Battery failing - coincidence?

[mmcgee]

I recently had to replace the reversing light switch. Had a (mechanic) friend do the work. He diagnosed the problem and was under the car but could not get to the switch to remove without an extended hex wrench. I ordered the part and a couple weekends later we replaced.

The issue is that before we removed/replaced the switch, the battery died. Once replaced, I jumped the car and let it idle for 15-20 minutes. Started up daily for a couple weeks. Late last week, it was dead again and I did the same (idle) with the same result. This morning, dead again.

The friend that replaced the switch tested the battery the day we installed the switch and his meter indicated it was a good battery - albeit the likely original (56k miles).

My question is this: Is there anything that we (he) could have done under the car that would be causing a continual drain on the battery? I don't want to spend the $150+ to end up with the same issue.

Thanks

[VR6OhMy]

I highly doubt he screwed up your battery by replacing that switch. Battery's can show proper voltage with a multimeter but still have dead cells and not put out the proper CCA's you need to turn the motor over. Mileage isn't the best indicator of the age of a battery, just go by its production date. 3-5 years is the average life span.

If you head to advance auto or the like and have them check the entire system for free.

[madkimchi]

I highly doubt he screwed up your battery by replacing that switch. Battery's can show proper voltage with a multimeter but still have dead cells and not put out the proper CCA's you need to turn the motor over. Mileage isn't the best indicator of the age of a battery, just go by its production date. 3-5 years is the average life span.

If you head to advance auto or the like and have them check the entire system for free.

You can do this at home. Just hook up the multimeter and put it where you can read the reading from driver seat and crank the engine. If the voltage drops a lot then you need a new battery.

[Aok303]

yeah sounds like the battery charges fine but cant handle a load. do what mad kimchi said
you will see it drop from 12 to like 6 not enough to run car well or at all or most auto part stores the tester they have charges it then simulates different draws to see if it fails

[mmcgee]

Thanks to you all. Will do what was suggested. In the likely event that I do need a new battery, any suggestions on best prices? I am in Houston TX area. Just in case it is now showing up in my profile, the vehicle is an '08 RS4.

[mmcgee]

$350 installed & programmed at dealer sound about right?

[madkimchi]

$350 installed & programmed at dealer sound about right?

Program what? A key fob? Battery should be $150 or so at the most for any off the shelf type. For $350 you can get some decent non flooded battery. Maybe even a light weight one.

If you need key fob programmed then search it real quick. It takes no more than 10 seconds to program it and you don't need anything other your key fob and your car.