Question about Plane Power backup generator

[Toddsanderson]

Hello,

I have a RV-14A with YIO-390 engine, plane power experimental 60 amp belt driven alternator, Plane Power 30 AMP accessory pad driven backup alternator, and VP-X power system all installed by SteinAir. My panel has a two position master battery/main alt switch and a separate rocker switch for the backup alternator. The previous owner told me to NOT engage the backup alternator switch unless the main alternator fails and then to turn off the main alternator and then engage the backup. SteinAir has not gotten back with me yet to give their opinion of proper operation.

The Plane Power website is very lacking in information; however, I did find one document that states that the backup alternator should be armed at all times and that it will automatically engage at 13.6V buss power. The VP-X shows that the backup alternator does indeed have power to the field when the master switch is engaged (even with the backup rocker switch off), so it does have the ability to produce power if needed, but I am not sure if the rocker switch should be activated after startup?

Anyone have the same setup or can clarify? Much appreciated!!

 

[MED]

I have a Plane Power belt driven alternator and a B&C stand-by alternator on my 14 with a VPX controlling everything. My panel was also built by Steinair. I do not turn on the stand-by alternator unless I turn off the primary. I watch the voltage drop before engaging the stand-by. I run on the stand-by periodically to make sure it will be available when needed. Not saying you can’t turn them both on, but I never have and don’t know if it is ok to do. I would ask Steinair to be sure. BTW - enroute home from Oshkosh this year my primary alternator failed over Indiana after ~343 hours and we flew home to South Carolina on the stand-by. The VPX announced “alternator fault” when the primary failed.

 

[Toddsanderson]

I have a Plane Power belt driven alternator and a B&C stand-by alternator on my 14 with a VPX controlling everything. My panel was also built by Steinair. I do not turn on the stand-by alternator unless I turn off the primary. I watch the voltage drop before engaging the stand-by. I run on the stand-by periodically to make sure it will be available when needed. Not saying you can’t turn them both on, but I never have and don’t know if it is ok to do. I would ask Steinair to be sure. BTW - enroute home from Oshkosh this year my primary alternator failed over Indiana after ~343 hours and we flew home to South Carolina on the stand-by. The VPX announced “alternator fault” when the primary failed.

Thank you - yes that makes sense since you have a B&C. My concern is with the supposedly built-in logic that the Plane power has to self energize. I just want to make sure I don't burn something up by having it armed. I have P-Mags, so not worried about losing the engine too. One thing I read on this site was a person that has A/C like my plane has that draws quite of bit of power. His Plane Power Backup supposedly automatically engages on the ground since the draw of it and other equipment exceeds the main alternators ability to maintain 14+V during ground operations.

 

[Auburntsts]

IIRC, it depends on what version of the PP backup alternator you have. Per the installation instructions, the FS1-14 (which is what I have) is designed to be turned on and left on along with the primary alternator. In this way if the bus voltage drops it automatically picks up the load. The other version, FS1-14B I believe is designed to be left off and only powered on when needed.

 

[Toddsanderson]

Would this schematic from SteinAir help with those here that are good at reading schematics?
Please note the error on the schematic. They have the switches labeled as J1 on the VP-X, but they are actually J2.

Thanks!

 

[Auburntsts]

Would this schematic from SteinAir help with those here that are good at reading schematics?
Please note the error on the schematic. They have the switches labeled as J1 on the VP-X, but they are actually J2.

Thanks!

IMO not really. All the schematic shows is your backup alt is controlled by an VP-X external switch. You still need to know the model of the backup alternator to know whether you should turn it on and leave it on until shutdown as part of your startup routine or to turn it only when you see a bus voltage drop/low voltage warning indicating a primary alt failure.

 

[Toddsanderson]

IMO not really. All the schematic shows is your backup alt is controlled by an VP-X external switch. You still need to know the model of the backup alternator to know whether you should turn it on and leave it on until shutdown as part of your startup routine or to turn it only when you see a bus voltage drop/low voltage warning indicating a primary alt failure.

