Stella - 1977D survivor, back on the road.

Oh, I agree that it's worth the effort and expense. As I said, I've been thinking of adding it. It would alert the rider to the most common charge-related issues, such as worn brushes and failed rotors.

I like the idea of the alternator light and numerical battery voltage used together. Rather simple and inexpensive, yet powerful tools.
 
DanielBlack said:
Now, with the lights circuit inline, cruising voltage was a consistent 13.7/13.8v. Not too bad.

Here's a concern: sitting at idle with my lights on, voltage dropped to 12.0/12.1v (12.5-12.7 w/o lights). As I took off, voltage would jump up to about 12.7v, then slowly raise to 13.8v. Not good for riding in city traffic. I'm going to guess this is a symptom of a tired battery?
Click to expand...

Yes, it is. I'd want to see the charging current draw on that battery.

Here's a budget test. Quickly, after a ride test, pull the battery and see if it feels hot...
 
The cruising voltage of 13.7/13.8 is a little low. The 12.0 at idle is also low.
These bikes do not charge the battery at the 1200 rpm idle, and there is no need to do so. You charge the battery as you drive down the highway.
On my bike I always see 14.2 volts as I drive down the road. At 1200 rpm I see about 13.0 volts.
A couple things that I did, and you can also do, is switch to a 40 Watt halogen headlight and an LED tail/brake light.
The change from a 55 watt to a 40 watt headlight, is a reduction of about 1.1 amp.
The change from a #1157 tail/brake bulb to an LED is a reduction of about 0.5 amp.
Total reduction of about 1.6 amp, which makes quite a difference.
I suspect if I went back to 55 watt headlight and a #1157 bulb, my voltage at cruise might be down to the 13.8 volts area.

The problem with only reaching 13.8 volts at cruise, is that the battery will never be fully charged. The battery needs to reach 14.1 volts in order to fully charge. Anytime I hear of lads having to use a battery tender during rising season, I know that their charging system is never attaining 14.1 volts.
 
My 2 cents worth. I did about 30 miles yesterday and monitored the voltmeter. My voltmeter senses the red wire from the battery at the ignition, is powered from the ignition brown wire and has a dedicated earth wire back to the battery.

With engine off and ignition on the meter reads 12.1V and I believe, or I want to believe, that this is the result of the filiment tails lights combined with the Boyer initial 10Amp draw and the rotor current. The battery is new - but perhaps there is an issue?? Must test for heat as per RG's comment above.

When Idling at 1200rpm the meter reads 12.3V but this rises to 14.1V between 1200rpm and 1800rpm - I think I will increase idle a further 200rpm. It may be that my rev counter is showing high??

I run a 35W head light to reduced battery load. While riding with lights on (1500rpm and above) I see the meter at 14.1V with very occasional flicker between 14.0V and 14.2V. If I pull up and stop the idle brings the voltage down to approximately 12.3-12.5V.

Edit after 2hour ride observing voltmeter (April 10th):
  • When engine cold and idling at approximately 900rpm the voltage is 12.1V.
  • When the engine warms up and idles at 1200rpm the voltage is approximately 13V.
  • Increasing the idle to 1400rpm increases the voltage between 13.6V and 14V i.e. unstable.
  • Idle at 1500rpm voltage stable at 14.1V.
  • During the entire 2hours when revs were above 1500rpm the voltmeter sat at 14.1V and very occasionally flickered to 14.2V.
  • Battery not heating up.
  • 3hours after the ride the battery showed 12.7V as measured at its terminals.
  • Starter motor turns over no problem.
  • Clutch much improved but still a little bit tight when sellecting neutral when stationary in 1st Gear - but smooth enough to live with.


Perhaps we all have something to learn about the condition of our batteries and charging systems???


Note: The purpose of my ride was actually to get the engine heated uniformly so I could adjust the clutch at the handle bars for ease of selecting neutral. The result was good and leaves ZERO free play when the engine had cooled overnight which is a finding others have reported on this forum. We know that within the first couples of minutes after startup free play will return due to expansion.
 
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Thank you for that data, it's a helpful comparison.

My bike is running a 60/55w headlight, and LED everywhere else. Including tail, dash, and the always-on stalks. All told, a conservative estimate of 7-8amps with the ignition thrown in. That's no more than 100w. IIRC, a stock alternator should be good for 150w.

The Rectifier-of-the-Week has passed the lofty benchmark of 75 total miles, ~50 w/lights.

The general trends of 14.2/1v initial voltage, slow to rise to 13.8v w/lights cruising, and 12.0v idle continue.

A tender has not been used since the 3-4 week sit three weeks ago. The starter continues to work easily and without sounding like it's strangled. The battery reads 12.6/7v when I turn the key in the morning. Using the starter pulls it down to 10.5 or 11v.

