Battery charging issues on 2005 Yamaha Zuma/BWS

[Deleted]

Hi dear members!
I have issues with the battery charging system of my 2005 Yamaha Zuma that I recently acquired in used condition. 
How can I figure out which part is the problem? In what order should I check things and what can I exclude as possible reasons?

Backstory: 
When I first got the scooter (about a month ago) the battery was working alright. Pretty quickly after though it would not be strong enough anymore to start the scooter, so I had to start using the kick starter. This worked fine for a while until I noticed the lights dimming and completely turning off and also the blinkers not working anymore. I assumed the battery was probably old and got a new one.
Worked fine for about two weeks now (I usually drive 2-5 miles distances few times a day and sometimes longer ones) but now the scooter stopped again to start electronically with the switch and I have to use the kick starter again. At the moment the lights and blinkers are still working as soon as the engine is running. 
This time, because the battery was new, I assumed that the issue is with the charging system. So I got a volt meter and measured the DC voltage of the battery and these where the results:

turned off ~ 11V
idle ~ 11V
revving ~ 5-6V

I'm definitely no expert, but after researching a bit I understand that revving the voltage should be at about 14V and idle should be at about 12V (I assume this is lower bc it has not been properly charged). 

From here I tried to make some research about what could be the reason and my next step was to test the voltage output of the stator. Here is where I am am kind of stuck, because the three cables coming from the cable of the stator towards the CDI are not clearly color coded (black, white, and red/yellow striped). In the video I found (https://www.youtube.com/watch?v=AZbg-krvZM4), it was said that the voltage should be around 25-35V with an idle engine, but what I measured on my scooter was about at 12-14V (if I measured right).

Now I am unsure whether this tells me that my stator is not generating enough voltage to charge the battery and I need to change it or whether I should take other steps first? 

Every help is very much appreciated!

[aeroxbud]

I would expect to see 13v on a new battery. This might help though.

[Deleted]

Thank you!
That is the reason why I believe something is wrong with the charging system.
Because the battery is almost new, but now after using it for two weeks it's already loosing power and the voltage while revving the engine is clearly not as high as it should be.

Or could there be another reason that I am unaware of?

[gooddog]

the video you posted from 49cc said the voltage AC should be around 50 or 60 volts AC at higher revs. you didn't mention if you were getting the 50 or 60 volts AC at higher rpms. I do not know which engine is in your zuma but likely minarelli type so go from there. has to be a manual somewhere out there that says what the AC voltage is out of the stator.

make sure that you are checking ac voltage out of the stator not dc. check dc voltage at the battery. after ensuring stator voltage is correct you may want to look at the voltage regulator/rectifier system which is where it switches from ac to dc and keeps the voltage where it needs to be for the battery to charge, somewhere around 13.5 to 15 volts dc or so. good luck on this and keep at it. I will try to find that stator voltage online.

[Deleted]

thank you! I was able to measure the AC voltage that comes out of the stator and I discovered that of the three cables one did not deliver any voltage at all. Because I do not feel confident enough to mess around with the stator I just ordered a replacement.
I used this video as help www.youtube.com/watch?v=l20k6vFoz2Y&list=PL29A15UHDMsy1qwApXO-8NWgUvIUGljlt&index=5
My zuma had the exact same cable connection so I could measure like described in the video.

I also measured the AC voltage that arrives at the regulator rectifier and it was the same as measured leaving the stator.
Then I also measured the DC voltage that is leaving the regulator towards the battery and it was only at 10V.

So to me it seems that the problem is the stator.
Planning to switch it out tomorrow and will update.

[Deleted]

Sorry for the long wait!

I replaced the stator but unfortunately the problem persisted and my battery lost charge.
So I also replaced the recitifier regulator a few weeks later and now the battery finally recharges!!

It must have been the regulator that does not deliver enough voltage to the battery.

Thank you for your help!