I bought My car new 3 years ago (but it sat for 1 year on Dealership lot)
So just about 4 years and when I asked them to test battery at AutoZone they said it needs replacing and something about 78%
So I assume they are telling me that the battery has 22% degraded in its ablility to hold the charge? I was a bit skeptical since the car shows no symptoms of a battery on its dying legs.
I have a small amp that is 100 RMS as part of my upgraded sound system and dont know how much of a strain the aftermarket touch screen stereo and amp put on the battery.
When I put a multimeter on the battery (myself at home) it registered 12.5 and when I put it under load it goes as low as 9.8 (as the car cranks up)
I have never put water in the battery so Im going to do that tomorrow