SL500 Consumer battery drain

[neo1]

Hi guys i am back again just invested in a low miles SL500 on a 2003 for a weekend play thing the car is great other than one issue, ive been on here before but had to open new account as could not remember my details

Ok the issue i have is a common one

consumer battery is discharging over 4/5 days and turning off the electrics etc,

I took it into auto electrics today and he says he has found the drain but i am not 100% convinced so here it is...

2a constant drain on rear battery and he showed me that the fan inside the Head unit ie sat nav screen internal fan is running constant even when the key is out and locked etc etc even after an hour its still going when the car has nit been used, he has checked the wiring and says basically i need a new head unit or command is it called ??

I was wondering if that seems possible or is it more likely to be the body control module or something powering it i dont know how the system works to be fair just dont want to buy a used sat nav and find out its no that thats all...

Any ideas guys would be greatly received

Rob (durham)

 

[Dogbreath]

hi Rob
I'm no where near clued up on electrics but couldn't you pull a fuse for the command unit or remove it to see if this is infact the problem as your electrics man has said...?
just a thought mate
Lee

 

[optimusprime]

Dog Do you lock the car after use ,and over night?

 

[Dogbreath]

Dog Do you lock the car after use ,and over night?

Is this for me....?
But yeh I do....!

 

[4life211]

Is backup battery that triger that .You should replace this battery .Its a small battery that is used for SBC if the main one fails.

 

[neo1]

Hi dont always as its parked in a secure garage all the time..

The consumer battery is brand new this week as the old one was not accepting charge due to keep going flat for long periods of time..

Rob

 

[neo1]

Bearing in mind the consumer battery on the SL500 is nearly as big as the starting battery at the front..

 

[Paul Grainger]

Mmmmmm well actually on my SL55 the consumer battery is at lest twice the size of the piddling little starter battery in the front! I only use my SL55 every couple of weeks and the consumer battery is always low if I don't leave it permanently connected to a automatic trickle charger when the car isn't being used. However, the COMAND fan doesn't continuously run on my car......

Paul G

 

[richard]

Common on early SL is an old tracker. They have nicad batteries, which fail and then the charging circuit tries to charge them all the time. An most early SL's needed trackers because thats what the insurance companies said at the time.

Lots of things can keep COMAND awake, it may not be the COMAND .


Richard

 

[neo1]

Hi i got a quote for a repair to the comand it appears its quite a common issue or so they say and the price was £195.00 i was going to send it in for repair but i have decided to swop out the whole comand and go for a full new head unit with sat nav and a few other bits..

 

[Thermal]

Hi Guys

Just as a heads up on this. I know of a C200 that was doing this exact same thing.

Lock the car, leave it overnight and battery drained in the morning.

The car had a small accident at one stage and although it was repaired perfectly, no-one noticed some slight damage to a temperature sensor that read outside temperature and supplied it to the ECUs. When driver walked away with car locked, the sensor was telling the car it was at -50C and car was 'afraid' to go to sleep fully.

Perhaps this might lead you to a thorough investigation that might help? Plug in a computer and get a full analysis of the car before you spend big money.

 

[BattyByron]

I know this is an old thread but my SL 500 suffered from the same problem consumer battery going flat after a few days. I discovered what it was.
It was the light in the arm rest as the clip is broken as most are, but while I was driving with my arm on the arm rest it stayed down, but when I left the car the arm rest had some tissues in it which expanded as no longer compressed and with the lid of the arm rest slight the light came on which was very difficult to notice, I disconnected the bulb very easy and the consumer battery has not gone flat since.