Hi all new to site with battery drain issue

Paul hayes

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Hi new to forum my Mercedes 2003 320cdi drains battery in 30mins
Have disconnect all fuses form all fuse boxes and relay
Removed all bulbs but still battery go flat can any one help
 

Blobcat

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Hello and welcome

Moved out into a new thread for you
 

AMGeed

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Where are you located?


It would be best to get the car to an independent Mercedes specialist (indy) who has the correct diagnostic equpment (STAR) to pinpoint the problem. The labour rates at an indy are less than half of main dealer rates and I'd trust one to find the fault quicker too.
 
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Paul hayes

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Hi west London
 
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Paul hayes

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Hi biobcat
Snap tit out !
 

LostKiwi

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'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
Do these engines have a block heater?
That's the usual cause of a bad drain if the battery is good.
 

Blobcat

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Do these engines have a block heater?
That's the usual cause of a bad drain if the battery is good.
W210 did, switch in the ash tray on my yr2000. Later ones were automatic below 5’C
 

Flyinspanner

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CLK320-A209 (sold CL500 & W168)
There can be many causes.

How are you with working on this yourself?

You’ll need a clamp meter.
Place clamp over battery cable, look at drain reading, and I imagine it to be high.

Pull fuses one by one until the drain disappears - you’ve then found the system with the drain. - you then have to decide how to fix that system.
Could be wiring, could be a component?

Headunits sometimes don’t shut down, but to drain a good battery in 30 mins it would have to be a really big drain, something would be getting pretty hot.

How old is the battery? Is it a good make? Have you had it load tested?

I had a battery fail internally/intermittently after 9 months, presenting just as yours. I spent hours chasing the drain.....
Changed the battery and all issues disappeared immediately.

EUrocarparts often have discount codes online to save 30-60% on batteries, it may be money well spent to rule out failing battery before you spend hours chasing down a fault or worse £££ at a garage getting them to try to diagnose.
 

Blobcat

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Regulator packs breaking down can cause an intermittent drain as it depends on where the alternator stops as to if it drains or not. Had that on a 911.
 
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Paul hayes

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Hi many thanks will buy a clamp meter
I have pulled all fuses one at a time
I have disconnected alternater and starter motor
 

LostKiwi

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'93 500SL-32, '01 W210 Estate E240 (RIP), 02 R230 SL500, 04 Smart Roadster Coupe, 11 R350CDi
Hi many thanks will buy a clamp meter
I have pulled all fuses one at a time
I have disconnected alternater and starter motor
Make sure when you buy a clamp meter you get a DC one. Most cheaper ones are AC only (and won't help).
 

Flyinspanner

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I think a drain of 60mA is OK after 10 mins.
(It takes some time for the car to ‘shut down’ after keys out.)
Remove boot interior bulbs or ensure switch is kept pressed.

If you removed all fuses, (front and rear?) is the alternator warm? =diode pack. And have you had battery load tested - Halfords will check for free.
 
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Paul hayes

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I think a drain of 60mA is OK after 10 mins.
(It takes some time for the car to ‘shut down’ after keys out.)
Remove boot interior bulbs or ensure switch is kept pressed.

If you removed all fuses, (front and rear?) is the alternator warm? =diode pack. And have you had battery load tested - Halfords will check for free.
Hi just fitted new battery flat in 1.5 hrs alternator disconnected starter motor disconnected
 

alexanderfoti

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Hi just fitted new battery flat in 1.5 hrs alternator disconnected starter motor disconnected

Not much left, what model is your car?
W210 320 CDI has an fuel powered heater booster.
W211 320 CDI has a PTC element in the dash that could flatten a battery in less than 2 hours.
 

Flyinspanner

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Battery control module? (Don’t know if your model has one?)

Some models have more than one ‘fuse box’ - check them for corrosion.

It’s a massive drain to flatten in 1.5hrs....

Are there any electrical items that don’t work/blow fuse when switched on?

Have you tried with clamp meter, pulling fuses one by one until you see the current drop?

Are the battery cables pinched/chaffed?
 

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