So I was looking through my garage and found a UPS of sorts. Its a 12V UPS (DC output) and uses a 12V motorcycle battery (GP 1272 f2). It's been in my garage for a couple of years at least. The problem is that this 12V battery is sitting at around 6.5 volts. After a day of charging its at 7.5 volts. Is it possible to get it back up to 12V? I've switched to using a 12V 6A charger now, but the current is reading 0A (It's an analog meter though). I've looked this up and haven't seen anyone online with anywhere near as low of a voltage reading, and was wondering if the battery is faulty, if it is dangerous to charge it, and if I can get it back to near full voltage. Edit: switched the mode to 2A, forgot about trickle charge. The battery charger is probably 20-30 years old so it doesn't care about voltage. Tested working on another battery.