Bob M or John T, W6 electrical problems

Thanks.

Lemme know, I just got home late n headed to the bed.

John T

Thanks.

Presuming the battery is discharging, my first suspicion is the problem is the new regulator.

Or (long shot possibility...) inside the ammeter box is there a wire carrying charging current located close to the backside of the ammeter? Reason: The magnetic field surrounding such a wire will screw up the ammeter reading.

Is is just me or is 25 amps charge really high?

I think there may be a hidden ground in the system somewhere, or maybe the battery is motorizing the generator. I find it hard to believe this much amperage is normal.

15 - 20 amps is the max you'll ordinarily get from a 3 brush generator. However if the generator polarity is reversed (ie. so both the generator and battery are pushing current in the same direction) 25 amps is probably not out of line. Nor is 25 amps good for the generator if allowed to run like this for more than a minute or two!!

Anyway next step is determine whether the generator is at fault or the problem’s with the regulator. Here’s how I’d do it (I’m assuming the wiring is in good shape and properly connected):

1 – Disconnect both wires at the generator. Tape the ARM wire terminal so it cannot be accidentally grounded.

2 – Run a temporary wire from the generator FLD terminal to a good ground.

3 – Take another temporary wire and connect one end to the BAT terminal at the regulator. Then briefly touch the free end of this wire to the generator ARM terminal. (This is to polarize the generator again.)

4 – With the free end of this wire isolated (temporarily tape the end), start the engine and run it at governed RPM. Now take a voltage reading between the generator ARM terminal and a good ground (generator frame). If the generator is working the voltmeter should read somewhere in the range of 15 to 30 volts or so. And assuming the battery positive post grounded, the generator ARM terminal voltage will be negative relative to ground.

If you get a very low voltage reading or if the ARM terminal reading is POSITIVE relative to ground, stop. It's the generator that's messed up. However if the generator output checks out:

5 – With the engine still running at speed, have an assistant watch the ammeter while you temporarily connect the free end of the wire installed in step #3 to the generator ARM terminal. (Expect a spark when you connect…) If the ammeter now indicates a full charge, the generator is OK – the problem is the regulator. However if the ammeter again shows discharge, the problem has gotta be the generator.

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Hope this makes sense, and advise what you learn!

If #1 or #2 it's definitely wired wrong! The ammeter SHOULD show only a couple amps discharge with the ignition "on" and the engine stopped/cranking.

If you haven't already I'd still recommend running the "open circuit" test I described a few posts earlier then see what happens.

Or maybe call in a exorcist - I don't know...

When I did this on my 'A' a number of years back, I actually had to run the generator as a motor for a few seconds with correct polarity to get it to take the proper polarity.

I think the repeated use while it was wired as a negative ground has permanently 'set' the magnets to produce a positive charge at the 'bat' terminals (i.e. negative at the ground, positive at the 'bat'). You can reverse this 'set' by repeated polarizations in the opposite direction (which is what running it as a motor does).

I'm working from memory here, but I think you can check the voltage at the 'bat' terminal by disconnecting the 'bat' (charging) wire and using a voltmeter to chekc the voltage at the 'bat' temrinal relative to chassis ground. If you take care with the voltmeter leads, you should read 6 volts at the battery (red to positive, black to negative).

At your generator, you should read 8 volts or so at the 'bat' terminal (wire leading to ammeter disconnected). This is again red to positive (chassis) and black on the 'bat' terminal itself.

My nickle bet is that you are getting NEGATIVE 8 volts at your 'bat' terminal. if so, polarization is the problem.

Good luck,
Clip

I recommend spinning by hand to see if it is positive or negative as I describe earlier. If it is negative (red lead always on chassis), run it as a motor for a second or two by jumpering off the battery (again, belt disconnected). Then, spin by hand again to see if you have 're-trained' it to produce the proper polarity. Once it reads the same polarity as the battery (you get a positive reading with red to chassis and black to the terminal) then you're ready for business.

Hope that makes sense and works for you.
Clip

Might even take it a step further and motor it for a fews seconds from a 12 volt battery (connected with the proper ground polarity of course). I figure the momentary higher current might more firmly establish the proper residual magnetism in the field coils.