Voltage Regulator

C

C R Hidalgo

Filing Flight Plan
Joined
Jan 4, 2020
Messages
5
Display Name
Display name:
Skyhawk4EVER
Happy New Year everyone!

I have to replace the voltage regulator and harness on a 1980 C172N (28V)and wanted to get any recommendations or experiences with the different ones out there. Plane currently has a Hartzel VR515GA.
I'm looking at a similar Lamar replacement, a Plane Power R1224 or a Zeftronics R25400.
Is replacement or overhaul of the alternator recommended at this point ? its has about 500 hrs.
I would love to have a little background knowledge when I discuss with the AMT.
Thank you.
 
I would do the alternator when you overhaul the engine, at least that’s what I did.


Tom
 
C R Hidalgo said:
I have to replace the voltage regulator and harness on a 1980 C172N (28V)
Click to expand...
A bit more info on why you need to replace the regulator and harness may help on alternator question.
 
Bell206 said:
A bit more info on why you need to replace the regulator and harness may help on alternator question.
Click to expand...
Thanks Tom.

It looks like the regulator was bypassed with the field wire not attached and a wire going straight to the battery from the alternator.
also harness wires are all cracked from age.
alternator change is more for "peace of mind"
 
C R Hidalgo said:
It looks like the regulator was bypassed with the field wire not attached and a wire going straight to the battery from the alternator.
Click to expand...
FWIW: Something appears amiss here, but still not enough info. Why was the regulator bypassed?
 
C R Hidalgo said:
Thanks Tom.

It looks like the regulator was bypassed with the field wire not attached and a wire going straight to the battery from the alternator.
also harness wires are all cracked from age.
alternator change is more for "peace of mind"
Click to expand...

I have to wonder what idiot did that. I would replace the battery.
 
Don't know.
But main reason why I want to replace the alt. , reg. and old harness.
Will probably replace all wiring from the firewall forward.
 
C R Hidalgo said:
It looks like the regulator was bypassed with the field wire not attached and a wire going straight to the battery from the alternator.
Click to expand...

That should have cooked both the alternator and the battery and just about everything else in the airplane. The output voltage would have been extreme if the regulator was bypassed. I suspect that the wiring was somewhat different than that if you didn't have a boiling battery or smoking radios and fried lights.

The alternator should be opened and inspected every 500 hours. The brushes wear and usually need replacing by the second 500-hour inspection unless there is extra load on the alternator such as having the landing lights on most of the time for traffic avoidance, or a glass cockpit that puts more demand on the system. When the alternator has to produce more, the brushes have to carry more field current and they wear out faster. Our G1000 172S had the brushes nearly shot at 600 hours.

Every so often I read on this forum of someone's alternator failing. 99% of the time it will be worn-out brushes, and if a brush gets short enough it pops out of its holder and the spring behind it starts running on the rotor's slip ring and completely ruins it. Now you're replacing the $500 alternator instead of the $20 brush kit. And an electrical failure at night or IMC is no joke. Alternators need care.

In an airplane that alternator is spinning near its redline all the time. In a car it might be at 30% of redline, which expains why they run so much longer than the alternator in your airplane.
 
Dan Thomas said:
That should have cooked both the alternator and the battery and just about everything else in the airplane. The output voltage would have been extreme if the regulator was bypassed.
Click to expand...
My thoughts exactly.....
 
Dan Thomas said:
That should have cooked both the alternator and the battery and just about everything else in the airplane. The output voltage would have been extreme if the regulator was bypassed. I suspect that the wiring was somewhat different than that if you didn't have a boiling battery or smoking radios and fried lights.
Click to expand...

100% agree. My WAG is that whomever is looking at this circuit and thinks the regulator is bypassed either doesn’t understand the circuit or is tracing the wires wrong. You could easily see 100+ volts and everything in the electrical system suspect if the field was on all the time.

I’ve installed several Plane Power alternators and regulators and have been satisfied with all of them. They’re my current recommendation when someone is looking for a replacement.
 
You must log in or register to reply here.
Back
Top