need help working out what went wrong

[jafo]

mate lives in the country and went to overtake another car, but the driver of that car was a smart ass and wouldnt let my mate overtake,
so my mate floored it and got to 180kmh then a huge bang and flash of light from under the bonnet now the car battery wont hold charge and he has to jump start it everytime he has to use it.
if anyone has any idea on what could have gone wrong,your help would be much appreciated
the car is a vk 6 cyl if that helps any

[craigvk]

Check the alternator. Try using another battery and see if it works. Check the charge voltage at the alternator for 30 seconds and see if it is steady at ~14.4V. Replace any frayed or dodgy wiring connected at the battery. Check belt tension.

[Garth]

huge bang, alternator volt reg having a spit, and the huge flash, will be the hundreds of amps that the alternator is trying to pump out with out the regulator, it's amazing it didnt try and stop the car, or spit a belt, normaly they just lock up when they go into run away mode

[Nobody Actually]

beat me to it garth, yeah, i'd be checking the alternator and regulator as well

and yeah, you've probably flash fried your battery too

[craigvk]

huge bang, alternator volt reg having a spit, and the huge flash, will be the hundreds of amps that the alternator is trying to pump out with out the regulator, it's amazing it didnt try and stop the car, or spit a belt, normaly they just lock up when they go into run away mode

Comon' Garth. You should know better than that. Alternators don't pump out hundreds of amps. This spare Lucas alternator I have here has a TIP 102 IC in it which is only rated at about 10A max from memory.

[Sammy]

if the thing runs once its jump started i'd be inclined to think the alternator is making enough power to keep the car going once its started, having said that i can't think of what a battery could do to make an explosion like that ... it would be more likely an alternator that would ...

anyways i'd be starting the car and while its running, remove the positive lead from the battery, if the alternator is good the engine will keep running, if the alternator is ****ed she'll promptly die.

[craigvk]

I just had another thought about this. It's possible that the alternator blew up, well at least the regulator part of it BEFORE the noticeable bang. What I mean is it's possible that before the bang happened, the alternator regulator failed and then it went bang.

The first thing I'd do is monitor the alternator output voltage for about 30 seconds and see if it stays steady at around 14 volt. It's possible the battery has run dry without any electrolyte in it. My brothers alternator regulator was half working for a while until I noticed it jumping up to 17 volt every few seconds. In the end it killed the electrolyte in his battery. Luckily I was able to bring it back from the dead and added new water and gave it a charge which took 17 hours until the charger said it was charged which is pretty long. It's been going fine now for a month.
So yeah, check the output voltage and the battery cells.

[Goon]

It could also be possible on the floggin drive, a wire earthed out or both postive and the negative battery touched earth at the sametime.

[craigvk]

It could also be possible on the floggin drive, a wire earthed out or both postive and the negative battery touched earth at the sametime.

The ignition would have probably cut out if that happened.

[jafo]

thanks guys that about what i told him so i'll have another chat and see what he thinks

once again thanks for your help

[VH Vacationer]

Comon' Garth. You should know better than that. Alternators don't pump out hundreds of amps. This spare Lucas alternator I have here has a TIP 102 IC in it which is only rated at about 10A max from memory.

I would hope the average alternator is capable of cranking out 50-80 amps....you need that sort of capacity to run all the electricals that people tend to wanna run.