Ml 280 edition 10 Battery drain.

Casper78

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Feb 3, 2018
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Your Mercedes
Ml 280 CDI 2008
Morning all.
Apologies if this has been posted elsewhere.
We have an ML 280 CDI and it has a really irritating battery drain problem. We initially replaced both the main battery and the auxiliary battery with no luck. We then had a diagnostic carried out by a specialist MB garage who stated it was the stereo head unit that was faulty and they wanted £2700 to replace it. Needless to say we bought an after market head unit which was fitted by a specialist (much better than the standard head unit by the way). Anyway, that still didn't resolve the problem. We then had it re diognosed by an independent company who narrowed the problem down to the alternator. Alternator replaced yesterday and then driven for 1 hour to ensure sufficient charge, returned to the car after half an hour and the battery was dead again.
If anybody can help with this it would be greatly appreciated and probably save my sanity (and bank balance)
Thanks in advance.
 

John Laidlaw

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BMW 530d X Drive Tourer M Sports
Welcome Casper, sorry to hear the problems
Was the regulator changed at the same time do you know?
 

Flyinspanner

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CLK320-A209 (sold CL500 & W168)
Wow, half an hour! That is a big drain.

You could buy a clamp meter which measures milliamperes and clamp it on battery positive cable.
With a fully charged battery, switch the car off, leave it 15 mins - (to allow normal shutdown of systems) it’s important you can see the meter without having to open any door etc. You also need access to all fuses. You note drain showing on meter, then pull a fuse, check if drain has changed. And repeat... hopefully you will get to one which, you pull and the reading drops dramatically- you’ve found your drain.
Do you have keyless go? Door handles can allow water ingress which could cause issues - it will be a tedious process, but if you can narrow it down at least you may be able to give your indie garage a solid direction to look in. I think “normal” drain of up to 60 milliamperes is considered ok. Good luck.
 

Flyinspanner

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CLK320-A209 (sold CL500 & W168)
Actually it’s a massive drain - a 100ah battery dead in 30 mins is a 200a drain!

Get the new battery checked, I had one fail at 9 months, (and we all kind of discounted it as it was so new)
Charge it and take it to Halfords/ or garage with good battery load tester.
 

Werra2006

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Mar 23, 2011
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Location
Oldbury
Your Mercedes
ML 280 CDi 2006
When you run the engine can you hear a little bit of rattling noise?

I had a similar problem and it was the power steering pump and belt that were gone. Bought an aftermarket pump with 2 year warranty for £80 on eBay and got it fitted for £60. In all paid I £160 including the new belt and the problem has not returned. If the pump is wobly and making the belt loose, then the battery is not recharging.........hope this helps
 

LostKiwi

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'93 500SL-32, '01 W210 Estate E240, 02 R230 SL500 (Malcolm Spec), 04 Smart Roadster Coupe
Does this car have a block heater? Thats a high drain item and another member had an issue with this recently.
 

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