Alternator doesn't charge? Regulator or Battery?

Hey mates,

since our Fraser Island trip during the last holidays I have an issue with my car not charging the battery anymore. Symptoms as follows:

- Battery lost it's charge quickly, car stopped after having the front lights on
- checked the voltage gauge in the dashboard, as long as I rev the engine (2500-3000 RPM) the needle goes up. If it's idling the needle goes down towards 10 volts and then the car shuts off.

- checked the charging voltage with a friend and his multimeter while car was running. Again, it goes up to 13 volts when I rev the car but goes down quickly when the engine is just idling. Turning the front lights on will drain so much power that the car will shut off.

- checked it with a brand new battery and the same thing happens

What I noticed: I checked the battery right after Fraser for it's water level. Water was right up to the level. I checked again after a week when we tested the voltage with a multimeter and I realised that all the cells were completely dry.

I topped the battery up with distilled water but I am not to sure if this will revive it.

What do you guys think? Alternator, Regulator and Battery? Did Murphy's Law get my by the balls? :/
HillsForThrills

Hey mate... Had the same issue with my 'Troll not long ago... If it's pumping up the charge when you rev it, but dropping at idle, I would guess it's the regulator... If it was the alternator, the charge would be low all the time... The battery probably ran dry due to the constant discharge and irregular recharge rate... Don't know what sort of Alternator you have, the reg may be easy to replace, with the 'Troll I simply bought a new alternator, as the reg is inside mine, and also that way I have a warranty and a brand new unit, rather than an old one with a new part... I'm not an auto 'leccy, but it sounds like the same issue as mine...
1mak OP

Yeah I think you're right. I need to find out if I can change JUST the regulator in the alternator. :)
ThatDude

Its the alternator mate don't bother trying to repair the regulator just chuck the whole thing out and put a new one in. done.
HillsForThrills

^ Just want to ask mate, what's your reasoning behind that? If the charge increases when the revs go up, the alternator isn't the problem, otherwise as I said, the charge would be low all the time... In all honesty, it could actually come down to a slipping belt, although under heavy acceleration that is instantly recognisable... Two auto 'leccy's have agreed with my diagnosis (albeit on my vehicle with the same issue...), and my best mate, a 15yr Mitsubishi mechanic... And TBH, even if you are correct, and the alternator is the problem, it's a simple case of renewing brushes, which is significantly cheaper than a new unit...

Actually Torsten, one thing to try mate, and shake ya heads if ya like, but give the alternator a THOROUGH degreasing and hosing... It is possible that you simply may have gotten sand/mud/grit inside the alternator itself, and is playing havoc with the electrical path... Have also seen that happen before... Good clean out, bingo, solid connections again... Also costs nothing, so is the best thing to attempt first... Obviously though, wait until it has dried before starting it up! :)
1mak OP

I did exactly this last week, sprayed it thoroughly with degreaser and ... tadaaa, it works fine. Had to buy a new battery though but they had some on sale today for 109 AUD (560CC, 124min) so that part is fixed. :)
HillsForThrills

^ Excellent! Glad to hear... :)
1mak OP

I got a battery charger from a made and did a pulse charge on that old battery for reconditioning. It seems that it keeps its charge at 13.3 Volts. Hmm, might get a dual battery setup for my Pajero now.
Mattnicholson

Did you find out if the rectifier is changeable? 

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