The very scientific test prescribed by 2M came back 'not really warm at all'. But I'm still researching good battery shops here in town.

Coming back from the show, I was just about home and couldn't turn in. I continued up Grand Ave. for another 15 miles. Stella and I have had a long 6 weeks, but today was a day for riding and she thankfully agreed.
 
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Daniel, Re: a battery for your bike.
I got mine from AzBatteryStore.com sealed maintenance free battery #WP14L-2, $68.11 delivered free to my door.
Super convenient and so far so good.
 
DanielBlack said:
...The very scientific test prescribed by 2M came back 'not really warm at all'. But I'm still researching good battery shops here in town...
Click to expand...

Well, that's actually a good sign. Battery may be OK. Only way to know for sure is a bench charge rate test. But, I'd lean away from suspecting the battery now.

As it stands now, it's starting and charging, lighting works. Without voltage monitoring, the typical owner would consider everything as A-OK.

If you wish to pursue further, may look into the current and voltage delivery to the rotor...
 
These alternators are good for 14.3 amps/200 watts at 4000 rpm. The 7 to 8 amps you use is not straining the alternator at all.
Your regulator is what is controlling the voltage you see. Its reaching a set point, and then it reduces the rotor current. You have a healthy battery. The true test is when you can continue to easily start the engine, with the starter motor, and never have to use a battery tender during riding season, which I guess is year round, down your way. You seem to have reached that point, but may need a few more months to prove all is well. If you don't have an on board volt meter, you should install one.
 
Here are some more electrical numbers from my bike:
Rotor brushes at 1200 rpm = 10 to 11 volts .................rotor current at 1200 rpm = 1.9 to 2.1 amps
Rotor brushes at 3000 rpm = 5.5 to 7 volts ..................rotor current at 3000 rpm = 1.0 amps
 
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Yes, RG's rotor brush voltages, use those as a guide.

Running above 2500 rpm, while the battery voltage is a bit low:

Voltage across the rotor brushes:

If low, suspect regulator or its voltage sense line.

If high (as it should be), suspect rotor, possibly high resistance.
 
Without lights: currents are a little low, voltages are in range.

1200rpm 11.3v 1.2A
2000rpm 12.7v 1-2A, erratic
3000rpm 6.6v .8A

With the headlight on.

1200rpm 10.9v 1.1A
2000rpm 11.5v 1.2A
2500rpm 12.7v 1-2A, erratic
3000rpm 8-10v, amperage all over
 
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Daniel, if those are the voltages across the brushes, they look okay, for a fully charged battery.

If your battery voltage was still low during those measurements, then the regulator is being fooled (or fooling itself) into thinking that the battery voltage is topped-out...
 
The amps are low.
Basic ohm's law.................. @ 1200 rpm, R = E/I or R = 11/2
= 5.5 ohms for my rotor and brushes
your bike @1200 rpm, R = E/I or R = 10.9/1.1
= 9.9 ohms for your rotor and brushes
assuming your rotor is around 5.5 ohms, where does the extra 4.4 ohms come from? Are your brushes 0.400" or longer?
Are the slip rings clean bright copper? Make sure the very small wire to each brush is still in good condition, not frayed.
 
So, the plot thickens, lol. Could that higher ohm reading from Daniel's brushes have contributed to all those rectifier failures?

This is a test I've never done but would like to. Anyone care to explain it more in depth? Is it as simple as touching the meter + to a brush screw and - to ground for volts? Or do you measure from brush to brush? And amps? Same meter connections but different scale on the meter? And I'm assuming the numbers you get, pumped through that formula, should reflect your rotor's ohm measurement if measured on it's own?
 
Hey, 5T. Any intermittent current/voltage fluctuations at the rotor/brushes will not induce enuff stator output stress to affect the rectifier.

To do this "brush current" test correctly would require 2 meters.

1 meter measures the voltage across the brushes, the (+) probe to the positive brush, (-) probe to the negative brush.

The second meter is the ammeter, measures the current thru the brushes. Could be done by disconnecting the positive brush's lead/lug, will need to put the screw back in there to hold-down the brush, and connect the ammeter to that brush and it's disconnected lead/lug. Could also do this at the regulator connector, remove the male/female positive connectors from the connector block halves, and connect the ammeter to those 2 connectors.

Connected like this, then you simply divide the observed "across brushes" voltage by the observed current, which will give you the combined resistance of the brush/slipring contacts and the rotor.

It's also really helpful to have a 3rd meter measuring the battery voltage, and note all 3 meter readings simultaneously.

Edit: The catch is, I'm not sure if Daniel measured the brush current, or the battery's charging current, a totally different thing...
 
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