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Premium Member
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Discussion Starter #1
Riding in the hot weather (finally at last). Have a pair of 20 Watt Optronics spots that I installed this winter and on a nice long ride yesterday had them on along with the headlamp. Don't know if it was the heat or the bright sunlight but my Kuryakyn LED battery meter did not seem to have any green lights going. Green occurs at 13 volts or over. I shut the spots off and continued home. The traffic noise was such that I couldn't tell if the fan was on too. No battery discharge seemed evident and I am sure it will be alright.

My question is with the elevated temperature and all that I have read on this forum about the R/R relocation because of heat, could that be affecting the charging system as it heats up? I have NOT relocated as I never saw the need. Anyone have any good knowledge on this? Will appreciate any input (no pun intended). :confused:
 

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CWO3 Navy (Retired)
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722 Posts
I'm thinking the driving lights are drawing too much power. This bike wasn't made for alot of electrical add-ons, especially those with huge power draws. You might try replacing other power draws like the tail light with an LED (Alternatives makes one that I use) that doesn't draw much power at all. Try running with the driving lights off and see if you get the green lights. I have the same meter and constantly get 1 to 2 green lights all the time.
 

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Premium Member
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Discussion Starter #3
Hi Cliff, the green lights are on when I ride normally. I changed the bulbs in the lights down to 20 watts to be within the output capacity that's really not my issue. The real question is: on a hot day when the bike heats up and there is more heat on the R/R does it affect the voltage output of the alternator?
 

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Love My Baby
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The real question is: on a hot day when the bike heats up and there is more heat on the R/R does it affect the voltage output of the alternator?
Gemguy, here's a good site to learn about how the Stator and the R/R and Battery work together to provide for the electrical needs of a motorcycle. Your question is worded incorrectly only because the R/R doesn't send electricity to the Alternator (Stator), it's the opposite. The stator runs directly off the engine to produce an electric current. It sends this current to the R/R to be regulated to the proper voltage necessary to charge the battery. The current then goes to the battery, charging it during idle and other running speeds. The higher the electrical demand the hotter the R/R gets. If the R/R overheats it doesn't work effectively and may get fried and not charge your battery. Then where does all that current coming from the stator go? It can then fry the stator. So I don't think a hot R/R changes the voltage output of the stator directly.

I hope I'm stating this correctly, as I'm not an electrician or motorcycle mechanic/techincian. Bottom line is that it's NOT GOOD for the R/R to get too hot too often. It's a weak link in the charging system. Relocating it to a place where it gets better air flow to cool it down is a good idea. Lowering the electical demand is an even better idea, as the higher the charging requirements on the R/R the hotter it gets. I think it's more important to change to LED lighting as this greatly reduces the electrical demand. You added 40 watts to your system and then noticed the voltmeter indicated poor charging. That's putting quite a strain on your R/R, possibly to the point where it's overheating. You can relocate it or lower the demand on it, or both.
 

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Premium Member
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Discussion Starter #5 (Edited)
Rubyrick, you are right I did mistate the system. The regulator/rectifier is what changes the alternator voltage from AC to DC and then regulates it to charging voltage of 12 to 14 volts DC. I looked into LEDs but the only practical thing is the tail light because in changing the directionals I would need to get the electronic flasher units So I wonder how much changing one bulb contributes to a lower current draw. I know it will but is it significant?

The question I would like to ask is if the heat of the day say a temperature of 95 degrees plus the heat coming off the motor on a hot day will affect the R/R to malfunction and possibly deliver a lower voltage to the charging system (or battery). That is what I was questioning.
 

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Love My Baby
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1,165 Posts
The question I would like to ask is if the heat of the day say a temperature of 95 degrees plus the heat coming off the motor on a hot day will affect the R/R to malfunction and possibly deliver a lower voltage to the charging system (or battery). That is what I was questioning.
Personally I don't think the external temperature is the major factor in causing an R/R malfunction. Certainly if you idle excessively on a hot day it might make a difference. But if your electrical draw is always high and you consistently idle a lot, even in nice weather, your R/R could overheat. If this is the case, relocate your R/R. It can only help.


