Charging Circuit being a PITA

So I had a failure to chooch at 3am last night downtown. Luckily I was able to bribe a construction worker to let me put my XJ750 on their site with a beer.

Anyways I have been fighting my charging circuit lately, I replaced the rectifier because I thought that was the root of my issue (crossed battery leads once a while back). Thinking that I solved my issue I rode across town and when I was coming back home last night I noticed I was running off the battery again, and right in the middle of downtown is where the battery died. Walked the battery home, trickle charged it overnight and took it back today to rescue my bike. Now that I have it at my house I took some measurements that will hopefully give some insight into what is going on.

Battery alone: 12.35V
Key turned on: 11.81V (my headlights are hardwired on from PO)
Idle: 11.79V
2K: 11.91V
3K: 12.03V
4K: 12.08

So it is clear that I am getting some voltage to the battery but I don't think I am getting enough umph to charge the battery. My next step is to buy some brushes and continue replacing part by part until this problem is solved...

 

What's the voltage when the battery is full charged?

Gary H.

 

Couple of items come to mind. How old is battery and what is the water level ( only use distilled water to service) it is possible battery is weak and your charging system is not able to give it enough of a charge. Even if you have 12 volts before start it could pull more on start and not fully recover. I'm just stating where I would start at if it were my bike. The other thing have you upgraded your fuse block to blade type fuses or do you have original fuse block? Quite possible corrosion on leads can cause intermittent charging issues. Good luck

 

Start at the source. Check the condition of the alternator brushes (wear indicators are mounded into the brushes) and clean the faces with an eraser.

 

Use this: https://www.electrosport.com/media/pdf/fault-finding-diagram.pdf

Go to D
There are two possible paths, the rotor (green/brown wires) which could be a problem with the brushes, the rotor or the wiring, or the stator (three wire wires).

If there is too much resistance and the rectifier/regulator can't flow enough current through the rotor, then there isn't a strong enough magnetic field for the alternator.
If there is too much resistance or a short in the wires from the stator, then the R/R won't get all three phases it needs to rectify the AC current to DC current.

 

Start with a fully charged battery.

Gary H.

 

put a switch on the head light or go back to a relay set up .

this link has full testing and specs for charging system as well as trouble shooting
The Ultimate Relay, Switch, Sensor, and Diodes Guide