C220D SE - Strange alternator/battery dead issue
Discussion
Picked up a 2005 C220 Coupe yesterday - 20 mile drive back to work. Half way there I get a battery/alternator warning come up on the dash. Just as I get to the car park I get several more warnings come up and just as I'm pulling into my parking space it seems the car is pretty much dead. Window takes 6 attempts to go back up. Obviously, the alternator wasn't charging the battery on the way back.
RAC got to the car this morning. Put a new battery on it. Alternator charging fine. Tested the old battery and it was just inside the "worn" zone of their diagnostics kit. They also tested for a draw on the battery which there was none. Drove back home with me and tested the alternator again, still charging fine. So it seems it's the battery right?
But this seems really odd to me. Why would a battery just stop charging half way through my journey back to work yesterday? There was no particular heavy load on the car (just had the radio on and lights set to Auto). I would have thought that the car being on and running would mean the battery would at least keep charge? Could it just be a total coincidence that the battery came to the end of it's life on my first journey after picking it up from the dealer?
RAC got to the car this morning. Put a new battery on it. Alternator charging fine. Tested the old battery and it was just inside the "worn" zone of their diagnostics kit. They also tested for a draw on the battery which there was none. Drove back home with me and tested the alternator again, still charging fine. So it seems it's the battery right?
But this seems really odd to me. Why would a battery just stop charging half way through my journey back to work yesterday? There was no particular heavy load on the car (just had the radio on and lights set to Auto). I would have thought that the car being on and running would mean the battery would at least keep charge? Could it just be a total coincidence that the battery came to the end of it's life on my first journey after picking it up from the dealer?
Possibly I guess. Not sure why a dealer would do that though? In fact he was using the car that morning to get the tracking sorted out and the car was still warm when I picked it up. Plus the battery doesn't look particularly old. In fact it looks relatively new which is why I'm suspicious that it's the battery that's at fault.
But thinking logically, if it isn't the battery, it can only be the alternator, or a wiring issue between the alternator and battery, both of which don't seem to be the case since it's charging OK?
But thinking logically, if it isn't the battery, it can only be the alternator, or a wiring issue between the alternator and battery, both of which don't seem to be the case since it's charging OK?
Follow up - charged the battery and managed to get the car down to Halfords. Picked up a Yuasa Silver battery and fitted it this morning.
On my way home this evening, car and battery had down all of ~5 miles of driving (though 45 minutes of the car on and engine running thanks to Canterbury's crap rush hour traffic) and the battery/alternator warning came on again.
Managed to get home, stuck a multimeter on the battery whilst the car was still running and it measured 11.7V, so it seems like the alternator is duff. Strange that it does work initially and then turns off/stops charging after a few miles?
On my way home this evening, car and battery had down all of ~5 miles of driving (though 45 minutes of the car on and engine running thanks to Canterbury's crap rush hour traffic) and the battery/alternator warning came on again.
Managed to get home, stuck a multimeter on the battery whilst the car was still running and it measured 11.7V, so it seems like the alternator is duff. Strange that it does work initially and then turns off/stops charging after a few miles?
jammy-git said:
Follow up - charged the battery and managed to get the car down to Halfords. Picked up a Yuasa Silver battery and fitted it this morning.
On my way home this evening, car and battery had down all of ~5 miles of driving (though 45 minutes of the car on and engine running thanks to Canterbury's crap rush hour traffic) and the battery/alternator warning came on again.
Managed to get home, stuck a multimeter on the battery whilst the car was still running and it measured 11.7V, so it seems like the alternator is duff. Strange that it does work initially and then turns off/stops charging after a few miles?
Do these cars have any kind of "smart" charging control that may need resetting when a battery is changed?On my way home this evening, car and battery had down all of ~5 miles of driving (though 45 minutes of the car on and engine running thanks to Canterbury's crap rush hour traffic) and the battery/alternator warning came on again.
Managed to get home, stuck a multimeter on the battery whilst the car was still running and it measured 11.7V, so it seems like the alternator is duff. Strange that it does work initially and then turns off/stops charging after a few miles?
Wholesale speculation on my part
I don't believe so, not going on what I've read last night on the Mercedes Club forums.
Had a quick further look this morning. That corner of the engine is caked in oil. Look like there's an oil leak from above the alternator somewhere.
I guess, once the engine gets hot, the leaks starts and causes an issue with the alternator....
Had a quick further look this morning. That corner of the engine is caked in oil. Look like there's an oil leak from above the alternator somewhere.
I guess, once the engine gets hot, the leaks starts and causes an issue with the alternator....
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