MauiLvrs
Well Known Member
That way works (AFTER) works SOME of the time.
The other way (BEFORE) works ALL of the time.
Van's Air Force
Don't miss anything! Register now for full access to the definitive RV support community.
Alternator OFF until after start a good idea?
- Thread starter ao.frog
- Start date
The other way (BEFORE) works ALL of the time.
That way works (AFTER) works SOME of the time.
The other way (BEFORE) works ALL of the time.
Some of us use Aircraft alternators on our airplanes and do not have problem operating them the way certificated aircraft manufacturers recommended them to be operated. (Off till engine is running)
Others go the cheap way and use automotive alternators that do not stand up to aircraft operation techniques and get them to work operating their aircraft like a car. Always on without and many do not have Over Voltage Protection. One OVP event can wipe out all the electronics in the aircraft.
If you take a poll of who has had alternator problems, the majority will have been automotive alternators operating like they do on a car but installed on an aircraft.
scsmith
Well Known Member
Current draw
One aspect of this discussion seems seriously lacking -- I think one post mentioned it tangentially.
The field coils draw about 5 amps. That's 5 amps that could be going to the starter.
For the first two years, I had a battery that was on the weak side, and if the plane sat for 3 weeks, it was marginal for starting. I could tell the difference in cranking speed with the field off rather than on. (that may partly be because of mechanical load to turn the alternator, as well as the lower voltage because of the field current draw).
I also start on a Light Speed Plasma II ignition, and if the voltage drops below 6 volts during cranking, it will not retard the timing to TDC during the start, inviting a kickback.
So, I left the field switch off until after engine start. No problems for 3 years. But for the last year, I have had a stronger PC680 battery that seems to hold higher voltage, so as a hedge from these discussions, I have changed back to starting with the field on. It starts OK.
But if you ever find yourself in a marginal battery situation, think about starting with the field off.
One aspect of this discussion seems seriously lacking -- I think one post mentioned it tangentially.
The field coils draw about 5 amps. That's 5 amps that could be going to the starter.
For the first two years, I had a battery that was on the weak side, and if the plane sat for 3 weeks, it was marginal for starting. I could tell the difference in cranking speed with the field off rather than on. (that may partly be because of mechanical load to turn the alternator, as well as the lower voltage because of the field current draw).
I also start on a Light Speed Plasma II ignition, and if the voltage drops below 6 volts during cranking, it will not retard the timing to TDC during the start, inviting a kickback.
So, I left the field switch off until after engine start. No problems for 3 years. But for the last year, I have had a stronger PC680 battery that seems to hold higher voltage, so as a hedge from these discussions, I have changed back to starting with the field on. It starts OK.
But if you ever find yourself in a marginal battery situation, think about starting with the field off.
MauiLvrs
Well Known Member
The manufacturer of out $400+ aircraft alternator says leave it ON.
Mountain Time
Active Member
Tailwheel or Nosedragger?
I'm pretty sure it depends on whether you have a taildragger or nose wheel, doesn't the angle of the alternator do something to the output waveform? Or maybe I am thinking of the effect of which primer is used . ...
I'm pretty sure it depends on whether you have a taildragger or nose wheel, doesn't the angle of the alternator do something to the output waveform? Or maybe I am thinking of the effect of which primer is used . ...
John Clark
Well Known Member
I'm pretty sure it depends on whether you have a taildragger or nose wheel, doesn't the angle of the alternator do something to the output waveform? Or maybe I am thinking of the effect of which primer is used . ...
Yeah, but don't forget add the effect of a downwind turn after departure and the percentage of Marvel Mystery Oil in the engine.
John S. Clark MS, ATP, CFI
EAA Flight Advisor
805 682-7483
805 689-2246 Cell
805 617-3231 Fax
NickAir
Well Known Member
battery switch before engine start
Here is the results from my request on this subject, with PlanePower.
They sell certified and experimental internally regulated alternators.
______________________________________________________________________________________________
I have a Van's RV7 and this summer, changed to your PlanePower alternator. I have also met others with your alternator.
