Author Topic: Why did my CT90 stop charging? *SOLVED*  (Read 5382 times)

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Offline Scott S

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Why did my CT90 stop charging? *SOLVED*
« on: October 28, 2017, 01:57:21 PM »
When I bought my K5, the turn signals would act like a kill switch. I was told about the rectifier upgrade and to get a fresh battery. When I checked, the rectifier had already been upgraded.

 I found one bad bulb in the rear; replaced that. Got and installed a new battery. Installed a new 6V flasher relay. At that point, the signals started working like they should.
 Fast forward to today. I took it out for a 15-20 minute ride and, while it ran great, I noticed that the turn signals didn't even light up, let alone flash. When I pulled into the garage, I couldn't see the headlight on the wall. Pulled out the multi-meter and I had less that 5 volts at idle with the headlight on low beam. I had just under 6 volts when revving.
 Well, crap....

 Pulled the cover and checked the battery ground. Checked again and I'm still just under 6V at idle or when revving. I may have gained a few tenths of a volt by re-seating the ground.

 Here's the thing: When I was testing out the system, before the new battery, etc., everything tested well. Here are the numbers I got BEFORE:

* Battery resting, after sitting overnight: 6.28 volts.

* At idle: 6.6-6.8 volts.

* Revved, with high beam on: 7.6-7.8 volts.

* At idle with no lights on: 17+ volts (I'm told that it's normal to see very high voltage with no lights to draw on the system)

 What the heck did I do? I made sure to check all connections on the rectifier, etc, when I was in there. Is there a particular wire or spot to start checking? Maybe I knocked something loose when installing the new battery?

 This is the flasher relay I installed.

https://www.ebay.com/itm/2FastMoto-Hond ... 2c6815596b
« Last Edit: October 29, 2017, 10:56:19 AM by Scott S »
'71 CB500 K0
'17 Triumph Street Scrambler
'81 Yamaha XS650

Offline Scott S

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Re: Why did my CT90 stop charging?
« Reply #1 on: October 28, 2017, 01:59:35 PM »
The only thing we changed from the previous wiring was to ground the battery directly to the frame.
Someone.... NOT me... had used these jubilee clips, or whatever you call them. The battery ground and the battery tender negative side were spliced in together.
I added a connector for the tender pigtail and put the battery directly to the frame.
Would having the battery NOT grounded into main harness cause the problem? Hmmm....maybe so....

Put the battery ground back to the main harness.
Still only getting ~6.2V on a resting battery and only ~5.7-5.8 with the engine idling AND revving. No change.
It goes up to about 6V with the lights off.
What now?

Here's the rectifier, as found:




 And now I have the battery ground back on the main harness.





 What else should I check?
'71 CB500 K0
'17 Triumph Street Scrambler
'81 Yamaha XS650

Offline Scott S

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Re: Why did my CT90 stop charging?
« Reply #2 on: October 29, 2017, 09:22:12 AM »
Got it, guys!
I decided to undo all of the crappy connections and when I rolled back the electrical tape on the main harness I found the RED/White wire completely broken and the other two had worn spots. I got rid of multiple connectors and spliced/soldered/shrink wrapped with the correct color wires.
I also added a second leg on the GREEN ground wire so I could go straight to the frame.



Much neater now.



I also cleaned up the connectors on the rectifier pigtail using the same method.




Much neater than before.




I'm now getting 6.5-6.6V at idle with the lights on. It jumps up to 7.7-7.8 when revved.
Turn signals flash bright and rapidly.
Even seems to run better!
'71 CB500 K0
'17 Triumph Street Scrambler
'81 Yamaha XS650