Topic: Nighthawk 550: Lights get brighter when shifting

[Laminar]

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The video should explain what I'm talking about - when I push the shifter either way, my headlight and running lights get brighter.

Also, my battery is not receiving a charge when the engine is idling or revved up, I can get about 40 miles before the bike dies.

I've installed a new wiring harness and hit every connection with WD-40. Suggestions?

[TwoTired]

Given the light dims when you rev it up, And having no battery voltage vs RPM data.

I'll take a guess the the slip rings might be dirty, and/or the the slip ring brushes in the alternator aren't doing what they should.

Cheers,

[Laminar]

And having no battery voltage vs RPM data.

Battery voltage stays constant no matter the RPM.

[TwoTired]

And having no battery voltage vs RPM data.

Battery voltage stays constant no matter the RPM.

Constant at what level?

However, the lighting output changes do seem to contradict your statement.

Cheers,

[Laminar]

My freshly charged battery reads just a hair over 12V all of the time (except for when I'm trying to get to my girlfriend's place but I get stuck at so many stoplights that the battery drains and the bike dies...). I don't know the exact figure because I'm using an analog multimeter on the 50V setting, but I do know that it doesn't move. I believe the light looks like it's getting dimmer when I rev because I'm slightly moving the handlebars and my camera is adjusting itself. In person, I can't see any change in the light output.

[TwoTired]

A fully charged battery should read 12.6-12.8V  after being fully charged and allowed to "rest" for two hours.
You won't be able to tell battery charge percent very easily with an analog meter, unless it is the expanded scale type.
Even so, the charging system should try to keep the battery at about 13.8 V  (14.5V max) when the engine is revved up.
Given the data you've provided, the bikes charging system isn't working (or working properly).

Below from Wiki: http://en.wikipedia.org/wiki/Lead-acid_battery

These are general voltage ranges for six-cell lead-acid batteries:

    * Open-circuit (quiescent) at full charge: 12.6 V to 12.8 V (2.10-2.13V per cell)
    * Open-circuit at full discharge: 11.8 V to 12.0 V
    * Loaded at full discharge: 10.5 V.
    * Continuous-preservation (float) charging: 13.4 V for gelled electrolyte; 13.5 V for AGM (absorbed glass mat) and 13.8 V for flooded cells

   1. All voltages are at 20 °C, and must be adjusted -0.022V/°C for temperature changes.
   2. Float voltage recommendations vary, according to the manufacturer's recommendation.
   3. Precise (±0.05 V) float voltage is critical to longevity; too low (sulfation) is almost as bad as too high (corrosion and electrolyte loss)

    * Typical (daily) charging: 14.2 V to 14.5 V (depending on manufacturer's recommendation)
    * Equalization charging (for flooded lead acids): 15 V for no more than 2 hours. Battery temperature must be monitored.
    * Gassing threshold: 14.4 V
    * After full charge the terminal voltage will drop quickly to 13.2 V and then slowly to 12.6 V.

[Laminar]

The Clymer manual tells me to check the voltage difference between the black wire on the harness side of the regulator/rectifier plug and ground, and that it should be 14-15V. It was the same as battery voltage, so it looks like it's probably a bad R/R.

[TwoTired]

I don't have access to a an 83 CB550 nighthawk wire diagram.  But, if the wires follow standard Honda color code conventions, the black wires are switched battery power.   So, it would make perfect sense that the black wires read the same as battery voltage.

I don't think your test proves the R/R is bad.  Doesn't prove it is good either.  You simply verified that the R/R is getting power from the battery.  The R/R uses that power in two ways; one to determine what the battery charge level is.  And two, it takes that power from the Black wire and delivers it to the alternator so that it can make power.  This is how it regulates, by adjusting how much of the battery voltage goes to the alternator.  If the battery is low it sends full power to the alternator, and the alternator makes full generation at whatever RPM it is spinning.  If the battery is full, it diminishes the voltage delivered to the alternator and the alternator reduces its output.

What does your clymer say the alternator rotor resistance should be?  What does the resistance measure at the disconnected wires going from alternator field (rotor) to the R/R?

Cheers,

[Laminar]

I don't have access to a an 83 CB550 nighthawk wire diagram.  But, if the wires follow standard Honda color code conventions, the black wires are switched battery power.   So, it would make perfect sense that the black wires read the same as battery voltage.

I don't think your test proves the R/R is bad.  Doesn't prove it is good either.  You simply verified that the R/R is getting power from the battery.  The R/R uses that power in two ways; one to determine what the battery charge level is.  And two, it takes that power from the Black wire and delivers it to the alternator so that it can make power.  This is how it regulates, by adjusting how much of the battery voltage goes to the alternator.  If the battery is low it sends full power to the alternator, and the alternator makes full generation at whatever RPM it is spinning.  If the battery is full, it diminishes the voltage delivered to the alternator and the alternator reduces its output.

What does your clymer say the alternator rotor resistance should be?  What does the resistance measure at the disconnected wires going from alternator field (rotor) to the R/R?

Cheers,

The manual says that the only way to test the rotor is to replace it with a known good one. I also found a couple errors in the wiring diagram in the back of the manual, so I don't trust what it says completely.

[TwoTired]

The manual says that the only way to test the rotor is to replace it with a known good one. I also found a couple errors in the wiring diagram in the back of the manual, so I don't trust what it says completely.

