GS850 charging system question.......

[zeke1883]

I have a 79 GS850, and never knew whether the bike was charging properly or not. Well, I bought one of those Heads Up Voltage Monitors, and now I know (somewhat) what is going on with this thing.

The bike seems to be charging, but not when the headlight is on high beam. If you switch it to low beam or turn the headlight off, the charge indicator LED lights up green indicating a charge rate of 12.8 to 15 volts. And it holds this state even when the bike is going slow around 20mph.

Now when the high beam is on, the LED turns yellow indicating a charge condition of 12.1 to 12.8 volts. Even under steady highway speeds of 60 to 70mph, it stays yellow. Only under quick acceleration does it shift to green and that is only for the time you are accelerating. As you reduce speed, it still stays yellow and never turns red until you really slow down or stop which is expected at idle.

My question becomes, have I got a problem here or not? I am assuming that regardless of the headlight position, it should always be charging in the "green" zone.

So I don't know if this is normal for one of these bikes or not. Anyone got any take on this? Appreciate any input. We are going on a 4 day weekend trip about 300 miles from home, and I am assuming it will be fine for this trip. I figure to keep the headlight on low beam for as much of the trip as I can since I am riding with 4 other bikes, I should be fine doing that, I don't like riding on low beam during the daytime, but if I am getting a full charge like that, it seems like the thing to do for now.

We haven't really had any battery issues with it so I assume it has been charging "enough".

Thanks
Zeke

By the way that monitor is an EXCELLENT product.

[BassCliff]

Greetings and Salutations!!

Hi Mr. zeke1883,

Yes, you have a charging problem. At speed you should see about 14.5v at the battery. Use the Stator Papers Fault Finding Chart, linked below, to find out what's going on with your charging system. First, be sure to check and clean every electrical connection and ground on the entire bike, from the headlamp bucket to the tail light, including the fusebox and ignition switch. You might improve your charging by moving the ground wire on the regulator/rectifier and connect it directly to the negative battery terminal. In case I haven't properly greeted you yet, here's my "welcome thang"...

Here is your very own magical, mystical, mythical, mind-expanding "mega-welcome". Please take notice of the "Top 10 Common Issues", the Carb Rebuild Series, and the Stator Papers. Now let me roll out the welcome mat for you...

Please click here for your mega-welcome, chock full of tips, suggestions, links to vendors, and other information. Then feel free to visit my little BikeCliff website where I've been collecting the wisdom of this generous community. Don't forget, we like pictures! Not you, your bike!

Thanks for joining us. Keep us informed.

Thank you for your indulgence,

BassCliff

[Larry D]

Cliff gives great advise. You have some kind of something going on there.

Does your meter give a digital readout or just a range indicated by colors ?

Best to take a good look, you may have something that looks like this.....

http://www.thegsresources.com/_forum/showthread.php?t=146532

[bwringer]

It sounds like everything is sort of working.

I bet if you carefully clean all the wiring connections, you'll regain your lost charging performance.

The three stator connectors are a good place to start. You may want to take the leg that goes up to the headlight switch and wire all three direct to the rectifier.

[Bufallobiff]

"You may want to take the leg that goes up to the headlight switch and wire all three direct to the rectifier."

I noticed that when I cleaned up the connections on my 850---Why?---I'm guessing it comes back on another wire to the rectifier from the switch?

[bwringer]

"You may want to take the leg that goes up to the headlight switch and wire all three direct to the rectifier."

I noticed that when I cleaned up the connections on my 850---Why?---I'm guessing it comes back on another wire to the rectifier from the switch?

It's a leftover -- the early bikes, like the OP's '79 850, ran one leg of the stator through the headlight switch. So if you shut off the headlight, one leg of the stator would be shut off so that the regulator wouldn't be overloaded.

The wires remained on later models thanks to corporate inertia (a powerful force), but they were just connected in the headlight shell.

Since it's now illegal to ride without a headlight, it's silly to even have a headlight switch and the extra six feet of wiring even on an early model. So just bypass the loop up to the switch and all the added resistance of the connectors, wiring, and switch.

The regulator won't overheat, and you'll very likely regain part of the lost charging performance.

[Steve]

You should really look into getting a different meter to check your system. If your green light is activated when the voltage is over 12.8, it's entirely possible that it could be as little as 12.85, making you think that things are all hunkey-dory when they're NOT. The reason I am thinking that your voltage might be that low is that the difference in the draw from low beam to high beam is very little. It is so little that you would have to be right at the lower threshold of your green light for it to cross over to yellow while on high beam.

.

[bwringer]

Agreed -- hook up a digital meter and report back.

A digital meter is $3 at Harbor Freight. Add a couple of zip ties or some duct tape.


Related to that useless loop of wire up to the switch (or headlight), it's pretty funny to watch people go when you unplug these wires on their bike and plug them back in differently...

[zeke1883]

OK, I have a meter and here is what it says

Bike off: 12.93v across battery (Battery 2 yrs old)

IDLE: Low beam: 12.83v
IDLE: High beam 12.56v
IDLE: No Headlight 14.1v

5k: High beam: 13.8v (takes a minute to climb to that level)
5K: Low beam: 13.7v
5K: Headlight off: 13.9v

I am going to try bypassing that on off switch and see what the story is.
I am still not exactly sure which wires those are, but I will try looking it up in the manual, Not real good at deciphering these schematics, but I will give it a try. I am assuming those wires are down under the left sidecover where the solenoid is.

[zeke1883]

More on the stator wires and headlight switch....

OK, I am REALLY confused, I am looking at these wires under the left sidecover, and I cannot figure out what wires come from the on/off switch.

There are like 4 wires that go up to that on/off switch, an orange, a dark green, a red/white and green/white.

The Dark green appears to go up to the tach lights
The orange appears to go to the fuseblock
The R/w goes to the regulator rectifier
The G/w goes to the generator


What 3 wires are you talking about tying together? I am not getting it.

I am not understanding what the "stator" is or where the wires are?
Is the stator and the generator the same thing?