My battery in my A4 was dropping charge over night.

I would leave it when going to bed and when driving to work the next morning the battery light would be on and the voltage meter on the dashboard would show it between 8 and 12 instead of just under 16.

I took it to a garage and paid for a new battery which included free fitting.

Anyway, this morning when I started my car I noticed that voltage showing to be around 12. The second I put my foot on the accelerator the battery charge shot back up to just under 16 and kept like that all the way to work. It seems to be every time I leave it over night it drops charge still and the next day's driving charges it up.

The leads me to suspect that the battery is still duff (despite being changed), but I am hoping that the fact the engine charges it so quickly means that the alternator etc. is fine.

Does this sound about right and have I been ripped off by the garage?

Thanks

 

Lalaland.

What was the outcome of your trip to the mechanic?

The battery should read 12.5 volts when you turn the key to the on position. The yellow battery light should come on with the key in the ignition in the on position. This tells you the light works.

When you turn on the starter motor, the voltage should drop to about 8 volts and when the engine catches, the voltage should be be between 13 and 14.5. Check with a digital voltmeter as the guage on the dash is only an approximation.

If with the car off after it has sat overnight, the battery voltage is less than 12.5, you may have a parasitic leak (ie short circuit) somewhere in the car. Make sure that all the interior lights go off and that you don't have anything plugged into the cigarette lighter.

Remind us why you had the battery changed in the first place. BTW, for 30 pounds inc instillation, it can't be much of a battery. What is the amperage of the battery?

 

The mechanic changed the cam belt, the auxhilary belt and the battery for £225, all inclusive (about $429.72 US).

I also think he changed the pre tenchnor thingy (sorry, can't remember it's name) as there's a wheel that looks like it holds a belt in the pile of parts he replaced. I can attach a photo if this will help to identify it?

He also did a mini service on the car (not including spark plugs or coolant etc, so very mini)

As for the battery, the reason it was £25 is because a friend's wife arranged the special price through the garage where she sends all her company cars.

When I first start the car the meter shows the reading to be just above half way, which is 12 I think. When running the engine etc. it's just below 16 volts.

But from what you are saying this may be normal?

I will watch the meter over the next few mornings to see if it drops below the 12 mark.

Thanks