Jump Starting

[CrustyClam]

Ok, so I think I mucked up a jump start looking at utube videos.

Had a few instances over a period were it seemed starting the car was a bit laboured. Did some some bits and bobs with doors and tail lift opens internal lights on for a few hours.Recently only done a few short journeys.

Anyway had a complete failure to start at the worst time as I needed to get my dog to the vet, no crank whatsoever. (Still need to get there but stuffed now until I have my car)

Suspecting battery and in haste I jump started with the wife's car, but I did it with the her engine running to What I suspected was a complete dead battery.

Great stuff mine sparked into life, sadly though with an error message to drive to the workshop without changing gear for the first time ever. I couldn't drive it for 15mins as I couldn't get it out of Park. But after a decent idle and a few turns off and on managed to get it into Drive.

Anyway my local Indy let me bring it down straight away after I explained the warning. (A big thanks to them) The battery is confirmed as caput, but until replaced won't be be sure if the error message which is related to the intelligent servo module is an actual fault or related to such a low battery condition.

Searching utube I did find an video when someone jump started there ml and afterward they needed the ISM replacing.

My question is really and the bumf above is to give context;


What is the correct procedure for jump starting, should I have done it when the other car was turned off and not up but not running? Reading comments about leaving the key out, should I have left out in my car, before I tuenwd on the wife's car.

I did check manual but it wasn't specific. Normally I'd take my time in doing such things, but was rushing to try and make an appointment time.

Cheers

 

[Tony Dyson]

Jump Starting a car

1. Budget jump leads are not suitable for today’s modern engines especially DERV
2. Position the two cars so your jump leads will reach both batteries
3. Lift the bonnets of both vehicles and turn everything off in both vehicles.
4. Ensure the vehicles do not touch and are in N or P
5. Do not lock, remove the keys from the vehicles and place out of transmission range.
6. Connect the red jump lead to the +ve (RED) jump starter post in the car you’re starting
7. Connect the other end to the donor car +ve battery terminal
8. Connect the -ve (BLACK) jump lead to the donor car -ve battery terminal
9. Connect the other end to the -ve jump starter post in the car you’re starting
10. Ensure the cables will not foul any moving parts in either vehicle
11. Start the (Flat Battery) car by the usual starting procedure and run at idle speed for 2 Mins.
12. Turn on lights and heavy consumers run at idle speed for 2 Mins
13. Disconnect jump leads in reverse order, turn off lights and heavy consumers.
14. No need to start the donor car or rev your engine above idle speed.

 

[ajlsl600]

Ok, so I think I mucked up a jump start looking at utube videos.

Had a few instances over a period were it seemed starting the car was a bit laboured. Did some some bits and bobs with doors and tail lift opens internal lights on for a few hours.Recently only done a few short journeys.

Anyway had a complete failure to start at the worst time as I needed to get my dog to the vet, no crank whatsoever. (Still need to get there but stuffed now until I have my car)

Suspecting battery and in haste I jump started with the wife's car, but I did it with the her engine running to What I suspected was a complete dead battery.

Great stuff mine sparked into life, sadly though with an error message to drive to the workshop without changing gear for the first time ever. I couldn't drive it for 15mins as I couldn't get it out of Park. But after a decent idle and a few turns off and on managed to get it into Drive.

Anyway my local Indy let me bring it down straight away after I explained the warning. (A big thanks to them) The battery is confirmed as caput, but until replaced won't be be sure if the error message which is related to the intelligent servo module is an actual fault or related to such a low battery condition.

Searching utube I did find an video when someone jump started there ml and afterward they needed the ISM replacing.

My question is really and the bumf above is to give context;

instruction ,should be in yr owners handbook .all mine have it in them


What is the correct procedure for jump starting, should I have done it when the other car was turned off and not up but not running? Reading comments about leaving the key out, should I have left out in my car, before I tuenwd on the wife's car.

I did check manual but it wasn't specific. Normally I'd take my time in doing such things, but was rushing to try and make an appointment time.

Cheers

 

[rorywquin]

Jump Starting a car

1. 
   
2. No need to start the donor car or rev your engine above idle speed.

My owners manual disagrees and I have always followed the procedure below.......connecting both batteries can quickly drain the donor battery if the recipient battery is very flat....

