Just installed a new AGM battery so I thought this would be a good time check the charging circuit. I've been using this pdf,  http://bbburma.net/Documents/JohnBates_ChargingCircuitTests3.pdf

Everything seemed to be fine up to the point where I went from 2500rpm to 5000rpm. Now I'm getting confusing readings from the stator continuity test.The battery  was reading 13V with the static charge removed and with the light circuit switched on it dropped to 12.6 so that seems to be good. At idle the voltage across the battery terminals went up to 13 and kept rising up to 14.5 at 2500 rpm. This also seems to be good.

However when revving past 2500 RPM the voltage slowly dropped until at 5000RPM it was back to 13V This seems to indicate a problem somewhere according to the pdf. The first test I did by checking the three different pairings of the 3 yellow wires coming out of the stator is what has confused me. I've checked the battery in the multimeter and it is in good condition but the readings I'm getting are strange, and the best readings I'm getting seem to indicate that there might be a problem with the stator.

Apparently I'm looking for reading >0.5 and <2 Ohms. When I check the three different pairings, the best result I'm able to get is 2.5 Ohms which according to the pdf, is bad. However I'll go away and come back and check the pairings again and I'll get all three reading 3.8 which is very bad. Or is it?

I'm wondering what could be causing the voltage to drop as I go from 2.5k rpm to 5k rpm and how bad is 13V at 5k rpm? It's a 2010 bike and I'm thinking if it's 14.4 at 2.5k rpm that maybe an over load circuit has kicked in to stop it rising further, Is this possible? I have not checked the AC voltage yet.

User, it's been a long time since I messed with a charging system, so take this with a grain of salt.

First off, there isn't any real over load circuit. Your regulator / rectifier is the closest thing, but if it goes bad you're looking at >15 volts at the battery at higher rpms.

The fact that your stator is producing good voltage at 2500 rpm and then drops off makes me think there is a drain somewhere else in the ignition circuit (so it's wasting energy at higher rpms). Maybe a pinched / damaged stator wire before the test leads? Or if you're testing voltage at the battery, maybe a faulty ignition coil that is sucking juice?

Like I said earlier - don't trust my memory when it comes to electric gremlins.....

Quote from: Big Rich on August 19, 2017, 01:25:53 PM
snip

OK thanks, I've order a new basic Fluke 101 for 60 bucks, and I'll check the RR with that when it arrives in a few days. Meanwhile I ran my current crap multimeter over the stator pairs again after a long ride today, I was getting about 10 Ohms resistance! WTF I think I'll just ignore that till I see what the Fluke reads.  I checked the AC voltage and each pair was getting 16VAC at idle and 60VAC at 5000, all three were the same so it's prolly the rectifier or some other bad wires. There doesn't appear to be any pinching in the stator wires but then they are in a very harsh environment under the stator cover.

hello

so iv had plenty of fun with suzuki charging systems and here is the best way iv found to make them work

first disconnect the alternater and with the bike off check for contiuity between the wires. ant 2 must have a circuit between them, if that passes then check between each wire and ground, there should be no connetion on any of them, now start the bike and check ac voltage, as long as your getting above 30 volts ac over 2000 rpm then its working fine ( again check between all pairs) higher voltage is better but 30 will do the job, now heres the fun bit, i wire my regulator direct to the battry (red to positive and black to ground ) now reconnect the alternator and start the bike, as long as your getting 12.5 or higher at idle your golden just dont go higher than 14.5, now bring the revs up to 5000 and look at your voltage, your aiming for 13.5 to 14.5 now if your not getting this dont panic, if its low 12ish volts then take your battry and put it on charge over night and test again, if its 15 or higher then you likely have a dud regulator.

this is how i run my bikes and i dont always use a suzuki regulator, you can get away with any 5 pin regulator as long as you wire it up right

good luck

Ditto on checking voltage between each of the 3 wires coming from the stator. The bike should be hot hot hot before testing stator. A stator can have good reading when cold but start to flake out when it's hot. Get it nice and hot and turn off the bike. Disconnect the stator wires from the R/R and start up the bike.  Test the voltage at idle and at 4k rpm for each of the wires coming from the stator. Should move up to 30v-40v maybe  higher. Test from first wire to the second...first to third.....second to third.....second to first and so on. The point is to test voltage between all three.

RPM's do affect the voltage from the stator. There are youtube vids of the process which helped me a lot.

OK thanks for the replies.

I bought a Fluke 101 for not much and this immediately solved the continuity problem with the stator. After pulling apart the two block connectors from the stator to RR and from the RR to the battery, and then giving them a spray with contact cleaner, my main problem was also solved. The contacts looked in good condition but there you go.

Congratulations! Enjoy your riding.

There is an excellent tutorial made by Kerry:
http://gstwins.com/gsboard/index.php?topic=38480.0

At 5000RPM, with the regulator disconnected, you should read 75V between the yellow cables. There are 3 yellow cables, so test 1&2, 1&3, and 2&3. All three measures should be close between them. Having one that is quite different means that there is something wrong with alternator coils.

I could read 71 in my bike, but anyway, it is close to 75.

The main problem in the GSs is the contacts getting rusted and dirty. Usually a contact cleaner makes wonders.