WOW! CHECK this OUT for VOLTAGE

The reason for regulators to be set around 14.5 volts is so that a lead-acid battery will receive a constant charge and not be overcharged. Since you do not have a battery, you don't have to worry about that.

The lights are made to run around that voltage since that is what the regulator has to put out for a battery. Lights are rugged and will run on a wide range of voltage. If you haven't already blown them out then you are probably fine.

Ignitions run off of current. Voltage doesn't matter unless the ignition has a fixed duty cycle and resistance. I assume the Boyer has a current regulator and variable duty cycle so an extra volt shouldn't phase it.

I'd say the 15.4 volts is not the cause of your troubles but it may be an indication of the true cause. Have you tried hooking up a battery again to see if that cures the running issues?

I suspect the regulator is oscillating which could explain the high speed miss and erratic voltage at lower speed. A digital volt meter won't tell you much about how the regulator is working when you don't have a big old lead-acid battery to smooth everything out. In that case, you really need to check it with an oscilloscope.
 
Thanks mrriggs, that's very useful indeed.

I was wandering why 15v would have an effect when none of my 10 amp fuses have blown, so there is no excess current. The element I am concerned about is the Boyer ignition, and you touched on that, too - ah! I don't know if the Boyer has a fixed duty cycle and resistance (but wouldn't that mean it could not respond to the curve in the ignition cycle?). If it has a fixed resistance I am guessing that would have an affect on performance (but, there is no excess current, so that can't be it, can it?). I don't know if Boyer has a current regulator and variable duty cycle, but I will do my best to find out (again, the first current regulator is the fuse, isn't it? or do you mean something else?).

I will get another battery. It looks like the excess voltage killed a cell in the last one, so I am a bit apprehensive about risking a new one - I will get the old one back from the shop, charge it, and there will be enough in there to test the running.

I thought I might struggle to use the multimeter without the battery - again, I will test the regulator with the battery hooked-up.

You say you suspect the regulator is oscillating which could explain the high speed miss and erratic voltage at lower speed - does this mean the regulator is past its best and should be replaced? The unit itself is bolted to the engine mount/frame which will give it some vibration.

ANLAF
 
ANLAF said:
I was wandering why 15v would have an effect when none of my 10 amp fuses have blown, so there is no excess current. ... (but, there is no excess current, so that can't be it, can it?). ... (again, the first current regulator is the fuse, isn't it? or do you mean something else?).
Click to expand...

Voltage and current are related, but two different things.

A fuse is not a current regulator and it can not protect from over voltage. The purpose of a fuse is to protect the WIRING in the event of a short circuit. If a component can be damaged from too much voltage then it should have voltage protection built-in. Or in the case of cheap parts like light bulbs, they simply burn out. If the increased voltage causes an increase in current beyond what the wiring can handle then the fuse will blow. However, increased voltage will not always increase the current. Even if the current does go up, there is no guarantee it will exceed the fuse value.

I will get another battery. It looks like the excess voltage killed a cell in the last one, so I am a bit apprehensive about risking a new one - I will get the old one back from the shop, charge it, and there will be enough in there to test the running.
Click to expand...

Did you have the excess voltage when running the battery? It sounds like you had only checked voltage when running off the capacitor. If the bike you are working on is the one in your avitar then my first thought is that the battery was killed by vibration. There is a reason why the factory rubber-mounted the battery in a rubber-mounted battery box.

If you are going to test the system with a battery then get a good one. Putting a known bad battery in to test the system could leave you chasing your tail.

You say you suspect the regulator is oscillating which could explain the high speed miss and erratic voltage at lower speed - does this mean the regulator is past its best and should be replaced? The unit itself is bolted to the engine mount/frame which will give it some vibration.

ANLAF
Click to expand...

If you get the same high voltage readings with a good battery hooked up, and you are sure the wiring is solid, then I'd say the regulator is defective.

If it only does it with no battery then you can't really call it defective since it was not designed to run that way. You then would need to figure out how to make it work or find a regulator better suited to running without a battery.
 
Mrrigs

I never recorded excess voltage at any time with the battery - even when it had begun to lose its voltage.

Vibration? yes, plenty of that, so if i do get another battery, then I will take your lead and get as much rubber in there as possible. I didn't know vibration killed batteries.

Thanks for the pointers on fuses, amps and volts.

I am interested, though, that if I get 15 plus volts now beasured on a voltmeter tapped into the circuit beteen ignition and fuses (using the capacitor) why would I not get that same reading with a battery? The regulator rectifier is not doing any different job battery of capacitor - or is it?

