Overvoltage question

Wireweine saves the day and perseverance prevails!

Because this site is worth it’s weight in gold! Wireweine’ comments from years ago in addition to the a Recent interav document he supplied me with gave me confidence there was nothing wrong with
my setup and that I needed a better ground between regulator and alternator. Once I tested that further I was able to reproduce and solve my issue. New conductor between regulator and alternator and now happy once again. Maybe my solvent spray down the other day dislodged some conductive something or another. After a full day of chasing my tail I’ll be sure to keep and eye on this one.

Happy 4th Everybody!
My baby gets some papa time for the 4th due to some perseverance and this website!

wireweinie said:

Most likely a bad regulator. Here's a troubleshooting guide from an old InterAv manual. Hope this helps. (Psst! Plane-Power SAL12-70 kit, just sayin')

Web

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Glad you got it working. Not clear though on your fix, did you reground both the alternator and regulator? My regulator is grounded where it is bolted down, alternator grounds to the engine mount I think.

The 6 volts field you mentioned had me thinking bad regulator, the only time field voltage gets down that low is when its charging than it goes way down below bus voltage, testing without the alternator on it should be near bus voltage.

The regulator was originally grounded via a machine screw (white conductor in photo below) that served as a mounting hole for the regulator itself. For 5 plus years this had not been a problem. It was theoretically grounded through its contact with the firewall. Not sure what exactly changed however that caused this to stop working. During my review of the wiring diagram I noticed my install slightly differed from the drawing. That difference being the ground for the regulator. In drawing it shows conductor “B” between regulator and alternator. When I removed original reg ground and instead connected a new conductor to the same ground that alternator uses, I resumed normal Ops. Wireweine supplied a troubleshooting doc for voltage measurements that my readings all came back as normal. I was using the ground terminal of the battery when taking my readings and that gave me the idea to find a better ground for regulator.

Eddie747 said:

Glad you got it working. Not clear though on your fix, did you reground both the alternator and regulator? My regulator is grounded where it is bolted down, alternator grounds to the engine mount I think.

The 6 volts field you mentioned had me thinking bad regulator, the only time field voltage gets down that low is when its charging than it goes way down below bus voltage, testing without the alternator on it should be near bus voltage.

Click to expand...

That makes sense you ran a wire from the ground on the regulator to the neg terminal on the alternator, your regulator was not grounded, now it is. That 6.9 volts on your field still puzzles me, that should be 12 volts or battery voltage until your alternator is on and charging.

Voltage from this reg will never be at bus voltage during operation.

The field of an alternator is just a coil that produces a magnetic field that is proportional to the amount of current (amps) flowing through it. The regulator is called that because it regulates or controls that field current flow. The regulator also forms a series circuit with the field coil. In a series circuit the current flow is the same in all components but the total voltage is divided among each component. The resistance of the field coil will never change since it is a fixed coil, therefore the the resistance of the regulator changes as the system voltage changes, always trying to produce around 14 volts out. With the engine off and electrical power on, the regulator sees a low voltage and reduces its resistance to allow a higher current flow. As stated above, a higher current flow in the field produces a stronger magnetic field, which produces a higher output from the alternator. After the engine starts, the alternator will start putting out power. Once the voltage sensing limit of the regulator is reached (around 14 volts) the regulator sees this and starts reducing the current flow in the field coil. During operation this happens several times a second.

So, depending on the operation of the alternator (engine off or on, low current load or high current load) the voltage measured at the field terminal will always be something less than bus voltage. AND each model of charging system will measure slightly different. For the InterAv system voltage checks, start at the alternator output terminal. This should read bus voltage of around 12 volts with engine off. Then check voltage at the regulator terminal on the back of the alternator. This should be 1 volt according to the troubleshooting chart. 1 volt because the power for this circuit is supplied through a dropping resistor shown between the reg and output terminals. The regulator + terminal should also read 1 volt because it is the other end of the wire connected to the alternator reg terminal. The chart calls for 1 volt at the regulator field terminal. Same reading at the alternator field terminal as it is the other end of the reg field wire and wires/relays/switches have no meaningful resistance.

Web

Another video for others that run into any abnormalities on their Interav charging systems. This video shows the DC voltage readings when multimeter + connected to the Reg Terminal on the Alternator and multimeter - connected to the grounding source of the Alternator and Regulator (these two are terminated at the same GND).
First measurement= .002 VDC: Master relay OFF, Alternator/Field OFF.
Second measurement = 6.91 VDC: Master relay ON, Alternator/Field OFF.
Third measurement= .94 VDC: Master Relay ON, Alternator/Field ON.
Fourth Measurement = 15.32 VDC: Master Relay ON, Alternator/Field ON, Engine Running.

Well, my previous “solution” has failed or the hardware has finally thrown in the towel. Was out on a flight when I observed a significant noise increase on my radio reducing my reception to next to nothing and in and out. Shortly thereafter, back to no positive deflection on my ammeter. Wondering if this is worth chasing via troubleshooting or time to move on. If moving on, Wireweinie has indicated that Plane Power is the way to go but when I research that solution it seems I must also relocate my oil cooler to the rear baffling (read:extra work and extra $$). I also see B&C 400 systems would work and even tout not having to relocate anything. Anybody care to weigh in on this?

Plane-Power will work but you'll need to bend the oil cooler leg.

Web

Wireweinie this “leg”?

Nope. That is some cobbed together piece for an inter-av alternator bracket. The best way will be to fab a new bracket leg or mod an original one to fit, with the alternator mounted.

Web

Web is a national treasure. I have an early c180 that has all new wiring and the plane power setup with R1224 regulator. I have noticed a flashing field light at intermittent times and decided to investigate more thoroughly this winter. I have a cgr-30 that measures amps and a digital voltage readout in the cigar lighter. The amps are all over the place- rapidly moving from single digit amps to 40s with the LED landing light on. Volts rapidly move between 13.5 and 14.2. With the engine not running bus voltage reads 13.2, bus voltage at the alternator field wire is 12.05, bus voltage at regulator reads 11.97. Bus voltage at the field switch is 13.18. The resistance in the field wire from alt to regulator is zero. The field wire is new (all the wiring is). Regulator is grounded to the main aircraft ground bus as is the F2 wire (alternator ground). I will build a new field wire tomorrow and run an additional ground from alternator to engine. Engine is correctly grounded in two places and the engine mount is the seaplane metal mounts. The extreme instability of the amps and voltage seems odd, and since I rewired the whole airplane it is highly likely I screwed something up. Any suggestions appreciated

Sounds like an intermittent ground somewhere.

I hope so, although the drop in voltage from bus to field is interesting


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Check all the crimps on the wires not only by pulling on them but push the wire into the terminal also. I had a gremlin that would come and go, it was not until I pushed on the wire instead of pulled that it I found it.
DENNY