I have a pair of Even h3 headphones that had a short to ground on the positive Voltage supply. The battery has a small circuit board attached to the terminals, similar battery ct's state "built-in battery protection circuit module PMC" for overcharging, overdischarging and short circuit protection. I think the circuit got stressed from being shorted to ground for too long too many times because the battery has
3.5 V after a short charge (connecting 4.5V directly to the terminals), but the output voltage from the circuit board is anywhere from 0 to 0.5Vdc.
I'm looking at charging modules on ebay since this is a simple problem and cheaper than a battery, can anyone recommend a charger module they've had good luck with?
These looks good to my inexperienced eye, but they're stated to be for an 18650 battery, I have a small flat battery, I don't know if this matters.
high current (3A) version
5V USB 1S 3.7V Lipo Lithium Li-ion 18650 Battery Charging Board Charger Module
lower current version USB 1S 3.7v 4.2v Lithium Lipo Li-ion 18650 Battery Charging Board Charger Module
My battery is similar to this, same 503040 battery but different ct. board.
TIA Mike