Todd, your photo shows a single but your question is about the PA30.

The system works in parallel. That is, if one goes out then the other remains. It's comprised of the generator or alternator (charging source), a regulator, and an overvoltage relay. The regulator takes the 13.8 volt output down to 12 volts from where is goes into the battery. In case of a power spike there is an overvoltage relay in line as well, and this is like a switch - if there is a voltage spike it shuts off the system. 

The system might be off line - maybe your battery is weak/old and not accepting a charge, or the alternator(s) are weak and not putting out enough voltage and the battery drains, or on one side or the other a regulator is bad or the overvoltage relay has failed. I had an overvoltage relay that failed of old age due to the contacts becoming toasted, and it is a potted component so you can't repair it - you have to replace it.

You might let me know if you have generators or alternators, and, if alternators, what brand it is. In the early PA30 Piper installed generators and most folk replaced these with InterAv alternator systems, which are actually about an early 1960s Motorola alternator. If you have a later PA30 then you have a Piper alternator which still has a separate regulator and overvoltage relay, as originally fitted. 

To trouble shoot you remove the alternator and take it to Autozone or O'Reilly's and they will run it on a bench and test the output. If the output is low it might be as simple as the brushes being weak, and they should be available through an auto parts dealer. 

You put 12 volts through from another battery and see if the regulator is allowing voltage through, and do the same with the overvoltage relay. Try to isolate the issue. 

Your plane might be fitted with a combination regulator and overvoltage relay - again, test it and see if it allows voltage through. Look for corrosion / sulfate build up at the contacts - clean them up. Look at every connection for acid build up, every contact, including breakers and switches. How old is the battery? 

The system is simple if you understand the basics of voltage and amperage ...... your solenoids and circuit breakers are obviously OK since you are able to start the engine ..... and your issue (as you stated) is that your battery goes flat after an hour and a half. That suggests that you charge the battery to a full level on the ground and that it is not getting adequate power from the system. 

It seems that since you have little electrical experience that this might be hard for an owner to figure out, so you might contemplate getting a mechanic to deal with this, or an electrician who understand aircraft. Remember, the system is simple, but you aren't getting adequate power to the battery, so you need to find resistance in the system. It is also an area which requires an A&P, not an unlicensed person. 

Usually the problem is a) worn brushes, b) bad regulator, c) bad overvoltage relay. But you have one set on each engine and the other side will pick up the load, so perhaps both are bad? The answer will be simple if you can find it.

@patricbarryThanks for the quick reply!  I do have 30 years or so electrical and mechanical experience and have been working with an A&P for the last 15 years or so.  I have both a single and a twin now.  I touched every piece of the single (almost literally) and now here we go on the PA30. I've grown to love the Comanche platform, so by nature, I need to understand how the work! I fly my projects, so I have a vested interest in doing it correctly. I appreciate your system overview and suggestions.  It's exactly what I was looking for.  It was much better than the SM! I believe this plane has paralleled generators. The battery is new. With the generators, there seems to be a chance of loss of polarity which in turn wants to damage points/contacts.  I wonder if that is a possibility? 

Todd

@toddhensley 

Loss of polarity is usually associated with the generator not being hooked to a battery for a substantial period of time (several days.)  It is not something I've heard of happening to a connecting system in service.

With generators I would focus on the points, commutator, and general cleanliness.  With any electrical system trouble I always start with bad ground connections.

@williamh Thanks! This project did set for a long time initially. I found a stuck contact in the switching regulator.  Cleaned it up slightly.  When I engage each generator now, at idle, I see a negative charging indication on my ammeter.  I'll see how things act at high RPM. 

@toddhensley That sounds exactly right - discharge at idle, and the generator will start making enough power to charge once rpm picks up.

I changed my 250 over to a solid state regulator five years ago.  I like the "make power even if battery dies" aspect of a generator, but am not to pleased with the "sparking relays to provide regulation and cut-out" of a old fashioned regulator.

The solid state regulator gets the best aspects of the generator without all that sparking and such.

@williamh I'll be looking in to those! I've always had a little concern about cramming all those sparking solenoids and relays under the hood with the Janitrol anyway!

@patricbarry

hi, I’ve been reading this thread Cuzz I have an issue in my pa-30 last couple of flights I’ve noticed a negative charge showing on the ammeter intermittently and under low rpm (under 1300-1400)...when I do my run ups my left engine shows a rise in the volt meter (12+ volts)  on my digital display and positive charge on the ammeter , but nothing from right engine.  In flight once at cruise I show 12+ volts on batt digital indicator but ammeter indicates a neg charge 🤷‍♂️... I also flight tested at night around the pattern and on the ground and basically Same results, except at night more of a load demand due to light, etc etc...and when I use a heavier load like landing/taxi lights and or flaps, the batt indicator starts flashing Cuzz voltage drops below 12 volts...my a&p is trouble shooting but he’s scratching his head 🤷‍♂️.  He checked batt and it seems strong (only 2 years old ).  He’s checked both regulators today and he can’t seem to figure out what could be the problem.. any feedback , advice or help on how to test the regulators, over voltage relay, generator, etc.   Thanks so much.

This isn't a PA30 problem, just a typical electrical problem.

It sounds like you have generators, which is why you are going negative at low rpm. The generator output drops at low rpm while your load (lights, radios etc., landing gear operation) is constant. That is why people install alternators.

Whether you have generators or alternators, you are not getting power from one engine. The components are the power source (13.8 volts), a regulator (to reduce the voltage to battery 12v level) and an over voltage relay (which has contacts inside which open if you have a power surge). All of this is designed to get 12 volts to the battery, and ship takes the operating electricity from the battery.

The meter is there to tell you if the battery is accepting power (charging or draining). 

Since are not getting charging on one engine you have either a bad regulator or a bad overvoltage relay. You don't mention if you have generators or alternators (you must have generators from your description) but it is insignificant since the system functions the same way. If you have a bad regulator it can stop power entirely or, as happened to me once, it fails to reduce voltage and boils the battery (which is not good). My guess is that you have a bad wire (check continuity) or check the overvoltage relay. The points in the overvoltage relay can corrode so the unit can fail. You can buy (Aircraft Spruce) a combination Plane Power regulator and overvoltage relay, so try that and I'll wager that you will regain charging.

You can fly your aircraft with just one side, daytime VFR, not IFR. But you do need to fix the issue. Hartzell Engines owns the approved systems and has a website that you can visit, but Spruce should have inventory.

Some people just won't let themselves be weaned away from generators  - I reckon alternator systems are better. 

Pat

@patricbarryb

thx pat I will share with the A&P , I guessing he will come up with same conclusion , but hoping your response will accelerate his arrival 😎👍Thx again 🙏

My issue turned out to be a stuck contactor in the switching regulator. A little TLC, and it's working properly for now.

Todd

@patricbarry

Some people just won't let themselves be weaned away from generators  - I reckon alternator systems are better. 

I do agree with this.  If my generator ever packs it in I will replace it with an alternator.

Switching regulator? I'm not familiar with the term. Perhaps this is the overvoltage relay? Or is it something on the generator / alternator?

Sorry.  Per the Service Manual, it's actually called the "Paralleling Relay".  It's the center one in the cluster of three located in the nose.