We are wondering what you recommend about Alt. switch settings for startup, testing and shutdown.
My configuration is with a Master switch, and a Alternator field switch. Standard wiring.
Please advise.
Tailwinds...
Nick
________________________________________________________________________________________________
Nick:
We have 4 RV guys here so I will give you the technical answer and the RV Pilot/mechanic answer. One uses no alternator switch.
Technical Answer: The technique does not matter. Some airplanes have no alternator switch.
RV Pilot/mechanic Answer: We tend to like alternator switches for two reasons. We learned to fly with and alternator switch. It is part of our run-up check to verify the alternator is working. If we want to work on the aircraft and the work needs the master switch to be on - we can leave the alternator switch off and that will prevent the alternator from sucking 3.5 - 4.0 amps from the battery every second during the maintenance project. You could accomplish this by pulling the field breaker. So it is a personal preference issue.
Long ago before modern avionics and modern alternators pilots were taught to turn the alternator switch on after engine start and turn it off before engine shutdown to prevent electrical spikes form damaging the radio, etc. Today's alternators and electrical devices are not subject to that same threat.
We appreciate your business.
Dick Carmichael
Tech Support
_____________________________________________________________
Here is the results from my request on this subject, with PlanePower.
They sell certified and experimental internally regulated alternators.
______________________________________________________________________________________________
I have a Van's RV7 and this summer, changed to your PlanePower alternator. I have also met others with your alternator.
We are wondering what you recommend about Alt. switch settings for startup, testing and shutdown.
My configuration is with a Master switch, and a Alternator field switch. Standard wiring.
Please advise.
Tailwinds...
Nick
________________________________________________________________________________________________
Nick:
We have 4 RV guys here so I will give you the technical answer and the RV Pilot/mechanic answer. One uses no alternator switch.
Technical Answer: The technique does not matter. Some airplanes have no alternator switch.
RV Pilot/mechanic Answer: We tend to like alternator switches for two reasons. We learned to fly with and alternator switch. It is part of our run-up check to verify the alternator is working. If we want to work on the aircraft and the work needs the master switch to be on - we can leave the alternator switch off and that will prevent the alternator from sucking 3.5 - 4.0 amps from the battery every second during the maintenance project. You could accomplish this by pulling the field breaker. So it is a personal preference issue.
Long ago before modern avionics and modern alternators pilots were taught to turn the alternator switch on after engine start and turn it off before engine shutdown to prevent electrical spikes form damaging the radio, etc. Today's alternators and electrical devices are not subject to that same threat.
We appreciate your business.
Dick Carmichael
Tech Support
_____________________________________________________________
Last edited:
Captain Avgas
Well Known Member
Well, don't keep us in suspense.....who IS the manufacturer of your aircraft alternator and specifically what did they say. I presume you have something in writing from them that you can reprint here for our enlightenment.
rjcthree
Well Known Member
What's missing in this is the automotive angle
Guys, not sure it matters to the overall thread, but alternators in cars, since about the mid 2000's, are mostly computer controlled, and do quite often get switched on only after the engine has established a running condition - but the engine is started with the alternator (and AC) offline. During this time, the alternator light is suppressed in the display. Once on, they are mostly left that way, but not always. The mild hybrids do quite a bit more with alternator control. Rick 90432
Guys, not sure it matters to the overall thread, but alternators in cars, since about the mid 2000's, are mostly computer controlled, and do quite often get switched on only after the engine has established a running condition - but the engine is started with the alternator (and AC) offline. During this time, the alternator light is suppressed in the display. Once on, they are mostly left that way, but not always. The mild hybrids do quite a bit more with alternator control. Rick 90432
Captain Avgas
Well Known Member
I have both a B&C L40 and an SD20 alternator on my RV7A and I recently asked Bill Bainbridge at B&C the following question:
What is your recommendation on this in respect of achieving the best service life from the alternators. Do you believe that switching on the field power after the engine is running will reduce the life of your alternators.
This is his verbatim written response:
You would be fine starting with both alternators off.