I looked into LEDs but the only practical thing is the tail light because in changing the directionals I would need to get the electronic flasher units So I wonder how much changing one bulb contributes to a lower current draw. I know it will but is it significant?
I posted a while ago on my documented reduced electrical draw when I changed to the LED brake/tail light from Clear Alternatives. Go to post #13 on this thread. I think it was significant and certainly worth the $50. I'm planning on changing to LED turn signals but I will do all 4 at once and use an inexpensive replacement for the turn signal relay from CruiserCustomizing.com, part # BBP-13-306. You can look up a prior post on this part HERE. All together this should provide a moderate reduction in your electrical load. I wonder if there is a headlight out there with a reduced electrical draw, that is as bright or brighter than the our stock headlight.
 

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Premium Member
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Discussion Starter #7
Rubyrick, thank you. If you can give me the stock numbers for the brake light and taillight bulb replacements in LED I would appreciate it. I will order and replace these 2 now. At some point I will consider replacing the front marker and directionals with the flasher unit. Is Clear Alternatives the cheapest place to buy these?
 

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Love My Baby
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Hey there Gemguy. Clear Alternatives is the manufacturer and seller of this part. It's an LED board for your tail/brake light. Works GREAT! Extremely bright. A bit tricky to get installed, but I did it myself and there's been no problems since.

I believe a fellow Vulcaneer named Bulldog actually got Clear Alternatives to design and manufacture this part for us VN750.com members. Just want to thank him for his good work.
 

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Hey there Gemguy. Clear Alternatives is the manufacturer and seller of this part. It's an LED board for your tail/brake light. Works GREAT! Extremely bright. A bit tricky to get installed, but I did it myself and there's been no problems since.

I believe a fellow Vulcaneer named Bulldog actually got Clear Alternatives to design and manufacture this part for us VN750.com members. Just want to thank him for his good work.
You believe correctly, and it does work great; I love mine.

Jim
 

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Rubyrick, thank you. If you can give me the stock numbers for the brake light and taillight bulb replacements in LED I would appreciate it. I will order and replace these 2 now. At some point I will consider replacing the front marker and directionals with the flasher unit. Is Clear Alternatives the cheapest place to buy these?
For the turn signals, try looking at Radiantz 1.85" dual intensity LED clusters when you get around to their conversion. They run $25-$45 online, but you can sometimes find them on eBay for $5 (which is where I bought mine). I posted a writeup on this forum on how to convert the stock bulb bases for simple plug-n-play installation.

Also, don't forget that switching to LED turn signals will require that you also switch the flasher relay from a stock thermal to a no-load electronic model ($12) to keep the 90 flash/second blinker rate.

Added note: I also converted all brake/running and turn signals to LED, even added a second LED brake light. However, I did installed grip heaters (36 max watts on full power) with a heat troller and mechanical voltmeter. I do notice a small voltmeter drops/fluxuations on the meter when running the grip heaters, but nothing significant. So, I got brigher/safer lighting and warm grips with no overall impact to the electrical system. Same would apply to your running lights.
 

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Stator, R/R and power consumption

Some (many) seem to think that the higher the demand for amps the higher stress on the stator and R/R. Well, I think differently. The output power of the stator almost entirely depends on the motor revs, and that power is always going somewhere. If it is not put to a good use, then it is converted to heat. And it is converted to heat in the stator and the R/R. Actually having no load at all is worse for the regulator as having a high load. At least that is my conclusion, someone knowing better the behaviour of a PM generator and a shunt regulator may correct me.

I also think that the external temperature is a significant factor for the well being of the R/R. To dissipate a certain amount of heat, the temperature difference from the R/R to ambient is constant. So the hotter the external temperature is, the hotter the R/R gets. Hot is not good.

So the best you can do to prolong the life of the stator and the R/R is to avoid high revs and if you live in a hot climate relocate the R/R (I wont - it is never that hot here).
 

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Old Truck Junkie
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Have you ever noticed that the gen on an auto gets really hot when charging a low bat?? You can also hear a whinning sound from it. I believe that the r/r controls the current coming out from the stator to the bat and the working electical units. So when there is no need for extra current from the stator it stay cooler, when a demand it put on it to generate energy it will get hotter. MHO.
 

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Car generators work differently (better). The regulator controls the alternator magnetic field stength, and only as much power is generated as is required. Heavy load -> high current -> more heat. The magnetic field in a motorcycle generator (most of them) is constant and as strong as they can economically make it. It always produces as much power as possible, and the shunt regulator works by consuming the excess power in the regulator and the generator itself. I remember reading somewhere that a PM generator is 'self limiting'. I guess that it means limiting short circuit current. A shunt regulator limits the voltage by shorting the generator. What I don't know is if the net result is less heat than you would expect.
 
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