Probably wise to not trust the Clymer.  I would obtain a Honda shop manual if I had that bike to repair.

I would guess that the rotor should be somewhere between 5 and 7 ohms.  I'm not sure your analog meter is capable of accurately measuring that.  You can get a digital multimeter for $10, $20, or $30 that will measure voltage more accurately, and be able to measure the resistance.

I'd still go in and clean the slip rings and check the brushes for full, low resistance contact.

Cheers,

[Laminar]

My analog meter is still left over from when I had my car torn apart, needed a multimeter, and the local small-town hardware store was the only place within biking distance. I do have a full-featured fluke at work I'll have to bring home tomorrow.

The Clymer's manual came with the bike.

[TwoTired]

Pretty cheap to have one of your own...

http://www.harborfreight.com/cpi/ctaf/Displayitem.taf?itemnumber=90899

[Laminar]

Man, you're quite the night owl...although I guess you're two hours behind me.

[Laminar]

Okay, I took another look at it yesterday since I managed to fix the fuel leak.

There are five wires that go from the alternator to the regulator/rectifier - black, white, and three yellow. The voltage differences between the white and yellow wires and ground were small to negligible, and the difference between the black wire and ground was equal to battery voltage - about 10.6 volts at the time, and it stayed constant at that level at idle, 2000, and 5000 rpm.

I looks to me like the alternator isn't putting out any voltage, so I'll need to fix/replace it. Could the RR be affecting the voltage going into it? Can I unplug the alternator from the RR to test it again just to make sure?

[TwoTired]

Back in reply #1, I suggested the slip rings need to be checked examined.

The alternator is in two electrical parts;  1- the stator, which provides the output power when in the presence of a rotating magnetic field.
2 - The field coil (in your case the rotor) which creates the rotating magnetic field

The field coil is an electromagnet, which takes some power from the battery, in order to energize the field coil.

Since the field coil rotates, you can't connect wires directly to it since they will twist off at about 10 RPM.  So, instead the are two round copper rings and brushes to make contact with them as the rotor rotates.

If these rings are dirty or the brushes failed, the rotor gets no power and the alternator can't make power output.

The brushes receive power via wires from the voltage regulator.  If those connections are faulty, the rotor gets no power and the alternator can't make power output.

The R/R get power from the battery and distributes enough of the that power to the rotor, to keep the battery charged.  The less charged the battery is, the more voltage it gives to the rotor.  If the battery is at a full charge of 14.5V, then the R/R reduces the voltage to the rotor and the alternator reduces it's power output so the battery won't be be damaged by over charge.

That's the way the system is supposed to work.  But, I don't have a diagram of your bike to tell you which wires to probe.

However, being a wearing component, it is common that the brushes wear out and fail to make proper contact with the rotor slip rings.  And, that is why I initially suggested to check them.

Yes, it is possible for the R/R to fail, and thereby deny voltage to the rotor.  If you are dead set on replacing it, you could try to see if that fixes it.

It is also possible that your rotor has its wires shorted, and provided it does have good slip ring to brushes contact, cause more overcurrents to be drawn through the regulator, destroying its function.  If this has occurred and you simply install a new R/R, it will likely fry the new one very soon ofter installation.

Were it my bike, I'd check the rotor coil resistance from the wires disconnected from the R/R.  If I could measure 5-7 Ohms, I would then check to see what voltage the rotor was getting from the R/R, and proceed based on the info gained from that investigation.  If I didn't get 5-7 ohms, I would check the slip rings first and then measure the rotor resistance at the slip rings.  If the rotor resistance is below, say, 4.5 ohms, I would get a replacement rotor, then check for correct R/R output.  If found faulty, then I would replace the R/R.  If none of these component were found to be faulty, I would check the R/R diodes for correct function, and measure the stator resistance.

Cheers,

[Laminar]

I tested the resistance across each of the three yellow wires coming from the alternator, and got 8-9 ohms in all cases.

edit: I meant to say 0.8-0.9 ohms.

[TwoTired]

If that reading is accurate (I have my doubts) the stator is bad.  Most stators have very large gauge wires, and resistance readings of 0.035 ohms (about).  It is difficult to measure such low resistances without special equipment and meticulous test technique.


Good luck!

[ken736cc]

These bikes charged poorly in low RPM situations. Honda made a later style "high output " stator that was given to riders under a product update . The quick test was to measure AC voltage between all combinations of yellow wires. If it could not produce at least 60 volts, it was bad. This applies to the 650 Nighthawk also.

[Laminar]

More testing - the black and white wires coming from the alternator are showing about 1V less than voltage across the battery, with no change due to RPMs.

I set the fluke to test AC volts, and measured the difference between each of the three yellow wires coming from the alternator. I'm not sure on the exact values, but I remember the reading to be something like 0.7V to 2V, depending on RPM - the voltage difference definitely increased with RPMs.

Resistance between each of the three yellow wires was 0.7-0.9 ohms.

Seeing that there's at least some change in voltage with respect to RPM, should I go for a new rectifier/regulator and see what that does?

[TwoTired]

I give up.

[Laminar]

I give up.

Oops, just caught your last reply on the last page.

[Laminar]

I just replaced the stator with one believed to be good only to have no change in charging capabilities of the bike. Boo.

[Laminar]

I give up.

Aaaaaand it was a bad RR. It's all working now that I wasted a ton of money and time on a new stator.