My supervisor has a Vector brand battery charger/jump starter. It uses a 12v/19ah agm (basically half a U1). He keeps running it dead somehow (I don't even want to know).
That ruined it. The battery had 10 volts and would not charge. Without a functioning internal battery, the entire unit is a doorstop. It goes through a POST and then shuts down with an error code.
There was a warranty on it, but Vector sent him a new jump start only model and refused to fix his. I guess they expected him to swap batteries.
Since we had nothing else to lose, I took the old batery home and tried to charge it with another Vector brand smart charger. It made a try and then gave an error code, too. This Vector has a desulfate function, so I gave it a try for a day, with no luck. Trickle charging from a 12v wall wart didn't work either, so I did both at once.
A first the voltage went over 16. The Voc on the wall wart is about 18. Then slowly the battery volts came down to about 13.5, and after another 1/2 day, the battery would take a proper charge by itself.
The battery has no swelling or cracking or leaks. It was mechanically sound, except for abusive discharging it would have been fine all along. I'm kind of suprised Vector hasn't gotten in trouble for this device anyway. The battery has warnings printed on it that say not to short it out, but that's is exactly what happens when you try to jump a car with it.
