BKDave

Hi, hoping someone here can provide a little info and knowledge.

I have a 1999 Audi Avant 1.8T that I bought used several years ago.

About 6 months ago it wouldn't start. I get a jump start and can plainly see the battery is about 5 years old. No surprise that when I took it to a local Pep Boys they told me I needed a new battery. No problem

They install a Bosch battery (part number H6-760B) with a 36 month warranty. Note I checked today and This battery shows up on their website as being the correct battery for the car.

6 months later aka 10 days ago, car wont start. I get a jump start and as I'm idling to let it charge, I can plainly see the voltmeter going up as I rev engine. But the instant I let off it drops a skosh. It drops a little further when I do something like open the power window.

I bring it back to pep boys, pointing out the above, and they tell me that the load settings were incorrect and that they will replace it under the warranty. However they end up charging me an additional $55 and supposedly give me a different and better Bosch battery. (part number 48-720BAGM) Note I cannot find this on their website and indeed the only info I can find on it at all is on a Mercedes SLK discussion board.

Wasn't too pleased about that but it gets worse.
I live in NYC and have only driven a grand total of 5 miles since this replacement. Drove it home and moved it for alternate side parking that's it.
Today a friend offered me free tickets to the NY Giants game but lo and behold the car was dead again. The voltmeter was again going up while car revving but dropping of significantly when I let off the gas. It had not done this the few times I drove it, nor had the previous battery until it died.

Now theyre telling me its the alternator. Which kinda makes sense, but then
why WASNT the alternator the problem on the prior visit all of 5 miles ago?
did I even need a replacement battery to begin with let alone " a better one" that cost 55 dollars more ?

Could the "incorrect load settings" on battery from 6 months ago have caused alternator issue?

As I cannot find anything about the second bosch replacement (part number 48-720BAGM) is it the entirely wrong battery and could that have damaged the alternator?

Am I misunderstanding the voltmeter completely?
I see it going up as a I rev and thought it indicated that charge was getting from the alternator to the battery.

Obviously I feel like they are messing with me and/or horribly bad and either misdiagnosed the problem to begin with and/or caused it themselves.


any info would be greatly appreciated.

G_claudz

Get another opinion from an auto electrician, it could be your alternator although when mine went bad, the battery light in the car stayed on and I was able to get the battery to charge if I drove the car above 100 miles per hour to get it to the mechanic.

David.Norton

A lead acid cell is a lead acid cell, you can change the size of it to alter the cranking amps, but you can do nothing to alter the voltage, it is just physics. So the answer is if the battery fits the car it is likely to be fine, and changing the battery didn't damage the alternator. So I think it unlikely that you needed another battery, and your car is of the age where the brushes in the alternator could just be wearing out. However, that being said it sounds like changing the alternator is beyond what you can do with it, so I would suggest you find a mechanic you can trust and let them check over the electrical, because there are other things beyond the alternator that can cause this. Mind you if you have a place to work, a few tools, and a voltmeter this is not a hard problem to sort.