Battery drain

[Hunty2198]

My battery keeps dying to the point it reads 3-4v. I've had the battery tested 3 times by different people and there is nothing wrong with it. I've been told it could be an intermittent relay fault. How can I diagnose the problem and get it fixed? W219 model CLS 63 AMG

 

[optimusprime]

So now its time to get the alternator checked for the charging rate , also ..On older mercedes cars the alternator regulator will do this battery drain over might .

 

[Lyserman]

Either get it to a good indie or buy one of these to suit the fuse holder
Car Fuse Current Amp Meter Battery Electrical Leakage Detector Tester | eBay

Then get the battery charged up and test each fused circuit until you find the culprit.

I would be tempted to get it on STAR first, that should tell you if something major has a fault. Could save a lot of time and money.

The alternator diode pack was another thing I would get checked... Oh! beaten to it.

 

[andy27168]

Hi,
I believe cars built after mid 2006 STAR can read the quiescent current draw if it exceeds certain values, so this should give a good indication on where to start looking.
Is everything in the car working as it should? electric seats and the memory windows etc. Alarm, electric steering column etc?

 

[HumberMart]

I was plagued with this on 2 different Crossfires (same as SLK).

First one was due to the resister that had blown on the heater fan motor, due to water leaking in through the air ducting. This is also common on old SLK's as you may guess.

The second one was a real pig to find, and I had to buy one of those devices listed above (although from Maplin).

It turned out to be the alarm system, but was easy to fix..... I just disabled it!

Then had the same problem on a Dodge Nitro, they have a common problem where the CANBUS just chooses to wake up on a night for no good reason, powering up a few systems. It's not a problem whilst in daily use, but if like our was, an occasional use vehicle, it became a real pain. I actually solved it by accident. I replaced the OEM head unit to one from China with a satnav built in. This involved fitting a £100 box to fool the CANBUS and stop it looking for the OEM head unit. This also stopped the battery drain!!! (think it was the power amp in the boot that was being switched on during the night)

 

[Hunty2198]

I've had the alternator checked and is fine. I have had problems with the radio/Satnav so it may be related to that. Will get STAR to run a check of the system and hope it will find the problem. Anywhere in the south that has STAR? Near Poole or Salisbury?

 

[andy27168]

I've had the alternator checked and is fine. I have had problems with the radio/Satnav so it may be related to that. Will get STAR to run a check of the system and hope it will find the problem. Anywhere in the south that has STAR? Near Poole or Salisbury?

Hi,
You have Startech in Poole
Home | Star Tech service centre Poole
Or Pentangle in Totton,
Home Page - Pentangle MB Ltd
I am also in Totton and have a STAR set up, if you wanted me to plug your car in.