Comand - Battery Drain

[Paul Grainger]

I purchased a fiesta before Xmas to use through the winter months. The CLK, of course, had pole position in my garage.

After approx one month of non-use, I decided to take the CLK out for a spin. It was a nice day, and I was sick of the fiesta.

When I tried the CLK, the battery was completely dead. I mean COMPLETELY dead. My test meter showed zero volts across the battery terminals. Somewhat suprised, I attempted to recharge the battery (fat chance) but not surprisingly it was completely useless (three years old).

After recovering from the shock of purchasing a new battery, I decided to trace the 'fault' that flattened the battery.

With ignition off, all doors closed etc, my test meter showed a steady 330mA current drain. The battery was (originally) 100 Ah - the maths is simple - no surprise that the battery was flat after a month.

I decided to pull the fuses one-by-one to find out which circuit was drawing current - perhaps not surprisingly when I pulled the radio circuit fuse the current fell to only 30mA. I have retrofitted Comand, TV, multi cd, & DVD player all on this supply so I suspected that the problem resulted from something that I had done.

However, a series of tests revealed quite a surprise. With the nav CD inserted, the current draw with 'everything off' is 330mA. Remove the nav CD - the current draw falls to only 30mA.

I was - as you might expect - slightly surprised. So I repeated the test on another car (work colleague with OEM installed Comand). Exactly the same results.

Has anyone else experienced this?

There is a lesson to be learned here. I have always left my nav CD inserted - I won't in future. It's not a problem if you are using the car regularly - but could be if you leave your car for a couple of weeks at an airport etc.

Comand users be advised!

Paul G

 

[sym]

Paul

That's a little worrying !

Interestingly, when the COMAND is switched off, I do hear the CD Drive spinning occasionaly - no idea why it does that. Possibly so that when you switch on and turn to Navi, it knows your exact position to display the map quickly. Perhaps because in your garage it couldn't get a GPS signal it was spinning away ? Just a stab in the dark.

S.

 

[craigyb]

Same problem as me, I think you wil lfind out that is probably the TV harness.

Where did you get your command from?

Craig

 

[Paul Grainger]

No - it's definately just the Comand. I started testing by pulling all of the plugs (C1, C2 etc) except the power connection. All harnesses, TV tuner, cd player, dvd player disconnected. Same results. Interestingly - the current didn't rise when all of these items were plugged back in again.

It's not just my Comand either - The other car I tried it on was original MB fit - same current drain.

330mA isn't a massive drain. I have had the Comand installed (with TV, CD, DVD etc) for 18 months - because I use the car regularly it hasn't previously been a problem.
BTW - the Comand came from Germany, brand new.

Paul G

 

[mapleleaf]

However, a series of tests revealed quite a surprise. With the nav CD inserted, the current draw with 'everything off' is 330mA. Remove the nav CD - the current draw falls to only 30mA.

I heard of this from my dealer ... well the workshop foreman actually. Its well known that if you take out the comand disk the battery doesnt go flat . It happened to me whilst I was working on my E class last year fitting comand, TV etc. - flat battery that is .