Technical How do you tell if its battery or alternator?

[hixy]

basically if i leave car for a few hours and come back to its flat, any asy way to tell without replacing 1? cold and damp seems to make it worse??


cheers

 

[Ffoxy]

Sounds like battery to me, cold weather decreases efficiency. Can you get a local Auto electrician to do a charge test and eliminate the alternator? Or check the off and on load battery charge and discharge rates?

 

[jug]

could be battery, alternator, or drain.

if you fully charge the battery then drive for some time, switch engine off, then try to start it again, is the battery flat?

if you fully charge the battery then fit it to the car and leave it overnight, is the battery flat in the morning?

do you have a multimeter?