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· Biker
1,756 Posts
charging system

Hi all,

I recently bought a Suzuki GS500 (02 reg) and I've been having problems with the battery. Initially I thought the battery was at fault however I've replaced this and still have issues.

If the bike is not used for a few days the battery has little charge left and when i go out for 20 miles rides it doesn't appear to be charging at all. Actually, the bike frequently cuts out towards the end of these rdies and then I can't get it started again due to dead battery.

I've followed the steps to check the R/R from the John Bates charging circuit test (and a bunch of other guides). Measurements are:
1. (battery) All off = 12.88 / 13.12. Idle (1200RPM) = 13.9. 2500 rev = 14.2. 5000 rev = 14.15 (However, this doesn't always happen, sometimes there is no increase)
2. 14.2
4. 60mv
6. 48mv
8. y1-y2 = 1.5 ohms. Y1-y3 = 1.5 ohms. Y2-y3 = 1.4 ohms
10. OL for all
12. y1-y2 = 65v. y1-y3=66v. y2-y3 = 65V
14. Red – y1 = 498mv. Red-y2 = 510mv. Red-y3 = 513mv
16. OL for all
18. y1 =514mv. Y2 = 512mv. Y3 = 510mv
Stator current (AC) at 5000 RPM between leads:
65v, 66v and 65v

These readings suggest that the stator is OK. According to the guides I'm using the readings for the R/R (14-18) are too low but they are all consistent.

The connection with the Red and b/w connects to the cable coming from the R/R and looks damaged/corroded. The yellow wires that also connect up to those coming from the R/R get fairly hot to the touch.

I'm not too sure what is going on here.
Charge battery and have it load-tested so you KNOW it is good,

So, you have 3 yellow wires from stator to R/R right? check connection between each yellow wire and stator core. If there is
continuity, the stator is bad and in one way or another will reduce voltage to charge battery. If there is NO continuity between
yellow wires and stator core and resistances are within guidelines, then stator is most likely good.

Does the rotor actually have MAGNETS in or on it? Some bikes use a wound rotor to make the magnetic field instead of
permanent magnets. This means that some electricity has to go into this spinning rotor to MAGNETIZE it, then with it spinning
inside or over the stator, power can be taken from the stator. IF the brushes are too short and not making contact with the
slip-ring/s rotor has no magnetic field and power will NOT be available from stator.

Almost sounds like RED goes to battery+ and b/w is Black wire with white tracer or skinny white line and is negative side?

The R/R can **** out in 2 ways, 1 not enough voltage to charge the battery if you don't have a shop manual, I'd say 14 volts
output is good. 2 two much charging voltage will 'COOK' the battery boiling off electrolyte.

So you have a plug from R/R that mates to a similar with 3 ylw wires and a Red wire and b/w to R/R? seems there should
be another heavy red wire that goes to Bat+ the red and b/w might be for brushes if rotor is a wound job.
Give me a holler might be easier . 727-204- 2767 if possible send some pics, meantime I'll see what I can find on checking R/R

· Biker
1,756 Posts
Hello Jack 27808,

O.Kay I found some info from a 650 Suzuki same wire colors, Red wire and BLACK wire with white tracer or stripe that goes
to a female connector or plug is what charges the battery. Black plug with spades or flat pins exposed is from stator and has
3 yellow wires...

This can be tested to see if it is good or not.1 Have multi-meter set for RX1 ohms, put red meter probe into connector w
RED WIRE, meaning probe makes contact with the RED WIRE contact.

2 BLACK meter lead touch to each of contacts in plug with YELLOW WIRES from stator in the video I just saw, no continuity to
any of 3 pins hooked to yellow wires. If meter shows resistance, say around 5 ohms on 1 lug but not other two OR on 2 lugs but
not all 3 then R/R is BAD.

BUT if it shows same on all 3, you got to next test, 3 Put RED meter probe into connector to make contact with the BLACK WIRE
w white stripe and touch each of the lugs connected to yellow wires of Stator winding with BLACK meter lead. You must have about
same resistance in all 3 yellow leads or NO resistance in all 3 yellow leads for R/R to be good, If two leads show 5 ohms and one
lead is open circuit R/R is bad. Check ALL fuses, some bikes use a fuse in the 'Battery charge circuit. Kindly let me know how this
worked out.

· Biker
1,756 Posts
Sorry I can't help you out more, Jack. As I said I saw this video and the R/R had the 3 yellow's a Red and a Black with a white stripe,
sometimes called a tracer so I really thought that would work for you, But being a bigger engine, this r/r that got tested in the video
was for a GS650, it might have heavier diodes BUT it has a RED+ wire and the BLACK WIRE w/ white stripe

So, You have a RED + wire and a GREEN wire coming out of the R/R? that is interesting because the R/R I saw had the 3 ylw's in
a black connector plug and a RED wire and a BLACK wire with the white stripe in a white connector, I'd say the GREEN is still the

The guy in the video was just measuring resistance with the OHM-METER function of the Multi-meter, using red probe in R/R's +
side of plug and going to the 3 stator leads with BLACK probe, then used the RED probe in R/R's - side of plug and checked the
R/R by going into the Stator leads, he was NOT checking voltage, just resistance, as you know, the ohm-meter puts out a little
bit of voltage, So voltage will go though a diode ONE WAY, if it goes though both ways, it's not a diode anymore.

· Biker
1,756 Posts
Jack, the guy who did the testing of the R/R kept referring to the red wire as Battery + so I honestly think we should also
consider it to be BATTERY+. Jack, everything you said before makes sense about the battery not being charged when you
took the bike out for a twenty mile ride only to die, due to lack of volts and amps. I had one go on my 91 Sporty 1200 and
I knew it because I checked voltage with bike running and only got close to 12 at 2500 rpm. Then I checked STATOR output
and had around fifty volts a.c. at 2,000 turns of the engine, The shop manual says between 19 and 26 volts a.c. per 1000 rpm
so I knew the stator was good. I bought another R/R and Battery, that was Oct 17th 2014 and has been working fine since.

Once you get this bike running AND charging, get a battery tender for it, I can't tell you enough how great they are.
My Wide Glide would take around four seconds to get running, and that is with the proper battery, YET put the BT on her for a
day and she starts up in less than half the time it does without a BT, Same with the Snorty, put the BT on her for 12 hours,
open gas valve, give her some choke, Starter peels the engine over like no effort needed and fires lickety split. Time for a beer.

· Biker
1,756 Posts
Nice that bike is running happy again, did you put a meter across battery to see what the charging volts are? Are you going
to get a battery tender? that will probably double the life of the battery. Last battery I put in my 91 Snorty1200 was Oct.
2014, and it is still going strong.
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