I'm looking for suggestions on how to troubleshoot a charging problem with my 2008 VN900 Classic. After winter break where I trickle charge my battery a couple of times, I can't seem to keep it charged. I use a battery buddy to keep it charged and find that even after a few starts and riding for an hour, the battery is drained to the point where I have to pop start it (relatively easy to do with just a little down slope). Based on what I've read on this and the other kawi Vulcan forum I would expect I had a bad stator. But my bike seems to be charging based on these measurements: with the key in the off position, the voltage at the battery is 12.45V, with the key on but the motor off, the voltage drops to about 12.1V, with the motor on at idle, the voltage is about 14.5V and when rev'd in neutral the voltage is about 14.0V. If the stator was fried I would expect little to no increase in voltage when the motor is on. Or am I mistaken? Maybe my battery is NFG? I'd sure appreciate some guidance on how to isolate the charging issue as I'm not keen on handing a blank check to my dealer. Does replacing the stator require any special tools? It appears they aren't that expensive to buy online compared to from kawasaki ($155 at www.regulatorregulator.com).
Based on the voltages you provided, the charging system would seem to be fine at 14.5 volts, but the battery at 12.45 to 12.1 appears to be very low. A fully charged battery should be 12.7 or better. And the drop from 12.45 to 12.1 just turning on the key is a harbinger of a battery issue, not a charging issue.
Also, the battery is far more likely to fail over the winter than the stator which is not being used, and the rectifier/regulator usually fails by by allowing excess voltage (above 14 or 15 volts), which is not the case. So----
Replace the battery and the problem should be gone.
Hope this helps, and
Hope its correct analysis as the battery is the least expensive part.
Pull the connector off the regulator. Measure the resistance across the 3 white wires going to the stator. Value should be 0.11 - 0.17 ohm (1-ohm scale). Start the bike and measure the voltage on across the same white wires and it should be 54V or more (250v scale). I saw the same voltage drop to 14.0 when revving if the battery has a bad cell. Also, 14.5v is high unless your idle is set very high. The headlight sucks the voltage at idle. I adjust my idle by voltage, 13.5v. Mine just did the same thing two weeks ago. This is my second battery in 3 years, switched brands this time.
If you are not riding all year long you'll want to leave the bike plugged into a float charger. Just pumping up the cells every once in a while won't cut it with these itty bitty batteries. Truthfully, it won't work that well on the bigger batteries but they have a lot more mass and won't show the ill effects so bad. If all you have is a trickle charger, hook a permanent attach point up to your battery so you can plug in all the time, then plug your trickle charger to the bike and use a daily timer to put voltage into your battery 6 hours a day. Monitor your voltage levels for the first week or two and modify that charging schedule. I've got a float charger designed to keep your RC field box battery at peak, I just plug that into the wall and put the output into my 12volt plug that I use to power the GPS/cell phone charger/air bed pump. Now, I did have that on a timer but found out the led circuit that is in the plug in of my extension chord drained the battery while it wasn't charging and I only had it charging once a day. So I just put it on permanent and didn't have any problems.
Marine cell batteries are designed to be deep cycled. They don't mind getting low on voltage so much. But the standard Car and Motorcycle batteries are designed to give you a large cranking amperage and then immeadiatly charged right back up and kept topped off. Deep cycling will corrode their plates quickly and you'll replace the battery more often.
Motorcycle charging systems have three phases which under normal circumstances, should be able to satisfy all of the power needs of the bike. You could almost look at it like three batteries in parallel. Now, if you lose one of the three batteries, the other two may be able to keep the voltage up on the bike at idle, supplying the headlight, ignition system, etc., but barely. Now, when you rev up the bike, the ignition system demands go way up and the two phases can no longer support the additional load and the output voltage sags. Another indication is sometimes the headlight dims in cadence with the signals at idle, or dims with the brake light.
Now, he may have a battery problem, but if so, it usually shows up at idle, too.
A good battery is essential for the charging system to function as it should, but with these symtoms as he presented them, I would be giving the old eyeball at the charging system.
Thanks for the feedback and advice. It certainly appears I have damaged the battery by not keeping it connected to a Battery Tender this winter. I re-verified my voltage measurements (12.2V with key off after a half dozen starts, 11.9V with key on/motor off, 14.4V idling, 13.9 with rpms up). I checked the stator resistances and outputs (,2 ohms and >60VAC between each wire pairing) and it looks good per Electrosport's decision tree (thanks - very useful guide). So my charging system appears to be working but my battery cannot maintain a charge. Hopefully replacing that and taking better care of it will solve my problem. I'll let you all know in a week or two (business travel all next week will keep me off the road, hope it doesn't rain next weekend).
Yes - I forgot to mention I buzzed out the RR and it appears fine - diodes aren't shorted or open anyway. Not sure how to check regulator portion other than the observation that the voltage at the battery when running is not too high or low indicating the regulator is properly shunting excess stator output from the + line to battery.