Roger that - thank you as I agree. Unfortunately, the mechanic that replaced the backup alternator (twice in 6 years) and the primary alternator (3 times in the last 6 years) properly listed the primary alternator in the logs, but the model number he put for the backup alternator does not match any of the part numbers Plane Power lists. He does specify it is a Plane Power 30 amp backup, but not a good part number. The last failure was the shear coupler being replaced. I have read about a lot of plane power failures. Of the 60 aircraft I have owned I have only had one alternator failure in a Piper Arrow. It was 19 years old and had 1950 hours on it. Same alternator that was in a Chrysler Cordoba, lol. My 14A is 6 years old and 650 hours TT. I have to think this many failures about has to be improper operation.

 

[Bill.Peyton]

Next time you have a failure of the PP alternator, replace it with a B and C. IMHO the PP alternators are junk. I had one of each fail before I switched. Do a search on VAF regarding alternators and reliability.


If the voltage regulator on the backup alternator is set for 13.8 volts, verses the main alternator, which is normally set for north of 14.2 volts, then you can leave the field switch on all the time. As previously posted, you can check the P/N of the backup to confirm this. If both voltage regulators are set for the same voltage,( usually around14.2Volts), then you must manually switch between the two.

 

[Toddsanderson]

Next time you have a failure of the PP alternator, replace it with a B and C. IMHO the PP alternators are junk. I had one of each fail before I switched. Do a search on VAF regarding alternators and reliability.


If the voltage regulator on the backup alternator is set for 13.8 volts, verses the main alternator, which is normally set for north of 14.2 volts, then you can leave the field switch on all the time. As previously posted, you can check the P/N of the backup to confirm this. If both voltage regulators are set for the same voltage,( usually around14.2Volts), then you must manually switch between the two.

Thank you Bill. Another question: What would happen if I am running my A/C on the ground causing the main alternator to drop below 13.6V which would automatic engage the backup? Would both unit feeding power to the buss be a problem?

 

[Bill.Peyton]

It should not harm either alternator.
I have two b and c's and test the the backup all the time just by applying (switching on) field voltage to the backup without switching off the main.
My backup is set for 14.5 volts, so it will pick up partial load when switched on.

 

[Toddsanderson]

It should not harm either alternator.
I have two b and c's and test the the backup all the time just by applying (switching on) field voltage to the backup without switching off the main.
My backup is set for 14.5 volts, so it will pick up partial load when switched on.

Excellent - thank you.

 

[agent4573]

I have the same setup on a 360 and the answer is it depends. The backup alternator can be regulated for either 13.6 volts or 14.2 volts. If you have the 13.6 volt version, you can leave it armed at all times and it will pick up the load when the primary fails. If you have the 14.2 volt version, you should have them on separate switches and only engage the backup once the primary fails.

the primary alternator is close to 14.2 volts and it sags a little under load, you may end up pulling most of your current from your backup and not realize it. This isn't immediately harmful, but it isn't great either. If your backup is providing most of the current, you'll never know if your primary fails, so you may go fly with a bad primary and never realize it. Youll also be wearing out your backup. If your average load is 20 amps and youre powering that from a 30 amp alternator, it's working pretty hard. If you pull that same current from the 60 amp, it's gonna last a lot longer.

You can figure out which one you have by visual inspection of the model number, or by turning off your primary and running on your backup while looking at your voltage gauge. I also do this every run-up to make sure both alternators are still working before takeoff. If you have the higher voltage one, I suggest getting an on-off-on switch for them, so you physically can't have both on at the same time.

 

[Toddsanderson]

Thank you. I will pull the cowl this weekend and see what I have. My backup is on a separate switch already. Primary alternator is on the main batt switch. It is OFF/BATT/ALT.

 

[dmattmul]

How to know when your primary alternator fails

If your backup is providing most of the current, you'll never know if your primary fails, so you may go fly with a bad primary and never realize it.

I see this quite often and there is a very easy way to understand when your primary alternator fails almost within seconds with most modern EFIS systems. Our primary bus under normal operating conditions runs in the 14.0-to-14.6-volt range. Normally back-up alternators kick in at 13.6 volts. Set your caution warning at 13.8 volts. Also, most modern EFIS systems have amp monitoring on the primary alternator B lead with a shunt or Ampac sensor. Set this at anything 10 amps or less (Most of our main bus avionics and lighting draw more than 10 amps). If your primary alternator fails, you should get a voltage warning and amp warning almost within seconds. Now you can monitor your standby alternator output to insure it is putting out enough amps through its B lead to understand can you continue your trip or land within the next hour.

Practice primary alternator failures (By turning off the field or pulling the breaker) to insure when your primary fails (It will) you have set the EFIS to alert you properly.

