Charging question on 305 CSR

I've been looking for my first motorcycle and came across a 82 305 CSR. I looked at it today. The guy said he had it on a trickle charger overngiht and it still would not start. I checked the batter voltage read 8 VDC. We got it push started and I checked the voltage on the battery while it was running. It read 22 VDC and also had about 5 VAC across the battery terminals.

I am guessing the voltage regulator is bad. But that 22 VDC seems awfully high. Could there be more wrong with this than just the regulator? Do motorcycles use alternators or something else? I just figured they were generators and was surprised to see the AC component.

I am very new to motor cycles but have messed around with cars a good bit. Also being an Electrical Engineer gives me some (only a little bit) of insight into this charging problem. So, I really appreciate any help.

Thanks,
HH'

Go to www.electrosport.com and find their troubleshooting page. They also sell stators(the wire windings) and regulators & rectifiers(although, most bikes have combination regs & rect. now

MFolks,
thanks for the link. That is a great site. I will be reading at lunch today.

Thanks!!
HH

If the problem turns out to be the voltage regulator (R/R), you might be able to use one from a Ninja 250 or whatever modern bike has one that is similar to yours (ie, similar charging system, same number of wires, & same/similar wire color).

Check out the Battery First. If it was charged but wouldn't crank the motor I'd suspect it to be bad. These need a good battery to charge properly. If the battery is bad, it will show a high charging voltage. Also if there is a problem with the charging system putting out to high, even with a good battery, it will overcharge it and lose the electrolyte. But you need a good battery first to check the system right. Make sure the connections are good. Lots of threads on charging here on KZR.

+1 - it sounds like the rectifier and regulator are shot. At best, all of the electrolyte is boiled out of the battery - at worst, one or more of the cells in the battery is screwed up. From the parts diagram, it looks like a combined regulator and rectifier, which simplifies troubleshooting. Do NOT just replace the battery (although that IS required), replace the R/R first.

AC voltmeters read the AC component of the voltage. DC systems can have pulses on them, but it's not true AC because the current does not reverse direction. However, if you block the DC, then what remains is the AC portion, which is what the AC voltmeter measures.

Perhaps you'd be interested in what voltmeters actually measure:
home.comcast.net/~loudgpz/GPZweb/ACvoltmeter.pdf

The high voltage reading on the bike can be a result of a defective regulator, or a loss of the sensing signal to the regulator, or a defective battery. A good battery will smooth out the voltage pulses, which will reduce the measured AC component. A defective battery may lose that ability. When the pulses doen't get smoothed out, the regulator may lose the ability to properly sense the voltage.

"AC voltmeters read the AC component of the voltage. DC systems can have pulses on them, but it's not true AC because the current does not reverse direction. "
Hmmmm....... I forgot that. Thanks for the reminder.

HH

I am planning on buying a battery this Sat and trying it out. If it starts but still has high charging voltage can I ride it about 15 miles? What could happen? How long would it take to cook the electrolyte out of a battery?

Right now it is at the owners parents house. I hate to run everybody around while I try to get it fixed. But I have no trailer so I need to either get it running right or limp it home.

Thanks,
HH

You probably won't kill anything irreparably if you keep the RPMs low. Pumping AC into your bike's electronics is never a good plan. The only thing that I'd really be worried about are the coils. Running it with AC in the mix can overheat the coil, so you could burn them out assuming they aren't already messed up.

The Voltage regulator is a plug-in part held on with a rubber band, as I recall, so if you can get one, I'd install it before I rode it.

Unplug the connectors from the reg/rec, and unplug the headlight.You should be able to ride over 100 miles on a fresh battery that way.

loudhvx wrote: Unplug the connectors from the reg/rec, and unplug the headlight.You should be able to ride over 100 miles on a fresh battery that way.

That'l work. I had to do the same thing a long time ago. Got me home.