PeterUbers

hi, I am posting for a friend, his car was purchased brand-new and meticulously maintained and has about 30,000 miles on it, still the original battery, and during some start ups it seems like the car was struggling a bit to start but it never once failed to start. He took it to a Mercedes dealer who tested the battery and determined the battery was totally normal however when the car was starting up it was drawing an excessive amount of current. Current draw once started seemed normal. No cel's and no codes. The Mercedes mechanic would not comment further without a diagnostic fee.

The car otherwise drives and functions perfectly, and most of his start ups see perfectly normal without any significant after abnormality heard or detected

thoughts? Thanks in advance

thefisch

Excessive draw upon startup but not while running? I guess that could be a sign of early starter failure if it is needing too many amps as it ages. Maybe no point in addressing that until something stops working.

But first I would suspect the battery given it's age at 5+ years and that it is easier and cheaper to replace. Seems to be holding up but could start to go especially with the summer heat. Unless they pulled the battery out to load test it disconnected from the car, the jury is still out. My old battery passed many tests even though it was my problem. These AGM batteries hold a decent surface charge and pass those tests, but they seem to lose the amps they can keep in reserve so a load test usually tells the truth.

PeterUbers

thanks for the input, I always value your posts!

do you think it's worth just changing the battery first?

thefisch

Some folks just change the battery at a certain age or at the first sign of trouble just to avoid the hassle . You could say your friend got their money out of that battery already.

If you'd take it to an auto parts store anyway for a replacement, I would remove it first and take it in another car (so you're not stranded) and have them load test it. I'm the kind to try and test things out. Otherwise, the new battery could be starting out with a disadvantage. Even then, a new battery could come with a 3 or 4 year warranty so you'd have some insurance.

z06michael

You need a starter, just fixed mine and now charging normal

PeterUbers

did you have the same scenario? What did you pay for a starter and install? Thanks

KEY08

The 550 really turns slow when the battery is failing. Especially if driven on short runs with no real chance to charge up. I know nothing about that excessive current draw diagnosis, but i would bet it is just a weak battery. Why not start with a new one and then go from there? It appears based on time alone that the battery is nearing replacement anyway.

z06michael

My car was just the same, it had a 450 mil drain from starter cranked slow, I already had a new battery 1 year old, listen to me I am in this business your car needs a starter, you can put a battery in if you want, unless something is different about you car it will be a starter. Take to dealer he will test it and he quoted me 1100 to replace starter and cable, don't replace the cable it is not necessary. It is a 1 hour job and it cost me 450.00 at a friends shop. Car is perfect after repair!

belarus27

i would check starter 1st
here is an older thread , where i hope ull find some useful info , been there done that.
good luck

https://mbworld.org/forums/e-class-w...2010-e550.html

SolidGranite

Well, it's been just over 3 months and I finally replaced the battery today. Early indication is start up is better but still not quite where I would expect it to be. However, I could also just be super sensitive to the issue and there is nothing wrong at this point. Car starts in about 1 full second of time before complete turnover. Overhead light flickers a bit, but not sure if that happens to others?

Fingers crossed the starter is ok but like someone else said, no sense in dealing w/ that until absolutely necessary. The car needed a new battery regardless which may not be the case w/ the starter. Car has a whopping 25k miles on it.

Thanks to everyone who contributed.

cc16177

I posted this in another similar thread but I have a 2011 E550 and I had the same issue. Replaced the battery first but ultimately had the starter replaced. My car is CPO so i'm not sure what the cost would have been as it was covered.

Totally fixed the problem!