Alternator or battery

Garef

Member
Pretty sure it's the battery but just want to check.

My old mans van runs and drives with a jump, but won't start on it's own.

Is it the battery or alternator?
 
Could be either or both.

Could be battery dead not holding enough charge to start it or could be the alternator not putting out enough voltage to charge the battery enough to be able to start it.

When the van is running, put a circuit tester across the battery and see how much the alternator is charging. It should be above 13.8 volts, ideally between 14.2 and 14.4 volts with lights etc on. (Those figures are about right top of my head).

If it's charging ok then, time for a new battery. A top up of di-ionised water may temperarily help.

If you test the battery on its own a good battery should hold 12.6 volts. I think anything below 12.2 is knackered.

Hope that helps, Ben.
 
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Garef

Member
Well I got it jumped again just there, disconnected the battery and it stopped. I read that this means the alternator is toast. Right or wrong?
 

PobodY

Moderators
Staff member
That generally means it's not making enough power to keep the engine going, but it could be that has resulted in the battery going as it would then be draining that instead. - I think I've got the other way around at the moment, but it's one of those sealed batteries so there's no way to top it up or check it... it's only a couple of years old so I'm a little surprised that it's failed.
 
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