Battery or charging issue?

[Skid Mark]

Gents!,
I went for a spin today on the 1100 unitrac. First good run since sorting the forks and head gasket. All seemed well, until after about 40 miles I was in slow traffic and stalled it. When Itried to start it it couldn’t turn over fully even one turn I check the voltmeter, it read about 11.5v. The light had been on for the entire journey but obviously this shouldn’t matter.
Anyway she went with a bump start and I made it home ( without the headlight being on). When running voltmeter reads about 13.5v but when Iswitch on the headlight, the voltage drops to about 12.5

So, does this sound like a battery issue or a charging issue.

[warren3200gt]

With no lights ideally you want about 14.5 volts. With them on 13.5 volts.
That said both your readings will be charging the battery. If it's a gel battery and at some point it's been almost totally discharged then when put on the charger it'll show as charged and read 12+ volts but won't be able to pump sufficient amps to turn the starter over.
First check all the battery and starter connections are clean and tight. Then try jumping it off a car battery (without the car engine running), if it's spins over OK and starts the issue is with the bike battery.

[Skid Mark]

Hi Warren,
After the spin home while headlight was off the batter is charged and will now start the bike as usual. It had a similar run immediately before I stalled it and when I pressed the starter it was proper flat, not just weak. But it did try turn over and all connections seemed good. It also started the bike after at least a week sitting there, so I don't think its the battery. however, the bike does appear to be charging, all be it at 13.5v. Is it possible it is charging but not giving enough amps to keep up to the head light? If so what could be the issue? Rectifier, Stator windings?
Cheers
Phil

[warren3200gt]

The stator output and test procedure are in the fsm.
Do you have a combined reg/rec or seperate units.
If the stator output passes then it can only raelly be the regulator or connections. Rectifier just converts ac to dc. Regulator limits supply to the battery to stop it boiling dry..

[KeithZ1R]

If you can live with an LED H4 Headlamp bulb, put one in and see what happens cos Ive been chasing that issue round for years on two of my Z1Rs

[Skid Mark]

The stator output and test procedure are in the fsm.
Do you have a combined reg/rec or seperate units.
If the stator output passes then it can only raelly be the regulator or connections. Rectifier just converts ac to dc. Regulator limits supply to the battery to stop it boiling dry..

Thanks Warren, I don’t honestly know whether I have the combined unit or separates, I will check when I get chance, but need to get a run at it. Work is getting in the way of biking!

[Skid Mark]

If you can live with an LED H4 Headlamp bulb, put one in and see what happens cos Ive been chasing that issue round for years on two of my Z1Rs

Comforting to know I’m not alone. I might try that Keith, thanks for the advice.