Alternator

[LMartin]

For lack of finding answers anywhere else…I am flying a C185 on Wip 3730s. A new alternator was put on within 100 hours. I just lost the new one today. It’s a Hartzell Plane Power and an IA said they are junk alternators, but I’m having trouble finding anything else. What’s a good alternator for an IO520D?


Sent from my iPhone using SuperCub.Org mobile app

[wireweinie]

What were the original symptoms and what are the symptoms now?

Find a new IA.

Web

[LMartin]

I had to start on battery and then turn the alternator on or it wouldn’t come online. Today in flight the low voltage light came on after about 30 min and wouldn’t cycle back on. On the ground, the regulator has a green light and a voltmeter shows 24v at the ACU and nothing at the alternator.


Sent from my iPhone using SuperCub.Org

[wireweinie]

Sounds like a stock ACU and Plane-power alternator, is that correct? Does your ACU use a small circular connector with three wires in it? If so which wire has 24V on it?

Web

[LMartin]

Yes. Alternator was replaced, the ACU was not. It was a wire with white shielding, on the left. Supposed to be the field.


Sent from my iPhone using SuperCub.Org mobile app

[wireweinie]

Judging by your pic and description, this should be the wiring diagram for your aircraft alternator system. With the engine off, battery and alternator switched on, check the voltage at the following points.
- ACU pin 3, should be battery voltage
- ACU pin 1, should be something less than battery voltage, but not 0 volts.
- ACU pin 2, should be battery voltage

- Alternator field terminal, should match voltage on ACU pin 1
- Alternator output terminal, should be battery voltage

Let me know what you find.

Web

[LMartin]

So far we have 0 on both the alternator field and alternator output terminals.


Sent from my iPhone using SuperCub.Org

[LMartin]

0 at both alternator and field alternator breakers.
0 at switch.
(Jaeden tested and got voltage at the pitot heat breaker, because we were worried that the multimeter wasn’t working)


Sent from my iPhone using SuperCub.Org

[wireweinie]

Look under the panel at the back of the breakers. They should all be tied together with an aluminum or copper strip. I suspect a bad connection on this strip. Since the output breaker is typically at the end of the row, start checking from that breaker and moving along the row until you find voltage. The bad connection will be between the last breaker with no voltage and the first one with voltage. Web

[stewartb]

B&C LX-60 alternator with their LR regulator. Easy field approval.

[LMartin]

Jaeden set his multi meter to 200 and got:

Pin 1 = 0 volts
Pin 2 = 24 volts
Pin 3 = 24 volts

Now field and battery terminal on alternator are at 24 volts.


Sent from my iPhone using SuperCub.Org

[Steve Pierce]

Recently installed a rebuilt alternator on a friend's Cherokee after troubleshooting the system. Shortly there after the alternator went out again. Troubleshooting showed it was the alternator. Sent back to the rebuilder, they found the issue and repaired. Alternator worked fine but the got intermittent. Finally got it to quit so I could troubleshoot and found the old original voltage regulator had quit. Replaced and all has been good. If someone had told me this story I would have questioned their troubleshooting but I checked and triple checked. Sometimes stuff happens in triplets.

[LMartin]

Thank you. The ACU has a green light, but it was underwater so we’re going to order both.


Sent from my iPhone using SuperCub.Org

[Ken Robbins]

If someone had told me this story I would have questioned their troubleshooting but I checked and triple checked. Sometimes stuff happens in triplets.

After having the same experience, more than twice, I now install the Hartzell Plane Power units only with a matched Plane Power ACU and fully rewire with fresh grounds. This has been 100% so far and I still don't understand why it seems to be needed. I think I understand electricity pretty well but repeat failures make me unstable. I have had the Plane Powers trip off intermittently and need reset in flight with new Lamar & Zeftronic ACU's with no amount of grounding or connection cleaning making a difference.
I have found that even with a matched alt & ACU there can be problems if the early in-line over voltage module is left in the Cessna's when running a regulator that has that function built in. Like Hartzell products or not, they seem to be the main producers today.

[LMartin]

I don’t know where the over voltage module is?


Sent from my iPhone using SuperCub.Org

[wireweinie]

I don’t know where the over voltage module is?


Sent from my iPhone using SuperCub.Org

On your system, the over voltage module is built into the ACU/regulator.

Web

[LMartin]

Oh good.


Sent from my iPhone using SuperCub.Org