How warm does your regulator get?

[yankee dog]

Was checking a few things out on the bike while it was warming up, and felt my voltage regulator after about 10 mins of running.  The voltage regulator was getting pretty warm as well as the stator wires that come from the rubber plug in the block and go to the regulator. The fins get almost too hot to hold your fingers on them after about a 10 count.

The bike runs good, puts out 14.3 volts at fast idle. I double checked regulator mounting bolts, removed, cleaned, replaced and ohm'd it out. I am getting excellent continuity from the regulator fins and the mounting bolts all the way back to the battery negative post. 0.00 ohms resistance.

Is this normal? Did I never really notice how warm it actually gets and am being paranoid? Thanks YD

[JW113]

So think about it this way. An Evo alternator will put out 32 amps at 4800rpm (I believe). At 3000, where probably most of your riding time probably is, it puts out less, so let's say 20 amps. The headlight uses about 5 amps, the coil about 4, and the tail light perhaps 1. Am I missing anything else? That's 10 amps of load.

So where does the other 10 amps go? Back into the battery after a start up. But once the battery gets charged, now where does it go? Into the regulator and gets shorted to ground.

So 10 amps, 14.4v, by my calculus that's almost 150 watts of power. Ever touch a 150 watt light bulb? They get kind of hot, huh? So now you know why the regulator is covered with fins, and sits up there in breeze. It has to dissapate all that unused power which gets turned into heat, and into the air...

-JW

[farmall]

Primitive shunt regulators have a lot of wattage to dissipate.

There are alternatives when replacement time comes.

http://cycleelectricinc.com/RECTIFIER.html

[JW113]

I've never used a series regulator. Heard a lot about them, just never tried one. Makes me wonder why the factory does not use them even to this day, when the electronics involved is probably no more expensive to do than a shunt regulator. Maybe this is how they sell more parts?

-JW

[yankee dog]

So think about it this way. An Evo alternator will put out 32 amps at 4800rpm (I believe). At 3000, where probably most of your riding time probably is, it puts out less, so let's say 20 amps. The headlight uses about 5 amps, the coil about 4, and the tail light perhaps 1. Am I missing anything else? That's 10 amps of load.

So where does the other 10 amps go? Back into the battery after a start up. But once the battery gets charged, now where does it go? Into the regulator and gets shorted to ground.

So 10 amps, 14.4v, by my calculus that's almost 150 watts of power. Ever touch a 150 watt light bulb? They get kind of hot, huh? So now you know why the regulator is covered with fins, and sits up there in breeze. It has to dissapate all that unused power which gets turned into heat, and into the air...

-JW

Yes, great explanation, thanks for that.

I took the bike out for a 40 mile ride, checking the regulator temp (touch) periodically along the ride. It was much cooler out in the breeze...Guess I never really put my hands on the regulator after the bike was running but sitting still for a few.

I did a complete electrical charging diagnostics, and everything is functioning as it should, good voltage output, no significant ac voltage to the battery, no resistance to grounds, etc.

Looks like it's all good. Thanks, YD

[JC 92FXRS]

I noticed the same as you after I replaced my VR recently (It's a cycle Electric). At low speed around town it will get very warm...cools down significantly "out in the wind". I monitored it for a while and all seems normal, guess that's why they're wrapped in that big ol' heat sink.
Cheers, Jeff

[yankee dog]

JC, thanks, yes, I guess it really was paranoia. It seems to be running and charging well. Guess I just never noticed the heat before. Still going to keep an eye on it. YD

[JW113]

Hey, it a Harley-Davidson. Wise to keep an eye on everything!



-JW

[JC 92FXRS]

Hey, it a Harley-Davidson. Wise to keep an eye on everything!



-JW

Nah JW...you're just too used them ol' Shovels!!   
Jeff