i have a 600w JBL mono-channel amp hooked up to 2 10" Sony Xplode subs and ever since i had it hooked up, my car would have problems starting (taking a long time to turn over) this would usually happen after my car has sat for a long period of time (i.e. over night, while at work etc) so i unhooked the amp from the battery about a month ago, and ever since then my car start fine every time. so my question is, do i need a new altinator or battery? i was thinking battery at first, but somene suggested a stronger altinator to supply more power.

oh, and yes i did check to make sure the amp is turning OFF when my car isnt on

 

General rule is battery starts the car, alternator makes power while the car is running. If you notice your headlights dimming (without your stereo on) off and on, it's your alternator. But I would start with battery, also check the water in it. That may be the reason that it won't start your car.

On the other hand, if it is cranking, the battery is doing its job.

 

Had the same problem with my car and figured it must be the 12 year old battery so I bought a optima yellow top and it starts great every time, then I installed my system and the alt couldnt handle the load so I bought a 135 amp and everyhting works great with everything on, no dimming or hesitations. Only cost me 250 for both