 

[Tony Dyson]

My owners manual disagrees and I have always followed the procedure below.......connecting both batteries can quickly drain the donor battery if the recipient battery is very flat....

View attachment 52225

Well I don’t think there’s a wrong procedure between the two, “there’s always more than one way to skin a cat” I believe the philosophy behind not starting the donor car is to mitigate the vulnerability of the donor car’s electrical and electronic components by keeping it switched off, perhaps not knowing entirely what the failed battery problem really is, if the car you’re trying to start doesn’t start after the first couple of attempts, you could always start the donor car then to prevent a flat battery.

 

[rorywquin]

Well I don’t think there’s a wrong procedure between the two, “there’s always more than one way to skin a cat” I believe the philosophy behind not starting the donor car is to mitigate the vulnerability of the donor car’s electrical and electronic components by keeping it switched off, perhaps not knowing entirely what the failed battery problem really is, if the car you’re trying to start doesn’t start after the first couple of attempts, you could always start the donor car then to prevent a flat battery.

Tony, I'd imagine that a current SL has a pretty sophisticated electrical system - The MB manual in my car recommends running the engine of the donor car......

Problem with connecting a "good" battery to a "bad" battery is that the batteries immediately try to equalise their voltages......boiling electrolyte and other nasties including melting rubbish jumper cables, and ruining the donor battery can happen....

 

[Tony Dyson]

Tony, I'd imagine that a current SL has a pretty sophisticated electrical system - The MB manual in my car recommends running the engine of the donor car......

Yes, I’ve read it and I don’t wholly disagree with it, it is in fact in line with most generic advice re jump starting cars, but I believe it is safer practice today not to have the donor engine running for the jump start process for the reasons I have stated earlier.

...
Problem with connecting a "good" battery to a "bad" battery is that the batteries immediately try to equalise their voltages......boiling electrolyte and other nasties including melting rubbish jumper cables, and ruining the donor battery can happen....

Surely if the 1st car creates such symptoms when connected to a donor battery the last thing you should be doing is attempting to start the engine of the donor car transferring that level of demand onto the Alternator, Voltage regulators and BCM to mention a few. A battery in that condition needs removing from the vehicle and professionally testing and repairing if possible.

Let’s not get out of perspective here, if we’re talking about the temporary below par discharge of a normally working battery that just needs a helping hand then a jump start from a healthy battery will do the trick 9 times out of ten, a deep cycle discharge needs repairing and that needs removing from the car and workshop treatment.

 

[CrustyClam]

Thanks guys,

Looks like I almost did the second procedure, but I should have started the wife's car, then connected the negative terminal. Both leads were connected when I started the wife's car.

Anyway will just have to wait and see if ISM is damaged through jump start, or reporting fault due to faulty battery. Gonna kick myself if I broke it through jumping it.

 

[John Laidlaw]

MB specifically don’t like spikes for some reason more than any other brand. That said they usually just go in the huff for a few hours

 

[CrustyClam]

Fingers and toes crossed it's just a huff

 

[rorywquin]

Yes, I’ve read it and I don’t wholly disagree with it, it is in fact in line with most generic advice re jump starting cars, but I believe it is safer practice today not to have the donor engine running for the jump start process for the reasons I have stated earlier.


Surely if the 1st car creates such symptoms when connected to a donor battery the last thing you should be doing is attempting to start the engine of the donor car transferring that level of demand onto the Alternator, Voltage regulators and BCM to mention a few. A battery in that condition needs removing from the vehicle and professionally testing and repairing if possible.

Let’s not get out of perspective here, if we’re talking about the temporary below par discharge of a normally working battery that just needs a helping hand then a jump start from a healthy battery will do the trick 9 times out of ten, a deep cycle discharge needs repairing and that needs removing from the car and workshop treatment.

Yes Tony you know better than the people that built the car......you are correct and MB are confused.

 

[pgh13]

I suspect that the people who built the car would say; 'Go straight to a dealer and buy a new one!' But maybe I'm just suspicious and distrustful,

 

[Tony Dyson]

Yes Tony you know better than the people that built the car......you are correct and MB are confused.

Your last comment is petulant and unhelpful. Comment on the post, not the poster.

