# Have you had to jump start a flat battery recently??



## DustyR (Jan 26, 2009)

I have to admit I have not had to use jump leads to start a flat battery for many years, however I have just purchased a new 'Heavy Duty' pair of jump leads ( just in case ) for the MH. 

I thought I knew how to connect ie first RED to RED then BLACK to BLACK on the batteries but according to the instructions this is no longer the correct way and if you do connect this way you risk blowing ECU's along with engine management systems, audio units etc.

Now the procedure is to connect the -VE lead from the donor battery to 'any suitable metal earthing point of the faulty vehicle'

Can anyone tell me the explanation for this as I cannot see what the difference can possibly be since there is a physical connection between the battery and the bodywork anyway ???


----------



## Rainbow-Chasers (Sep 2, 2008)

There may be an earthing point on the engine/engine bay area, as on many modern vehicles. Failing this, some enigines have a metal loop used for lifting the engine in/out on one end of the engine/mount area. This can be used - all else fails, try the bonnet catch on the slam panel!

Anything that is substantial and metal, and mounted to the body will do! Preferably unpainted if possible! There is usually a nut or bolt somewhere! Just be sure that it is well away from any moving parts!


----------



## merlinsdragon (Sep 15, 2009)

I have had sixteen breakdowns due to an electrical fault the advice was to connect the negative to the body work and to lift up the cover to use the charging point in the engine compartment, after a lot of NOT working it was decided that it was better to disconnect the battery and charge from the inside As the earthing system did not work well enough to jump start as it should have from the engine area, that too had to be jumped from the inside the van, directly to the battery. The theory is that the chassis makes the negative circuit along with the engine compartment in my van's case a compass on a peugeot base 07 reg van (I also had the dreaded water problems as well) . The dealer also had to change both the leisure battery and the vehicle one,as well as the starter motor (all due to the water ingress problem ,they said but it still crops up when you don't want it to, so run your van regularily and put it on mains at regular intervals , this appears to work)


----------



## steco1958 (Mar 5, 2009)

The procedure to jumpstart a car or Mh is very simple, but instead of me typing it just CLICK HERE

Just remember contacts on the flat battery and the earth connections need to be cleaned off and possibly re made


----------



## DTPCHEMICALS (Jul 24, 2006)

Wednesday morning at 5 o clock.
Why do Fiart fit the battery with positve pole at the rear under the scuttle.
not easy to get a jump lead on in the dark

Dave p


----------



## teemyob (Nov 22, 2005)

*Starting*

One very important thing to remember!

When you have started the dead vehicle.

Turn on the headlights, heater fan, radio and anything else you can think of and run for a few minutes BEFORE turning off the engine of THE DONOR VEHICLE

Failure to do so could send a surge to the vehicles electronics resulting in severe damage. In my case it was around £875.


----------



## advancedroadcraft (Jun 24, 2009)

*Re: Starting*



teemyob said:


> One very important thing to remember!
> 
> When you have started the dead vehicle.
> 
> ...


Never heard that one before...& I thought I knew it all 

Which vehicle (donor/recipient) gets damaged in your scenario?

Not challenging your rule (believe me the threat of a £875 bill means that I will always follow your advice from now on) just not clear.


----------



## advancedroadcraft (Jun 24, 2009)

DustyR said:


> Now the procedure is to connect the -VE lead from the donor battery to 'any suitable metal earthing point of the faulty vehicle'
> 
> Can anyone tell me the explanation for this as I cannot see what the difference can possibly be since there is a physical connection between the battery and the bodywork anyway ???


The idea of using an earth point away from the battery is to avoid the chance of a spark (as you connect/disconnect the lead) anywhere near the (hydrogen) gas a battery may be giving off.

And you do know that there's a right order and a wrong order to connect the ends of the +ve & -ve leads to the good & bad batteries, don't you? (I guess the instructions that came with the new leads covered that.)


----------



## SpeedyDux (Jul 13, 2007)

Rather than risk frying the ECU, nowadays I use the Easy Start system. 

That takes about 20 minutes to put enough charge into the flat vehicle battery from the donor vehicle battery (or, in a MH, the leisure battery).


----------



## teemyob (Nov 22, 2005)

*Re: Starting*



advancedroadcraft said:


> teemyob said:
> 
> 
> > One very important thing to remember!
> ...


Donor, cost me dear on a Mercedes 416CDi Sprinter. I was starting our Daughter's Boyfriend's Mother's car (old Astra) that had gone flat on our drive.


----------



## advancedroadcraft (Jun 24, 2009)

*Re: Starting*



> Donor, cost me dear on a Mercedes 416CDi Sprinter. I was starting our Daughter's Boyfriend's Mother's car (old Astra) that had gone flat on our drive.


So, almost inecvtably you b****r up the nice new shiny one to get the rattletrap going. As they say, "No good deed goes unpunished"!


----------



## Rosbotham (May 4, 2008)

If it's an X/250, there's terminals under the bonnet that should be used rather than the battery terminals themselves.

Of course, if the MH battery is totally dead, you first have the challenge of solving the puzzle of how to open the passenger door to get to the bonnet release catch...there is a trick.


----------



## DustyR (Jan 26, 2009)

Rosbotham
Have found the battery terminals ok in X250, I just wanted to know why connecting to these points is any different to the battery terminals themselves, in that there is a risk of damaging the cab electrics when connecting directly to battery. Its just me trying to understand the theory behind it.

Of course in the X250 where the battery is located under floor in cab it makes it much easier to connect to the engine bay points.
However, as for checking the electrolyte levels it is not easy at all as there is a big terminal plate on + ve which covers 3 cells


----------



## Rosbotham (May 4, 2008)

I've no specialist knowledge of the X/250 wiring, but had assumed that there wasn't a direct connection between the terminals and battery...had assumed there was some form of circuitry inbetween to prevent a whump to the electrics when the jump start's attempted. I know as much as the manual cautions against ever using the battery terminals direct (except it's one of the stages in the puzzle to unlock the passenger door to open the bonnet to get to the proper terminals...).


----------

