Am I asking too much from my stock alternator by adding an audio amplifier to the system?
I added a 260 watt 2 channel amp to the car’s audio system about 10 years ago and, although it works fine, I think my battery life is suffering. After driving a while with the amp on, the car seems to have barely enough power to crank the engine after I have shut it off. This happens even after installing a new battery. My alternator is a 105 amp unit and the batteries I buy are Group 24 size rated at 820 CA, 690 CCA.
Do I need a higher output alternator? A higher capacity battery? A second battery to drive the amp? Any advice would be appreciated.

 

105 amp alternator should have no problem at all with
a 260 watt amp-you may have a weak alternator or
an electrical problem.You won't need a 2nd or oversize
battery for only 260w.What does the voltmeter show
when you have the amp cranked and other electrical
loads on?

 

Had the alt checked and I was told it was OK. I don't have any headlight dimming or other symptoms. It just acts as if the battery is drained low after driving and playing the audio system. The dash volt meter still holds just above 13V while running in all conditions. I will keep looking and checking for now.

 

What is the battery holding when its not running? i.e. if you let it sit for a while (several hours/next day). Have you ever completely drained your battery? The issue that I had not too long was that my battery was fully discharged a couple times (including a length of time when it just sat and didn't run). The battery would turn over the motor but barely (and I have an aftermarket high torque mini starter), I ended up taking the battery back to autozone, changed it out with a new one and it was like night and day.

If that isn't an issue, check the wire from the alt to the battery (charging cable) for corrosion, looseness and damage.

 

Thanks for the input. I thought some of the same things. Changed the battery out about 6 months ago (it was 3 years old) and it did seem to improve but only for a few months.

The car does sit for periods of about 2 months (Jan-Feb; too cold for a conv and July-Aug; too hot for a conv) but I keep a "Battery Tender" on it while it is sitting. None of my batteries are allowed to become even slightly drained - I learned a long time ago it is no fun!

I will check and/or replace the battery leads. I am thinking it may be my problem since the starter, alternator, and battery are all fairly new. The leads are the originals so, after 20 years, they probably need it anyway.

 

Yeah i was having this same problem not to long ago turns out i have an electrical problem.