I have 2007 Audi A6 2 litre estate.

I have a nearly new  high powered battery.

 I can fully charge the battery and less than 24 hours later the battery is to low to start the car.

I have had the. Car checked by an auto electrician.

the alternator is delivering 13.6volts

the jump poles in the engine bay are  showing. 13.4volts

when I turn off all equipment but leave the engine 

running no leakage detected.

no idea what to do next any ideas please. 
 

don’t want to take it to main dealer with open ended problem . Too expensive.

car starts straight away when use a external battery booster.

 

Hello Steve,

Thanks for being in touch. 

A couple of points:- Alternator delivering 13.6 volts seems a little low to me - I would have thought almost 1 volt higher would be better. 

Battery discharges in 24 hours to a state of being too low to start the car, points to a (very) significant drain. 

You say ‘no leakage detected...’ How are you assessing whether there is a ‘leakage’ or not? 

Make of nearly new battery?

It would only be a guess that there might be a discharge through the alternator, but obviously a guess it would be. 

Subject to your answers to the above, it would seem your best bet would be to use the services of a trusted local auto electrician, unless you have the equipment and knowledge to investigate this yourself. 

Kind regards, 

Gareth. 

 

Have already been to auto electrical who spent 2 hours checking the. Electrical systems couldn’t find a fault

OK, sounds like my suggestions were unfortunately of no use. I’m sure you will appreciate Stephen that providing full details of what has been done so far, saves making suggestions which have already been investigated. Still...

I’m not sure what your/your auto electrician’s view is on the (lower than normal?) alternator output, and obviously there is a major discharge issue, although your AE could not find where. Of course, that assumes your battery is not at fault.

Oh, you didn’t tell is the make of the battery Stephen. 

Kind regards, 

Gareth. 

p.s. I take it you have tried disconnecting the battery while standing (say overnight) and checking whether the car starts under this test. 

 

I haven’t will give it a try. I don’t want to disconnect the battery every time I turn the engine off.

OK then Stephen. Disconnecting the battery was suggested as an additional test, to assess whether you have a battery or a significant discharge issue here. Surely, you will understand this was not suggested as a long term solution to the problem. 

Once you have carried out this test, and armed yourself with the result, you will need to find yourself an alternative more competent auto electrician who can examine the car and diagnose the cause.

I am sure you will appreciate that trying to diagnose the cause without assessing the car i.e. via. the forum will be an impossibility, although we can suggest the procedure of how you go about investigating it yourself, if you are armed with the correct meters and a knowledge of what you are looking for.

Perhaps you can update the forum following the battery disconnect.

You still haven’t told us the make of the battery/batteries.

Kind regards,

Gareth.