Probably A Stupid Question but Have to Ask

[va_blue_stang]

My bike will not charge the battery unless I ground the green wire then it comes to 14.5-15v. Has anyone tried hooking a ground to a switch and the green wire so they charge the battery in short intervals while they ride?
I'm going to replace it when the cash flow is a little better but looking for a way to not have to drift start the bike at every stop I turn off the engine during.

Thanks for all the help on here guys, Mitch

[TopCatGr58]

Hey Blue Stang,

Well, first of all, hopefully you've deduced from this that your Reg/Rect possibly isn't working properly. Now, whether it's actually FRIED, or perhaps there's corrosion to both the wires for the Reg/Rect, as well as where it grounds to the frame?

The green wire is how the Reg controls how much charging action you are getting out of the ALT, and running at full charge could eventually overcharge your battery, boil it away, etc.! You've got an XJ, and it IS charging so your brushes are good. The XJ requires more operating juice due to the extra electronics, once the engine is over 2500 rpm, it has reached the peak charging rpm, and IF the field coil is energized, will crank out the voltage you've seen ALL THE TIME. The REG dynamically controls how much field coil voltage is sent to it, so it's not a simple on/off scenario.

I think it could be difficult to determine how long to throw the Charge/On switch while riding, as well as remembering to turn it on and off so that you wouldn't boil your battery away, but also not drain it too much so that you couldn't electric start it!? Also, due to the possible surge/shock of the charging system coming ONLINE when running at 2500+ rpm might also not be good. SO...you would need to be able to let it run down close to IDLE speed before switching it ON as well!

All that being said, I don't know why it otherwise wouldn't work, but I'm not an electronics GURU, so I'll let folks like GEEZER, Davinci, CyWelch and others chime in!

T.C.

[va_blue_stang]

Thanks T.C. for the advice.
It will start off the battery when i'ts a cold start, but after it has ran for a while and the motor is hot the starter will not turn fast enough to start the bike it just barely cranks. After it sets and is cooled completely it has power to start again.

[va_blue_stang]

I think my battery may be the problem. The meter only goes up to 12v at 4k rpm with the battery hooked up. I can unhook the negative from the battery while it's running and I 14volts at 4k rpm.
Does this sound like a battery or wiring problem?

[cywelchjr]

I think my battery may be the problem. The meter only goes up to 12v at 4k rpm with the battery hooked up. I can unhook the negative from the battery while it's running and I 14volts at 4k rpm.
Does this sound like a battery or wiring problem?

If grounding the green wire makes it go up to 14.5 to 15 volts it's not the battery, it's most likely the regulator although it COULD be connections the grounding making it work makes that less likely as that still leaves many of them in the circuit. As a matter of fact, grounding the green wire and getting full charging voltages is one of the tests that is used to verify that the field coil and stator coils are good and normally verification that the problem is the regulator portion of the charging system, so typically unless you have some pretty dirty connections in that green wires connections between where you are grounding it and the regulator you have just confirmed that you need to replace the regulator.

BTW, working when cold and not when hot is common, the engine unless things are REALLY cold in which case the battery's ability to provide cranking power is compromised, the engine actually takes more power to crank when hot then when cold because the compression is higher on a hot engine than on a cold engine, and this is a greater factor than the difference in friction from the cold vs hot oil.

[cywelchjr]

I think my battery may be the problem. The meter only goes up to 12v at 4k rpm with the battery hooked up. I can unhook the negative from the battery while it's running and I 14volts at 4k rpm.
Does this sound like a battery or wiring problem?

Oh, another thing, with design of these charging systems you should NEVER disconnect the battery with the engine running, you take a chance of damaging the regulator if it's not already damaged. But the regulator if working properly should always be able to pull the voltage up to at least 14 volts if grounding the green wire will do so.

[va_blue_stang]

Thanks for all the help, guess I need to figure out a work around for a few weeks till I can get a regulator. Not fun always looking for hills to park on so I can drift start the old beast.