firebirdman68

Please help !

hope im doing this right , new here ... ok have a 2003 E320 sedan W211 , the red "battery visit workshop" light is on ... main battery ok , charging system ok , 14.2V at idle , aux battery relay removed tested ok . aux battery dead ! replaced aux battery . still have the light on and still no charge to the aux battery . all recalls done ! is it the BCM in the trunk ?

thank you for your help !

n0n0tme

Did you trickle charge the aux battery before installing it in the car? When I installed mine the autoparts store needed to charge it for a couple of hours after I poured the sulfuric acid in the battery. Otherwise the car will charge the battery and it may take a while for the light to turn off..

firebirdman68

the battery came fully charged 12.9V . just checked it again . thank you for the reply !

firebirdman68

Just talked with Neil at MB customer care ! or should i say Dont give a crap customer care ???? I am totaly shocked that this car is 8 years old and I cant even seem to get a direct answer of what it might be ! Now neil says the red battery light meens the rear battery is bad . that is what im getting .... but its the aux battery that went bad .... he said i should get a white light for that one .. so when I asked why did i get a red light for the rear battery yet the front battery is the one that is dead ???? why did the white battery light not go off ??? In all my years ive never seen such a mess !!!! not even my old 1973 XKE series 3 V12 roadster was this bad !!! God save the queen !

firebirdman68

OH ! and he also told me I should not believe what I read on the internet or forums cause you dont know what those people actually did ! found that an insult !! cause im the worst for being on the computer to get answers ..

Ichabod

About a month ago, we had similar signals in our '06 E500, but although the initial M-B roadside service diagnosis blamed the batteries, the in-shop testing indicated that the alternator was gradually dying, and could put out 12.9 volts when the only load was the tester, but couldn't keep up at all when we had on the lights and wipers and AC on the road the previous day, which triggered the red warning. (It finished the dying process while I was driving it to the shop.) So we got a rebuilt alternator under warranty and now everything seems OK again.

firebirdman68

alternator/regulator charging fine . thank you .

PlatinumPi4u

At how many miles did your alternator go for? I have 95k miles in my 06 E500, and I too get the red battery warning frequently....

Ichabod

62,000 miles, which is about 1/2 what I would expect from such parts on a Volvo or SAAB, or a Mercedes from the '80s.

PlatinumPi4u

My independent tech told me I was still on the original battery (trunk) but i'm not sure about the Aux battery.. I'll have to take a peak.

He said the batteries usually go at 85k -90k, and I know the alternator should be replaced between 80 to 120k miles too.

62k does seem a little short. If it was under warranty, I would not except a rebuilt part, as rebuilt alternators do have a chance of failing early, depending on the quality of the rebuild.

and holy **** - as i'm looking, the stealership wants between $997 (discount) or $1330 (retail) OMG - that is like highway robbery! I think I paid $400 last time I had to buy an alternator