alternator pumping out too many volts

Post by **DIRTY ROCK STAR** » Tue Mar 10, 2009 4:40 am

Guys

my battery wasnt charging or so it appeared.
took the alternator too an auto elec it was tested quickly and appeared fine.

got home and with some mates put things together and tested alot of things...
it seems to be working fine.
then after about 1 minute it keeps putting out more and more volts until at about 16v it pops the fuse between it and the battery isolator.

has anyone got any ideas why that would be happening?
is it just a matter of a new regulator?

i really need this sorted as tuff truck is 2 weeks away.

Cheers

Tony

Post by **drivesafe** » Tue Mar 10, 2009 7:20 am

Hi Dirty, the usual cause of runaway voltage from an alternator is a bad earth, failing that, it’s another trip to the auto electricians.

Post by **DIRTY ROCK STAR** » Tue Mar 10, 2009 7:30 am

cheers mate.

i will check the earth straps etc tonight...
we checked a few last night but not sure as we were chasing faults?

the truck just got back from mechanics having new gbox fitted.
so its possible something might be loose or damaged from that too as the bloke who works on it wasnt there.

Post by **ZookiDave** » Tue Mar 10, 2009 10:14 am

sounds like u could have an open circuit. probably best to drag the truck into the terrace and see if Hunter River Auto Sparks or Terrace Auto Electrics can have a look at it 4 u, there normally pretty switched on to that sort of thing.

Dave

Post by **bunder_ute** » Tue Mar 10, 2009 5:29 pm

hey mate it sounds like a regulator problem... is it internally regulated?? some external regs can be adjusted thats all

Post by **DIRTY ROCK STAR** » Tue Mar 10, 2009 7:02 pm

i bought a new regulator today.

havent been able to put it on yet. tomorrows job.

but if that doesnt fix it i think it will go to an auto elecs for sure.

Post by **DIRTY ROCK STAR** » Wed Mar 11, 2009 7:29 pm

new regulator hasnt helped at all.

anyone got other ideas?
know a decent auto electrician around port stephens?

Twon

Post by **-Scott-** » Wed Mar 11, 2009 8:55 pm

Is the regulator sensing the battery voltage properly? If the regulator sense input looks at battery voltage to determine if it needs to ramp the alternator up or down. If it doesn't see the enough voltage (none, or too little) it will ramp alternator output to maximum.

Some later model Pajeros feed the battery sense signal via the same fuse as the indicators. Blow the indicator fuse (such as through dodgy trailer wiring, or simply too many lights on the trailer), and the alternator outputs more than 15V.

Post by **bunder_ute** » Wed Mar 11, 2009 10:04 pm

so..... First off why did you originally think it wasn't charging?? Was it because your battery kept going flat??Take it to an Auto elec and ask them to check the diodes out.. If it has a diode out it can cause the battery to discharge and may also cause it to over charge. AIso have some one check you battery aswell, one of the cells may be bad. have had a few before that do similar things as you are describing. What brand of alternator is it? What car is it running on?

Post by **3.8BUNDY** » Thu Mar 12, 2009 5:47 am

I dont know if this is going to help or not.
I had the same problem with my alternator pushing out 19v. The auto elec told me why ( when it gets to technical, I turn off) but the gist is he had to replace the alternator.

Post by **3.8BUNDY** » Thu Mar 12, 2009 10:29 am

3.8BUNDY wrote:I dont know if this is going to help or not.
I had the same problem with my alternator pushing out 19v. The auto elec told me why ( when it gets to technical, I turn off) but the gist is he had to replace the alternator.

Just spoke to the Auto elec.
It was more like 16v and it was the Regulator which is part of the alternator on the GQ, therefore the whole thing had to be replaced.

Post by **DIRTY ROCK STAR** » Thu Mar 12, 2009 8:41 pm

cheers paul and others.

yeah its putting out like 16v.
im borrowing an alternator and starter as spares for TTC tomorrow from a mate.
im also goin to pickup a 2nd hand alternator in sydney on sat while im down in the big smoke.

its a bosch 85amp alternator on a holden 304 V8 motor in my landcruiser comp truck.

so yeah had a play with th truck. had a mate helping who wired th alternator. now it isnt blowing any fuses but its putting out close to 15v...

main thing i saw as a problem was the charge light kept coming on.
i took it to local 4wd shop to get gbox removed for rebuild they said it needed jump starting. thats what had me worried up front...

Post by **bunder_ute** » Fri Mar 13, 2009 12:54 pm

in that case mate I would say someone has jumped started it the wrong way.... And damaged the rectifier.

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