heavy tabs (like power tool high current packs) without blowing the internal fuse (after several quick welds). All of the AC wiring inside is too small. I plan to overhaul that wiring with heavier wire and move the fuse from 30A to 40A.





I am also considering getting a welder like this.

 

[DThames]

what are you useing for a tab welder and BMS?

Oh, the BMS is a 20A unit that is about $2 from AliExpress.

 

[Supervstech]

Will 12.6V max be enough for the use? Most SLA devices require 14V charging, and float around 13.8, and cut out at 11V...

be EXTREMELY careful using that battery. Explody cells don’t like misuse...

 

[DThames]

Will 12.6V max be enough for the use? Most SLA devices require 14V charging, and float around 13.8, and cut out at 11V...

be EXTREMELY careful using that battery. Explody cells don’t like misuse...

It is just a battery (with BMS), not specific for any device. It will be charged on a Li-ion balanced charger. Most use will be a sprayer pump and a tiny inverter. The box is better than shrink wrap when it comes to getting it banged around outside.