How does a new battery fix various issues?

[Jon M]

I've noticed several issues recently, including the right rear window moving slower than the other three, and the steering wheel controls for the radio not working as they should; it would take multiple presses, up, to change the station or volume. Down worked fine.

I discovered the other day that the reserve time on my battery was about 10% of what it was a month ago. I went ahead and replaced it. The $100 is worth the peace of mind, to me.

I realized today that the window issue is gone, as is the steering wheel control issue. That one I could imagine having to do with a reset due to loss of power, but the window?

If the vehicle is running, isn't all of that running off the alternator? And if so, am I potentially looking at a bad one? That battery was dated 10/16. It was the one in it when I bought it in January, so it's had at least two batteries in 5 years (the in-service date was mid-2012).

It's going to the dealer for other issues on the 14th, so I'll have them test the charging system, but I'm just curious how changing a battery could resolve these two.

 

[Douglas Goglio]

I believe the vehicle runs off the battery and the alternator just keeps the battery charged. The vehicle doesn't run directly off the alternator.

 

[machine4321]

Technically, it runs off of both. You can disconnect the battery from a running car and it should continue to operate. This is hard on the alternator of course if lots of things are running. with all of the draw of new cars the battery needs to be good.

 

[Frank1669]

Only thing I can think of is you improved the ground when you switched the battery.

 

[thefranchise713]

May have had a cell failing, and low voltage does a LOT of funny things to a car. When my battery was failing, I had literally twenty-thirty fault codes stored in a number of vehicle modules.

Essentially, at least in my experience, low voltage or weak batteries in general can cause a lot of unpredictable issues, not to mention a hard load on the alternator trying to keep up.