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MG MGF Technical - How good is the MGF at jump starting other cars ?

This may sound a dumb question, but I'm going to ask it anyway.

A collegue at work has just got back from Santa Clara where she was working for 6 months. Not suprisingly, the alarm had sent her battery flat on her car.

I offered to use my 'F to jump start her Cavilier. Her car wouldn't start, but as she started to pump the accelerator pedal, I heard the revs on my 'F go up and down. The car then stalled. She was only attempting the jump start for less than a minute.

I immediately attempted to start the 'F, but it wouldn't start. All I heard was a light machine gun type noise coming from the engine bay.

It took a push start to get my car started again.

Has anyone any thoughts on what happened and why? (I'm not jump starting anyone else, thats for sure !!)

Cheers,

Daniel.
Daniel Ginger

If your battery is in good condition it should be able to start anything up to a 2.0 litre engine, even it takes a couple of minutes.

The reason for the car stopping, is because of the massive load exerted on the alternator, which is why it's never a good idea to jump start with the engine running (unless you apply plenty of throttle)

You probably have never had to punish your battery when starting the F, so any problems associated with larger current drains might go un-noticed.

then again it might be nothing more than all the juice your car was producing was being donated to the cavalier, hence no power to run yours!, I'd get the battery checked anyway.

Nick
Nick

Modern engines are pigs to jump start because of the huge electric requirements.

I remember when my Pug 205GTi suffered a flat battery, attempts to start it from friends Festa (intentional spelling error) almost caused that car to stall.

The trick is to keep the 'donor' car's engine running, keeping the rpm at around 2-3000 rpm. With the two cars' batteries contected together, do not attempt to start the 'recipient' car for about 5 minutes- allowing its battery to trickle charge. Then, after 5 minutes, ensuring that the 'donor' car's revs are kept high, attempt to start the 'recipient'.

This method I have found to be most successful- that pesky 205 always had a flat battery; no lights on warning buzzer!

HTH

Rob
Rob Bell

I've jump started a Mini & a Porsche (not at the same time though!) using the F - with no problems at all :o)
Wish I'd got the pictures!
Dot

Jump starting should not be taken lightly on modern computer controlled vehicles. Trying to jump start a completely dead battery or a damaged,shorted battery can cause huge transients (voltage spikes) in the circuit and can easily damage your computer. When jump starting always find out if the recepeint battery is completely dead, if so, charge with battery charger -your alternator will thank you for it. If you know that battery is partially dead because something was inadvertantly left on, it is usaully o.k. to jump start.
a

...which then leads to the question....is it inadvisable to jump start an F whose battery is flat...to avoid possible damage? As a frequent jump starter of my (and other people's) older cars I would like to know if I should avoid this for the MGF.
Tony

I had my radio fried on a Rover 216 that was jump started (by the RAC). I guess this is due to a voltage spike - I have since heard that this sometimes happens, has anyone else got similiar experiences?
Ian

After a recent jump start from a new series Golf, which has had absolutely no problems jump starting my F, the interior lights, clock etc failed. Nothing terminal but guess something was a bit amiss somewhere.

So

Any advice on better batteries or some easy way to prevent the car being dead after 2 mths in my garage ?

Jump starting really is a pain and for all that dosh I can't believe the system just runs down to death.
Simon

Hi Gang,

If the battery is standing idle for such long periods, it will be prone to suplhates forming from the bottom of the plates upwards. this drastically reduces the amount of current available for starting. You can get batteries which can take this sort of use but they are quite expensive. I would recommend running the car regularly to give the battery something to do (and this applies to any car) rather than expect it to be fully charged all on its own.

Nick
Nick

Oh No!!

Don't push start an F, or any other car with a cat!!

You can get unburt fuel passing into the exhaust the igniting in the cat and a big bill at your next MOT.

To re-iterate advice above runn donor car engine at 2-3000 rpm for a few minutes first, especially if you have puny jump leads as they will not be able to carry the current required to turn the starer on the disabled car, but will be able to carry the lesser currents required to charge the disabled car's battery where the charge is stored ready to start the car.

Incidentally never try to push start any car with EFi or electronic ignition with a completely flat battery even if it does not have a cat, some charge is needed to run the fuel pump and electronics and injectors, if the car starts it may well run badley because various settings are out of sync. Most systems perform a check and prepare for starting first and cannot do this with out power.
Andrew

I have used my F to jump start another car, but I have very good leads and I always run the motor first. I had no problems. Then again I run my F every day so the battery has a lot of excercise :-)
Tony Smith

This thread was discussed between 02/02/2000 and 10/02/2000

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