Battery Drain

[Michel]

My 1999 CLK320's battery goes flat after a few days being parked.
I thought the battery might have been on its way as it was more than four years old
So I bought a new battery and it's still doing the same.
Two days and it's dead as a door knob.

I called the electrician who checked it right through.
The battery is in excellent condition and there are no leaks in the car.

He reckons the alternator might have a faulty diode or two and thus is draining the power from the battery after being stopped for a day or so.

Any one encountered that problem?

 

[SEL_69L]

If the car is only being driven only occasionally, install a battery isolator switch. I have one on my car. All you have to do is lift the bonnet and turn a knob on top of the switch assembly.

It won't cure the problem of the battery draining, and the dashboard clock will have to be re set and the radio re tuned, but I never use those items anyway.

I don't drive my 6.9 often enough, but I DO give the battery a re charge once a week to kid the battery as if the car is being driven often.

The battery in my 6.9 is now more than SEVEN! years old.

Also helps if you have a four pin (rather than a five pin) fuel pump relay.
When you turn the ignition switch, the fuel system pressurises instantly like most other cars, rather coming up to full pressure over about four seconds.
The engine starts on first compression every time, thus stressing the battery much less.

 

[BenzBoy]

Might be simpler to fix the problem rather than rely on an isolator switch - and then you won't be left wondering if the car will work or not...(did I turn off the isolator or not).
Regards,
Brian

 

[Michel]

Might be simpler to fix the problem rather than rely on an isolator switch - and then you won't be left wondering if the car will work or not...(did I turn off the isolator or not).
Regards,
Brian

Indeed... I was wondering if anyone had faced that kind of problem before

 

[Styria]

The faulty alternator sounds a more than plausible symptom -at least with a car that's not jam packed with computers, sensors and microprocessors. I tend to think that your Convertible may have its fair share of any of those units.

On Gleaming Beauty, some six weeks ago, I noticed without warning that the alternator light stayed on - there had been no warning signs, except that I would disconnect the battery to stop the electrical system from 'draining' the battery - that's what Ii suspected, but I have been proven wrong since. Some of you might recall one of my threads in which I described the symptoms of a 'weak' battery. The culprit, of course, turned out to be the alternator. Maybe some of this may help - possibly also that Helmet, with his experience, may be able to advance some clues. Regards. Styria

 

[Helmet]

H Michel.

Try unplugging the seat modules and see if it still goes flat. Its a common problem. If its not one of them I have a CAN tester that can tell what control unit is not going to sleep. If the alternator is charging OK I doubt that its drawing current.
Another simple option would be to install a Ctek trickle charger, I think this would be a wiser option than an isolator switch.

 

[SEL_69L]

I mainly use a toroidal ring trickle charger once a week, not the isolator switch. The bonnet has to be opened for both. The charger always sits on a bench, directly in front of the bonnet star.
No need to set the charger up. Just lift the bonnet, and connect to the terminals

 

[Afro107]

Most trikle chargers will push the battery well above 15V and that can damage electronics. Exllent for intermittent use if charger is less than 3A and battery is disconnected from the car but may require demineralised water top up.

Decent 3 stage chargers cost ~$50 and do exccellent job in recharging (constant current), equalising (14.99V) and maintaining (13.8V) the battery.

what puzzles me is that an auto electrician "checked" for leaks (and found none) but could not check the alternator

 

[WiSeGuYY]

one of my friends in france use charger to conect to his parked cars which not in use to make sure the battery is not dead .

tarek

 

[RANDYS]

I have a similar era c203 and can leave it for weeks no worries. So it is not the nature of the beast to run down a battery quickly even running the security system.

You have a drain: Either -

a systems device which is covertly sucking the juice
: BUTthis has been tested and dissmissed.
[


I have heard of the dodgey diode in the alternator theory before- rather than sitting fat dumb and happy when not turning, it is quietly discharging the battery: This is testable and should be explored.



Or you have a standard device -eg a boot light- that is not switching off.

In all scenarios an auto lectrican should be able to measure drain from the battery. I am guessing about 1 amp or 12 watts if it takes 2 days/nights. About 1 light globe's worth.

While you think about arranging the auto electrican again, charge the battery..disconnect the earth for 2 days..reconnect and hey presto!.bet it starts.

It will just prove there is a drain..it has to be scenario 2 or 3 and i'm favouring 3 from 2000kms away.

 

[Michel]

Thank you all for the multiple scenarios and suggestions.

I'm going to charge the battery and then park the car and disconnect the alternator cable and leave it for a few days.

If by then it is flat again, then there's definitely a drain.
If it is still charged, then the culprit has to be the alternator.

 

[SEL_69L]

Dunno about battery chargers pushing above 15 volts. My charger is volt limited to 13.5 volts. When the battery lifts to 13.5 volts, there ain't no more charging, irrespective of a mistake of forgetting and leaving the charger connected indefinitely.

It's a bit overfilling a bucket: when it gets full, it can't get any fuller.
When the battery gets to 13.5 volts and equals the delivery voltage of the charger, there is no nett flow between either of them, either way.
No nett potential, therefore no flow.

 

[Michel]

I did the exercise of charging the battery and then leaving the car parked for a few days with the alternator disconnected.

And, the battery went flat presto!

 

[BenzBoy]

Clearly time for a new car ......

 

[Michel]

Clearly time for a new car ......

But Paula loves this car, the colour, the driving and the wind in the hair...

 

[BenzBoy]

But Paula loves this car, the colour, the driving and the wind in the hair...

Ah yes, but I am sure Paula would like something reliable - http://www.rolls-roycemotorcars.com/phantom-family/phantom-drophead-coupe/
Regards,
Brian

 

[motec 6.9]

Hi Michel i had a talk last night with a friend who is electrician. He supported Helmet about the seats being a possible fault in door module. He also said check if boot light remains on and leaving key in will cause a 300ma drain. Hope this helps i/would take helmet up on his offer as it seems to be very common fault with this model.

 

[Michel]

Ah yes, but I am sure Paula would like something reliable - http://www.rolls-roycemotorcars.com/phantom-family/phantom-drophead-coupe/
Regards,
Brian

Dear Brian,

Paula is very grateful for your offer.
Although she prefers a lighter colour, she'll gladly accept that one

 

[Michel]

H Michel.

Try unplugging the seat modules and see if it still goes flat. Its a common problem. If its not one of them I have a CAN tester that can tell what control unit is not going to sleep. If the alternator is charging OK I doubt that its drawing current.
Another simple option would be to install a Ctek trickle charger, I think this would be a wiser option than an isolator switch.

How early do you open on Monday?
I could drop it around 7:30am as I'm catching a flight o/s for a few days.
Any chance of a lift to the international terminal?

 

[Styria]

How early do you open on Monday?
I could drop it around 7:30am as I'm catching a flight o/s for a few days.
Any chance of a lift to the international terminal?

Try and ring Helmet on his mobile. If you haven't got the number, give me a call. Regards Styria