Electrical Problem With 6 Volt 3 brush

[ottoa]

I have a problem with my 1946 WL's generator/wiring system. Last November, I lost the generator when the third brush grounded out, taking out the cutout relay too. I have had the generator rebuilt professionally, and output checked. Here's the problem; the bike starts ok, with my VOM connected to the frame and the positive terminal of the battery, I start the bike. I have adjusted the third brush to the position nearest the positive brush, the VOM shows 6.5 v at idle, and the generator light is off. When I rev the motor up to what would be 45 to 50 MPH, the VOM shows 7.75 v. If I keep the engine at that RPM, the Voltage slowly creeps up at .1v until it soon exceeds 8.00 v. Over 8.0 volts, the battery cooks or I lose the headlight (burns out). I have tryed another rebuilt generator with the same result. Any Help would be apprecatiaed, I want to get back on the road.

[AdminGuy]

Excellent! I love it when people post elect. problems. I don't have alot of experience with this stuff yet. But it's fun learning how to rebuild stuff. Perry will have a good answer. Thank-you for the VOM readings. Tacoma WA? Is your name Tim?

My two bits would be ahhhh....isn't the (mechanical) regulator supposed to dump the excess current? Third brush sets it, reg. dumps it on over. So my uneducated guess would be regulator not functioning, and would test for that. But I know very little and look forward to anyone elses comments.

Note; I said mechanical reg. - as it will eventually fail. Go soild state and just stick the black box over modern stuff to hide it. That's very much a personal decision. I enjoy riding alot more than I enjoy trouble shooting. So that's my big intro sales pitch for Perry. Hhahahahahh.....he's got'em, and they are the Dutch cats pyjamas.

Did you get caught in the rain in Nov? Insulate terminals w/ silicon caulk. Or dead bug your components. ie caulk up the boards and squish them in.

I feel in the Pacific North West Generators should have rain shields or something.

[Perry Ruiter]

The thing to remember is that the position of the third brush controls the AMPS being output, not the VOLTS. The battery is what controls (limits) the volts. I've seen a six volt generator with a bad ground put out 15 volts. So ... at this point I'd suspect either a bad ground at the battery or the battery itself is marginal. Also you mention the headlight bulb blowing. Was the test done with the lights off or on? The way a third brush is designed the output "doubles" when the lights are turned on (to match the increased demand).
Paul - on the Harley three brush there is no external regulator, just a cut out It's sole purpose is to prevent the battery from discharging through the generator when the generator isn't producing (eg: bike is off) ... Perry

[jww]

Don't currently have a generator/cutout problem but this is great info, Thanks Perry johnny

[ottoa]

Perry. Thanks for the infomation. The battery is less than 8 months old. I will check out the ground tonite when I get home. One of the guys here at work has expericnce ground strap problems in marine electronic's when a braided ground strap is provide and just crimped, which is what it appears I have. I will let everyone know the outcome.

Otto

[joe]

if you look in a good 45 motor manaul it shows you how to set the 3rd brush so you get the proper amps i set my 49 servi up by the book and it worked fine

[ottoa]

Perry and everyone,

I found the problem and am in the process of fixing it. Thank you for all your suggestions and options. Here's what happened.

I checked the battery ground by jumpering it from the battery terminal to a good frame bare spot. I had already read the resistence and the voltage of the ground strap without running the engine. Some difference in resistence and voltage, but not great. Started the engine, voltage not running as wild, but still in the 8.0 to 8.5 range. Check voltage at generator and it was running at the same voltage as the VOM on the battery. By this time I'm thinking "New Battery". My neighbor is into old cars and hot rods. He suggested that before I do any thing else, I put a jumper from the frame of the generator to the negitive post of the battery, if the generator works under control, then somewhere there is a bad generator/engine/frame ground.
BINGO generator putting out 7.5 volts at highway engine speed. As the 46 is my current rider, I am going to install a permnant jumper until I restore the bike or have time to pull the engine etc.

Again Thank you All

Otto

[ottoa]

Problems Still

The phantom returns. Since the last post, the bike has been running well except I am still burning up headlight and tail lights. I have installed a ground wire from the generator frame to the - terminal of the battery, the Tedd's battery blew the top off and I have repaced it with a new HD Classic 6 volt. Voltage still drifts up to over 8 volts at highway speeds. The third bush is at the end of its travel closest to the Positive brush. I have checked the current flow with my VOM set for DC Amps. Idle - 1-2 amps with the lights on or off. At road speed the current moves up to 2.5 or so then starts ticking up to 4 to 4.5, drops back, ticks again etc. I have also replace the cutout relay with a new electrionic one. The generator was rebuilt by a repualble outfit as I understand it.

I'm getting tired of frying batteries and replacing head ligths.

