Yamaha Cygnus 2008 battery/electrical issue

[gman30000]

Hi all, im try to diagnose a the following issue.

About a month ago, I started my scooter to ride home from work a 20min ride all fine apart v low on fuel.
Practically home my scooter stutter and jerked and seem to lose power for about 5 seconds but did not cut out, I continued to ride home no problems.
Once home I turned the scooter off and tried to start it again out of curiosity, but it wouldn't turn over properly as if the battery was flat. Strange as started it fine 20 odd mins ago.

So charged the battery and next was fine and has been until two days ago.
Used the bike day before no problems, next morning battery flat again!
So I charged it last night and put it on the bike this am and fired up fine.

Okay some info:
the first time it happend and I charged the battery end voltage was 14. something.
This time end charge voltage was only 12.8.

When connected to scooter and the scooter is running the voltage 13.81 ish, but when revving the voltage does no increase.

So I think some power must be going to the battery to increase the voltage from 12.8. to 13.81 when scooter is running?

So whats your thought?

Thanks in advance

[jaffa90]

What`s the battery voltage the morning after when connected to the scooter and when it`s off the scooter over night?
Also you may have a battery drain when not in use, so google how to check for a battery drain check.

[gman30000]

I will check in the morning.

Do you think I need to check stator?

[Easy-X]

Where are you checking the charging voltage? If it's at the battery terminals then don't forget there's a regulator so a consistent voltage over the rev range is not surprising...

Also, how old is the battery? It might not be holding charge as well as it used to.
____________________
Husqvarna Vitpilen 401, Yamaha XSR700, Honda Rebel, Yamaha DT175, Suzuki SV650 (loan) Fazer 600, Keeway Superlight 125, 50cc turd scooter

[gman30000]

About year and half.

Yes I thought same thing about regulator.

[gman30000]

Okay just checked 10mins ago and battery was reading 12.61v