USB powerbank/handwarmer


I recently purchased an USB hand-warmer/powerbank for my wife. One came defected due to the USB not working properly but it charges and works well. The company sent me a replacement and told me to keep the defective one. But the battery doesn’t last long on these things.

My question is, can I remove the battery from one and stack it on top of the one that’s working perfectly. Solder the 2 batteries together, then connect it back to the wires according to - and +, will that increase the runtime?


There should be no problem

glue the banks together
remove electronics from defective
connect batteries parallel to the other bank

Thanks Lexel.

One important thing
when connecting both banks together the cells should have the same voltage.
if yot there will be a high current damaging cells

you can connect em with a 0.5-2 Ohms resistor to equal the voltage