For 43 years and 97K miles there have been no issues with the charging system on this CX500C. It does have an Ignitech though installed many years ago. It gets used a lot during the summer months.
This past weekend my good fortune ran out.
I was on a 35 mile backroads ride on a perfect day.
About 25 miles into the ride my GPS kept shutting down and I kept restarting it. A few miles later making a turn I noticed the turn signal indicator was dim. That's when I started to worry. I got to my destination and put the bike in neutral. The neutral indicator did not come on. I shut the bike off and tried to restart it - just a faint click from the solenoid. The headlight bulb was barely lit.
I used my premium AAA to get it towed home.
The battery is only a year old and has given no problems. I slapped the charger on it for a few hours and it started easily. With the engine running I measured it's voltage - about 12.2 volts - certainly not charging properly.
The next day I pulled off the Reg/Rect for some tests. All the rectifier diodes measured good. The 3 stator windings all measured around 1 ohm and there were no shorts to ground. All the connector terminals were shiny and corrosion free. There was a solid ground connection from the battery to the engine and the regulator. The 20 A fuse was intact. The R/W charging wire from the solenoid terminal to the regulator was intact.
I even set up the regulator on the bench with a signal generator driving about 50vrms at 200HZ into the stator inputs one pair at a time. With a 500 ohm load across the output I could see the rectified pulses getting through in each case. When I touched the black sense line to the load I could see the input and output pulses clipping at about 15 volts. This convinced me that the regulator was probably good.
I put everything all back together and fired it up. At idle the battery voltage was about 12.2vdc. When I revved it up to 2K RPM the battery voltage went to about 12.4vdc. This indicated some level of charging.
I got out a current clamp and measured the charging current in the R/W wire - about 2 amps at idle, 5 amps at 2K RPM. Similarly, I measured the current through the fuse - about 7-8 amps at any RPM. Looks like some charging but not enough to maintain the charge.
Then I explored the sense wire. It disappears into the wiring harness and is not really assessable anywhere convenient. Surprisingly, at the regulator it measures about 11.5vdc with the key turned on (running or not), which is about .7volts below the battery voltage. Is there a diode in this circuit? I don't see one in the FSM wiring diagram. I measured about .6 ohm from the the regulator end to the + battery cable (disconnected). What causes that? These measurements indicate that there's over an amp flowing in the sense wire. This doesn't seem right to me.
I'm inclined to jump it over to the fused battery feed which is nearby to see if that helps.
I'd love to hear any additional ideas.
This past weekend my good fortune ran out.
I was on a 35 mile backroads ride on a perfect day.
About 25 miles into the ride my GPS kept shutting down and I kept restarting it. A few miles later making a turn I noticed the turn signal indicator was dim. That's when I started to worry. I got to my destination and put the bike in neutral. The neutral indicator did not come on. I shut the bike off and tried to restart it - just a faint click from the solenoid. The headlight bulb was barely lit.
I used my premium AAA to get it towed home.
The battery is only a year old and has given no problems. I slapped the charger on it for a few hours and it started easily. With the engine running I measured it's voltage - about 12.2 volts - certainly not charging properly.
The next day I pulled off the Reg/Rect for some tests. All the rectifier diodes measured good. The 3 stator windings all measured around 1 ohm and there were no shorts to ground. All the connector terminals were shiny and corrosion free. There was a solid ground connection from the battery to the engine and the regulator. The 20 A fuse was intact. The R/W charging wire from the solenoid terminal to the regulator was intact.
I even set up the regulator on the bench with a signal generator driving about 50vrms at 200HZ into the stator inputs one pair at a time. With a 500 ohm load across the output I could see the rectified pulses getting through in each case. When I touched the black sense line to the load I could see the input and output pulses clipping at about 15 volts. This convinced me that the regulator was probably good.
I put everything all back together and fired it up. At idle the battery voltage was about 12.2vdc. When I revved it up to 2K RPM the battery voltage went to about 12.4vdc. This indicated some level of charging.
I got out a current clamp and measured the charging current in the R/W wire - about 2 amps at idle, 5 amps at 2K RPM. Similarly, I measured the current through the fuse - about 7-8 amps at any RPM. Looks like some charging but not enough to maintain the charge.
Then I explored the sense wire. It disappears into the wiring harness and is not really assessable anywhere convenient. Surprisingly, at the regulator it measures about 11.5vdc with the key turned on (running or not), which is about .7volts below the battery voltage. Is there a diode in this circuit? I don't see one in the FSM wiring diagram. I measured about .6 ohm from the the regulator end to the + battery cable (disconnected). What causes that? These measurements indicate that there's over an amp flowing in the sense wire. This doesn't seem right to me.
I'm inclined to jump it over to the fused battery feed which is nearby to see if that helps.
I'd love to hear any additional ideas.