Rectifier or Stator Fail?

[maxstu]

Yep. All above is correct.
Tomorrow will take vAC readings from isolated new JMP stator.

Will report back tomorrow.

[HaggardRider]

Are you able to provide an external charge whilst running the engine up to temperature? If the symptoms remain the same, would that not suggest something other than the charging circuit?

I'm surprised how quickly your batteries became unable to restart the engine so would at least like to rule out anything else?

[jm2]

*IF* it is soley the stator output falling as it gets warm; then consider the other 'half' of the equation.
Inspect the flywheel - are all the magnets in place.

I am not convinced that measuring the (unloaded) output voltage of the stator coils is terribly useful (given that there is some output and its about the same each phase).  Is this the correct stator for a cbf1000 (suppliers error).

[Art]

My most recent experience is this - On a 900 mile sortie of The South West and South Wales in October 2022, 500 miles in I made a 45 minute fuel, comfort break and nose bag stop at Barnstaple and experienced a slow crank, no start issue. No problem, no dramas, I grabbed a pair of jump leads from the forecourt shop and a very nice elderly gent allowed me a jump start off his Astra and I'm off.

134 miles later I make a fuel stop in Cardiff and I'm in and out on the button.
155 miles later another 45 minute fuel, comfort break and nose bag stop in Reading, again it starts on the button.
Another 92 miles on the clock I stopped for a comfort break and experience the second slow crank, no start of the day.
Forward planning, I'd parked up at the top of a gentle slope which was enough of a run down for a bump start which got me the final 28 miles home.

At home the multimeter read 11.2v at the battery which I then put on the Optimate4 for 12 hours. In the morning I'm getting good numbers everywhere I test:

12.8v battery's level of charge (after surface discharge) and holding;
12.3v with ignition on;
13.2v with engine running at 1,200 RPM;
14.1v with engine running at 4,000 RPM;

All appeared good, after a few more slow cranks I got around tuit with some more testing:

RR to battery loom/ground voltage drops of 0.05v positive and 0.09v negative;
0.1Ω resistance between all three of the stator output cables;
"OL" continuity between the stator output and chassis ground;

Still couldn't find a root cause until I eventually tested the stator outputs at 4,000 RPM, I can't remember if I disconnected the stator or simply back probed the connector, but there it was, the only clue to a failing stator: 35vAC A-B; 8vAC A-C; 40vAC B-C.

New stator ordered, fitted and tested at 45vAC on all three phases at 4,000 RPM and it's been on the button for the past 4,000 miles since, apart from a crank no start issue this weekend that required some 25 or more five second bursts of full throttle/no throttle for the engine to fire up, which I take as good sign the charging system is now keeping the battery fully charged. Make of that what you will and whether a stator output of 45vAC is any better or worse than 40vAC I do not know, it's simple a reference point for any future testing.

[maxstu]

Interesting reading from the above posts. My many thanks to all contributors...

Okay. More testing today shows up my limited abilities for understanding how a motorcycle wiring circuit works. As Art mentioned, if l don't give the correct info; how could l possibly expect a helpful reply.

Working from battery back to stator has given me false readings. So l turned it around.

And, here is the skinny. Finally, l have made some headway with this charging issue.

New JMP stator is fine, and acting as it should. R/R is good, too.

Stator isolated puts out excellent vAC. Stator and RR connected puts out perfect voltage at 14.7v too. However, plug in the RR to the red/green connector and it gets some kind of electrical heat impedance (?)

Forget about cold and hot readings. This is simply about timing and from where l took MM readings.

For instance. I start bike from stone cold. Perfect reading throughout charging system.  On idle 14 vAC to 41vAC at  4000rpm from new JMP stator. 14.7v at RR. 14.5 at battery. Great.

As bike warms there is an electrical blockage after the RR.  So voltage starts to slide downwards. Disconnect red/green lead and RR voltage is spot on. Connect red/green lead and voltage goes from 14.7v to 12.4v and dwindles as RR start to heat up.

However fitting temp leads direct from RR output to battery terminals doesn't correct charging voltage?

I need to find RR green earth terminal ground point. Any pointers?

Sorry for misleading you kind and helpful fellow biffers.  But by plugging in stator and RR after a few minutes, while testing (to prevent battery going flat), led me down a rocky and false path.

Kindest regards,
Stuart

[Art]

The RR chassis ground is under the petrol tank on the right hand side of frame. However, between the RR and chassis ground there are two splits within the loom:

1) To the rear lights cluster and options connector

2) To the fuel pump, radiator fan, diagnostic link, side stand switch, horn, lean Angle sensor, headlamp & front lights and turn signals

Is there anything anything connected to the Options connector? The options connector is a 6 pin yellow connector taped up behind the wiring loom under the right rear cowling.

Is there anything connected to the Data Link Connector? The DLC is a 4 pin red connector hidden in a white sheaf under the riders seat behind the ABS modulator.

Is the radiator fan running when you get low voltage readings?

How are the heated grips powered and are they switched off?

What work if any has been done since the charging system was OK to it failing?

[maxstu]

Finally got there, with my thanks to Art and other contributors.

The regulator rectifier earth wire connection, found under right side of fuel tank, attached to frame, was causing electrical impedance (?). 

Setting my multimeter on the continuity setting, l touched one probe on the RR bike side connector socket and the other on the terminal ring bolted against frame. It recorded high numbers and no beep. The drawback of living near the coast and winter riding, l guess. 

Once cleaned, the voltage stabilised at battery.  Still not as good as expected. But now sits comfortably within healthy battery recharging area.

12.4v at idle. 13.4v at 2500rpm. 14.1v at 4000rpm. And just 0.20v difference between RR and battery voltage.

However, the left headlamp takes a whopping 0.5-7v out of the system. Tested by removing fuse. Then removing bulb.  Same draw.

All earth points, terminals and electricals cleaned and smeared with dielectric grease.


Many thanks
Stuart

[dlgtruck]

Hello,
I just had a stator go @ 30k miles.  Out riding and stopped for a minute then battery appeared dead on re-start.  Got a boost but soon had the ABS lamp flashing and lights were yellow.  Kept the revs up and got home to test the battery which was 2 years old and fine.  Tested the stator using test methods and it was flaking with the readings.  Put in a new stator with a new reg sitting in reserve and all is good again. The burnt coils were the deciding factor to replace it even if it seemed to pass 95% of the testing.

[Art]

 

Feel free to introduce yourself here

If you had studied the ABS lamp flashes you would have seen a repeating sequence of six long flash followed by one short flashes which translates to TC61 'power supply low voltage'. Have a read here on How to read the ABS codes and reset the stored codes

Testing the charging system should be done with the engine at normal operating temperature, false charging system output readings can be had from a cold engine. The last stator I replaced gave good readings when cold and poor readings when hot, removing the stator cover revealed all 18 windings were burning out.