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Discussion Starter #1
Blame One1 for putting this out there for consideration :).

Context is trying to reduce the electrical load, thereby reducing the demand on the VN750's anemic charging system, and *maybe* extending the life of the stator as the principal desired benefit.

The biggest non-continuous current draw I see while riding is the stock cooling fan motor. Frankly, I hate to see it come on, because when it does, I'm drawing more juice than the stator can produce, regardless of engine RPM. Battery voltage will fall below 12V at highway speeds, and occasionally below 11V at idle (when I'm stuck in traffic and the measured temperature off the road is well above 100 degrees F).

Supposedly we can fix this by replacing the standard fan motor with a brushless one. Anyone got any specific recommendations as far as a compatible replacement? I don't mind doing the research myself, but can't seem to find any relevant specifications for the stock motor (current rating, RPM, etc.) to use as a starting point.

Our charging systems and/or stators thank you in advance for your support :).
 

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I'm looking! Hopefully there will be a solution that comes soon. Just started my search
 

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I've been thinking the answer is a separate fan relay, outside the junction box. That's the last relay still working in my JB. My charging system is tip-top, but I still get low voltage and even a rare backfire when the fan runs in hot weather/low speed conditions.

In those conditions, I can hear the stator howl.

Been talking about this since last Fall, but my riding stopped 3 months ago, so haven't gotten to it. It's just a $5 relay and some wire. Take the fan connections from the JB and put them on the aftermarket relay. Or, make all new connections independent of the harness, and of course the JB.

The JB is a black hole for voltage.

hmrct, if you don't have the Two-Wire Mod, you might check into it.
 

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My reasoning for thinking it's the fan relay in the JB.... If the fan was the problem, I would think it would have always been a problem, from day one and on every bike. This seems like a problem that has to develop, it's not built-in.

My bike was fine for three years after the stator and r/r were replaced. Then the Junction Box started having problems.

I did the Blue-Wire Mod when the stator and r/r was done in 2014. Everything was fine for almost two riding seasons.

In late 2015, the start circuit died and I came up with the Two-Wire Mod. Everything has been fine, except late 2016, I began to notice the brownouts during fan operation at low riding speed. Saw the same problem right away when riding this Spring.

People have opened JBs and found melted relays and overheated circuit boards. I would bet at least two relays are melted in mine. The start and fan relays.

I'd also bet, a brushless fan motor on the same JB circuit will still show power loss. Wired independently, it should be fine and reduce power demand, but I suspect the stock fan would be fine too.
 

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Discussion Starter #5
The JB is a black hole for voltage.
So it has been said and demonstrated many times :).

hmrct, if you don't have the Two-Wire Mod, you might check into it.
Blue-wire mod, yes. So far, not the two-wire mod. The Blue-wire mod made sense to me as far as bypassing a potentially problematic relay. As a bonus, the headlight is on when the ignition switch is on, just like most normal bikes. NOT having the headlight come on until the engine is running is a neat idea that failed miserably in execution on the VN750. That bit of Rube Goldberg compensatory technology wouldn't even be "a neat idea" if FedGovCo hadn't mandated headlight ON all the time and then coerced bike manufacturers into making the headlight switch a useless item :-(. Fargin' bastiges!

I'll take another look at the two-wire mod. I'm of a mind to give it a try with the notion I can undo it if I don't see any of the claimed benefits. I think the bypass of the neutral safety switch was the reason I didn't go ahead and "just do it" back when.

Apropos of nothing, my TOC MCCTs arrived yesterday. Gorgeous workmanship. Maybe not worth the price to some of the cheapskates on this forum :), but as some have said, it's nice not to have to worry about the quality of an item that, if it comes apart at 6,000+ rpm, things go sideways in a hurry. Besides, too much other crap on these bikes to worry about without adding more crap to the plate :).

One1: thanks for taking on the research project. What I've found so far...

There are a few references to the Muzzy's fan blade (presumably more efficient than the stock plastic blade assembly), but as best I can tell, it's no longer available :-(. (Can't verify that here at the day job because access to auction sites is explicitly blocked). SPAL fans show up at the top of a short list when searching for "low current draw radiator fan". Don't know what the diameter of the VN750 stock fan is (haven't gotten motivated enough to break out the tape measure yet), but a 7.5" SPAL fan draws about 5.5A @ 437 CFM. That's part of why I was wondering about the current draw and CFM rating (or RPM) of the stock fan. If a 9" fan will fit, we can get 590 CFM with a 6.5A draw. As expected CFM increases with the current rating. Just gotta figure out what the baseline specs are to know what options are viable.
 

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Discussion Starter #6
Ok... Reviewed the two-wire mod, and I'm gonna give it a try. Looks like it's tied-in intimately with the blue-wire mod, as in, if you don't bypass the headlight relay in the JB, the two-wire mod kills your headlight. Yes, there's a variant of the two-wire mod for people that don't/won't do the blue-wire mod, and it was nice to see that.

Reason for revisiting the two-wire mod... I've NEVER seen over 13.2V out of my charging system, and been wondering what you guys are smoking who are seeing > 14V. Reckon it's *way* past time for me to quit being stubborn about trying a "usually solves this problem" fix.

Sorry for the off-topic post in this thread.
 

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One last note about the Two Wire mod and I'll get outta here.....

There are three relays in the Junction Box: fan, start, and headlight.

The JB start relay is redundant, not needed, rarely used in any other start circuit, and is prone to failure. It's redundant because there is already a much heavier and better start relay under the right side cover.

Thought that info was in the first post of the Two Wire thread, but I see that it's not.
 

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Off topic, my TOC's are my favorite thing on my bike. You can describe them as perfect, heavy duty, etc, but in the end it boils down to "properly done". You can't do better.
 
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