Electrical gremlins (1 Viewer)

[NZBJ71]

Hi

I am having an electrical gremlin that is starting to hack me off.

The symptoms are loss of electrical power after 15-20 minutes of running, the volt guage drops off and the vehicle will stall out at idle.

On the surface appears that the alternator isn't charging, however i have had an auto sparky go over it and he couldn't fault it (vehicle was only just warmed up) as the alternator was charging perfectly. however, after leaving the shop 20 minutes later the volt meter was dropping off and it wouldn't start when i stalled backing into my garage. It did start half an hour later.

has anybody had issues with alternators not charging when hot??

The engine is a GM V8 running a GM alternator (internal regulator)

Thanks
Tony

 

[inkpot]

Howdy! Could be the alternator. Can you swap in another one to test it? Could also be a heat induced problem such as a ground in the starter, or even the primary battery cables. John

 

[watrob]

Sounds like the internal reg has a fault, when it gets hot something is breaking down in it, could be diode or a retifier starting to go.

The Reg is not all that expensive and are easy to put in, if its not the Reg and it's the windings in the Alt then you got a spare REG, which is good to have. Cheaper to go this way than buy a new Alt if its not needed.

 

[WES1977]

regulator, i've ran with out mine with no problems. My cruiser just wouldn't charge. You can run on a charged battery for a long time. Get a Volt meter and check you battery voltage while off and then while running. When you refered to the volt gauge are you talking about the AMP meter?

I think you have a short to ground.

 

[watrob]

regulator, i've ran with out mine with no problems. My cruiser just wouldn't charge. You can run on a charged battery for a long time. Get a Volt meter and check you battery voltage while off and then while running. When you refered to the volt gauge are you talking about the AMP meter?

I think you have a short to ground.

See you love your dogs, Merry Christmas.

 

[WES1977]

See you love your dogs, Merry Christmas.

yes love dogs and they love my cruiser

 

[Pin_Head]

Your description is a little vague about what "loses power" and how you know the power is lost and what you mean by the "voltage meter drops off". Stock cruisers have amp meters, not volt meters, so this is confusing. What happens when it "won't start"?

I would tend to believe the shop about the alternator being OK. If your battery is OK, then I would think that the most likely problem would be a bad connection in the main power feed to the chassis. The fusible link is a known problem source.

 

[NZBJ71]

Their is very little of the factory electrics still in place and the vehicle has a volt meter installed on the dash. When i refer to loss of electrical power basically the volt meter drops from 14v (normal running) down to 10v or less.

With the electric fans, fuel pump, efi running and possibly no charge from the alternator then the battery would drain down pretty fast i guess.

i have checked all the earths straps, connections, resistance, amps (from alt and from battery under load) and nothing appears to be an obvious cause. I haven't got around to taking it for another drive to try and replicate the fault. Taking it for a drive and getting it hot looks be the only way to check the alternator output under hot conditions.

I'll try a new regulator and see what happens.
Thanks for the thoughts

Cheers
Tony

 

[Pin_Head]

I'll try a new regulator and see what happens.

Guessing is the expensive way.

Instead you can just hot wire the field ("F") terminal to apply full alternator output and see if the power goes up. Just run a short piece of wire between the alternator B+ lug to the F lug.
If the voltage jumps up when you jump it, then the regulator or its circuit is bad. If the voltage does't increase at the B+ lug, the alternator isn't putting out.

Have you checked the "Engine" fuse? The regulator runs off this circuit.