Topic: Too much power

[bil4hire]

 
I am tring to fix a problem with my 82 CB650SC Honda Nighthawk
I lost power last year while riding the bike and the battery went dead and the bike quit.
I recharged the battery and tested the voltage at the battery while running and it was loosing power while it ran.
So I replace the rotor, stator and rectifier/regulator this year to get some new electrical parts on the old bike.
Since then when I test the voltage at the battery I am seeing 17+ volts DC at the battery at 5000RPM's (not right)
Sent the reg/rect. back to Electrex and they tested it and didn't find any problem with it.
Now I cannot think of what I can check next to find where this extra voltage is comming from.
I need a hint on what to check next to fix my overpowering bike system
Thanks,
Bill

[TwoTired]

Are you testing with a fully charged battery?
Where are your probes when you take the measurement?
Do the voltage measurements at the battery differ from what is measured at the regulator?

[bil4hire]

The battery is fully charged and I'm testing right at the battery connections.
I haven't tried to check right at the regulator/rectifier output.
At idle everything looks OK and as soon as I rev the motor at all the volts start climbing.
I've metered the connections on the bike and even tried to bypass the ignition connections by shorting the feedback connection (with the help from the techs at Electrex)
and still the same outcome.

[TwoTired]

The RR makes regulator decisions based on what it thinks the battery voltage is.  If there is a fault in the sense wire between the battery and the RR, it can't make correct decisions.

[Robert]

Just as a thought, one of my digital multimeter (a cheap one) reads only nonsense at hi rpms, I suspect this is because there's not really a perfect DC Voltage produced at hi rpms (regulator switches the exciter coil AKA rotor off an on many times within a second).

Another multimeter (even cheaper, but an analog one) reads 14-15V which is good plus I don't have any problems with the charging system.
So if you're diagnostics: >overpower< is solely based on the measurement, and there are no other symptoms such as primaturely burning out bulbs (would be the case with 17+ V)  etc., it could also be a measurement error and your charging system is well.

[bryanj]

Definately check with another meter, also put a blinker bulb accross the battery and see how "bright" it gets. Another thing is treble check all the ground connections to the frame are good, not corroded and /or painted.

[eldar]

Yeah if you get to 17 volts, after a bit your battery would start to boil and you should have bulbs popping.

[bil4hire]

I haven't let it charge at 17 volts for long, the headlight gets pretty bright when I rev her up a bit.
I borrowed a analog meter and tested with that and it shows 17+ volts when reved up. At idle the battery voltage drains down to normal until I rev the motor a bit again.
The tech at Eletrex had me short the output of the reg/rect (red/gr) to the voltage sensing wire input at the reg/rect (bl) and test it then and the voltage still goes up to 17+volts at 5000rpm's.  Even when I test at the voltage sensing wire into the reg/rect it shows 17+ volts when reved up

[TwoTired]

The tech at Eletrex had me short the output of the reg/rect (red/gr) to the voltage sensing wire input at the reg/rect (bl) and test it then and the voltage still goes up to 17+volts at 5000rpm's.  Even when I test at the voltage sensing wire into the reg/rect it shows 17+ volts when reved up

Okay this is subtle, so read carefully.  You may have done this already.  But, it is not implicit in your post.  The regulator has local terminals for battery voltage sense that includes both Plus and minus terminals.  Compare the voltage sense relative to local ground at the RR, to find out if it is different than what reads directly across the battery terminals.
Alternately, measure for any voltage difference on the sense line to the regulator and for any voltage loss in the ground return between RR and battery minus.  To do the latter, place one lead on the minus terminal of the battery and the other lead on what the RR is using for a local ground return reference.  Ideally, each of these latter two measurements should read 0 V.  There should be no difference in potential between what the RR is seeing at its terminals and the potential read at the battery terminals.
If the RR is not limiting the peak voltage when it sees more than about 14.5v across the terminals it is using to monitor the battery, than either the unit is not functioning, or there is something wrong with the wiring from the RR to the alternator.

Do you know if your alternator uses a field coil or permanent magnet to create the magnetic field in the alternator?  I do not have schematics for your bike.

[bil4hire]

I'll try the tests and do some checking on the wiring and connections,  and the bike alternator uses a field coil to create the magnetic field in the alternator.

[TwoTired]

Okay, then the RR should change the current fed to the field when it thinks the voltage at the battery reaches  about 14.5 volts.  Make sure the wire from the RR to the field is NOT somehow connected to the battery. And, that when the RR senses 14.5 volts at it's output, the voltage to the field should reduce, thereby reducing the alternator output voltage.