I bought a really cheap”5600mah” power bank for about $4.
These things can be found everywhere on the net.
When I got it, I didn’t work with my phone (I suspect that it does not have enough current).
I should have expected it not to work since it was really cheap.
So I had an idea: I should salvage the 18650 cells inside. So I did just that.
Then I had another idea: I should use the power bank to charge does cells
This is what the inside looks like:
The cells are connected in parallel
The module is based on the TP4213 IC.
The output may be useless but the charger works fine although slow
It charges the cells to 4.16V before stopping.
The cells themselves are also fine as far as the eye can see.
The cells are anonymous with no text on it.
Unfortunately, I have no way of telling the capacity.
I took out the batteries and and added some contacts from an 2xAA battery holder.
My soldering work here is embarrassingly sloppy but it does work.
It’s hard to solder around the corners.
I only used hot glue to glue the contacts, so every time I touch the contacts with a soldering iron, they would melt and move.
The plastic also melted a lot.
The most important thing to remember when doing something like this is to make sure there are no shorts.
Since the batteries are connected in parallel I can either charge one or two cell but the voltage difference should be only 0.5V or less.
For more info on parallel charging click HERE
I am treating this thing like a lit candle every time it is plugged in.