Troubleshooting procedure for charging at 18v?

[DuctTape]

Got a fancy one wire alternator. Battery is about four years old, mostly sitting I storage. 99% sure battery is fully charged. Need help in the right troubleshooting steps.

I checked voltage with meter at batt terminals to verify volt gauge in vehicle was right - 17.9 volts.

I figure my best bet is to go get the battery tested, right? Since the voltage reg is internal and brand new, I'm thinking maybe the reg in alt is getting confused by a bad battery.

Is there any way to bench test an internal regulator on one of these one wire beasties?

Pretty sure running 18v will do Very Bad Things to electrical system but not sure as I've never run across this problem before.

Tia for the help.

 

[broncnaz]

Not much to trouble shoot if this truely a one wire alternator the regulator is bad. 1 wire regulators sense voltage at the one wire so if its not regulating then its bad.

 

[Broncobowsher]

Just because it is now does not mean it is good/working right. The alternator output post should be the highest voltage in the shole system. If you are cooking the battery that much then the alternator isn't backing down like it should. The "sense" wire is not working correctly. Double check that isn't needed to be looped back to the alternator output.

I have seen some people take an off the shelf GM alternator and call it "1-wire". It isn't, itis 3-wire. The feed, sense and turn on. I have heard that some of these will self turn on if spun good enough. that leaves the sense wire not hooked up. Leave this off and it doesn't sense any voltage in the system, so it goes full output. Sounds exactly like what you are experiencing.

Exactly what alternator are you running? Please provide a link to the source.

 

[patterdale]

Not much to trouble shoot if this truely a one wire alternator the regulator is bad. 1 wire regulators sense voltage at the one wire so if its not regulating then its bad.

X2
The one wire configuration simplifies and eliminates a lot of troubleshooting. The internal regulator is not doing its job properly.

 

[DuctTape]

Thanks guys.

So i can just pull the alt and replace the regulator right?

Frustrating on a brand new part...

 

[DuctTape]

Exactly what alternator are you running? Please provide a link to the source.

On a crate engine from engine factory. I don't have a brand/model but they are very clear in their wiring instructions - one wire to battery pos post.

I didn't like the idea of no protection, so I ran the alternator to a maxi fuse first, then to side post on std bronco solenoid, jumper from that post to battery.

Starter crank is also hooked to that post (I have a starter with it's own solenoid), but I don't think that matters as the alt should still be sensing from the battery. I'm using the old solenoid just because it is easier than having to tweak the wiring harness.

 

[DuctTape]

Follow up: battery had a bad cell. Replaced the battery and now charging at correct voltage. Thanks for the help.

 

[Broncobowsher]

I would keep checking it just to be sure. Overcharging the battery will make a bad cell. A fresh battery may have enough capacity to absorb an overcharge without showing up as over voltage right away. Just want to make sure you fixed the problem and not the symptom. Run it at speed for a little while and make sure the regulator is actually regulating and not just letting the voltage keep creaping up.

 

[DuctTape]

I would keep checking it just to be sure. Overcharging the battery will make a bad cell. A fresh battery may have enough capacity to absorb an overcharge without showing up as over voltage right away. Just want to make sure you fixed the problem and not the symptom. Run it at speed for a little while and make sure the regulator is actually regulating and not just letting the voltage keep creaping up.

Good point and not one I considered, will do.

 

[ransil]

local parts store test alternators for free