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Not for me. Battery is brand new (installed in August 2020). Auxiliary battery is old but is also fine (in any case it is not connected to main circuit unless triggered).
Let's see. I will get the car back today and find out.
What was the original electrical issue on your CL55?
Original issue was it was eating alternators just like your car. I had my battery tested and all came ok. What's weird that happened today is I put the battery charger on the car and it was at 68% but when I disconnect the battery from the car and charge the battery alone it was at 98%. I think the charger has a hard time charging and getting the info of the battery when its connected to the car since I grab the battery charger clip to the... idk what its called Ill put a picture...
Original issue was it was eating alternators just like your car. I had my battery tested and all came ok. What's weird that happened today is I put the battery charger on the car and it was at 68% but when I disconnect the battery from the car and charge the battery alone it was at 98%. I think the charger has a hard time charging and getting the info of the battery when its connected to the car since I grab the battery charger clip to the... idk what its called Ill put a picture...
Thanks. My battery's voltage is fine when connected. It passed the load test and pretty confident with it since it's Bosch.
What is voltage drop in your battery when connected vs. not connected with car off?
Last resort. Heard a sound from it too hence how I found out.
e55aed - bumping an old thread as i am experiencing alternator/charging issues on my m113k (SL55) and wanted to know if the BCM issue you had threw a code on Star or how did you determine it was that?
Was there a sounds or something you mentioned that led you to determine it was the BCM? I have a basic foxwell 5300 scanner and it shows zero codes on my car but it only holds 11.5 to 12v that is after 2 new batteries installed the past 3 months. i replaced the voltage regulator about a year ago and am wondering if the entire alternator now needs replacing at 75k miles? am assuming my issue is the alternator since i dont have the voltage spikes you mentioned 14v at WOT and back to 12 which sounds like was related to BCM.... any feedback would be greatly appreciated!
Having read this, one thing I’ve also not seen mentioned is proper programming of the bcm for the type of battery installed. Bcm, was a common issue to check for visually but definitely check digitally. When I had my 55, I had to make sure this was correct when upgrading the battery otherwise the charging rate is not correct.
e55aed - bumping an old thread as i am experiencing alternator/charging issues on my m113k (SL55) and wanted to know if the BCM issue you had threw a code on Star or how did you determine it was that?
Was there a sounds or something you mentioned that led you to determine it was the BCM? I have a basic foxwell 5300 scanner and it shows zero codes on my car but it only holds 11.5 to 12v that is after 2 new batteries installed the past 3 months. i replaced the voltage regulator about a year ago and am wondering if the entire alternator now needs replacing at 75k miles? am assuming my issue is the alternator since i dont have the voltage spikes you mentioned 14v at WOT and back to 12 which sounds like was related to BCM.... any feedback would be greatly appreciated!
yes, the bcm was making a high pitched sound. Indeed it may be the alternator for you. Would get one that has a warranty so if it goes you can swap it. You should have a burning smell and potentially whining from alternator if it's bad.
Bro I am on my 4th alternator and battery NO LIE and from reading your story the BCM has to be what is wrong with my car also. I did a couple of dig races on a cool night and on my way home BATTERY/ALTERNATOR light comes on. Turned the car off and bam won't start back up. Aux battery is fairly new 2020 sticker on it. Where did you order yours from? How much? What was the cost to getting it all back together. Does it need to be coded? I don't have a STAR program but wish I really did to figure out things if you know the exact one I need for a 2003 e55.. thanks
I am having this exact same problem with my '04 e55. bought the car last year september, 1st alternator died december, its replacement died in april and now come september again this one is gone. no idea why. i have a stock electrical system, ill check my BCM with star but i dont really expect to see much, so i might just replace the bcm and get a warranty alternator and see what happens.
this alternator right now makes a very noticeable burning smell and it whines a little, so its def gone
at the very least ill be good for another few months before i can expect the next alternator to go lol
Bro I am on my 4th alternator and battery NO LIE and from reading your story the BCM has to be what is wrong with my car also. I did a couple of dig races on a cool night and on my way home BATTERY/ALTERNATOR light comes on. Turned the car off and bam won't start back up. Aux battery is fairly new 2020 sticker on it. Where did you order yours from? How much? What was the cost to getting it all back together. Does it need to be coded? I don't have a STAR program but wish I really did to figure out things if you know the exact one I need for a 2003 e55.. thanks
I got my BCM from Ebay for $80 I think at the time. Here's the part number. Wishing you the best of luck. My indy replaced it for me.
Should be the same part number for you, if you send me your vin can check on star
I am having this exact same problem with my '04 e55. bought the car last year september, 1st alternator died december, its replacement died in april and now come september again this one is gone. no idea why. i have a stock electrical system, ill check my BCM with star but i dont really expect to see much, so i might just replace the bcm and get a warranty alternator and see what happens.
this alternator right now makes a very noticeable burning smell and it whines a little, so its def gone
at the very least ill be good for another few months before i can expect the next alternator to go lol
Very likely the BCM, sounds very similar to my hellish experience. The weird thing is my burnt alternator started not burning and working again after I let the car hibernate for a few weeks. Not a long term solution though as the voltage (which I permanently had on the center of my guage cluster during this nightmare) was not stable at over 13v consistently hence the alternator will eventually give out under stress (seems to happen when you floor it).
Also worth reading this on aux battery. It is not even connected to the main circuit and only kicks in if main battery voltage is low, hence almost never the source of the problem: https://www.scribd.com/document/4374...l-Batery-W211#
02-07-2021, 02:31 PM
