Hope someone has an idea!

Last week, having used the key fob to lock the car, within three hours the battery was totally flat as the key fob wouldn't even unlock the doors.

Connected a battery charger across the battery and the charger fuse blew.
Disconnected the battery earth lead and then charged the battery. I got a BIG spark when I reconnected the lead and the car still wouldn't start although the ignition would come on; also the radiator fan started to run (very strange).

I put an ammeter in series with the negative lead and the battery and with the car switched off and totally dead, the current drain was 18 Amps!!!!!

Now obviously something is wrong and the only things I can think of which handle that much current is the alternator or the starter motor.

Don't really have a clue how to go about isolating the problem. I can't start the car to take it to the garage because as soon as I connect the battery to the car, the voltage drops to around 11 volts just after the big spark.

I have tried another battery with identical results and current drain still in excess of 15 Amps.

Help please???!!!!

Foto

 

Hi Fotoflyer,

Sounds like the alternator is not charging back to the battery, have a check on the alternator, if its a starter problem it wont turn or crank.

Let us know your findings, & try to charge the battery back

rockerfella174

 

Have put it into my local garage. They say the battery is completely knackered and are awaiting an electrician to come with the correct diagnosis software. Failing that it will be a tow to the local Merc garage and a remortgage, lol.

Foto

 

Recently I have noted "Auto lights inoperative" warning and wipers going crazy on second intermittent setting with very little rain.

Last evening a neighbour reported the radiator fan working some 2 hrs after stopping. INvestigated and it stopped when bonnet closed.

This morning dead, no alarm no light no....

Local garage tells me that a low battery might set up random activity.

Breakdown man on his way. Will report back

 

Well, I have the car back.

On the 270CDI there is something called a "heater booster". Apparently this is required because the engine is so efficient "53mpg on motorway" that not enough heat is transferred from the engine into the heater system to get any heat into the interior. So a heater booster element is used to keep the coolant temperature up. It shorted to earth which is why the battery drained so quickly. Total cost £1,200!!!!!!!!!

I suppose if one is going to run a Merc, one has to be prepared for the maintenance costs. I've only just stopped crying, lol.

Foto

 

C280 has been in garage for a day. Lots of relays had tripped out but no indication of what caused the massive short out of battery. Computer man with "box of tricks" arrives today, sounds expensive. Disheartened by C270 cost.