Dead Battery - Help.

[cjcor]

I bought a 2007 S211 220CDI 10 days ago.

This morning, I unlocked the car as usual. The lights came on. Put the kids into their seats. Turned the key, it failed to fire. Tried to turn again, nothing. Now even the key refused to move.

I have now connected the battery to my tickle charger. The indicated voltage is 4! The battery is dead?

Is this the way a normal battery dies? Or is there something amiss?

 

[Giantvanman]

It could be that the alternator has not been charging the battery (the garage could have charged the battery via a charger before giving it to you and it has gradually discharged) or the battery is failing to hold a charge. The battery needs testing as does the voltage coming from the alternator (should be over 14v I believe).
This will give a clearer picture of what's happening.

 

[cjcor]

Many thanks for the quick response. I bought it privately. How would i go about testing the alternator?

 

[cjcor]

I just went back to the car. The charger is now showing 3.4v. So in the space of half an hour the battery has lost 0.6v? Is this possible?

 

[Ted]

Are you sure you are checking the voltage correctly?
If the indicated voltage was 4 then the lights most certainly would not have come on.
Test the voltmeter on another battery.

If the readings you have given are correct, AND the charger is working correctly, then you most likely have a parasitic drain. You will need to disconnect the battery (negative terminal only), charge the battery and locate the cause of the drain.

 

[brucemillar]

Some "intelligent" chargers will not charge a battery that is dead or has very low voltage. Is the charging light coming on in your charger ?(assuming it has a charging light)

You may have to get the car jump started so that you can get enough voltage to test the battery and the alternator.

To test the alternator. You need a volt meter. with it connected across the battery terminals you should see 14.5+ VDC at 2.5K RPM. If you have this then I would think that your battery is dead and needs replacing.

Are you in the AA or RAC? They should come out and test all this for you. Failing that you need to get the battery properly tested or risk replacing it (lose your money) if the battery is not the problem.

 

[mersum1es]

Something is wrong.... Voltage of 'normal' drained dead battery is around 11V. If it has lower voltage than 10V it means that one ore more cells are totally damaged/short circuited/broken.

 

[cjcor]

My charger is showing an error sign, saying it will not charge a battery when it dips below 4.8v. It is constantly dropping. Now down to 3.0.

 

[cjcor]

i am with a breakdown service (not AA or RAC). Will get them down.

 

[Ted]

My charger is showing an error sign, saying it will not charge a battery when it dips below 4.8v. It is constantly dropping. Now down to 3.0.

Ah. That is the first thing that needs sorting.
As Bruce says, many modern chargers will not charge a battery which is that flat.
Still strange that the lights came on and the battery is showing 4 volts.

 

[brucemillar]

Ted

I had this with a caravan/Leisure Battery. My CTEK said it was charging but is wasn't. Hmmmm.

OP. If you get a new battery. Keep an eye for drain (as Ted says) s you may have an underlying issue draining the battery. It may simply be that the battery you have is old and duff. Good luck.

 

[cjcor]

I tried to jump start the car. When I connected the jump leads and turned the key, the clock started moving anti clock wise. The glow plug light went off. I then turned over but it wouldn't start.

 

[cjcor]

Ah. That is the first thing that needs sorting.
As Bruce says, many modern chargers will not charge a battery which is that flat.
Still strange that the lights came on and the battery is showing 4 volts.

Nothing comes on now. The lights came on when I opened the car first thing in the morning. Now, nothing comes on.

 

[cjcor]

I put back everything together, disconnected all jump leads, tickle chargers, etc. Opened the door, the instrument cluster lit up. Turned the key, hey presto everything is working. The car started within minmum fuss!

 

[grumpyoldgit]

Check both battery leads are clean and tight and also the earth strap to the body.

 

[grober]

Sounds like a loose battery connection then- hopefully.

http://www.mbclub.co.uk/forums/electronics/107101-flat-battery-s211-e-class-its-boot.html

 

[cjcor]

command not working. initial logo comes on, but not working.

 

[cjcor]

Sounds like a loose battery connection then- hopefully.

http://www.mbclub.co.uk/forums/electronics/107101-flat-battery-s211-e-class-its-boot.html

Battery connections are rock solid.

 

[dog68]

I had a car that the clock started going anticlockwise, turned out to be the alternator regulator.