10s and 12s discharge capacity test

I want to test the capacity for a few older used batteries.
Ideally with selectable discharge rate, but if not, thats fine.
What is the best way of going about that?
My lipo charger (imax B6) has this feature, but only goes up to 6s.


You’ll only be able to pull 3A at 12s, but it’ll keep constant current and record wh and ah out, with settable cutoff voltage. Cheap and very useful tool.

Get the one at above link. There are many fakes. The ones with the pink fan and big graphical display do not have digital control or 4 wire sense.