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Not charging

swjohnsey

Well Known Member
Went to the Houston fly-in in the RV-4, everything normal on the way up. After taking off at Sport Flyers I noticed I was not charging. O.K. turn off everything, radios, etc. and get the discharge rate down to 2 amps. I have one mag and P-mag plenty of battery to last hour flight home, plenty of little airports on the way to bail out. About 20 minutes in I start to get charge again. About 10 minutes from home I start to get big spikes in charging on and off.

What's going on. I didn't build the RV-4 so I'm not familiar with the charging system. What is the normal alternator? Does it have seperate voltage regulator? I'm going to start digging through paperwork to start to sort this out.
 
There are the standard checks on all the electrical connections. I had similar symptoms and my fix was in the master switch. The wires on the switch were not secured properly ( loose). Once tightened the problem went away temporarily. I replaced the switch at next annual and have not seen the issue re appear. I am second owner as well and think the switch may have been worked on before.
 
I didn't build the RV-4 so I'm not familiar with the charging system. What is the normal alternator? Does it have seperate voltage regulator? I'm going to start digging through paperwork to start to sort this out.
It?s not just in the paperwork, but pull the cowling and take a look at the alternator itself and determine what you have, it?s easy to tell the difference. If it?s an older -4 it?s probably 50\50 on having internal or external regulator. There isn?t really a ?normal? alternator for these things, but I?d guess that more recent builds have internally regulated units... in the case of using an automotive type, the standard unit is the Denso 14824, 14684, or 14870. Different part numbers but basically the same unit from NAPA, Autozone, O?Reilly, etc.

Good luck!
 
Never occurred to me to look at the master switch. It first flew in '91 but has been re-engined. I took a look at it when I changed oil about 10 hours ago, belt and such looked good. I should have taken a picture of it with the phone but . . . Cowling comes off tomorrow.
 
The on/off again nature is sounding a lot like something loose.

Check for wire ends not crimped well, push on tab connectors that have loosened up, etc.

Dont forget to check the engine ground path.

Good luck.
 
The on/off was more like a pattern instead of random. I'm suspecting voltage regulator.

It could still be a bad connection. The connection heats up due to high resistance, breaks continuity, cools enough to regain continuity, cycle repeats.

Take a close look at the connections on the back of the alternator, those connections are subject to a lot of vibration and can break if not well-supported. If you have an external regulator it may very well be a mid-'70's Ford unit, VR166 or similar, available at your local auto parts store. The reg has to be well grounded to be reliable.

https://www.amazon.com/Standard-Motor-Products-VR166-Regulator/dp/B000C805SW#ace-g1639449406

41M3MEZ16KL._AC_UL115_.jpg
 
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I have something similar marked Chrysler with a marker. It might be my voltage regulator.
 
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Alternator problem

I have an RV-4 with a Plane Power AL12-EI60/B that I installed new when I built the plane in 2007. The airplane now has 451 hours on it. About a week ago I noticed the 5 amp field breaker had popped. I reset it and continued flying. When I stopped to fuel the battery was down and the breaker was popped again. Flew it home and started checking things. I isolated it to the alternator which has an internal regulator with a blast tube directing air to the regulator. Removed the alternator and removed the brushes to check them. They were in excellent shape but I noticed that the rear bearing was very loose. I called Plane Power and talked to the technical staff. They stated that the loose bearing would caused the brushed to bounce and the breaker to pop. Said to fill out a warranty investigation request and submit for a RMA. I sent the alternator back and they are replacing it. Some warranty after 13 years.
 
Guessing is fun. Already mentioned: Could be loose connection. Could be voltage regulator. Could be bad switch...
 
I got all the cowling off. The alternator and belt look good. The battery is fully charged so I think it is working properly. I found the voltage regulator (I think, has a terminal marked field). It is marked "Chrysler" and I found a Mopar regulator that looks very similar, says constant 13.5v output. It appears from the wiring diagram that there are only two connections, ground and field.

I was hoping to figure out what kind of alternator was on there but there are no obvious markings.

In poking through the threads I found that it is the alternator off the '79 Honda.
 
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Damint! Replaced the voltage regulator with what came off a Mopar Ch P3690732 and still no charge. Got a new alternator on the way 14129 new off ebay for around $50.
 
Damint! Replaced the voltage regulator with what came off a Mopar Ch P3690732 and still no charge. Got a new alternator on the way 14129 new off ebay for around $50.

Have you taken your old alternator to an automotive parts store to have it tested?
 
Check the FIELD wire connector where it plugs into the alternator. The spade terminal has an uncanny ability to break in half inside the plastic connector. (& you won't see it till you actually look inside that plastic connector.)
 
Have you taken your old alternator to an automotive parts store to have it tested?

No. I'm not even sure they can test an alternator with external voltage regulator. I've already ordered another alternator, I might pull the other one off and have it tested out of curiousity.
 
Check the FIELD wire connector where it plugs into the alternator. The spade terminal has an uncanny ability to break in half inside the plastic connector. (& you won't see it till you actually look inside that plastic connector.)

I'm out to pull the cowlings off . . . again. I'll check that.
 
No. I'm not even sure they can test an alternator with external voltage regulator. I've already ordered another alternator, I might pull the other one off and have it tested out of curiousity.

They can do it, lots (most?) of older vehicles had external regulators.
 
