Battery problem
 

My first real issue cropped with my SL at 4,000 miles. The car was dead. Had to be towed in.

I travel frequently for my job. I had an error msg (Consumer electricals offline) a couple of weeks ago. Interior lights, seats, etc. would not work. After driving a mile a so, the error went away and all components started working again. A week later the same thing happened.

This Monday, the car was totally dead. The tow truck jump started it, but I have never seen the dash so lit up with error messages. I had it flatbedded to the dealer. They couldn't find any unusual electrical draws and replaced both batteries.

Hopefully I won't have another problem.

Anyone else have a similar problem?

do you lower the top frequently with the key?

were at around 7000 miles and nothing like that has happened.

The car uses two batteries to avoid just this sort of problem - a static current drain which will flatten the battery if left unused for more than a few days. I'm not using my car much at the moment because of the weather and I often get that message for a couple of minutes after starting, which allows the alternator to top up the battery in the trunk which runs the non-essential stuff.

The theory is that the smaller battery in the engine bay should never go flat (other than internal discharge over a period of many weeks) and therefore always be available to start the car. Once the engine is running, the alternator has more than enough capacity to run the ancilliaries - and this car has a voracious appetite for power.

Sounds like the solution of replacing batteries is a good start, but I remember from a technical briefing last year that there's a complex control unit responsible for handling both batteries, charging from the alternator and so on, and it's possible that it is not working properly. A good test would be to artificially flatten the battery in the trunk and check that you can still start the car.

i have this problem in my car too. i don't drive it too much, i use an Audi for everyday driving, SL has only 4000 kilometers done and there were many situations that i wanted to use it but the batteries were empty. but there is a special kit a kind of a battery charger so you can keep it loaded charging the battery all the time in the garage without driving it. it really helps.


Maciek

What is the kit called?

It's simply called "Charge holding device". I'm not sure if it is available in USA because i'm from Poland. But i think you should try to ask your dealer about it, i think he should have it.

Maciek

Car came back from the dealer after repairs. According to them, the main battery is in the trunk. The smaller battery for the appliances is in the engine compartment.

They said they found a bad cell in the trunk battery which was draining the auxillary battery first, then finally drained the main battery. They could not find any electrical draws other than the bad cell.

We will see

Sounds odd to me.

They've got the batteries round the wrong way. The smaller battery in the engine compartment is dedicated to starting the engine and should not be drained by any demand elsewhere. If the battery in the trunk goes flat because you've left the lights on, there's still power to start the engine and get going.

If the starting battery fails, the battery in the trunk can run the whole car, so you should only be in trouble if the battery in the engine compartment has a bad cell AND the trunk battery has been allowed to go flat.

Replacing the batteries is simple and quick, it will be interesting to see if it's solved your problem. If I were you, I'd carry a pair of jump leads to get a jump start from a passing VW Camper Van until you're 100% confident about it.

down here in texas i've rarely ever seen a VW van :D