Charging system fault?

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Oldbloke
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Charging system fault?

Postby Oldbloke » Sun Jan 15, 2017 3:37 pm

Hi

When I first bought my F650 I read that reg/recs could give trouble due to being sited under thhe seat of early models (mine is a '94) so re-sited it to the back of the seat in the air flow and added an LED voltmeter to monitor what is happening with my charging system. That was about 6 months ago and all has been well until recently.

My voltmeter usually reads 13.9 volts whilst riding at 2000 rpm or more and about 14.5 volts at tickover. About a week ago it started reading 12.9 volts above 2000 rpm then fluctuated between 12.9 and 13.8 volts not dependent on whether the lights were on or not. It sat at 14 - 14.1 volts at tickover.

Suspecting the battery, whose age I have no idea of, I replaced it with a Motobatt AGM battery and today went out for a first spin with this in place. Same readings as recently.

I have three questions for the electrical wizards amongst you;

1) Does this sound like the reg/rec is giving up the ghost? I thought if they did that they went up dramatically in charge rate.
2) I have to check continuity at the alternator wires according to my manual. If you'll pardon the expression where do I stick my multileter probes to do this?
3) Ditto above for resistance at the altenator.

Many thanks to those of you who bothered to listen at school and know this stuff, but I was always a dreamer and obviously missed this lesson in physics.

Ian

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Galactic Greyhound
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Re: Charging system fault?

Postby Galactic Greyhound » Sun Jan 15, 2017 7:57 pm

Hi Ian,

Normally you would generally expect to see the following voltages with a voltmeter directly across the battery terminals:

Ignition Off: 12.0 - 13.0 volts.
At idle (below 2000 rpm): 12.0 - 13.5 volts.
Above 2000 rpm: 14.0 - 14.5 volts.

These voltages are general expectations.

The voltages may vary depending on the condition of the Battery and whether high load circuits (headlights, heated grips) are switched on.

A reading of 12.9 volts above 2000 rpm is suspicious especially if it shows variation from 12.9 to 13.8 volts no matter if the headlights are on or off.

The 12.9 voltage above 2000 rpm is low and appears indicative of a fault either due to a faulty component or to corrosion in a connector.

Before getting too involved, disconnect the Rectifier (4-way) and Alternator (3-way) connectors and inspect the male and female pins for corrosion.
Spray both halves of the connectors with Contact Cleaner (Halfords) and connect/reconnect a few times to abrade the pins.
You might then also apply a LIGHT application of Vaseline to the FEMALE half connectors to help protect against water ingress and corrosion before finally reconnecting.
Vaseline can be cleaned off with petrol if doing future maintenance on the connectors.

Next thing to check are the two Brown earth wires going from the Battery negative (earth) terminal to the Rectifier connector half.
Check that these are sound where they are connected onto the Battery Negative terminal - disconnect them for inspection if you have not already done this. They should be cleaned to bright metal along with the battery negative terminal.

Next, check the Main Earth connection from the Battery Negative terminal to the bike's engine/frame is sound. Again, you might disconnect this for inspection, cleaning to bright metal and applying a THIN smear of Vaseline before reconnecting.
Note that ALL the mating surfaces for this connection MUST be cleaned to bright metal so include the engine casing/frame connection in the cleaning.

The Alternator has three Yellow wires - one for each of the three phases (windings). One end of each of the windings are all connected together (the common centre point) and the other end of each winding is brought out to the connector on three Yellow wires.
Think of the Alternator windings being like a 'Y' - each of the three arms of the 'Y' have one end connected together at the common centre point.

To test the Alternator windings, you need to disconnect the 3-way connector and measure the resistance of each Yellow wire in turn to the common centre point connection. This will give you the resistance of each winding. Set your multimeter to the RESISTANCE Range around say 100 Ohms. Touch the meter leads together first to verify that the meter reads 0 Ohms.

Alternatively, if you can't get to the common centre point, you might measure between one Yellow wire to each of the other Yellow wires in turn. This will give you the resistance from one winding through another winding (think of the 'Y') so you should measure twice the actual resistance of each single winding.
The important thing in this case is NOT the actual resistance measured but that the resistance is the SAME for each of the two measurements taken.

If you still have problems after checking out as above, then suspect first the Rectifier and see if a replacement cures the problem.
Last edited by Galactic Greyhound on Sun Jan 15, 2017 8:10 pm, edited 1 time in total.
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" - It works!

Oldbloke
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Re: Charging system fault?

Postby Oldbloke » Sun Jan 15, 2017 8:09 pm

Hi

Many thanks Ced. I have a day off work on Tuesday so will follow your plan and report back.

Ian

Oldbloke
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Re: Charging system fault?

Postby Oldbloke » Tue Jan 17, 2017 4:52 pm

Hi

I followed your comprehensive steps and have ordered a new reg/rec from Motorworks as everything else appeared to be fine. Actually for a 22 year old bike with 67000 miles on it I would say it's in good condition. The wiring is ok, the alternator checked out fine and all will hopefully be fine when I replace the regulator.

Thanks once again for your help.

Ian

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Galactic Greyhound
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Re: Charging system fault?

Postby Galactic Greyhound » Tue Jan 17, 2017 5:19 pm

Hi Ian,

At least you have eliminated earthing/connector corrosion being the cause.

Let's see what happens with the new reg/rectifier then.

I wondered if moving the reg/rectifier might have caused overheating and subsequent failure but you posted that it was in the air flow.

Increased vibration might be another cause of failure.
Ced.

R1100RT 1996.
Sent by Boson Quantum Transmission from the Starship 'Galahad'.
http://www.researchgate.net/publication ... ing_bosons" - It works!

Oldbloke
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Re: Charging system fault?

Postby Oldbloke » Wed Jan 18, 2017 9:26 am

Hi Ced

Thanks for the thoughts.

Your last point has a lot of validity as I already realised that how I attached the reg/rec to its new location meant it was solidly mounted. I'm looking at alternative places or a rubber mounting for the new one.

Ian


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