Outer Limits 4x4 Board

Having starting trouble, yesterday it wouldn't start in the morning, after going for a long drive the previous night (so i'm thinking the battery's not holding charge), but NRMA tells me its my Alternator, as their multimeter only read 12. sumthing at idle.

So I went down to a sparky's to make sure, and on his multimeter it reads ~13.4 at idle, and goes up a bit revving, so apparently the alt is good. But, engine off, he put the battery on a 'load tester' and it wasn't reading as high as it should, and then after when I went to start the car the battery was dead.

Now, this morning, it started fine How can a battery not hold its charge one night and then hold it fine the next? And if the auto elec's machine says the battery's cooked, is that definate? Cause i think NRMA are going to be reluctant to replace my battery (under warranty) since sometimes it starts and sometimes it doesn't, i'm worried they'll try and blame the alt

The way those voltages are varying so much, I would check your battery cables and connections before doing anything, especially your earth straps.

Just an idea.

check the connectors too. make sure the cables have a good solid connection to the battery

checked all the cables and connections, every things attached and tight.

Could it be the voltage regulator?

what did the sparky say about the alternator?

he said it was fine cause it was charging at ~13.4v Thats all we did to test the alt, put a multimeter to the + cable while the engine was running, and then again when it was off.

what is the charging voltage at full load ie all lights and spotlights on


13.4 volts is at the lower end of the charging scale

I think it was around 12.5-12.9, but I'm not 100%

with that sort of voltage it wont charge the battery

i would be taking the alternator off, take to an auto elect, get him to test it .

it may be brushes or the voltage regulator

13.4 is what i would expect ynder full load

fair enough. hopefully in a week or so I should have a spare 2nd hand one to play with, just cant afford to not have a car atm.

But the question still remains, if the leccy has tested the battery, and it fails on his machine, is the battery rooted? or could the alt not charging properly make it seem that the battery is dead (i realise that the battery not getting charged properly will shorten its life) I just don't want to throw out a perfectly good battery.

charge it on a bench charger and see how it goes

STIKA wrote:charge it on a bench charger and see how it goes