All electrical items shut off after a few minutes.
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From: Suburban Washington DC
1995 S280 5-speed
All electrical items shut off after a few minutes.
New to me 2007 S550. It starts just fine but if I turn it off, after a few minutes, everything seems to be dead. The remote won't lock or unlock the doors or trunk. None of the doors pull-in closing works.When I open the drivers door, the gauge cluster stays off and the power seats don't work.As soon as I put the key in the ignition, everything comes back to life. But..............the cluster randomly turns off again in 30 seconds or a minute or two even with the ignition on. It was cutting out half a dozen times while trying to scan for codes. This doesn't happen when the car is running. And I left it unlocked and just now the alarm went off. If I disconnect both batteries, will that keep the alarm off? Any thoughts on the issue?
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S500
what size is the front battery? if its a small 35amp one then there's a massive one in the boot hidden - few people change either
these eat 37 amps with just the key on - very few batteries cope even when brand new -
these eat 37 amps with just the key on - very few batteries cope even when brand new -
Thread Starter
Super Member
Joined: May 2002
Posts: 540
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From: Suburban Washington DC
1995 S280 5-speed
The front one is a Mercedes battery so it could be original? The rear is aftermarket. I'll test them and also connect a programming charger to see if these issues stop. I did notice the voltage drop to 11.79 volts while using the scan tool.
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2007 S600, 2007 Chrysler 300 SRT8, 2000 C5 Corvette, 2017 Mustang GT, 2023 300C, and a 2019 Lincoln
When the big consumer battery in the trunk starts to fail, the car slowly turns off all electrical components due to low voltage. The big battery in the rear usually lasts about 10 years or so depending on how well maintained the car is. If your charging system is sub-par, the battery will die much sooner. You need 12.0 volts at rest. You need 14.2 volts while running. Anything less and you will have problems. Check that serpentine belt for any looseness around the alternator which would cause low charge. Keep us posted.
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Very low. Incidentally, most trickle chargers won't charge when the voltage of the battery is lower than 9 volts. You may not have any success charging that big mother in the trunk. Some posters have pulled the cell covers and added distilled water to cover the tissue and then try to charge it. All other things being equal, I would just replace it for reliability.
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S500
charge them for 48 hours - then turn the key on and 20 mins later the volts will be under 12v again - they pull far too much current - the ONLY action is drive it or add a power supply if you need to do diagnostics
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From: Suburban Washington DC
1995 S280 5-speed
Charger stops charging after 15 minutes as a safety measure. Battery is toast. Got an H8 in the basement that's been on a maintainer for years waiting to be used. Tests at 895 CCA. It's not an AGM though. How important is that? Really wondering how old the battery in the car is.
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Not surprised at dead consumer battery. Could be due to age (probably) or it could be due to poor charging system. Swap that big mother and start it up and let it run. Better yet, take it for a ride for twenty minutes. Then check both running and non-running voltage. You need 12 at rest and 14+ running. If not, report back here.
Good luck. Keep us informed.
Good luck. Keep us informed.
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From: Washington, DC
2007 S600, 2007 Chrysler 300 SRT8, 2000 C5 Corvette, 2017 Mustang GT, 2023 300C, and a 2019 Lincoln
All the more reason to check the serpentine belt, belt tensioner, and pulleys for slippage on the alternator reducing the charge. Smart money says a battery really dated 5/23 was killed by a bad charging system. If belt is tight, check output voltage of alternator. Could also be a bad alternator.
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2007 S600, 2007 Chrysler 300 SRT8, 2000 C5 Corvette, 2017 Mustang GT, 2023 300C, and a 2019 Lincoln
And if the charging system checks out good, and you kill this newer battery you replaced in the trunk; then you have a parasitic drain. But before we go there, let us know about the newer battery and its voltages at rest and running. We try to do a full diagnosis here.
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as Mercedes cars age they all seem to get more voltage hungry - the likely explanation for that is more and more electronics ageing means magically (as designed) volts waste away and in worse cases modules forget to fall asleep as they were supposed too
most owners never have an issue if they drive at least 10 miles a week
but if you're a hoodie wanting to loiter about upsetting people and listening to crap on the radio when parked or the even younger generation wanting to view mind rot trash on video sources - go buy a power station and plug it in if expecting it to work for more than 3 minutes
most owners never have an issue if they drive at least 10 miles a week
but if you're a hoodie wanting to loiter about upsetting people and listening to crap on the radio when parked or the even younger generation wanting to view mind rot trash on video sources - go buy a power station and plug it in if expecting it to work for more than 3 minutes
