robl45

Does anyone know how long you need to drive these cars in order to charge the battery? I've had no issues with starting until yesterday when I went to start the car and it just wouldn't crank. I drove a minute away in the same development to a friends house and when I went to leave 2 hours later, engine is not cranking at all. I've had batteries get weak before but usually the engine is trying to crank, lights are dimming or something. This was totally normal except the engine wasn't cranking. I honestly didn't think it was the battery, but rather than get towed, I asked my friend if he had cables and we tried jumping it which worked and it started.

I've had no indications of low voltage or anything come up, although I have noticed when listening to the radio at work during lunch with the car off, the car will turn itself off fairly quickly. I drive about 17 miles to and from work. That should be sufficient to charge the battery shouldn't it?

Celicasaur

FWIW my E55 used to do this when the battery went flat. It didn't even bother to try and crank, it just stayed dead.

Could be any number of things, but the obvious things to check would be:
Is the battery getting 14V+ with the engine running
Does the battery have something like...12.4-12.6V when the engine is turned off and after the car has been driven for like...half hour or 45 minutes.

If both of the above check out ok, then you have a drain somewhere. Either that or your car is doing what my E55 was doing....it had an airmatic malfunction whereby it would constantly try to adjust itself through the night (you can hear the pump n all that stuff whining away and working) until the battery was drained.

robl45

I just tested now and also tested the battery this morning before going to work. Before Work after sitting all night, battery was 12.45. Now it was 12.45-12.52 right after I got home. With car running at idle. It was about 13.6-13.7. That seems a bit low?

otakki

I always recommend hooking this car up to a battery tender/minder whenever it's not driven because this car is an electric hog that will ruin a battery in no time. The battery is pretty much in a semi-discharged state at all time. I sure hope MB can install a port so I can just pop open a flap and plug something from a battery conditioner easily.

robl45

You can plug through cig lighter with adapter for maintainer. I'm getting ctek mus 4.3 But I'd like to figure out if what I'm reading is correct.

homeofstone

Check and make sure you have an AGM battery. If not, then I suggest getting a new AGM battery.

Celicasaur

Yeah it does seem ever so slightly low I suppose. Those figures tell us that it's not being charged to what a battery normally would get charged to after a drive.

Either try a new battery as homeofstone suggested or get the alternator tested. Might be cheaper and a lot simpler to opt for the battery first though.

But on that note...I wonder if the brush pack on the M156 alternator might need to be replaced in the same way that it needed to be replaced on the M113K after a few years? Hmmm....

robl45

I'm assuming its got whatever battery came with the car. If battery is only getting to 12.45 it wouldn't be the battery assuming the battery can go higher which it would if I hooked up a charger to it. Are the Mercedes supposed to charge it higher? 12.45 is only like 80% I believe.

homeofstone

Don't assume the battery is original. It may be an aftermarket non-AGM battery, which cannot last under the loads that the E63 puts on it. All my cars, except for the 65 Mustang, need an AGM battery or the battery will die if the car sits for 4 or five days. To save money a few years ago I tried a non- AGM battery in my E500 and what I really did was waste my money.

robl45

Lets assume its not the battery, should it be charging the battery to 12.6 volts or not?

robl45

So I did look and the battery is an original mercedes battery, not sure if it was every replaced but it looked nice and clean.

I got a reading the other day of 12.6 so I guess it is charging the battery. I noticed before this happened and the car wouldn't start that the command system was shutting off fairly early when I was listening to music with the engine off. I never once got a warning about low battery voltage though.