Electrical/charging Issues

[peterg]

I’m having electrical/charging issues that I need help with. I suspect the issue is with the reg/rec.


Specs:
1980 Special stripped and rebuilt in 2016/17.
Motogadget unit
Xscharge PM
Xscharge reg/rec
Above 2 items were part of a kit from xs650direct/mikes
Boyer ignition installed 2 years ago
Lithium battery new 2 years ago
Mikuni VM34 carbs
Starter solenoid doesn’t work and is corroded. Clicked when Start button pressed but starter motor doesn’t turn. New one on order.

Rode twice this year for 25-30 minutes

Starts well
Generally runs well
Battery shows 13.8 volts on onboard voltmeter before starting
Charges when running above idle to 14 volts
Stator shows same continuity for all three readings

Issues:
Fluctuating voltage between 11 and 13 at idle - headlight dims
Sputters and shows fluctuating voltage between 11 and 13 at speed after 20 minutes riding.
When turned off and back on immediately after running voltage shows 8-10 volts. Instrument lights stay on. After a few minutes rest voltage is back up to 13-14.
No positive readings when checking reg/rec. Not sure I did it correctly. Multimeter is new and works as it should on a single diode.
Continuity between positive and negative on reg/rec.

Attachments:
Wiring diagram.
Reg/rec specs. Note that the battery connects to the starter solenoid and from there to the rest of the bike.

My guesses:
Burned out reg/rec.
Short in circuit due to corroded starter solenoid

Any comments would be appreciated.

Thanks.

https://tcbros.com/products/replacement-voltage-regulator-rectifier-unit-for-xs650-pma-kit

 

[Jan_P]

Can be a nasty heat dependent problem
I believe the solenoid can be bypassed
please measure voltage around there

If the Gr and R are connected at the same post on the Solenoid
It perhaps is possible to take them away from the solenoid post and join them not connected to the Solenoid at all
Taking care not grounding by accident.

I don't have any experience of this setup so please be careful
And read manual for M unit and so.
But I would consider to after the Solenoid bypass -- Reconnect back to stock and
then consider to disconnect the alternator and reg / rec
Please do the read up if a PMA can stand that without overheating
Or someone else chime in

And test ride close to home on battery only . A stock bike would run without any charging at all
Se if problem goes away

Good start Info by the way

 

[JJames]

I don't know much about Lithium batteries but a standard battery can show a good voltage but fail under load. Check out load test or voltage drop test. I believe Lithium batts. discharge differently. Maybee someone else can elaborate.

 

[peterg]

Thanks guys.

This is a new problem that corresponds with the solenoid not working.

I have a new solenoid and rec/reg on the way. I’ll replace the solenoid first and see if that solves the problem.