2010 ML350 Bluetec battery won't stay charged
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2010 ML350 Bluetec battery won't stay charged
Alright mystery team here's one for ya...
We have a 2010 ML350 Bluetec. Starting about a month ago the battery started going dead. We had it at the dealer for some emission work and they read a code saying the battery should be replaced but we didn't do it due to the price. Few weeks later after 2 days of not driving the car the battery was dead. I replaced the battery and figured it was my fault for not heading the warning of the dealer. 2 weeks later the battery goes dead again after a couple days of not driving it. No abnormal driving issues, no warning lights on the dash, no new codes. I replaced the battery along with the auxiliary battery and tested it for a few days every morning my wife went to work. It read 14 + volts. I figured maybe it was a bad battery or something got left on and drained it. Car has been running great for 2 weeks. My wife drove home friday afternoon and now Sat evening the battery is already dead again. Still, no check engine lights, no codes, no driving issues. My first thought is the alternator but wouldn't there be a light on the dash? What could be drawing the battery down SO much in a 24hr period the car nothing on the car works and it won't start? If it's a drain it has to be a pretty big one.
We have a 2010 ML350 Bluetec. Starting about a month ago the battery started going dead. We had it at the dealer for some emission work and they read a code saying the battery should be replaced but we didn't do it due to the price. Few weeks later after 2 days of not driving the car the battery was dead. I replaced the battery and figured it was my fault for not heading the warning of the dealer. 2 weeks later the battery goes dead again after a couple days of not driving it. No abnormal driving issues, no warning lights on the dash, no new codes. I replaced the battery along with the auxiliary battery and tested it for a few days every morning my wife went to work. It read 14 + volts. I figured maybe it was a bad battery or something got left on and drained it. Car has been running great for 2 weeks. My wife drove home friday afternoon and now Sat evening the battery is already dead again. Still, no check engine lights, no codes, no driving issues. My first thought is the alternator but wouldn't there be a light on the dash? What could be drawing the battery down SO much in a 24hr period the car nothing on the car works and it won't start? If it's a drain it has to be a pretty big one.
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From: In the Shadow of the Tetons
2013 ML350 Bluetec
Your job now is to find out what isn't going to sleep. Brute force method is one fuse at a time... There are other more graceful methods; "search" is your friend.
Seems like I remember the front seats being a weird source of problems.
Seems like I remember the front seats being a weird source of problems.
Last edited by rapidoxidation; Jul 22, 2025 at 12:05 AM.
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From: Colorado
G550
Pulling fuses is usually what you need to do. This can be made easier if you have a digital multimeter to monitor the battery current activity while you're yanking fuses one at a time. There are YT videos on how to do this.