Advice from MB is for the jump starting of a car with a failed battery and does not provide any specific advice for the donor car and secondly, would you seriously expect MB to caveat the potential for unexpected damage to electrical/electronic components to a donor car in the jump starting procedures? I think not, as pgh13 has already alluded to, they would welcome the owner and their cheque book to help them fix it. While I’m on the subject I also have a second issue with the MB procedures and that is advising the customers to connect and disconnect jump leads while the donor car’s engine is running... really?

 

[rorywquin]

Your last comment is petulant and unhelpful. Comment on the post, not the poster.

Advice from MB is for the jump starting of a car with a failed battery and does not provide any specific advice for the donor car and secondly, would you seriously expect MB to caveat the potential for unexpected damage to electrical/electronic components to a donor car in the jump starting procedures? I think not, as pgh13 has already alluded to, they would welcome the owner and their cheque book to help them fix it. While I’m on the subject I also have a second issue with the MB procedures and that is advising the customers to connect and disconnect jump leads while the donor car’s engine is running... really?

You are determined to defend your, according to MB instructions, incorrect first post.

I was actually being very helpful by posting an extract of the owners manual. You then decided to find fault with what MB recommend and I gave a well balanced response which you again, had to dispute.

Apologies if you are offended by me calling you out on your procedure. I'll follow the MB recommendation and not yours!

PS I was being sarcastic...not petulant!

 

[Tony Dyson]

You are determined to defend your, according to MB instructions, incorrect first post.

I was actually being very helpful by posting an extract of the owners manual. You then decided to find fault with what MB recommend and I gave a well balanced response which you again, had to dispute.

Apologies if you are offended by me calling you out on your procedure. I'll follow the MB recommendation and not yours!

PS I was being sarcastic...not petulant!

I don’t know from where you got “Your, according to MB instructions” statement from because it wasn’t me! Maybe this is the reason for your initial misinterpretation and responses to my first post? I read the section in my OM as I’m confident that most owners have done in theirs and didn’t agree with it on the two points I’ve mentioned, starting the donor engine and connecting/disconnecting jump leads with the engine running, these are the reasons I didn’t quote MB verbatim initially and provided my own opinion of how to jump start a car, MB or not.
No-one is obliged to either agree or abide by it and there’s no need to apologize for ‘calling me out’ as I will always be prepared to provide the philosophy behind an opinion if asked, especially when a recommendation flies in the face of popular opinion, indeed, up until reading all the horror stories on this and other forums over the last Year, associated with the susceptibility of MB and other manufacturers Controllers to external electrical anomalies, I too would have started the donor engine to get a little charge into the recipient battery to aid starting but not any more, the potential risk is far too great to the donor vehicle for the benefits, in my considered opinion, not MB’s. Your sarcasm didn’t escape me so I’ll settle for Petulant with sarcastic comment

 

[CrustyClam]

Thankfully all ok now the new battery fitted. Phew!

 

[John Laidlaw]

Thankfully all ok now the new battery fitted. Phew!

Good to hear, typical MB behaviour then !

 

[rorywquin]

I don’t know from where you got “Your, according to MB instructions” statement from because it wasn’t me!

You seem to have misread what I wrote.

Applying the rules of grammar, the use of commas in my sentence means.

"According what the MB user manual tells the user to do, the method you recommended in your first post (not starting the donor car) is incorrect."

 

[Botus]

on modern car's you seldom connect to the battery, you may damage something....

ones with sensitive electronics have (or should have) both a dedicated earthing point and a separate positive connection neither of which are the batteries own terminals

I would always have the donor car running prior to the last connection to the flat car.... and as alternators make better volts and amps at 2000 rather than tickover I always bring up the donor car's revs and hold around 2k, if its really dead I even wait a few mins before cranking the flat one over

here u go just found this

http://www.mercedesmedic.com/how-to-jump-a-mercedes-benz-the-right-way/

 

[rorywquin]

on modern car's you seldom connect to the battery, you may damage something....

ones with sensitive electronics have (or should have) both a dedicated earthing point and a separate positive connection neither of which are the batteries own terminals

I would always have the donor car running prior to the last connection to the flat car.... and as alternators make better volts and amps at 2000 rather than tickover I always bring up the donor car's revs and hold around 2k, if its really dead I even wait a few mins before cranking the flat one over

here u go just found this

http://www.mercedesmedic.com/how-to-jump-a-mercedes-benz-the-right-way/

I suspect the reason for a jumpstart connection is to do with the battery being under the floor (wife's B class) or (as in my car) buried in the boot.