Hi,
I recently bought honda civic 2000, 4 doors. the original battery was over overheating, so i bought a new battery and after 3 weeks it started overheating. thanks to costco i could return the battery and get a new one. My question would be why the battery car overheating and what should i change/replace/fix. could it be that it is overcharging?

Thanks so much.

 

Have the alternator tested. It may have a bad voltage regulator that is allowing the system to be overcharged.

 

I took it to a mechanic and he says just to replace the alternator cost + labour, but not sure if that will fix the problem. How can i test the alternator? Could it be anything else like fuses?

 

Do you have a multimeter? They're cheap, and it will give you an idea of how much voltage is making it to your battery. With the car running you should get around 14 volts. It very likely has nothing to do with fuses.

 

Measure voltage across the two battery posts with the engine idling and all electrical accessories off.

 

Take the alternator out and take it to autozone, Napa, etc. most of these chin auto parts stores will test you alternator for free.