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My bike does the same thing.

 

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Thyratronman wrote:

I just put a voltmeter on my 81 interstate and I noticed that when I come to a stopsign, the voltage drops to 11=12 volts and no matter how fast I race the engine even above 3000 RPM, it will not go above 12 volts. Once I start rolling and I'm off the hand brake, the voltage goes to 14 volts and stays their while I'm going street speed. As soon as I slow down, and hit the brakes and stop, back down she goes to 11-12 volts and will not change. Any Ideas? Thanks guys and Gals, any info will be appreciated. Gary

Gary, that is somewhat normal on the early Wings.. The charging systemhas marginal output at best& only keeps up at higher engine RPM's.. I think that if you rev it long enough sitting still with the brakes on it will show some charge.. It seems to take a LONG few seconds for the charging system to react to the RPM increase on a hot engine (I don't know if it is a heat thing or it takes a few moments for the generator rotor to toss the oil off & start charging..

As a test, try lightly applying the rear brake (just enough to allow the brake lights to come on) while riding down the road at 3000-4000 RPM's,, if the voltage stays up then your system is normal..

Also check the water level in the battery as that can allow the voltmeter to act real strange as the batterywon't accept a charge easily..

Twisty

 

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Gary, My '85 aspencade gets a voltage drop when I have the brake lights on, but will recover slowly if the engine is revved up. For me, it turns out that the extra lights on the Aspencade seems to overload the main hot wire from the battery to the ignition switch and to the fuse block when the brake lights are on.

If you put a voltmeter directly on the battery, you may find it has a higher voltage than the built in meter.

 

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I have found when you test a bike at idle, the resting voltage won't go higher than the battery charge, especially since the lights are on. When you rev it, you get charging voltage of 13.5-14+v

 

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Thyratronman wrote:

I just put a voltmeter on my 81 interstate and I noticed that when I come to a stopsign, the voltage drops to 11=12 volts and no matter how fast I race the engine even above 3000 RPM, it will not go above 12 volts.

Doesn't sound too abnormal, if the battery is staying charged so the bike cranks and starts okay should be good enough!

 

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Thanks everyone for the info, this seems strange to me but It's good to know that it appears to be a normal mode of operation... Seems like a redesign of the voltage/current regulator circuit may be in order.

 

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Thyratronman wrote:

Thanks everyone for the info, this seems strange to me but It's good to know that it appears to be a normal mode of operation... Seems like a redesign of the voltage/current regulator circuit may be in order.

It's probably been operating pretty much like that for the past 24 years, wasn't the best possible design, but it works!

 

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Thyratronman wrote:

Thanks everyone for the info, this seems strange to me but It's good to know that it appears to be a normal mode of operation... Seems like a redesign of the voltage/current regulator circuit may be in order.

Thyratronman, it really has nothing to do with the voltage regulator (maybe a little in the rectifier diodes though), at idle that baby lets all the output from the generator pass through,, it is the generators output at low RPM's that is the issue.. The spec is something like (0 amps) to (-3 amps) into (well out of) the battery at idle.. Honda purposely kept the output low so the regulator wouldn't have to sink all the extra current to ground as the RPM's came up to cruise speed. Unlike an automotive alternator the rotor in the generator is a FIXED magnet so that means the generator's output is RPM controlled & the voltage regulator just sinks the extra unneeded currentto ground.. That system works good if you don't try to run a lot of extra lights or accessories..

If you want to improve your generator's idle speed output just raise the idle speed a little, it doesn't take much to improve the idle output with a little extra RPM.. You can also replace some of the light bulbs with low draw LED's or shut the headlight off at idle..

Twisty

 

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 I don't think they make an "EC" harness for an '81... but... I picked  about .8 volt at my voltmeter by cleaning each and every battery terminal and connection on all the fuses ,and fusible link pointstill they shone, and  doing the same to all the ground straps..... corroded connections cause a lot of Voltage loss... but the major loss is  all those high current brake, and running lights.. SilverDave/forums/images/emoticons/emoticonsxtra/cooldj.gif

 

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Hi Thyratronman, a good cleaning of all the connections often makes a big difference to the readings at idle.

 

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:waving: Thanks everyone for all the great comments on the Gen problem, or lack thereof. I have been riding a little over a 1000 miles now and it appears that everything is ok. I cleaned all the battery connections and installed a new (used) fairing and rewired it with larger wire and a ground return to the battery which helped brighten up the lights a bit. I also discovered that the ground wire (Battery) on the frame still had the original paint under the ground connector. I cleaned to the metal under the ground connector and that helped the starter a bit. The LED idea is a good one. I replaced the signal light breaker with a solid state unit that has a relay output so the LED's will work properly no matter how light the load is. I really appreciate the expertise of all the Forum readers, your awesome!!!!. Thanks much, Gary