So there you have it. Both Plane Power and B&C have stated in writing that their alternators will not be subjected to damage by switching on the field power after the engine has started. It is relevant that Plane Power manufactures internally regulated alternators and B&C manufactures externally regulated alternators, so both types are covered. They both manufacture certificated and Experimental alternators.
This argument about switching alternators on after engine start has been swirling around on VansAirforce for years and dozens of builders have come forward with "anecdotal" opinions either way. This thread alone has been running since 2008. And yet it amazed me that no-one had previously bothered to ask their alternator manufacturer what they recommended.
Well, now we know. Buy a quality alternator and switch it on before engine start, or after engine start....in terms of alternator longevity, it doesn't matter.
What is your recommendation on this in respect of achieving the best service life from the alternators. Do you believe that switching on the field power after the engine is running will reduce the life of your alternators.
This is his verbatim written response:
You would be fine starting with both alternators off.
So there you have it. Both Plane Power and B&C have stated in writing that their alternators will not be subjected to damage by switching on the field power after the engine has started. It is relevant that Plane Power manufactures internally regulated alternators and B&C manufactures externally regulated alternators, so both types are covered. They both manufacture certificated and Experimental alternators.
This argument about switching alternators on after engine start has been swirling around on VansAirforce for years and dozens of builders have come forward with "anecdotal" opinions either way. This thread alone has been running since 2008. And yet it amazed me that no-one had previously bothered to ask their alternator manufacturer what they recommended.
Well, now we know. Buy a quality alternator and switch it on before engine start, or after engine start....in terms of alternator longevity, it doesn't matter.
Last edited:
Yes, this is a funny thread - but mostly because no one defines WHICH alternator setup they are talking about - and it makes a difference. Are we talking internally regulated, unmodified automobile units, internally regulated, modified units, externaly regulated auto units, externally regulated aircrfat units....? If you look into it, you'll find that it makes a difference, and one size does NOT fit all.
When folks say "I do it this way", but don't give their configuration, the input doesn't do anyone any good. And if they don't understand the difference between the configurations, they haven't done any research.
Paul
Captain Avgas
Well Known Member
Marc Ausman of Vertical Power does not agree. He believes any alternator can be safely switched on after engine start. In fact that's exactly what the Vertical Power solid state systems do.
This is what he has to say on the matter.
"IMO, there's no point in having the alternator field on prior to engine start. The alternator is not spinning so it won't generate any power. Since the voltage regulator is trying to bring the voltage up to 14 volts (from 12 volts), it is drawing current (typically 3-4 amps) and not producing any benefit with the engine stopped.
When the field is on, the alternator also generates a load on the engine proportional to the amount of electrical load needed. I haven't done any formal testing, but consider the electrical load during start.
After you start the engine, the Vertical Power VP-200 then automatically turns on the alternator field, then the avionics. Each device is turned on with a short delay (1/10 second) before the next device is turned on. This gives the voltage regulator plenty of time to adjust to each new load being turned on".
Walt
Well Known Member
VP400 field operation
Hmmm.. maybe I'm missing something but looking at the VP400 manual and the diagrams (couldn't find the VP200 info) I don't see how the VP400 would sense engine running to control the field (it would need a tach input). According to the info in the manual the alternator field is on when the master is on. It may turn the field off when you hit the "start" button and then with a short delay turn it back on?
Turning the alt field off with a "start relay" would make sense, but can't say that I've seen this implemented in the certified world.
From the VP400 manual:
The VP‑400 provides bus voltage (positive) power to the alternator
field input or voltage regulator from J12 pin 11. This pin is configurable
and you set its circuit breaker value up to 5 amps and assign it to be
controlled by any of the switch inputs (or be always on). When the
specified switch input is grounded by the alternator field switch, then
J12-11 turns on. It works the same as the other power circuits with the
following special considerations:
? J12-11 turns off if there is an over-voltage condition and
?overvoltage? is shown on the Display on the Alternator circuit.
