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Voltage Fluctuation

O

One For The Road

Member
Hi All,

When for a ride today and noticed my voltage gage would fluctuate. I have never noticed this before. For the past few years (as long as I have owned it) the gage would read just over 14 volts. It did not matter what RPM the motor was running. It would stay at 14 volts. Today it would be as normal then every few miles it would drop to about 12volts then go right back up to 14. The bike runs and starts fine.

When I got home I used my DVM (one from Harbour Freight ... not their cheapest one) and measured the following.

Battery voltage with bike off ... 12.90 volts
Engine running at idle ... 13.90 volts
Engine running at 2500 RPM ... 14.05 volts

I ran the motor for a few minutes but the gage would not drop back to 12 volts like it did on the road. It stayed at just over 14 volts.

I left the DVM on the battery then shut the motor off. The voltage slowly dropped back to about 12.90 volts.

I checked the battery connections and they were tight. I have not checked any other connections yet and I have not checked the stator output. I need to read up on how to check that.

I don't know how old the battery is but it is a Odyssey Extreme.

Has anyone else had a similar problem ... or have any ideas what might cause this.

Thanks for your help.

Steve
 
I had pretty much the same thing last week when I rode my 2005 FLHTCI to work. It was dark and I noticed my headlight dimming and brightening. Looked at my volt gauge and it was fluctuating from 9 - 14 volts. When I got home from work I removed the seat and checked the connections at the battery. The screw on my negative post was loose just enough that it tightened up about 1/2 turn oh the bolt connecting the cable to the battery. I took it loose and cleaned everything with a small wire brush. Reinstalled the bolt and no more fluctuations. Check your battery connections and connections at the starter. I know you said you checked the battery connections but a corroded connector will lose continuity between the wire / cable and battery even with a tight connection.
 
As Lobo suggested check the other end of the connections also. Until you can catch it doing it and have DVM your not gonna know for sure. I wouldnt hold a great deal of confidence in the fairing mounted stock volt meter but you never know...
 
You may also want to do a load test on the battery seeing you don't know the age of it.
I'm with Bodeen as far as these funky gauges, not always accurate.
 
Hi,

I did the original post concerning voltage fluctuation on my 2005 Ultra. I have a question as to what readings I should get. Here is what I have measured so far. It is a two pin stator to regulator system

Battery Voltage with bike off ... 12.4 volts
Battery with bike running ... 12.2 volts at any rpm.

I disconnected the stator to regulator and checked readings at the connection stator to regulator.

Stator Pins ... 0.02 ohms between pins
Stator pins to ground ... both pins read open circuit (high resistance)

Voltage on regulator pins 11.95 volts bike not running

I read that there should not be any voltage at the regulator pins. If voltage was measured the diodes would be bad and the regulator needs to be replaced. Can anyone confirm this.

I have not measured the output voltage of the stator yet.

Thanks for your replies.

Steve
 
You are correct on the voltage at the regulator pins. It should be -0- Vdc. If you measure your stator output it is in AC voltage. Should read approx. 20 Vac per 1K rpms. Readings on your stator you posted look good.
tourbox
 
Mine always fluctuated,when I had a Streetglide,the only bike so far I had with that gage.Like tourbox said,looks like they are in a normal range.
 
Hi,

I checked the stator output. It measured about 24v per 1000 rpm. With the other measurements it looks like the voltage regulator is toast. I ordered a new one from DB Electronics. I will let you know how it works out once it gets here.

As a side note for all you sparkies I took the old regulator out and put it on the bench. I got my old but trusty Sears 4 amp charger out and measured the output. It was 13.8 volts. Then I hooked the charger to the regulator. Charger ground to regulator ground and charger positive to the wire that feeds the battery. I took my voltmeter put the black lead (ground) on the regulator ground and measured the voltage to the pins that connect to the stator. I measured 17.6 volts. Can someone smarter then me explain why the voltage at the stator pins was almost 4 volts higher. Just curious.

Thanks

Steve
 
Hi,

I received the new voltage regulator and installed it yesterday. It was late in the day so all I did was start the bike and check the voltage at the battery. It was about 14.4 volts. RPM did not seem to change the voltage.

This morning I took it out for a ride. Voltage on the gage was about 14.4 or so volts. Everything seemed okay. Bike started and ran fine. I had ridden about 15 miles when I noticed the gage had dropped to around 12 volts. RPM did not matter. The bike was running fine but the voltage continued to slowly drop. I rode it about 6 miles home. Seemed to run fine.

I pulled into my garage and shut off the bike. Then I noticed smoke coming from the front of the bike. By the time I got off the smoke was POURING from the regulator and it was sizzling ... dripping black stuff onto the floor. Over 10 minutes or so it slowly stopped smoking.

After I let it cool I removed the regulator. You could see on the bottom where ir melted.

I put the battery on my charger since I thought it may have been run down from riding it the last 6 miles or so. The charger has a amp gage and it showed very little amp draw ... like it does then the battery is charged. I measured the voltage at the battery with the charger off and the bike off. It measured about 12.8 volts.

I start checking why the regulator went out. I checked the stator pins to ground ... open circuit. Then the pin to pin reading. It measured about 0.05 ohms. I went to check the stator output but when I turned on the key to start the bike the whole bike was dead. Pulled the Maxi Fuse and it was burned out. I jumped the fuse terminals just to see if the lights and things worked ... they did. So now I am on my way to get a new fuse. I will check the stator output when I get the bike running.

Any thoughts on what would cause the regulator to burn up. I bought it from DB Electrical. It was made in China.

Thanks;

Steve
 
Hi,

Me again ... I replaced the Maxi Fuse. Everything looked fine. Bike started right up and ran good. I measured the stator output. It was:

24.5 volts at 1000 rpm
44 volts at 2000 rpm
70 volts at 3000 rpm

I didn't go any higher than 3000 rpm.

Thanks,

Steve
 
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