ANLAF
 
ANLAF said:
I am interested, though, that if I get 15 plus volts now beasured on a voltmeter tapped into the circuit beteen ignition and fuses (using the capacitor) why would I not get that same reading with a battery? The regulator rectifier is not doing any different job battery of capacitor - or is it?

ANLAF
Click to expand...

If that was a true 15 volts DC then it would not make a difference if there was a battery or not. The problem is that the voltage you are measuring is not a true, flat, DC voltage.

A shunt type regulator (SCR or MOSFET) regulates the voltage by shorting out the stator coils ahead of the rectifier. So the input to the rectifier is either full voltage (over 15 volts) or no voltage. Since it is a three phase system, the cycles overlap which helps average the rectifier output.

Series regulators open the stator coils rather than short them out. Since the stator is a big inductor, opening the circuit causes a huge voltage spike. If left unchecked it would blow through the insulation on the stator wires so the regulator has to step in at some point and shunt the voltage spike. So, in a way, a series regulator is still a shunt regulator. It just shunts a high-volt low-amp signal rather than a high-amp low-volt signal.

With no load and no battery or capacitor the regulator will switch wildly on and off (oscillate) and the output would never settle on a steady voltage.

At low speeds and with high electrical load, the number of ON cycles will be greater than the number of OFF cycles so a capacitor can help fill in the gaps and prevent the regulator from oscillating. It still won't be a smooth DC output but it is good enough.

At high speeds and with low electrical load, the number of OFF cycles can be great enough that the capacitor can't hold enough charge to fill in the gaps. That is when you start having issues.

A battery will take the ragged signal from the alternator and smooth it out much closer to a true DC signal.
 
That's really very interesting, mrrigs, and thanks for taking the trouble to explain.
If the voltmeter reads 15.4v with the capacitor, does that mean the smoothing properties of the battery is likely to make that reading say 14.4v? If so, is the reliability of the capacitor set-up (allowing spikes at various revs, ie the ratio volts to amps changes) dependant, then, on the type or quality of the regulator? The next question is the obvious one - which regulator will owrk best with Hugh's PMA and SPARX capacitor? If the answer is the reg/rec supplied with the PMA (and the rec part is working fine) is it likely that 14v-15.4v is, after all within the acceptable range?

If the answer is that Hughs reg/rec is working fine, then I have to work out why the bike has been running fine since installing PMA and battery and later the capacitor, then nose-dived with cutting out at low revs (greater number of ON cycles), and spluttering at high revs (greater number of OFF cycles).

I understand a little more...

ANLAF
 
Briilliant. I like that, TwoMany. Whay's th i(t)? It looks, perhaps like a representation of the resultant direct current (all ON and no OFF).

Good to see a visual - so one of three phases is going forward, the second in stasis, the third going back to the alternator (micro-seconds, of course).

That's sending heat back to the alternator though, isn't it - and as mrriggs says, the coils absorb most of it.

ANLAF
 
Well, you're getting closer. Your next challenge is to google '3 phase rectification', and observe the rippled DC output. I'd put a link here, but getting too many 'net crashes out here...
 
VERY revealing, pekka. Thanx. It appears that even with a battery in the system, the shunting induces much greater ripple than I'd seen with exciter type alternators. Imagine the waveforms if a capacitor were used instead of a battery. Figures 16 and 17 reveal the little-known relationship of rotor/ignition phasing. The practical implication here is that, for those folks (using PMA and capacitor) experiencing kickstart and/or running ignition issues, simply re-indexing the rotor by 5° (or 1/2 pulse width, depending on number of rotor magnets), may solve those ignition issues. Since rotors are installed at random positions, this could explain the random number of members experiencing ignition issues.

http://www.xs650.com/forum/showthread.php?t=33983&highlight=phasing
http://www.xs650.com/forum/showthread.php?t=33992&highlight=phasing
 
It is very interesting, fellers. The PMA/capacitor relationship is not a precise relationship given the random magnet distribution. In effect, then, advancing the timing 5 degrees (is that the equivalant of re-indexing the rotor?) might resolve the issues - I think I am way off track with that line of thinking.

Anyway, I have my new battery, and later I will see what happens there, i.e. what the voltmeter reads, and what the multimeter reads between battery + and -. Are there any other indicative readings I can make? I haven't got an oscilloscope, mrriggs (I can see how that would be very useful).

