My alternator charges briefly over 17v when cold

schuy1 · 30th November 2012, 06:18 PM

Originally Posted by haydent

well i feel like im going to cry and the missus is going to go tropo at me when she finds out...

i got a new set of brushes and regulator through ultra tune for $160, and just finished swapping them over and putting the alternator back in

and its still doing it !!! ;(

im thinking now there must be something broken in the alternator itself...

also when putting the vaccuum pump back on i broke one of the bolts...

it seems my standard kingcrome torque wrench aint so accurate down in the low torques that these little bolts needed, this is the second time ive run into trouble with trying to do low torque with this wrench, previously stripping the thread on the centrifuge filter cover bolt hole.

Standard Torque wrench that goes up to, say, 150ft/lbs will NEVER do to torque bolts requiring 10ft/lbs, no matter what the lower reading say. The spread is just too much for accuracy and the cheaper the wrench the greater deviation there is. use a lbs/inch type for those lower settings.

On the alternater I feel for you but the great problem with modern alternators is that they are a throw away item, Yes you can get parts but by the time this is needed the rest is had its use by date too. The man that does electrics here despairs when some1 lobs in with a dead newish alternator! and hes been in the game for 40+ years!

cheers Scott

**haydent** · 30th November 2012, 06:28 PM

thanks so much, you really confirm my thoughts.

with the alternator, as mentioned it is ~2years old reproduction part.

do you think it could be anything else ?

schuy1 · 30th November 2012, 07:19 PM

Originally Posted by haydent

thanks so much, you really confirm my thoughts.

with the alternator, as mentioned it is ~2years old reproduction part.

do you think it could be anything else ?

Would just about put a sheep station on the alternator

as really what else could be making it spike? other than itself?

Cheers Scott

**haydent** · 30th November 2012, 07:37 PM

thats what id thought about it as these ones dont have a sense wire, they manage output internally

**haydent** · 30th November 2012, 07:40 PM

also i tried different battery

**haydent** · 1st December 2012, 11:47 AM

Can someone explain to me how these alternators vary their output?

**Mundy** · 2nd December 2012, 08:03 AM

Originally Posted by schuy1

.......the great problem with modern alternators is that they are a throw away item, Yes you can get parts but by the time this is needed the rest is had its use by date too. .....cheers Scott

From my recollection, alternators haven't changed much over the years but if anything, they last longer. As I recall, alternators started being standard in vehicles in the mid 60s replacing generators. The latter had a separate voltage regulator box but the alternators had the rectifier (ie conversion to DC and the voltage regulator) built into the back of the alternator housing. It was a standard repair to put in an external rectifier after about 30k miles (about 58k km).

The output of my alternator varies with temperature. First thing, cold, it puts out about 14V. Once hot, it puts out about 13.5V.

An output 17V sounds like the rectifier is stuffed. I don't believe its expensive for an auto electrician to put in an external rectifier, although I've not needed to do it for a long time.

**haydent** · 2nd December 2012, 08:52 AM

thanks for your input,

i have already tried replacing the regulator and brush box with new ones, same problem.

so ...

**haydent** · 4th December 2012, 06:45 PM

Originally Posted by schuy1

Would just about put a sheep station on the alternator

as really what else could be making it spike? other than itself?

Cheers Scott

well good news, another alternator fixed the problems !

thanks again.

schuy1 · 4th December 2012, 08:16 PM

Aha!! Very good

Ya know, If I keep thinking about stuff I have to get 1 right!

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