Battery Kill Switch

[Barrowboy944]

I am having an issue with the battery going flat (ML430)....the battery is fine (if disconnected its ok) so somewhere there is a drain that cannot be found thus far; rather than throw money at a problem that may never be fixed properly I am thinking of fitting a battery kill switch. Can anyone advise of the amperage I would need to consider as there are so many options online.

Thanks

Paul

 

[BTB 500]

Cranking a big V8 with cold oil would be hundreds of amps. Maybe look at jump leads rated for engines of approx. 5 litres and see if they quote a current rating.

Alternatively find somebody with a clamp ammeter who can measure the actual current being drawn when you start it up (then add a safety margin on top). An auto electrician would obviously be able to do this.

 

[Ted]

At a guess I would say around 500 amps to be safe.

 

[RBYCC]

What problems will you have in resetting electronics everytime you disconnect the power ?

 

[Auto-mobile]

What problems will you have in resetting electronics everytime you disconnect the power ?

Stereo
Clocks
One touch on the windows
Bas/ESP

 

[dog68]

Can you not detect the battery drain? a kill switch is only a temporary fix IMHO.

 

[carat 3.6]

You can find a battery drain with a cheap multimeter, realy not that hard to do.

 

[Barrowboy944]

carat If you could advise the best way to find a drain I would appreicate it......the previous owner left it with MB for 8 days & they found nothing...2 days after he got it back the battery was flat again.....not sure if its intermittant or just they couldnt be bothered to check...

my previous experience with main dealers of the MB kind is to stay away at all costs!!!

 

[dog68]

^ spam reported.

 

[RBYCC]

carat If you could advise the best way to find a drain I would appreicate it......the previous owner left it with MB for 8 days & they found nothing...2 days after he got it back the battery was flat again.....not sure if its intermittant or just they couldnt be bothered to check...

my previous experience with main dealers of the MB kind is to stay away at all costs!!!

Paul

There are a few methods to find the parasitic drain.
Typically removing the earth cable and put a multimeter in series with the negative post and earth cable.
The amp/milliamp reading will give you the value of the parasitic loss.
From there it's usually going to the fuse box and removing one fuse at a time until you discover the parasitic loss.

There is a neat fuse adapter which eliminates the battery disconnection.
Remove a fuse, insert the adapter and the circuit load is read.
This is what auto electric specialist shops in the USA use.
There is a much more comprehensive series of adapters made by Pulsar (#9030), but all you need is the most common standard blade fuse adapter

I did a search and found UK source...not familiar with them as I'm in the USA

http://www.google.com/url?sa=t&rct=...JPWTpXFkCmCDQBSeLyRIw&bvm=bv.1355534169,d.dmQ

http://www.amazon.co.uk/dp/B003A60GU0/?tag=amazon0e9db-21

You want to focus on circuts that are energized all the time.
Most Mercs have an inherent battery drain problem due in most cases to the alarm/security systems.

In the winter unless I'm driving a car everyday, I install battery tenders to assure no dead battery !!

Ed A.

 

[grumpyoldgit]

carat If you could advise the best way to find a drain I would appreicate it......the previous owner left it with MB for 8 days & they found nothing...2 days after he got it back the battery was flat again.....not sure if its intermittant or just they couldnt be bothered to check...

my previous experience with main dealers of the MB kind is to stay away at all costs!!!

Here's a video of the procedure to follow How To Perform a Parasitic Draw Test - EricTheCarGuy - YouTube

Alternatively is there an good Auto Electrician in your area.

Could also be worth getting the alternator checked as diodes or the in built regulator can fail and cause a drain. (Had it happen on a Ford).

 

[cl55 amg]

I had the same issue on my CL55 it went to 2 recommended auto electricians for a total of 4 days and both couldn't find any issues.. the car would last 4 days without being driven before the battery went flat.

 

[Barrowboy944]

Thanks guys for all the info thus far ..will try the various methods & report back...any other advice welcomed.

Regards

Paul

 

[mersum1es]

Not sure how sensitive CAN buses of your ML are (whats the model year?), but be sure that your car is in a 'sleep' before start pulling fuses...

 

[nigel cross]

try unplugging the electric seats

 

[Barrowboy944]

The car is a 2001 "X" reg model........can you advise how long it is before the car "goes to sleep"

Thanks

 

[paul m]

approx 20/30 mins

 

[kris83]

my father in law had a 190e with a kill switch fitted in the glove box and i cant remember why he said it was fitted . Just spoke to my father in law and he mentioned a light under bonnet that didnt go of when in was closed causing the drain at the battery

 

[kris83]

i know you have said the battery is fine (when disconnected) but have you had it tested for a faulty cell. when its connected to the car it is under load due to alarm system so will drain quicker. Off the car its subjuect to no load so wont drain as quick. most battery suppliers will test the battery and alternator for free. hope this helps .