RD400 overcharging

[D.e.e.]

Hello everyone, I have a 76 Rd400 that was/is overcharging 15.6v and killed the battery. Replaced the battery and voltage regulator/ rectifier from HVC. Now it is charging up to over 19v while revving. Saw a video online that stated if the feed wire has resistance it will cause overcharging even though the regulator is working properly. The handle bar switch is new. Any suggestions on where to start looking for a bad connection? I don't want to call the regulator bad untill I've checked everything else. Sorry for the long post. Thanks
Dane

[Barrie]

1st thing is to check all your earths (grounds) are good , clean and tight.

[D.e.e.]

All grounds are solid and clean. Even ground from engine to frame. Grounds in harness have been redone and soldered. All white wires to stator measure .5ohms between them.

[pidjones]

Might be "infant mortality" of the regulator.  My GL1000 was charging at 17.8 volts, so I installed a real el cheapo ebay rectifier/regulator just to see and it sets right at 14.8 now. I also installed a digital voltmeter permanent to keep an eye on it.

[D.e.e.]

Regulator/ rectifier is new from HVC as of yesterday. That is the one charging ar over 19v. Old one was at 15.8v.

[forexer]

the part from HVC although it's new could be bad from stock - I have had this happen to me several times from Autozone

Also at 19V you may have ruined your battery - I'm not sure however you may want to check the specs and see if its within limits

Good Luck!

[D.e.e.]

Only ran for 5 seconds before shut off. Battery is fine.

[Striker1423]

5 seconds and the voltage shot over 19? there tends to be a bit of a voltage kick when starting bikes, but 5 seconds wont usually be enough to kill anything. What is your resting battery voltage?

If it's sitting pretty at like 12 to 12.5 the battery is good. If its low like, 10 to 11 volts, after charging and letting it sit for around an hour, then your battery is suspect and can cause the regulator to send current right off the hop to try and recover said battery.

[D.e.e.]

Battery is at 12.9v

[1976RD400C]

If the brush with the green wire on it is grounded because of a bad insulator or where the green wire connects to it is somehow touching ground, it will charge full blast. The brush and the green wire from it to the regulator must be isolated and not grounded in any way.

[m in sc]

the only way it will over charge is a bad regulator.  Nothing at the motor side will cause it to over charge, just NOT charge.  the brush wires on an rd just turn the electromagnet on the rotor either ON or OFF. this is dictated by the regulator as the + voltage is routed through there for the rotor. 

[pidjones]

the only way it will over charge is a bad regulator.  Nothing at the motor side will cause it to over charge, just NOT charge.  the brush wires on an rd just turn the electromagnet on the rotor either ON or OFF. this is dictated by the regulator as the + voltage is routed through there for the rotor.

Yep. Infant mortality happens in electronic components. Even better vendors don't (can't in most cases) test components. Shipped untested from the factory in China.