Yamaha FZ6 S2 charging issue - battery, rectifier or stator?

[Arfa__]

Got a 2007 FZ6 S2 which broken down a few days ago. Started on button in morning to go to work, started on button leaving work in evening. But half way home (~6 miles), engine management light came on, pulled over, dash died. Wouldn't start, flagged up a error code 46 - 'faulty chargin system'.

Since, I've charged battery and bike started fine, so now I'm trying to diagnose the faulty part(s).

After full charge, battery shows 13.1V. Idling: 12.2V. At 5k, 12.1V.
- According to Haynes, regulated voltage output should be 14.1-14.8V.
Half hour later, battery still started bike. But 3 days later, it was flat - reading 6-7V.
Battery is a good Yuasa, fitted Nov 2018 (so says fill sticker on it).

I checked current leakage, disconneting neg terminal and measuring current between it and battery: zero.
- So I don't believe there's a short or current drain.

I checked regulator, again only getting 12.1V out of it at 5k.
I checked reverse / forward bias on rectifier: all three diodes in each direction check out fine.

I checked stator output.
22V AC at idle, 70V at 5k output.
But resistance across the coils is a bit high: 0.7 ohms.
All three coils are consistent.
- According to Haynes, alternator stator coil resistance should be 0.22-0.34 ohms @ 20C


So now I'm still not totally sure what's knackered.
The battery going flat in space of 3 days implies a duff battery.
Not getting 14+ volts from rectifier indicates something dodgy there.
The high resistance on the stator implies it could be on way out, even if output voltage is high.

Any ideas on narrowing down things more? What parts would you stick your money on?
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Beginner Biker Adventures Blog
Yamaha FZ6 S2 2007

[mentalboy]

The battery is fooked...BUT it sounds like it was the regulator that killed it... AND the stator's probably fubar'd too.
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Make mine a Corona.

[Nobby the Bastard]

No voltage from the rectifier is most likely the stator.

Unplug the stator, start it up and check across each pair of the three wires with you multimeter set to ac and range suitable for 30v.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Arfa__]

[Arfa__]

[Hong Kong Phooey]

[Arfa__]

[Nobby the Bastard]

70 v ac from the stator is incredibly high. I'd expect no more than about 30v.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Arfa__]

OK, I'm getting more and more convinced to just replace all three together, stator, reg and battery and hopefully resolve all charging issues in one go.

Genuine new parts are silly money - £330 for stator, £220 for rectifier!

So, looking at aftermarket stuff on Wemoto, M&P and ebay. Are Touramax or Electrosport brands alright? Any I should avoid?

M&P have Electrosport branded stator and reg for £97 and £67 quid.
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Beginner Biker Adventures Blog
Yamaha FZ6 S2 2007

[Nobby the Bastard]

Ignore me, 70v @5k is fine.
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trevor saxe-coburg-gotha:"Remember this simple rule - scooters are for men who like to feel the breeze on their huge, flapping cunt lips."
Sprint ST 1050

[Arfa__]

[Nobby the Bastard]

[Tankie]

Put the battery on charge , replace the reg/ rectifier, easy
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Always learning, everyday is a school day

[mentalboy]

[Arfa__]

I'm going with you mentalboy, just ordered new stator, reg and battery. Sledge hammer approach, and avoid faffing about and needing to buy parts twice if the stator takes more stuff out.

Thanks everyone.
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Beginner Biker Adventures Blog
Yamaha FZ6 S2 2007

[mentalboy]

[Arfa__]

So, aftermarket regulator and stator turned up today. Batterr on backorder (thanks for not teling me about that M&P...)

Just checked resistance on new stator, it also read 0.8 ohm across each coils. hmm. Then checked resistence of probes touching, read 0.4 ohms - ahh! Damned mulit-meter is reading high.

So, that would imply the stock stator on my bike is reading 0.3 ohm per coil, which is within range. And with 70VAC at 5k revs, output seems acceptable. So, I may leave that on for now, and will try just new reg and battery initially. Just hoping I get new battery soon with all the current lockdown in place...
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Beginner Biker Adventures Blog
Yamaha FZ6 S2 2007

[Polarbear]

That's what I'd do.

New reg/rec and battery, multi meter at the ready, fire it up and check voltages.

Don't quote me but I would have thought you have plenty of time to check the charging circuit without killing anything and hopefully all will be fine.
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Triumph Trophy Launch Edition