Stator voltage

I was trying to check my charging system after reading how to do it here :biggrin. But I'm confused about the stator readings...

With the engine on at 4k RPM, a multimeter should read more than 60V AC between the three yellow cables. All the readings I got were 10.5 AC at iddle and less at higher RPM. I have the cables soldered so I guess that could be the reason?

Voltage at iddle at the battery is between 13.8 and 14.1. Voltage at 4k RPM is 13.5V.

I am checking all this because since two weeks ago I have noticed that the voltage drops (checked on the dash) at any time from 13.6V to 12.2V and then recover again. These drops are not due to the fans since the can happen at 40C or at 90C.

This morning, after a 30min ride, I stopped the bike and when I fired it up again, the clocks reset. The solenoid is a yamaha unit just a couple of months old and all the connexions are tight.

Just 2 questions

1. Do I have to unsolder the yellow cables to check the voltage comming out from the stator?

2. If the readings at the battery are good enough to say that the stator is ok, what can be causing these drops in voltage?

Cheers Kiwi. Will check tomorrow again.

**Update**

After changing the battery the bike was showing the usual 13.5V at iddle before I left home to work this morning. Checking the voltage on the dash at every red light, battery still showing 13.5V. then at 76C the voltage went to 12.2V at iddle for no apparent reason. When the voltage dropped I reved it up and the voltage went momentarely up to 12.8V to fall again to 12.2V at iddle. This is random as the voltage can go up suddenly to the normal 13.5V. This suggests that the charging system is somehow working but the fact that the voltage drop is random makes difficult to check the cause.

Stator readings when I got to work were 62VAC at 4k RPM AND 70VAC+ at 5K RPM. All three fases reading were the same and the cables were not overheated when I checked after 30min ride. Stator reading ok as per manual then but again I cannot know what would be the voltage reading on the dash since you have to disconnect the three yellow cables to do the stator readings. Nightmare!!!

When the voltage goes to 12.2V at the dash, the reading at the battery is just under 13V which as per the manual is not good enough. When reading 13.5V at the dash, voltage at the battery is a helthy 14.03V.

So, I will have to leave the iddling until the voltage drops to 12.2V and very quickly disconnect the three yellow cables and check again the stator voltage.

Any other ideas on how to make sure the stator and reg/rec are good?


I'm riding to Barcelona in two weeks time and this problem is making me a bit nervous...

Kiwi,

Ok, will check resistance between the 3 yellow cables as advised.

Voltage at the battery checked with multimetre

Iddle 14.02V
2500 RPM 13.7V
5000 RPM 13.45V

Battery is good, I only installed it last night after charging it for 12h in an optimate lll.

Thanks!

Thanks Kiwi, I undertand it up to a certain point. I am a bit lost on how to check whether the Reg/rec is good or not. I have been reading the aprilia manual and it gives you a table to check the resistance between the three yellow cables and the cables on the white connector (on the RR). As per this table, all readings should be either ∞, 2-∞ or
3-∞. My questions is ∞=infinite so the multimetre should show it in any particuar reading or it should show it as 0 ?

DAZ5738 said:

This sounds all to familliar with me now....lol lol... What Year is the bike mate? are you having any other problems with the bike besides the clock resetting?? My other friend has just bought a new factory, and his bike runs great as you would exspect but on checking his reading on the clock dash for what voltage it runs it also has dropped into the 12's when running it. Personally i dont think the readings on the bike are greatly accurate...

Click to expand...

It is an 02 bike. I suspect the RR might be faulty although I have to check and confirm it.

Tks

DAZ5738 said:

If you do have a faulty RR try out Timemachines on ebay for a replacement..very good prices and quick delivery mate...Aprila OE is very expensive......Good luck :thumbup

Click to expand...

Cheers :thumbup

**UPDATE**

Find the cause!!! but need some clues on how to sort it out. I was getting crazy coz everytime I took the rear fairing off and check the voltage, everything was fine but the moment I put it all back together, the voltage would go down again. Well, the problem is when I plug the rear lights connector. The lights themselves work well so I can guess is a corroded earth somewhere? I put WD-40 on that plug but no luck. Anyone can tell me where I can locate the earths and the best way to clean them?

I anyone thinks it could be something else apart from a corroded earth, pls say it.

Tks

Sorted!!! Front break switch got stuck and breaks lights were draining the battery. I have soaked it in WD-40 as well as all connectors I could find and cleaned all earth connections and it seems it's working fine but will keep an eye on it as I want other vehicles know when I am breaking and when I am not!! Tks everyone.