ANLAF
 
TwoManyXS1Bs said:
Figures 16 and 17 reveal the little-known relationship of rotor/ignition phasing. The practical implication here is that, for those folks (using PMA and capacitor) experiencing kickstart and/or running ignition issues, simply re-indexing the rotor by 5° (or 1/2 pulse width, depending on number of rotor magnets), may solve those ignition issues. Since rotors are installed at random positions, this could explain the random number of members experiencing ignition issues.
Click to expand...

Figure 16
GPZbattWave1300LiteOnCloseup.jpg


Figure 17
GPZbattWave1300LiteOnCloseup.gif


Check out the scale of that trace. That is showing a single revolution of the crank and each one of those little bumps is a pulse from the alternator. The bumps are only adding 0.053 volts RMS to the 12.9v base voltage (this is an AC scale trace), and the ignition is only pulling it down 0.110 volts.

I don't see where re-indexing the rotor 5° would have any effect.
 
On the topic of regulators/rectifiers (sorry for the slight off-topic):

I built a linear shunt regulator for an XT350 once. I wanted a DC system to power LED's and stuff but sold the bike before actually implementing the LED's.

XT350 is a one phase AC-system so the implementation was rather simple: Lift the stator GND connection, fit a full wave rectifier, a darlington PNP transistor as the shunt element and a zener diode as the voltage reference and a capacitor to smooth out the DC.

As the rectified voltage would rise above the zener threshold (and the transistor Vbe) the transistor would shunt the excess voltage (and convert the excess power to heat). But it would not short the stator just "clip" the voltage to desired level.

This worked just fine as a regulator but heat generation was a bit of a problem (I did not have a proper heat sink). Voltage was nice and steady but I had to keep lights on all the time so the transistor would stay in safe temperatures... :doh:

Similar system should work with our PMA's also. Just would need a good heat sink. Not sure how it effects the stator coils though (short circuited vs. driving a "variable" load)

Pekka
 
mrriggs said:
I don't see where re-indexing the rotor 5° would have any effect.
Click to expand...

On that trace, with a battery in the system, it doesn't. But replace that battery with a cap, and slower kickstart speed, those bumps become RC sawtooth. The draw of a coil in dwell could drain the cap (depending on cap size/type) to voltage levels much lower than the battery supplied drop (pictured above), especially since kickstarting usually begins when the rider senses the start of the compression stroke, when the coil would normally be conducting (or just about to).
 

Attachments

  • rc5.jpg
    rc5.jpg
    32.1 KB · Views: 88
pekka said:
On the topic of regulators/rectifiers (sorry for the slight off-topic):

I built a linear shunt regulator for an XT350 once. I wanted a DC system to power LED's and stuff but sold the bike before actually implementing the LED's.

XT350 is a one phase AC-system so the implementation was rather simple: Lift the stator GND connection, fit a full wave rectifier, a darlington PNP transistor as the shunt element and a zener diode as the voltage reference and a capacitor to smooth out the DC.

As the rectified voltage would rise above the zener threshold (and the transistor Vbe) the transistor would shunt the excess voltage (and convert the excess power to heat). But it would not short the stator just "clip" the voltage to desired level.

This worked just fine as a regulator but heat generation was a bit of a problem (I did not have a proper heat sink). Voltage was nice and steady but I had to keep lights on all the time so the transistor would stay in safe temperatures... :doh:

Similar system should work with our PMA's also. Just would need a good heat sink. Not sure how it effects the stator coils though (short circuited vs. driving a "variable" load)

Pekka
Click to expand...

Any guess what I'm working on. :wink2:

mrriggs said:
I'm actually designing my own regulator/rectifier now. It will be incredibly inefficient and [hopefully] get hotter than hell.
Click to expand...

On a three-phase alternator the output should be rock solid with no need for a battery or capacitor. It should also put less strain on the stator since there will be no current surges from shorted coils.
 

Similar threads

R
'81 XS650 Chopper Problem
Replies
8
Views
1K
650Skull
650Skull
Hardfahrer
Main fuse blowing...Sometimes. Need Advice.
Replies
9
Views
2K
XSAndy
XSAndy
J
xs EFI conversion fuel system issues
2
Replies
20
Views
3K
wrigh06
W
F
A few questions on charging/ignition setup
Replies
6
Views
967
flamesnm
F
M
An Adventure in Firsts: '83 XS650 Heritage Special Build/Rebuild
38 39 40
Replies
785
Views
83K
Jim
Jim
Back
Top