Voltage drop

[Guest]

Have an ‘82 GS850 that keeps dropping voltage immediately when I start it up and drops further when it’s reving

Before connecting: 12.5v
At idle:11.99v
2000 rpm: 8.51v
5000 rpm: 7.39v

then when I return to idle it lands near 11.89v

replaced the stator and R/R, same issue but now when I turn on any extra lighting (brakes/directional), the voltage drops to 11.5v and does not return to 11.89v

Battery is new

[Steve]

If you have replaced all the components, your issue is either with the wiringe betweeen them or you may have faulty components.

Even with somewhat marginal systems, your drops are rather large, so I would suspect wiring and/or connectors. I would suggest checking voltages at several places along the wiring path. Do them in a systematic manner, you will be able to see where your drops are. It would help to connect your bike to a car battery with jumper cables. If the battery is still in a car, DO NOT HAVE THE CAR RUNNING WHEN CONNECTED TO THE BIKE. EVER. Not even if you need to "jump start" the bike. NEVER.

Start with the key off, then measure battery voltage. Turn the key ON, measure
- battery
- both sides of MAIN fuse
- both sides of the other fuses

With the engine running at idle, do the same measurements.

With a helper holding the engine speed about 3000 RPM, do the same measurements.

Let us know what you find.

.

[Cohiba24]

Re-checked the connectors on the stator/RR, one was loose so I reconnected them with gel.... that caused the voltage drop to reduced significantly.

replaced the new battery with a better brand one and now charging system works. Quick tests all passed

thanks Steve!

[Nessism]

If you want the charging system to last you should rewire the entire system, and consider installing a SH775 R/R. Failing to rewire the bike can result in major harness damage due to overheated wires.