? If a secondary alternator is configured then only one alternator
can be turned on a time (except for Config 4 where each
alternator operates independently). If one alternator is turned on
when the other is on, then the most recent one to turn on remains
on and the other is shut off, regardless of switch position.
Hmmm.. maybe I'm missing something but looking at the VP400 manual and the diagrams (couldn't find the VP200 info) I don't see how the VP400 would sense engine running to control the field (it would need a tach input). According to the info in the manual the alternator field is on when the master is on. It may turn the field off when you hit the "start" button and then with a short delay turn it back on?
Turning the alt field off with a "start relay" would make sense, but can't say that I've seen this implemented in the certified world.
From the VP400 manual:
The VP‑400 provides bus voltage (positive) power to the alternator
field input or voltage regulator from J12 pin 11. This pin is configurable
and you set its circuit breaker value up to 5 amps and assign it to be
controlled by any of the switch inputs (or be always on). When the
specified switch input is grounded by the alternator field switch, then
J12-11 turns on. It works the same as the other power circuits with the
following special considerations:
? J12-11 turns off if there is an over-voltage condition and
?overvoltage? is shown on the Display on the Alternator circuit.
? If a secondary alternator is configured then only one alternator
can be turned on a time (except for Config 4 where each
alternator operates independently). If one alternator is turned on
when the other is on, then the most recent one to turn on remains
on and the other is shut off, regardless of switch position.
With all due respect (and I mean that, Marc is a great developer), I don't know that Marc is an expert in alternators (and neither am I), but I do know that there are differences in the circuitry and design of internal regulators versus external regulators. All "alternator systems" are not alike, and what works for one may not work as well for others. There are a great many anecdotal incidences of early death in automotive, internally-regulated alternators being used on airplanes when they are switched on/off with the engine running. New folks should understand that before they make their own decsions on how to operate there's. Making the wrong shoice is rarely a safety issue, but it can cost money.
Never ending debate? Sure - so long as people don't determine the parameters for debate, they will never agree on anything. If what you want is to cloud the issue, then be obscure; if you would like to eventually give people meaningful guidance, then fully define the debate.
I don't have all the answers, but I try to encourage people to ask good questions.
southtarnation
Well Known Member
This thread has thoroughly confused the @$&! outta me. ...it doesn't take much at all.
Last week I had planned and wired up a alternator switch to use with my externally regulated unmodified Honda alternator and the VP-X.
Then I decided to remove the switch and set the alternator pin in the VP-X to "always on".
I think I'm going to change it back... I was happy that I wasn't going to have to by another ten pack of Aveo Rockrack switch covers just to get the single alt. cover I need.
I guess I need to read some more in the vp-x manual about it but I dont think it even addresses automotive setups.
...it doesn't take much at all.Last week I had planned and wired up a alternator switch to use with my externally regulated unmodified Honda alternator and the VP-X.
Then I decided to remove the switch and set the alternator pin in the VP-X to "always on".
I think I'm going to change it back... I was happy that I wasn't going to have to by another ten pack of Aveo Rockrack switch covers just to get the single alt. cover I need.
I guess I need to read some more in the vp-x manual about it but I dont think it even addresses automotive setups.
Norman CYYJ
Well Known Member
I have owned cars with internal regulators and cars with external regulators, they are on at start up so what is so different in an aircraft?
Couldn't agree more. The only reason to have a switch is to have the ability to turn off the field manually.
ColoRv
Well Known Member
Turning a far larger engine with a far smaller battery. For comparison, my truck engine is 6.7L or about 409 cubic inches. That is a bit larger than our 360 cubic inches but it takes two batteries three times the size of my odyssey to do it. My car is low compression 2.5L or about 152 cubic inches so much smaller than our 360's and takes a battery at least double my odyssey. The purpose of shutting the alternator off is current draw I believe, though aviation batteries do seem to get better and better....so the decision is yours whether or not its worth the bother.
As for switch or no switch....if you're at 12k feet and a main buss shorts to ground, that switch saves your life. The smoke alone would really ruin your day. Leaving that switch out isnt even a consideration for me, even with the VPX. I did run the question by Marc at vertical power and he didn't hesitate to quote a story much like the one I just did. Put the switch in, even if you never touch it.
