Jump Starting a s320

[gtie]

Hey all!

Maybe someone here can answer an arguement that arose recently .

Firstly Id had better explain what happened

An associate of mine recently came into possession of a 94 S320.
On the secound day the car was in his possession, had the misfortune of leaving the lights on overnight and running down the battery.

He proceded to jump the Benz with the (battery still in the car) from a charged battery on the ground.( Connected Positive to positive and Negative to Negative). (Charged Battery was not connected to any car)

What happened when the car started was the wipers would not work / Indicators stayd on in hazard mode and Rear window heater would not work.

Diagnoises was made that the Module that controlled these had blown as well as the unit that sits in front of it ( Back up unit).

Arguemnt that has arisen is

1) Were the Units blown by the " Jumping Starting"

and if so why ....as the batterys were in parallell ...so wouldnt the voltage be the same.



or is this just a coincidence and the units were adout to go anyway .

Thanks

 

[type49]

Hey all!

Maybe someone here can answer an arguement that arose recently .

Firstly Id had better explain what happened

An associate of mine recently came into possession of a 94 S320.
On the secound day the car was in his possession, had the misfortune of leaving the lights on overnight and running down the battery.

He proceded to jump the Benz with the (battery still in the car) from a charged battery on the ground.( Connected Positive to positive and Negative to Negative). (Charged Battery was not connected to any car)

What happened when the car started was the wipers would not work / Indicators stayd on in hazard mode and Rear window heater would not work.

Diagnoises was made that the Module that controlled these had blown as well as the unit that sits in front of it ( Back up unit).

Arguemnt that has arisen is

1) Were the Units blown by the " Jumping Starting"

and if so why ....as the batterys were in parallell ...so wouldnt the voltage be the same.



or is this just a coincidence and the units were adout to go anyway .

Thanks

Malc may correct me here as this is his speciality The alternator on this car can give out over 100 amps & will power the items on the car first & the battery gets whatever is remaining. A totally flat battery cannot except much of a charge, making it possible to overcharge other systems. It is recommended that when jump-starting one of these cars, you switch the lights & blower motor on before cranking, so there is somewhere for the amps to go. Does this make sense??

 

[television]

Malc may correct me here as this is his speciality The alternator on this car can give out over 100 amps & will power the items on the car first & the battery gets whatever is remaining. A totally flat battery cannot except much of a charge, making it possible to overcharge other systems. It is recommended that when jump-starting one of these cars, you switch the lights & blower motor on before cranking, so there is somewhere for the amps to go. Does this make sense??

You are correct,some wrong or misleading info given out by MB, they say that the heated rear window is the best to load the system, but as that is key 2 a lot more is turned on. The joke is you cant turn it on with a flat battery. Saying this the SAM (the bit that had to be replaced) is live the whole time
so the headlamps are as good as any.

malcolm


Malcolm

 

[gtie]

Thanks

Thanks!



J.P

 

[jberks]

I know there have been other discussions , but i'm still a bit unclear on this.

Are we saying that the correct procedure for jump starting a Merc is to switch on dipped headlights to soak up any surge first and then connect a battery or other car?

Presumably the same procedure applies if you install a new battery too?

What's the safest procedure if you have to give someone else a jump start?

Assuming we can reach a consensus, perhaps this should be a sticky thread on the electrical section.

 

[television]

I do intend to put together some sensible answers to the starting of cars.

MBs guide has not been thought out very well, as I said earlier, you cant turn on heated sets or the window as they are Key 11 and key 11 is not accessible when the battery is flat.

Malcolm

 

[kth286]

gtie

Your associate had better fix his "lights on" warning buzzer that is fitted as standard on those cars and is obviously not working.

It should activate as soon as the key is removed from the ignition.

 

[gtie]

Thanks

Ill pass it on

 

[eric242340]

So now your the expert and not MB? I despair, Malcolm try to get this right and it would be better if you did not challenge MB, you will loose

Malcolm[/QUOTE]

 

[mad-dan]

Also, can I ask, when jump starting a car, is it not the correct procedure to connect the negative on the car with a flat battery, to a grounding point rarther than directly to the battery?

 

[eric242340]

Also, can I ask, when jump starting a car, is it not the correct procedure to connect the negative on the car with a flat battery, to a grounding point rarther than directly to the battery?

Connecting direct to the battery is fine, but connect the ground first.

 

[mad-dan]

Connecting direct to the battery is fine, but connect the ground first.

After checking my hand book it would seem you are correct, i was sure i had read some where that you shouldn't tho, it must of been with one of my old cars.

anyway, i did notice someone said earlyer in this thread you should turn your lights on when jump starting, my had book tells me i should not. it says turn on the heater but NOT the head lamps.

I dont have a scanner, but I have taken a picture of what it says.

here's a link to the picture

http://img129.imageshack.us/img129/4697/jumpstartdt8.jpg

Hope that is of use to someone.

 

[television]

So now your the expert and not MB? I despair, Malcolm try to get this right and it would be better if you did not challenge MB, you will loose

Malcolm

[/QUOTE]

Don not spoil every thread eric.
The wording from MB says for the 203 and 210 and 211
" when jump starting it is better to turn on the heated rear window and heated seat, rather than use the headlamps"

I can understand their reason for this,as the seats and window can accept voltages in excess of 17v and the bulbs cant. Also cars with rear SAMs are active all of the time, but not the logic, as I said earlier if anyone knows how to activate these on a flat battery then do tell me of my wrong thinking. They are key 2, whilst if you can turn the key with EIS you cant turn the window and the seats as they are logic controlled. no voltage = no logic its not rocket science. You may as well try and set a mains time switch during a power cut.


I think that if I told MB of this they may re word the whole thing.

 

[jberks]

The wording from MB says for the 203 and 210 and 211
" when jump starting it is better to turn on the heated rear window and heated seat, rather than use the headlamps"
.[/QUOTE]

I assumed that these would come under the 'comfort' features that shut down under low voltage. So, you couldn't switch them on.

 

[Ultymate]

The safest way of connecting jump leads is make the positive connection on top of the battery then make the earth to a good point on the chassis away from the battery that way no flash sparks around the top of the battery, same thing at the donor end as well, no risk of igniting any hydrogen this way :wink:

 

[television]

The wording from MB says for the 203 and 210 and 211
" when jump starting it is better to turn on the heated rear window and heated seat, rather than use the headlamps"
.

I assumed that these would come under the 'comfort' features that shut down under low voltage. So, you couldn't switch them on.[/QUOTE]

This is my point JB, either way way, battery too low to crank or flat, it is not possible to turn these on.

The always active part of the car is the rear SAM. Computers,TVs and other electronics fail at switch on, and hardly ever when running. A variable power supply starting at Zero and then winding up to the 12.5 volt would be the perfect answer, but not practical to use once say in every 5 years.

My Local garage man said yesterday that at Heathrow they have a man just for starting MBs.