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Wiring of external alternator
Hello again here I am with more questions. I now have my external alternator mounted on my '86 SEI, wired and done a quick test, voltage reading at the battery at 1350 engine RPM = 14.39 volts which is great Big Grin . I do some basic wiring on race cars, bikes ect. but most have the factory wiring harness and charging system that I'm tying into, no big problem, or I'm installing a 1 wire race unit.

The one thing that puzzles me :? is why we only use 1 terminal of the 3 terminals on the alternator when doing our conversion when using the stock Denso style alternator. I understand that using a switched source to the exciter terminal activates the charging mode of the regulator, I also understand that there is a terminal we can use for a warning light installation, but what about the sensing terminal commonly used for remote voltage sensing to maintain adequate voltage and amperage throughout the wiring harness? Is it because we don't experience the voltage and amp drops even with the extra lights and gadgets we add on or what? I've never seen this explained anywhere and it has peaked my interest, can someone explain?

Thanks

TN
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#1 02-03-2007, 06:31 PM,
OF the three one is a dummy connection, the white wire is for what we use to call an "idiot light" it would take place of a volt meter, lighting up a "BAT" indicator light when it wasnt charging.

The sensing would be done I imagine, through the internal regulator which shuts of current over 14.9volts.
The only stupid questions are the one's that are not asked.

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#2 02-03-2007, 07:31 PM,
Tricky,

Plan on hooking up one of those 'idiot lights' in the fairing as an early warning in case the alternator ceases to charge. That part is fairly simple, the terminal that the light hooks to acts as a ground until it reaches a set RPM, then it will allow voltage to flow thru that terminal to the bulb. Since the bulb will have the same amount of voltage on both sides it will go out since no ground is present to form a circuit allowing the bulb to light. Got that part.

So basicly without the extra voltage sensing wire providing reference for the regulator to compare output to 'downstream' wiring harness voltage the internal voltage regulator would open to produce a constant voltage to its set voltage of say 14.3 - 14.9 once initial turn on RPMs are reached. Does this sound right?

My factory dash volt meter will show about 1 full volt below what is at the battery via my Digital Muiti-Meter, any way of upgrading this circuit other than rewiring the stock meter with a relay and hooking it up at the main fuse next to the battery? Or do I need to leave as is to get an idea of how much voltage is being drawn off thru the harness? Just want to make sure that I have enough 'juice' when the intercom, radio, cb, extra lights and all the necessary systems are operating. May even look into adding a couple of aux. driving lights (hum got a couple of KC Highlighters off my 4 wheel drive - make good high beams :twisted: )

TN
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#3 02-03-2007, 08:18 PM,
I suspect the one volt difference is an error in your bike's panel meter. Since a volt meter uses a very small amount of current improving the wiring most likely won't make much difference.
Current: GL1100 GL1500 Previous: GL1200SEI
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#4 02-03-2007, 11:03 PM,
TN, just so you know you are not alone, on my LTD (with the stock charging system) my voltmeter next to the radio has always read .6 to .7 volts lower than the charging voltage I get across the battery terminals => 14.7 at the battery is 14.0 on the meter.

This has always bothered me and I have been tempted to pull the fairing off to get at and clean the connector on the inside left of the fairing that feeds the stock meter. I suspect, however, it has to do with the meters themselves as I have seen other posts for LTDs/SEis with low volts showing on the stock meter.

TNroadrider Wrote:Tricky,

My factory dash volt meter will show about 1 full volt below what is at the battery via my Digital Muiti-Meter, any way of upgrading this circuit other than rewiring the stock meter with a relay and hooking it up at the main fuse next to the battery? Or do I need to leave as is to get an idea of how much voltage is being drawn off thru the harness? Just want to make sure that I have enough 'juice' when the intercom, radio, cb, extra lights and all the necessary systems are operating. May even look into adding a couple of aux. driving lights (hum got a couple of KC Highlighters off my 4 wheel drive - make good high beams :twisted: )

TN
Paul from Ohio
85 LTD
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#5 02-04-2007, 01:28 PM,
Hi pauln,

I've noticed some other post as well about the factory volt gauge showing lower voltage, I wonder if there is that much drop in voltage thru the harness before the gauge? I've thought if we were able to tap into the battery source (using a switched relay) if you could by-pass the factory harness and go directly to the meter from the battery if it would show the same voltage as our DMM does at the battery. However i know that if I'm showing 13.5 volts on the dash that I'm charging 14.2 - 14.5 at the battery, I'd just like a more accurate dash display is all, jsut for peace of mind, even though my 1500 didn't even have a volt gauge, but I mounted one on my Kawasaki and Yamaha.

TN
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#6 02-04-2007, 01:37 PM,
TNroadrider Wrote:Hi pauln,

I've noticed some other post as well about the factory volt gauge showing lower voltage, I wonder if there is that much drop in voltage thru the harness before the gauge? I've thought if we were able to tap into the battery source (using a switched relay) if you could by-pass the factory harness and go directly to the meter from the battery if it would show the same voltage as our DMM does at the battery. However i know that if I'm showing 13.5 volts on the dash that I'm charging 14.2 - 14.5 at the battery, I'd just like a more accurate dash display is all, jsut for peace of mind, even though my 1500 didn't even have a volt gauge, but I mounted one on my Kawasaki and Yamaha.

TN

The voltmeter on mine reads slightly over one volt low.
I tried a temporary jumper straight from the battery to the gauge, it went up .1 volt which leads me to believe these meters arent that accurate even though they're digital.
Someday I'll pull mine out to see if there's a calibration POT inside.
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#7 02-14-2007, 08:17 PM,
There's no calibration pot in the meter. It's strictly solid state. The usual cause of error is a resistor or resistor pack's value not being exactly in the center of it's accuracy range. I doubt 1% resistors are used in these gauges, if they're 10% tolerance that could account for a volt error. The actual reading at the panel really doesn't make all that much difference anyway, it's any change in that reading that's important.
Current: GL1100 GL1500 Previous: GL1200SEI
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#8 02-15-2007, 10:18 AM,
I agree with exavid .The voltmeters you buy and even the ones that come in a lot of automotive applications are at best just a good indicator(not that accurate)Just watch for a permanent drop in voltage on the gage.It will fluctuate a bit normally,but if there is a steady drop you're in trouble.
Fatwing Chris
If Id'a known it would last this long I would've taken better care of it !!!
[Image: NewBabyPicsSpring024SmallCustom-1.jpg]
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#9 02-15-2007, 06:33 PM,


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