[Perry Ruiter]

Sorry for the delay. Again I re-iterate the position of the third brush controls the amps. It has nothing to do with volts. If you've got a good ground and a good battery (which it sure sounds like you do), then I think it's time to have the generator gone over by someone with experience on Harley generators (this is not a slam against whoever worked on the generator before). A likely cause would be a bad field coil. As for the amps fluctuating like that, again it might be a field coil, or perhaps an out of round commutator and/or brushes not free in the brush holders. Does the high voltage and amp spikes only occur with the lights on? (this might narrow it down to one of the two field coils). What ohm reading do you get from the switch terminal and the aluminium end casting? Should be around 7.4 ohms ... Perry

[ottoa]

Perry,

The switch post to the aluminum housing reads 7.5 ohms. The ticking was with either the lights on or off. I changed out the generator to the one I have for the 1941 UH I'm restoring. I just ran the bike with the other generator with the VOM set for amps between the frame ground strap and the negitive terminal of the battery. At idle current is from -1 to 1.5 amp-lights or no lights. With the engine running at the equivalent of 40 mph in 3rd, the amps go up to 4 to 5.5, again lights or no lights. Judging from the headlight and tail light, I'm up to 8 or more volts. At lest with the other generator, the ticking is not there. The third brush is all the way as close to the positive brush as the holder will allow. My review of the electrical system diagrams and Bruce's schematics indecates the only things in the system with out the lights on are the coil, cut-out relay, timer, and switch. Where and what do I check next?

Otto

[Perry Ruiter]

Otto - everything obvious seems fine. The coil is the main draw with the lights off. The design of the 32E is that output increases when the lights go on (to compensate for the demand from the lights) and the fact the output stays basically constant with the lights off or on indicates this is happening. At this point if it was me I'd pull the generator apart to verify everything is good in there. Sorry I don't have any easy suggestions or silver bullets for you ... Perry

[ottoa]

Perry,

I just got the generators back from the shop. Both of the generators and cut out relays ( one mechanical and one electronic) check out to spec. no adjustments or replacements required. I am getting a 6 amp draw when the points are closed, Questions and Answers (the red book) state 2 to 3 amps? I have checked the switch (aftermarket new last year) and can find no shorts or high resistence! I have the new HD Classic battery and a ground wire from the generator frame to the battery negitive terminal. Any suggestions would be appreacated. I have run 3 brush generators for years and this one was working before loseing the thrid brush holder and I have always been happy with them!!

[Perry Ruiter]

Ottoa - when you say with the points closed, I assume you mean the ignition points rather than forcing the cut out points closed. Indeed, I would expect the ignition circuit to consume around 3 amps (give or take). The Harley manual says to set up the generator to output 4 amps, which will cover the ignition's needs and leave a little extra to keep the battery charged (this is with lights off). If you're pulling 6 amps, that sounds like too much. With the engine off, you'll have the gen and oil lights on (likely around an amp for the pair) so you're still a couple of amps high. You can check the primary circuit of your coil with your ohm meter (these are the terminals sticking out each side). Disconnect the wires to get a true reading. Then take a voltage reading of your battery. Now using Ohm's law you can determine how many amps that coil will pull (amps = volts/resitance). Unfortunately, I no longer have a Harley (blush, blush) so I can't go out and get some known good values for you. Hopefully someone else can chime in, but, if we want 3 amps, your ohm's reading will have to be around 2 ohms (given a 6 volt system).
One problem I did recently run into while helping a friend wire a 47 knuckle, was the (repro) ignition switch shorting out. As the switch is rotated, the centre pin is forced down as the brass rod moves up and over the contacts. The centre pin was a hint too long and would touch the dash base causing a momentary dead short (the centre pin and brass rod are electrically hot). A few moments on a grinder fixed that ... Perry

[ottoa]

Perry, and anybody else who might have a suggestion.

I have been all the way through the electrical system now. I had all of my generators check with my cutout relays and are working to spec. 2,500 rpm - 4 amp. - 6.6 volt. Coil resistence reads: 1.2 ohms. Too low for the expected 2 to 3 amp draw with the points closed by my calculations. What I don't get is that this should drag the generator and voltage down at idle (which it does) however, the idot light doesn't come on and the lights are still very bright. As soon as I give the throttle a little nudge, voltage goes over 7.5 volts. I have checked all of the circuits, checking the amp. draw of each. Each one seems to be about right using ohms's law and power formulas. The headlight is about 30 watts and draws 4.7 amps. The idiot lights draw .3 amps and the tail light draws .7 amps. The compete light curcuit with idiot lights off draws 5.55 amps.

It all looks right except for the coil/points which still draw 5.9 to 6 amps. As soon as I get the engine started, voltage goes to 7.0 at a fast idle and over 8 volts at road speed. How could the shorted coil kick the voltage up? Help.

Otto

[Perry Ruiter]

Otto - I'm fresh out of any bright ideas. However, I'm not (yet) convinced the coil necessarily should be the focus ... Perry