Trunk Battery / Consumers Offline

[N1KSX]

Hi,

The SL has been sat for a couple of weeks unused, and now nothing works. No aircon, no ESP, no nothing!

The trunk battery is 100% DEAD. Currently been on charge for 30 hours and still going.

This is my third battery and keep having this problem. I don't remember the last time all the electrics actually worked in the car.

if I take it to Mercedes will I get charged a fortune?

Any solutions?

Also I've only gone and clicked the boot down (1 click) without the battery in the boot, is it easy to open manually?

Thanks

[stevcons]

This just seems to be 'part of the drill' with these cars, kinda like the ABC system... it is just inevitable problems.

Firstly, you should have your alternator tested. If it is not charging the accessory battery (trunk) or not adequately charging, it needs to be replaced. [note: if you are going to replace it, you can get one on ebay for about 1/4 of what OEM costs]

Secondly, you can replace the battery with a non-mercedes one for $140 or less with oem fit (vented, etc.). From my experience, you have to replace these batteries every 4 years or so regardless (autozone or the like are typically giving 5 year replacement, so you may be able to get these free in the future).

Lastly, I disconnect my negative terminal (simple, socket-wrench loosening and tightening job) whenever the car is going to sit for more than about 3 days. There are so many electric consumers constantly drawing current, it is a good idea.

Opening the trunk is as simple as using the physical, metal key from your key fob, turning the key to the side and pulling on the trunk latch manually. [the key slot is located facing down above the license plate]

Hope this helps (if nothing other than misery-company)

[lonnie77]

If the car is going to sit for more than a week it will need a trickle charge on the trunk battery. I'm not sure if you could just disconnect the cable. Does anyone know what is useing the trunk battery when the engine is off? You should not let the car sit, Drive it, Drive it like you stole it!

[N1KSX]

Thanks for the advice

The replacement battery in there now is a 75AH 650A battery, with 3 year warranty so I will take it back if it's nackered

However it seems to be almost charged now (indicator turning green)



However it seems very difficult for the key to turn in the lock
Does it turn clockwise or anti clockwise?

Thanks

[N1KSX]

UPDATE!

The battery finally charged after three full days!

The battery is reading 12V and 13V with the engine on, so I presume the alternator is working?



HOWEVER
Still have some electrical problems...

-AC isn't working (AC Off button is constantly lit and won't go off)
-VISIT WORKSHOP sign in red on dash, with picture of battery.
-Keyless entry/go not working.


Any ideas?

[lonnie77]

I'm not sure if the star will be needed to reset or activate clear the problems.

[N1KSX]

I've noticed that the display has gone a bit bad, like the LCD display is broken.

ALSO, the backlight on it does not go off at all, could this be causing the drain?
Is it replaceable?

[N1KSX]

Just measured the current on the rear battery
Bear in mind the car had settled down and was in 'locked' mode, but boot was open so the light in boot was the only thing on.

By calculation the 10w bulb in the boot should draw 0.8333 amps.

The reading on my ammeter was 3.2A!!!

:O

[donubenz]

You can turn off trunk light (see handbook) or pull bulb to isolate.
Leave meter on and pull fuses one by one till the drain stops to isolate/find the circuit that is drawing. These cars do have a draw to keep systems up to date but not as much as you have. Is the meter reading reliable?
Also when I had the battery symbol on the dash it was the front battery flat and the car would not even try to turn over, The shop had dropped the car back after a service on a Friday night and turned the switch too far. Leaving one side parking lights on till I found it still glowing when we got back Sunday night!
Mine only goes about 2 weeks before I get "convenience functions unavailable" with a year old battery. You do need to use them regular or put a trickle charge on with a smart charger if you park them up.
Good luck
Don

[N1KSX]

Is there only one fuse box? (behind the drivers seat?)


I will also try charging the starter battery and see if that helps