What chronic problem can kill a car battery over time?

Not a mechanic, but could it be the starter?

My (completely uneducated) guess would be that you’ve got a short or some sort of electrical wiring problem that’s draining charge. This seems to be a fairly common problem – maybe some of these will have some helpful hints.

Time to call Click and Clack.

Have you tried getting a second opinion on the alternator? Are you taking it to the same shop each time?

Happened again this morning (hence this post). Shop said the battery was “bad” and tested the alternator for several minutes saying it was “good”.

One bad battery. Ok. Two bad batteries. Alright. Three. Maybe (if they’re all cheapos). But four bad batteries in a row?

I suspect some kind of parasitic draw… could be the factory radio keeping the clock and presets alive. Or the keyless entry radio receivers. But I’d’ve really thought that’d be accommodated in the battery’s expected lifetime.

I’ll probably try the fuse-by-fuse test to get an idea.

a parasitic draw. Have you tried recharging the battery, and its not charging? That usually means that you have an electrical problem, on a wire that’s not suppose to be hot.

Gremlin under the hood with a hammer Have you got the garage to look at the car to see whats up ?

A battery is a pretty passive device. It just sits there and waits to provide some power for something. Most of the time it is like a bucket of water, just sitting there, full, with little to do.

There are two possible causes for your problem. The first has been covered above in some of the posts, a possible short which will continuously drain the battery making it necessary for the alternator to keep charging it all the time, leading to premature wear.

The second possibility is that the battery is getting TOO MUCH charge. The alternator or voltage regulator keep charging the battery when it doesn’t need it, and the voltage they are exposing the battery to is too high, say 16 volts instead of 12.

You probably have something wrong with your charging system. Take the car to a shop that specializes in auto electrical systems.

So… when the shop tested my alternator this morning, they possibly missed an over-charging condition. Is that typical?

They get more money from you if you have to keep going there , it does happen at places like that .
It happens here with the smaller lesser known garages

They get more money from me by having to replace my battery for free?

My suspicion would be the voltage regulator. They are usually but not always part of the alternator.

Of course, you could also have a short somewhere; one of those sneaky ones with enough resistance to drain the battery but not enough to actually get a spark shower or melt stuff.