Last edited:
scsmith
Well Known Member
Not necessarily true
I would not assume that it is on at start. When you move your ignition key to 'start', LOTS of circuits are disabled, specifically to reduce currrent draw during start-up so the starter can crank better.
On my car, headlights go off, radio goes off, fan blow goes off. Alternator field excitation goes off.
As soon as you let the key spring back to "on", everything comes back on.
I would not assume that it is on at start. When you move your ignition key to 'start', LOTS of circuits are disabled, specifically to reduce currrent draw during start-up so the starter can crank better.
On my car, headlights go off, radio goes off, fan blow goes off. Alternator field excitation goes off.
As soon as you let the key spring back to "on", everything comes back on.
WingsOnWheels
Well Known Member
This is the direction I am going. I am using a Double Pole switch with one side for the Battery contactor and the second set of contacts for the Alt field. For emergency/maintenance use I will have a pulable breaker on the Alt field, but otherwise there is no separate switch for the Alt. If the master is on, the alternator is on. If I am sitting in the hangar working on the system and need power for an extened time I will just pull the breaker.
After reading this entire thread, I do see the advantage of reducing current load by leaving the field off for start. It is not something I have ever done in the past, but if you are stuck somewhere with a low battery this might make the difference.
The best of both worlds would be some king of soft-start for the alternator that would let the field voltage rise gradually. Maybe a resistor and capacitor? Just thinking out loud...
On a side note. Back on the '73 Nova a owned years ago I kept having alternator problems. I eventually installed a 100amp one-wire alternator. In this case there is no field connection at all, just a single wire to the battery. I assume there is some kind of internal control circuit that senses where the alternator is turning and then energizes the field. If it weren't for the added complexity (and one more thing to fail) this setup would make a lot of sense if you could include and external kill switch (just in case).
Last edited:
Toobuilder
Well Known Member
A fusable link right on the alternator pigtail takes the "arc welder" out of the system if you get a dead short. I have the typical split master and a breaker... Wish I had dumped the split master in favor of a single toggle when I re did the panel.
nineninefour
Member
The only perspective I can offer, having neither built not flown an RV yet, is as a system safety engineer: increasing complexity, without added redundancy, in either equipment or operation lends itself to increasing failure rates.
A switch to disconnect a fault, in addition to a fuse, is good insurance. But having to manipulate that switch every time you start or stop, while trying to do everything else and maintain vigilance outside the airplane, is inviting unnecessary failure. It's not the one switch, it's everything else PLUS the one switch.
A switch to disconnect a fault, in addition to a fuse, is good insurance. But having to manipulate that switch every time you start or stop, while trying to do everything else and maintain vigilance outside the airplane, is inviting unnecessary failure. It's not the one switch, it's everything else PLUS the one switch.
Sorry for resurrecting an old thread, but it is exactly an issue i want to address. I think i read through every page, and am in complete surprise that nobody else has reported my exact same issue.
A quick back story. At around 300 hours and 2 years, my plane power alternator started to fluctuate and cycle from on to off while in flight. We are talking about 100% working to 100% nothing. Voltage would go from 14.1v to battery voltage 12v to 14 to 12. These cycles got more and more frequent day by day. Field breaker is fine. After talking with PP, i sent it back. Bench testing said it was normal. hmmm???
Ok, now i have a new alternator. 2 months and 40 or so flawless hours later, the SAME thing has started happening again!!! I double checked wiring, connections, etc.
Then I realized that the issue was strongly correlated with how difficult my start-up was. If it was a longer start, then the issue was way way more likely to happen on the flight. If I had a great quick start-up, then the issue was definitely less likely to happen.
That is when i first discovered this thread. All of my starts had been with Master ON Alternator Field ON. I recently started testing starts with Master ON and Alternator Field OFF. Lo and behold, the issue is more or less gone with my so far limited testing.
I am still worried about my alternator. It still want to do more testing and try and isolate the entire field wire and maybe connector as well. However, I can't believe i am the only one to notice this so far, TWICE in a row. I cannot be THAT lucky.
