I installed a new Plane Power 60A alternator in my RV4 and it worked flawlessly for 26 hours. Now, the 5A field breaker wants to pop upon start up. Doesnt matter if I have the alt switch on or off during starter engagement, it still wants to pop the breaker. This is intermittant - doesnt always happen. Battery is good, nothing wrong with wireing firewall forward. I have not opened up my breaker panel yet for inspection. Does a breaker ever go bad? Thanks for your help.
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Plane Power alt problem
- Thread starter hempy.4
- Start date
Lycosaurus
Well Known Member
Breakers can go bad, though somewhat unlikely.
I would look at the ground connection from your alternator. The alternator is bolted to the engine alternator bracket, and obtains a ground there. PlanePower suggests installing a ground strap from the alternator casing to the engine casing.
It is recommended to have the alternator field on when starting (minimizes current surges in the alternator). If the alternator field is off, and the filed breaker (5A) trips .... there's something wrong with your wiring or the breaker. The field breaker should not be popping.
If on the other hand, you are referring to the alternator output breaker (60A), that could be caused by flaky wiring or ground. I would check the ground strap, and make sure your wiring lugs and bolts are all tight and in good shape.
On my 60A alternator, I have an 80A fuse. This is to protect wiring/battery from an internal alternator short to ground (damaged rectifier). If you have a breaker, 60A should be adequate.
Having said the above, you may want to clarify your statement as to which breaker trips, and when it trips (once running at full power, on startup, full load, no loads etc).
I would look at the ground connection from your alternator. The alternator is bolted to the engine alternator bracket, and obtains a ground there. PlanePower suggests installing a ground strap from the alternator casing to the engine casing.
It is recommended to have the alternator field on when starting (minimizes current surges in the alternator). If the alternator field is off, and the filed breaker (5A) trips .... there's something wrong with your wiring or the breaker. The field breaker should not be popping.
If on the other hand, you are referring to the alternator output breaker (60A), that could be caused by flaky wiring or ground. I would check the ground strap, and make sure your wiring lugs and bolts are all tight and in good shape.
On my 60A alternator, I have an 80A fuse. This is to protect wiring/battery from an internal alternator short to ground (damaged rectifier). If you have a breaker, 60A should be adequate.
Having said the above, you may want to clarify your statement as to which breaker trips, and when it trips (once running at full power, on startup, full load, no loads etc).
The 5A field
...breaker pops on STARTUP. Seems to have nothing to do with alternator load. I can taxi around with ALL day lit up like a Christmas tree and the self regulated Plane Power alt does its job. (obviously during the times the 5A breaker does not pop). I can put a ground strap on, but the alt mount, bracket, bolts are all new and shiney...you would think it would be a good ground...I will check other ground straps...engine to firewall etc.
...breaker pops on STARTUP. Seems to have nothing to do with alternator load. I can taxi around with ALL day lit up like a Christmas tree and the self regulated Plane Power alt does its job. (obviously during the times the 5A breaker does not pop). I can put a ground strap on, but the alt mount, bracket, bolts are all new and shiney...you would think it would be a good ground...I will check other ground straps...engine to firewall etc.
Lycosaurus
Well Known Member
That does sound strange. Two things I would do... I would swap out the 5A breaker with another, see what happens. Also speak with the people at PlanePower and see if they have heard of similar issues/problems.
My PlanePower has worked flawlessly for 75 hours now... same 5A breaker. I use a Klixon breakers.
Me being the internal geek that I am, I would pull the breaker (open it, not remove, yet) and bypass it with a handheld analog ammeter, and start the engine a few times to see what is actually going on with the current flow through that breaker. That will tell you what you need to know.
If the current ever surges up around or past 5 amps, you know the breaker is fine and you get to start chasing other gremlins. If you never get that high, even after several starts, replace the breaker and go fly. If you really want to make sure, put the meter in series with the breaker and watch the needle as you start - if the breaker pops below its rating, toss it.
If the current ever surges up around or past 5 amps, you know the breaker is fine and you get to start chasing other gremlins. If you never get that high, even after several starts, replace the breaker and go fly. If you really want to make sure, put the meter in series with the breaker and watch the needle as you start - if the breaker pops below its rating, toss it.
Lycosaurus
Well Known Member
Over voltage?
Another thing to check.... is it being tripped due to overvoltage protection? Monitor the alternator voltage .... over 15 v (maybe 16v) may trip the breaker. Your charging voltage should typically be showing around 14.2 volts.
Another thing to check.... is it being tripped due to overvoltage protection? Monitor the alternator voltage .... over 15 v (maybe 16v) may trip the breaker. Your charging voltage should typically be showing around 14.2 volts.
D-Dubya
Well Known Member
5 Amp Breaker Popping
One other thing that could be happening is that the wire going from the breaker forward to the alternator could occasionally be going to ground. If the wire is starting to wear through its insulation (maybe at the firewall penetration), then that could lead to a ground that will pop the breaker. I've seen something similar on another RV-7, but it was with the stand-by 20 amp alternator.
A ground would also explain why it took a few hours of run time for the problem to rear its ugly head, as it typically takes a while for engine vibration to wear through insulation at a sharp point. And it might also explain why the breaker popping is intermittent, as it might take the engine to wiggle just right for the bare wire to short out against the firewall or whatever else it's touching.
If the other things you're trying don't work, then you could test for a ground with an ohmeter. With the master switch off, connect to the wire or breaker terminal and a ground, then grab the wires in a few places and pull on them to see if you can recreate the ground problem. My diagnosis from a distance, for what it's worth.
One other thing that could be happening is that the wire going from the breaker forward to the alternator could occasionally be going to ground. If the wire is starting to wear through its insulation (maybe at the firewall penetration), then that could lead to a ground that will pop the breaker. I've seen something similar on another RV-7, but it was with the stand-by 20 amp alternator.
A ground would also explain why it took a few hours of run time for the problem to rear its ugly head, as it typically takes a while for engine vibration to wear through insulation at a sharp point. And it might also explain why the breaker popping is intermittent, as it might take the engine to wiggle just right for the bare wire to short out against the firewall or whatever else it's touching.
If the other things you're trying don't work, then you could test for a ground with an ohmeter. With the master switch off, connect to the wire or breaker terminal and a ground, then grab the wires in a few places and pull on them to see if you can recreate the ground problem. My diagnosis from a distance, for what it's worth.
How did you solved it?
HI there, Im having exactly the same issue... 60 amps plane power on my RV8... the alternator field breaker jumping out, or overvoltage (15.2v) or excessive amps... Everything works fine until I land, or on the next flight same day, when the engine is hot and all sort of issues happen.
How did you solved your issue?
HI there, Im having exactly the same issue... 60 amps plane power on my RV8... the alternator field breaker jumping out, or overvoltage (15.2v) or excessive amps... Everything works fine until I land, or on the next flight same day, when the engine is hot and all sort of issues happen.
How did you solved your issue?
