I've been dealing with a weird charging issue on my 2003 CBR600F4i. Prior to starting the bike, my battery will read about 12.75V. After starting, it jumps up to ~14.3V or so. It hovers there for around 30-60 seconds and then immediately drops back down to ~12.75V. From here it slowly ticks downward and eventually causes the bike to die. It can take a while (20-30 mins) if I'm riding it because when the engine is under load it loses power slower but even at 5k+ RPMs it doesn't exceed 13V again so there is definitely an issue with the charging system.

I ran the diode test on the rectifier and it was reading healthy on all the touch points so it doesn't seem to be a rectifier issue. A couple years ago, I replaced the stator and regulator/rectifier so I'm somewhat familiar with that particular issue (replaced the stator before I realized it was actually the RR).

I also ran through the "fault finding flow chart for motorcycle charging systems" and ended up at the "Bad connection in the positive lead from RR to battery (+)" diagnosis but I haven't been able to identify a bad connection. I traced the wires the best I could and nothing looked out of place but I'm not really sure what I'm looking for.

link to flow chart: http://www.electronicamotos.com.ar/t...ng-diagram.pdf

Can anyone give me advice on what to do next? I'm kind of hitting a wall where I've sort of diagnosed the problem but am not sure where to go next.

Thanks!

 

Hello Brandon,
Personally I think you have a very simple (and possibly a repeatative expensive) problem,
However the right diagnosis is always a matter of structure and order.
So the first thing is to make sure you remove all the fairings that might be in the way when measuring the charging circuit.
Second is to start the bike and make sure that the bike is charging that first 30-60 seconds.
You can do that by inserting a 0.1ohm resistor between the rectifier and the battery and measuring the voltage over the resistor. Or a current measuring device, however these can often handle a limited current. I would count on a maximum of 20amps.
Measure the absolute voltages on the AC wires of the stator before the connector, before the rectifier after the stator connector, after the rectifier between the battery, and last on the battery clamps.

From there is is getting only easier.
When the problem occurs just measure the voltages on the same places again mentioned before.
There where the voltage is higher than before is most likely before the problem. There where the voltage is lower than before is most likely after the problem.

However I don't think you're looking at a connector problem. My bet would be that a thermal safety is kicking in.
If you start the bike after fully charging the battery, measure the time between kicking on and the voltage dropping to 12.xx
Then start and stop the bike a couple of times to drain the battery a lot.
Then measure the time again before the charging system turns off.
When this time is significantly shorter than before, the problem is most likely current related.
This would make it almost certainly a thermal issue of electronics.

Please let us know of the progress...

 

@chris0986 Thank you for your reply. I will try to find some time in the next week or two to run these tests and will keep this thread updated with my progress.