Anyone else notice something like this? Maybe if everyone is made aware of this correlation, others might recognize the issue???
Thanks,
Jae
A quick back story. At around 300 hours and 2 years, my plane power alternator started to fluctuate and cycle from on to off while in flight. We are talking about 100% working to 100% nothing. Voltage would go from 14.1v to battery voltage 12v to 14 to 12. These cycles got more and more frequent day by day. Field breaker is fine. After talking with PP, i sent it back. Bench testing said it was normal. hmmm???
Ok, now i have a new alternator. 2 months and 40 or so flawless hours later, the SAME thing has started happening again!!! I double checked wiring, connections, etc.
Then I realized that the issue was strongly correlated with how difficult my start-up was. If it was a longer start, then the issue was way way more likely to happen on the flight. If I had a great quick start-up, then the issue was definitely less likely to happen.
That is when i first discovered this thread. All of my starts had been with Master ON Alternator Field ON. I recently started testing starts with Master ON and Alternator Field OFF. Lo and behold, the issue is more or less gone with my so far limited testing.
I am still worried about my alternator. It still want to do more testing and try and isolate the entire field wire and maybe connector as well. However, I can't believe i am the only one to notice this so far, TWICE in a row. I cannot be THAT lucky.
Anyone else notice something like this? Maybe if everyone is made aware of this correlation, others might recognize the issue???
Thanks,
Jae
I agree. I am pretty sure that i already tested that by by-passing the field switch/breaker and tying it to the master switch. Also, i am still using the same alternator switch/breaker now, and no problems so far as long as i keep the alternator off during start.
I am not excluding anything at the moment, so one day i will swap the switch/breaker out to see what happens. So far so good, though with the new start method. Keeping my fingers crossed.
Hi JaeSorry for resurrecting an old thread, but it is exactly an issue i want to address. I think i read through every page, and am in complete surprise that nobody else has reported my exact same issue.
A quick back story. At around 300 hours and 2 years, my plane power alternator started to fluctuate and cycle from on to off while in flight. We are talking about 100% working to 100% nothing. Voltage would go from 14.1v to battery voltage 12v to 14 to 12. These cycles got more and more frequent day by day. Field breaker is fine. After talking with PP, i sent it back. Bench testing said it was normal. hmmm???
Ok, now i have a new alternator. 2 months and 40 or so flawless hours later, the SAME thing has started happening again!!! I double checked wiring, connections, etc.
Then I realized that the issue was strongly correlated with how difficult my start-up was. If it was a longer start, then the issue was way way more likely to happen on the flight. If I had a great quick start-up, then the issue was definitely less likely to happen.
That is when i first discovered this thread. All of my starts had been with Master ON Alternator Field ON. I recently started testing starts with Master ON and Alternator Field OFF. Lo and behold, the issue is more or less gone with my so far limited testing.
I am still worried about my alternator. It still want to do more testing and try and isolate the entire field wire and maybe connector as well. However, I can't believe i am the only one to notice this so far, TWICE in a row. I cannot be THAT lucky.
Anyone else notice something like this? Maybe if everyone is made aware of this correlation, others might recognize the issue???
Thanks,
Jae
It does sound like your field wire circuit is cutting out on you thus turning your alternator off intermittently
I have been flying with Nippon Denso alternators since 2006 in my RV-7A. I have had many over voltage issues with these alternators. I purchased the original ND alternator from Vans. As far as I know they do not sell them any more (just Plane Power)
After years of testing & researching how these internal regulator alternators function with one of my hangar mates, we discovered that the internal regulator to use is the Transpo IN256 which has a sensor lug to detect the voltage
Your problem could be similar to mine. Simply put - Your "ships" wiring could be lying to your regulator.
I fixed this problem on my ND alternator by installing a sensor type IR and jumping a sensor line from the charging lug "B Nut" to the IR lug. Now the regulator "senses" the voltage output of the alternator thru a 6" long wire "not my wiring system"
Hope is helps - Good Luck
Clark
Hi JaeSorry for resurrecting an old thread, but it is exactly an issue i want to address. I think i read through every page, and am in complete surprise that nobody else has reported my exact same issue.