 

[agent4573]

I see this quite often and there is a very easy way to understand when your primary alternator fails almost within seconds with most modern EFIS systems. Our primary bus under normal operating conditions runs in the 14.0-to-14.6-volt range. Normally back-up alternators kick in at 13.6 volts. Set you caution warning at 13.8 volts. Also, most modern EFIS systems have amp monitoring on the primary alternator B lead with a shunt or Ampac sensor. Set this at anything 10 amps or less (Most of our main bus avionics and lighting draw more than 10 amps). If your primary alternator fails, you should get a voltage warning and amp warning almost within seconds. Now you can monitor your standby alternator output to insure it is putting out enough amps through its B lead to understand can you continue your trip or land within the next hour.

Practice primary alternator failures (By turning off the field or pulling the breaker) to insure when your primary fails (It will) you have set the EFIS to alert you properly.

This is mostly true, but both the 60 amp primary and 30 amp pad mounted alternator from plane power are regulated at 14.2 volts. So if you have the higher regulated version of the backup, you can't use this setting to know when the primary fails. That's why you need 2 switches, so when the primary fails you see the voltage drop and turn on the backup. If you run the 13.6 backup, absolutely set up the alerts like you said and it works great.

 

[Toddsanderson]

Well, now I am confused. The logs were correct. It is model 16-1020 backup alternator which is not listed. I suppose I will have to call hartzell to find out what this alternator is.

 

[MED]

You may want to consider installing a blast tube for cooling the stand-by alternator. Otherwise, not much cooling airflow in the back of the engine.

 

[Toddsanderson]

You may want to consider installing a blast tube for cooling the stand-by alternator. Otherwise, not much cooling airflow in the back of the engine.

Thank you. I will do that next month when the condition inspection is due.

 

[Toddsanderson]

Called Hartzell and gave them the part number of 16-1020. That cross references to the FS1-14 which is the 13.6V cut in model, so the correct procedure for use would be to engage it before the main alternator is on for first flight of the day and then turn it off, turn on the main alt, and then arm the backup with the switch. Thanks for the suggestions here.

 

[Toddsanderson]

Ran the plane today and tested the alternators. I left the main alt off and turned on the backup and it did what it should maintaining about 13.8V and ramped up to 25 amps since the plane just was started. Turned off the backup alt and turned the main alt on and was charging at 14.7V.

The VP-X does not allow both alternators to run at the same time.

 

[dmattmul]

Amp Monitoring

This is mostly true, but both the 60 amp primary and 30 amp pad mounted alternator from plane power are regulated at 14.2 volts. So if you have the higher regulated version of the backup, you can't use this setting to know when the primary fails. That's why you need 2 switches, so when the primary fails you see the voltage drop and turn on the backup. If you run the 13.6 backup, absolutely set up the alerts like you said and it works great.

That is why I said this: Also, most modern EFIS systems have amp monitoring on the primary alternator B lead with a shunt or Ampac sensor. Set this at anything 10 amps or less (Most of our main bus avionics and lighting draw more than 10 amps). If your primary alternator fails, you should get an amp warning almost within seconds.

 

[dmattmul]

Testing EFIS alarms

Ran the plane today and tested the alternators. I left the main alt off and turned on the backup and it did what it should maintaining about 13.8V and ramped up to 25 amps since the plane just was started. Turned off the backup alt and turned the main alt on and was charging at 14.7V.

The VP-X does not allow both alternators to run at the same time.

Not that Todd did not do this (I don't know) but this is an excellent way to ensure ones EFIS alarms are set correctly. Over the last few years, I have seen more than one airframe that had voltage and amperage monitoring installed but not set up. Seems some of us are better builders than getting newer avionics set up correctly. You should get a warning of some sort (either master or caution) for both voltage and amperage when one shuts off your primary and or back-up alternator. Failed alternators are probably the number one fault ones sees and knowing very quickly when this occurs one should know, especially with electrically dependent engines. I've seen airframes fresh out of an annual (They were not the builder) with the EFIS alarms not set up correctly.

My guess is the A&P's on this sight have seen their fair share of an EFIS not programmed properly.

 

[Toddsanderson]

Good post. I just set up all my alarms and also set up the backup battery colors for the display. Now that it is set up the way it was intended to be used it is a very good way to know if you have a problem immediately.