I've spent a very long time trying to work this out, but some websites seem to conflict the information - or I'm completely missing the point.
I have a rechargeable battery:
It is to charge from a vehicle 12V or 24V (battery runs through a circuit board...it's designed for vehicle tracking).
What I'm trying to work out is:
I have one of the batteries connected to a PSU, but the current needle flips up a few bars, then drops straight back down. The battery was flat, so I'm not really sure what's happening. Appreciate any help understanding this.