Battery drain in cold weather

[OneForTheRoad]

That is a good line of thought. My car does have a the heater system which will keep the car warm for period of time after switching it off, to activate this, you click on the rest button. Maybe it is this system which is playing up. I have no idea how to isolate this though. If anyone can shed any light on how to turn this off for troubleshooting, that would be great!

Stop turning it on i guess ?

 

[55AMGCLK]

That looks like a report from a device that injects an AC waveform into the battery and checks the impedence. In my experience a load test is a more accurate method of determining battery condition.
Also the charging test looks to be low. 13.7-14.3 used to be the acceptance criteria but these days I would look at anything under 14.0 volts with a little suspicion.
Also, if it is a wet battery, I would check the s.g. with a hydrometer to determine the state of charge.
That should give you a good idea of battery condition/state of charge.

Thanks for the info Ted, the test was done by National Tyres this time round. Probably just time to order a new battery.

 

[55AMGCLK]

Stop turning it on i guess ?

I have never used the feature, if something is causing it to malfunction and turn on over night, that could explain the battery drain. I will be ordering one of the due testers to see what is going actually going on, it may just be the battery on its last legs.

 

[wrdcc01]

Are your door mirrors warm before you start the car? Good advice on the head unit fuse as there maybe an anti condensation heating system in it to protect the optics of a cd/dvd player. Maybe a rechargeable battery in the alarm sounder that's going bad and drawing excess charge current from the main battery, or operating the indicators in the middle of the night. Are you using the correct weight of oil? Too thick and it maybe putting a little bit more strain on the starter motor and drawing more current. A few things that come to mind where the cold is a factor.

 

[55AMGCLK]

Are your door mirrors warm before you start the car? Good advice on the head unit fuse as there maybe an anti condensation heating system in it to protect the optics of a cd/dvd player. Maybe a rechargeable battery in the alarm sounder that's going bad and drawing excess charge current from the main battery, or operating the indicators in the middle of the night. Are you using the correct weight of oil? Too thick and it maybe putting a little bit more strain on the starter motor and drawing more current. A few things that come to mind where the cold is a factor.

I have checked the wing mirrors and they are not warm before I start the car. I have pulled the Command fuse to see if that makes any difference and have charged the battery using the CTEK. I will need to check the draw on the alarm. Oil in the car is from Mercedes 0-40 from memory. I either use MB oils or Mobil.
Thanks for the pointers.

 

[Tezz]

You could try pulling the radio fuse. My 07 GL and 07 CLK 63 had the same problem and it turned out to be the head unit CD constantly spinning up. I also use a CTEK trickle charger....

I just had to do same on my car, pulled fuse for command so far drain stopped

 

[OneForTheRoad]

I have never used the feature, if something is causing it to malfunction and turn on over night, that could explain the battery drain. I will be ordering one of the due testers to see what is going actually going on, it may just be the battery on its last legs.

Sorry, the way I read it as you were using rest . My take on this is that the cold sorts the wheat from the chaff , a dying battery will fail in winter , a healthy one won't. Change it or charge it ....