battery problems

[Daniel50]

hear is the story. i left my interior hatch light on accidentally for a few days when i was out of town. so the battery was completely dead. i put in an old battery i had laying around. started up and worked great. its about 3 weeks later now. the car is now having charging problems it looks like. the battery gauge would jump all around. then it would stay low at all rpms and jump up from time to time and then go back down by the 2nd whitle line from the bottom. now the car doesnt move up at all and the gauge is at the last white line. is my battery bad? alternator? something else?

 

[BlueThunder1988]

Is it still charging and starting okay? (Maybe the gauge is just ****ed.) Easy to pop the battery and alternator into an autozone or equivalent for a free test.

 

[HISSIN50]

did you put your original battery back in, once you charged it up?

are all the connections tight?

i second getting the stuff dynamically tested or bench tested at the parts store. it could be a bad battery, which will inhibit the system from working too hot.

good luck.