Quicktwinturbo

Few months ago, I replaced the battery because it was deeaaadd for some odd reason.. My mech and others thought the voltage regulator, alternator might went bad..... However, after installing a new battery, everything seemed OK (I checked the voltage using dyno mode). System was charging properly.. Well today, I went out for some go kart action with my bud who just purchased a Brabus CLS K8. CAr did feel a lil slow (did couple 150+mph runs on the interstate though.. It def felt slow) and on my way home, Battery / Alternator warning light came on again…

When I got home, I checked the vol again (dynometer) and it was 11.8 when the car was on...Even when I rev'd the engine, Vol stayed same. That proves that the system is not charging properly.

Is it possible that some of cable got loose on the way home? I just don't see how alternator on our car can go bad on a 05 model cars. Even my 1999 hyundai never had this issue and still rocking on stock battery at 90,000 miles.. My C55 has about 35k miles now.

Any one else had this issue and share what your local dealer did to resolve this problem.
It’s really hard and expensive to get C55 parts in Korea. So if it’s the alternator, I’m thinking about getting one from the US and ship it over here

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So I was reading the owners manual and saw something interesting.. Battery / alternator warning can be triggered if "POLY-V-Belt" is damaged...
I really doubt that is the case for me though..

c55asleep?

Samething happened to me took it in for warranty and they changed the voltage regulator and all was fine after that.

Gramma_Benz

Mine went out about 6 months after I had battery problems due to my seat module draining my battery all the time.

My mechanic said my alternator was probably working overtime for a long while while I was having problems and made it prematurely fail.

Could be different for you, but just sharing my experience.

Quicktwinturbo

Hey bud!
Actually, my mech once mentioned about the vol regulator... But once I got the new battery, everything seemed fine .. I hope its the reg.. Cuz I heard new alternator for our car is very pricy..

Gramma B,
Thank you for your comments.. I'll check that as well

ashura

i'm not sure what the problem was but i just had an electrical problem in my c55 fixed under warranty. the battery died and when we tried to jump start it, wouldn't jump start at all so ended up towing it to the dealer. not sure if this is related to your problem or not but for what its worth...

ohlord

shop test the alternator under load and tell you if the stator or diode is functioning or the VR is good or bad?Any good auto electric shop should have the meter.
If not a bosch rebuilt with warranty for the C55 is only $250 have it boxed up and posted over.
Inspect the belt,don't jump it via the battery,don't jump it via the underhood post with the key in the ignition.

Quicktwinturbo

Thank you all for your comments.. I did take to to my mech today and problem was solved by replacing old Voltage reg with a new one. Quick $250 fix.... ......

willc55

The same warning lamp just turned on for me today, what is the test that they did to determine whether it was the alternator or voltage regulator? Is there something I should be looking for in Dyno mode to clue me in?

Quicktwinturbo

Just take it to the dealership.. It's hard to tell.. More than likely, it's the regulator.. Alternator won't go bad so quick on 05-06 cars... If you are out of warranty, change the regulator first since it doesn't cost alot... Good luck!

willc55

Yeah, out of warranty, so I will definitely instruct the shop to try the regulator first. I'm really hoping its not the alternator, after buying all those christmas gifts and flying back and forth to chicago, my repair the C55 fund is running dangerously low.

c55asleep?

Change the voltage regulator 90 percent it's that. Mercedespartsuperstore has it for about $150 dollars.

c55asleep?

Like quick said it's hard for a alternator to go out so soon. Believe me when it happen to me I was scared after see the price of the alternator. Put a screw driver behind alternator to see if it's magnatizing.

mb_c55amg_guy

I had the same problem a few months ago...i had it towed to the shop...and they did some tests...it turned out to be the sams? we have 2? one under the hood, and one in the trunk? aparently they got wet, but since i was under warrenty they replaced them.