A quick back story. At around 300 hours and 2 years, my plane power alternator started to fluctuate and cycle from on to off while in flight. We are talking about 100% working to 100% nothing. Voltage would go from 14.1v to battery voltage 12v to 14 to 12. These cycles got more and more frequent day by day. Field breaker is fine. After talking with PP, i sent it back. Bench testing said it was normal. hmmm???
Ok, now i have a new alternator. 2 months and 40 or so flawless hours later, the SAME thing has started happening again!!! I double checked wiring, connections, etc.
Then I realized that the issue was strongly correlated with how difficult my start-up was. If it was a longer start, then the issue was way way more likely to happen on the flight. If I had a great quick start-up, then the issue was definitely less likely to happen.
That is when i first discovered this thread. All of my starts had been with Master ON Alternator Field ON. I recently started testing starts with Master ON and Alternator Field OFF. Lo and behold, the issue is more or less gone with my so far limited testing.
I am still worried about my alternator. It still want to do more testing and try and isolate the entire field wire and maybe connector as well. However, I can't believe i am the only one to notice this so far, TWICE in a row. I cannot be THAT lucky.
Anyone else notice something like this? Maybe if everyone is made aware of this correlation, others might recognize the issue???
Thanks,
Jae
It does sound like your field wire circuit is cutting out on you thus turning your alternator off intermittently
I have been flying with Nippon Denso alternators since 2006 in my RV-7A. I have had many over voltage issues with these alternators. I purchased the original ND alternator from Vans. As far as I know they do not sell them any more (just Plane Power)
After years of testing & researching how these internal regulator alternators function with one of my hangar mates, we discovered that the internal regulator to use is the Transpo IN256 which has a sensor lug to detect the voltage
Your problem could be similar to mine. Simply put - Your "ships" wiring could be lying to your regulator.
I fixed this problem on my ND alternator by installing a sensor type IR and jumping a sensor line from the charging lug "B Nut" to the IR lug. Now the regulator "senses" the voltage output of the alternator thru a 6" long wire "not my wiring system"
Hope is helps - Good Luck
Clark
Smilin' Jack
Well Known Member
Plane power tech response
I contacted the tech support at plane power and here is his response.
Jack:
In modern times it make little difference. Some aircraft are not manufactured with alternator switches. Personally, I like having the switch. I like to start the engine and I want to see the Alt Lamp illuminated. Then I turn on the alternator switch and I want to see the Alt Lamp go out - "my alternator is working". I operate in reverse when I shut-down.
Another advantage is; if you want to work on something electrical and you need the Master Switch on - you can keep the alternator switch OFF and prevent the alternator from consuming 3 - 4 Amps every second off the battery. Additionally, if you have the alternator switch on for engine start - know you are taking 3 to 4 Amps away from the battery's energy to start the engine.
Beyond the above there is not really a meaningful reason to do it one way or the other.
Dick Carmichael
Tech Support
So from the horses mouth it really does not matter, I personally keep mine off during start
Smilin' Jack
I contacted the tech support at plane power and here is his response.
Jack:
In modern times it make little difference. Some aircraft are not manufactured with alternator switches. Personally, I like having the switch. I like to start the engine and I want to see the Alt Lamp illuminated. Then I turn on the alternator switch and I want to see the Alt Lamp go out - "my alternator is working". I operate in reverse when I shut-down.
Another advantage is; if you want to work on something electrical and you need the Master Switch on - you can keep the alternator switch OFF and prevent the alternator from consuming 3 - 4 Amps every second off the battery. Additionally, if you have the alternator switch on for engine start - know you are taking 3 to 4 Amps away from the battery's energy to start the engine.
Beyond the above there is not really a meaningful reason to do it one way or the other.
Dick Carmichael
Tech Support
So from the horses mouth it really does not matter, I personally keep mine off during start
Smilin' Jack
