Hello to all I'm new here and I'm looking for some help, I got a UPS today with a 12V 5AH battery, witch on my system lasts allmoust 2 min, and I took my car battery witch is a 12V 35AH, and hooked it on to the UPS and did some testing with a 25W light bulb, and it looked promesing on the volt meter, it showed a small spike from 12.89V to 12.38V and after one min it started to go up up after 2 min the UPS shut down, the voltage was about 13.90v, I took off the car battery and the voltage kept growing till about 14.50 when I got scared and took the battery out side in case of any thing, when I looked againe after 30 min it was 12.98V constant. Can any one help me out and tell me what do I need to do, if I whant to put a biger battery, on the UPS. And If any one can tell me what happed that made the voltage go up like that. Personaly I think the battery started to boil. Thank in advace and best regards to all.