Charging problem

It could be the alt field wire as someone mentioned. Checking that first is quick and easy. When I first got my plane I was flying in the pattern at night doing landings and my xponder had a glitch which the tower noticed just after my 3rd takeoff and before I landed I lost my radio and then complete electrical just after landing. The problem was the alt field spade came out of the plastic clip plug. Of course that happened before I upgraded my panel which didn’t have a warning light for the alternator. Now I would get an audible warning with my glass panel of a charging problem before having the battery bleed down to nothing
 
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Parts stores can easily check near any alternator. Better to find a local Auto Electric repair shop as they would understand it's workings and easily rebuild it for very low cost (just tell them it's on your tractor, not a plane)
 
Parts stores can easily check near any alternator. Better to find a local Auto Electric repair shop as they would understand it's workings and easily rebuild it for very low cost (just tell them it's on your tractor, not a plane)

New one is only $50, rebulit half that.
 
New one is only $50, rebulit half that.

The "new" alternator may actually be an off-shore reman or clone. It is possible to get good service from these remans or it is possible to get a real clinker with sketchy workmanship. If you have a local alternator shop my first choice would be to have them look at the alternator and replace anything needed. It is important to have reliable bearings.....bad diodes might keep the alternator from charging but bad bearings can potentially result in bits and pieces of alternator in the engine compartment or a slung belt if we are lucky.

I've been using "1977 Honda" alternators (14184) in my RV-6 for twenty years. I've had three....one of which ate the bearings in a couple of years, the other two giving good service (currently flying the third one). But anecdotal evidence seems to indicate a possible decline in reman quality the past few years.
 
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The 14129 I bought is listed as all new, probably a clone. When I get it on I will take the take-off to a starter-generator place in Corpus Christ for a post mortem and possible refresh as a spare.
 
So pulled the alternator this morning and took it to Autozone for testing. Guy said it was putting out 8v. Just for grins I asked them if they had anything in stock that would fit. Nope, not for 14129 or 14184 but they can get one in about a week. Fortunately my new alternator off ebay will be here on Thursday.
 
No joy in Mudville! Installed the new alternator. Only glitch was one hole in the alternator body was bushed to a smaller size and the bushing stuck out. Had to cut it off flush. As a precaution, took the alternator to Autozone and had it tested after getting the pulley on and it tested O.K. Was going to fly to KPIL to watch the CAF take off for 4th fly over. Not charging, back to KIKG.

So, new alternator that I know works. New voltage regulator that I'm not sure works. I need some help trouble shooting. The alternator has the plastic connector with two spade terminals. I can't see anything damaged. There is also the connector that goes on a post terminal that might be the field. The voltage regulator is out of a car. It is sealed and has two terminals, one that was marked "Field" that is a post terminal and the other out of the epoxy sealed back. I am guessing the epoxy sealed wire is the input and the "field" is the out to the alternator.

What sould I be getting in and out from the voltage regulator with the master switch on and engine not running. What should I see to the alternator field master on, engine not running.

I am pretty sure the ammeter is working correctly as my voltage is slowing going down and I have two different sources for voltage.
 
The 14129 I bought is listed as all new, probably a clone. When I get it on I will take the take-off to a starter-generator place in Corpus Christ for a post mortem and possible refresh as a spare.

Ah, you had the solution already!

Pack it all up (new alt & VR) and take it down to your starter-generator place and ask them to show you how it's supposed to be wired up. Not the parts store, they are good at looking things up but most likely wouldn't have the right experience to advise how it all works.
Also, confirm your Alt switch is actually working...
 
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Something is loose

Several very smart guys on here have suggested that you look for a loose connection - that's where I'd start.
 
Several very smart guys on here have suggested that you look for a loose connection - that's where I'd start.

I'm off to look for loose connections and blown fuses. The original alternator tested bad. The RV-4 has a mixture of fuses and circuit breakers. I'm thinking there has to be a fuse/circuit breaker for the alternator field and possibly one on the output end as well. The master switch in a twofer, both sides seem to be working properly.
 
Well.....if you don't know where all the fuses and circuit breakers in your plane are located and what each one does......guess this is a good time to figure all that out.

Your alternator is functionally the same as my 14184, the only difference is the mounting ears. The 14129 is for mid-60 to mid-70's Toyotas, the 14184 is mid-70's Honda, both are 35a.

I don't know anything about the Chrysler regulator, but know for a fact the 1975 Ford LTD regulator works nicely with these alternators. If you need wiring pinouts I can look those up for you. The alternator and regulator MUST be well grounded.
 
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I'm off to look for loose connections and blown fuses. The original alternator tested bad. The RV-4 has a mixture of fuses and circuit breakers. I'm thinking there has to be a fuse/circuit breaker for the alternator field and possibly one on the output end as well. The master switch in a twofer, both sides seem to be working properly.

A high resistance master switch can play havoc with the charging system by creating random breaker trips.
 
And check the wires on the alternator to ensure nothing has loosened up. A loose field wire would also cause an issue.
 
Field wire is tight, double checked when I reinstalled alternator. Also took a close look at plastic connector to make sure nothing was broken and made sure it was pushed in securely. Also went back and double checked the connections to the voltage regulator. Went back and checked circuit breakers. Visually checked fuses (multimeter dead).
 
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