" learning about these different model alternators can be quite the blur without a concise spec sheet for each one. "
____ For n-c.models, there's only three different types of 4-pole alt.stators. _ Yours is the newest-type referred-to as the '28-watt' model, which Ducati employed on the 160-MonzaJr & 66/67 Scrambler models.
" Not sure I understand what your saying, "only one of your (4-pole) alt.power-coils can now be full-wave rectified (if so desired).
____ I'm sorry about my added contribution to the confusion concerning your particular replacement power-coil.
My quoted wording was with the assumption that you've only ungrounded just the power-coil which was originally intended for the ign.system, (thus converting it from 1-wire, to 2-wire), and left the double-winding power-coil grounded as stock,, thus converting your alt.stator from 3-wire to 4-wire. _ And providing that that lighting/charging power-coil is still grounded, (as indicated in your scheme-drawing), then IT can-not be full-wave rectified.
This is the circumstance which you had left me to assume.
__ On the other-hand, I could've guessed that your replacement power-coil is rather instead actually another ign.power-coil, which you've also converted to 2-wire.
But all things haven't consistently added-up for me to have reached any definite conclusion one way or the other, so we're still getting everything ironed-out now.
" I though if you had both ends of a coil, your AC__ What is your intention to do with the ign.power-coil, now that you've got it ungrounded ?
could be full-wave rectified. "
____ Yes indeed, that's quite correct (if it's kept from making any direct-contact with 'ground') !
So-then I gather that your intention is to convert your ignition-system from the stock energy-transfer/"magneto" type, to a battery-powered type of ign.system ?
__ So while you now certainly have ungrounded your ign.power-coil and converted it to 2-wire for that possible purpose, your other power-coil is (at THIS-point) not so concretely cut-&-dry ! ... Cuz if your-chosen "replacement coil [lighting coil]" is another stock/28w.type lighting/charging-coil, then it's grounded windings will provide current-pathways for partial short-circuits (when attempting full-wave bridge-rectification).
" I was planning to do this with both coils individually then combining the positive voltages after the rectifiers. "
____ I-myself have never tried to do such as that modification with the 28w.type alt.stator, however I have done pretty-much the same with the '40-watt' alt.model. _ And it worked quite well enough with the ign.power-coil powering the ign.system & keeping the battery charged, while the lighting-coil's (full-wave rectified) power-output only became switched-on along-with the main-lights.
That particular 40w.type modification worked just fine with a 6-volt battery,, and at slightly higher RPM running, also worked well enough with a 12v.system.
__ I had always wanted to try replacing the lighting-coil with an additional ign.power-coil, so as to then be more suited for a rather complete 12v.system.
Perhaps this is also your idea as well ?
" I still haven't thought it completely out.. "
____ Since you seem to have a higher than average understanding of what's-what on most all of this related stuff, I'm sure I'll be able to help guide you through most if not all the options which you'll now have the pick from.
" I have a shorai 6V large AH battery, "
____ That could possibly be all you need for system voltage-regulation.
" a DC COIL "
____ ALL ign.sparking-coils work from 'DC' !
Your Duke's stock ign.coil should've been the 'Green-labeled' version.
" an after market headlight maintaining the 25W/25W bulb "
____ Your modified system ought-to handle a 35/30w headlight.
" I will be putting together a schematic soon. "
____ Looking forward to seeing it.
"from the thread you pointed to____ The lighting-winding shares it's coil-core with the bat.charging-winding... so exactly how did you specifically determine that the lighting-winding was "bad" ?
it states the red/white(.7ohms and .3ohms respectively) "
____ I'm thinking that's a mistake, as the entire coil-winding should be between .5 to .8 ohms,, and-thusly with the lighting-winding being about .45, and the charging-winding being about .25 (+/- .1-ohms).
" I measured (.25ohms and .08ohms respectively) "
____ Wow, I'm somewhat surprised that you've got an ohm-meter which is able to read-out below .1-ohms.
__ Anyhow,, while the ".25" is a likely correct reading, the ".08" is most-likely the reading of a developed 'short-circuit' within the measured winding-circuit. _ (And if that's the actual case,, then whenever you unwind & stretch-out that coil-winding, it's ohm-reading should then return to normal.)
" nearly the same values the O.P. of that thread (common failure point?) "
____ That does seem rather odd to me,, as not only am I unaware of any such "common failure point", it seems too coincidental that any two coil-windings would happen to fail near the same winding-point, (unless of-course both examples possibly have obvious rotor-inflicted damage across the same neighboring set of winding-loops, or something the like).
It would be fairly interesting to study both power-coils, to learn exactly what's-what with each of them !
" I purchase a NOS ducati coil, it most likely is an ignition coil"__ From where did you get your replacement power-coil / "[lighting coil]" from ?
____ Okay then, it now seems rather certain that your replacement power-coil must really be another ign.power-coil, instead of being a replacement "lighting coil", (as it's resistance-level is too high for a lighting-coil).
__ So now with it also having a pair of wires (isolated from ground), it too could be full-wave rectified !
" I do not have the #'s here in front of me, but I believe the #'s I purchase corresponded to Italian #'s for ignition coil on the motocross model. "
____ In any case, it doesn't really mater much at all.
" the coil is approximately the same resistance as the ignition coil. "
____ Indeed quite so,, and you can confirm it's an ign.power-coil by the number of loop-turns of it's (rather thinner) winding around the coil-core. _ As I think it should thusly have near 44-loops, (whereas a lighting-coil is closer to just 34).
" My intention was to run two approximately even powered coils to power the entire system. "
____ So long as each power-coil is individually rectified before having their power-outputs connected in parallel, they then don't have to be evenly matched !
But if you ever expect to have them both dumping their combined power into your system while with the lights turned-off, THEN you ought-to have a voltage-regulator installed as well.
" I'm not using stock parts so attempting to "balance the loads" is not something I want to try. "
____ Not sure of exactly what you really mean, but if you're actually referring-to attempting the goal of balancing the available alt.power to the load-system,, then it doesn't really matter whether any parts are stock-items or not ! _ It still pays to not dump excess power into your load-system whenever it doesn't have any use for it !
So you could always run with the lights left turned-on, or-else turn-off the output of one of your power-coils whenever running with the lights turned-off,, or otherwise, (instead of a simple switch), you'll need a regulator-unit (to cope with such unbalanced power to load ratios).
" If my alternator cannot put out enough juice to keep the system happy I will have to turn off the headlight so the excess can then charge the battery back up. "
____ With just a mere 25w.headlight, your concern is considerably way-off. _ However with greater than a 45-watt headlight, THEN your worrisome-thought is a more likely scenario.
" This is all an experiment!"
____ Maybe from YOUR point-of-view, I suppose,, but I've already done the likes of this modification (with a '40-watt' alt.version) decades ago, and it works without any issues on a 6v.system !
However it's now looking pretty-clear that you are going to be trying-out the very same alternator-modification that I always wanted to try-out for a 12v.system, which would indeed make it an "experiment" from MY point-of-view. _ (But still, I expect it too would also be a fairly easy success, as well [as it was for 6v.systems] !)
" (white with blue stripe and white with red stripe for the ignition coil____ What wire-colors were you able to choose for your intended circuit hook-ups ?
for the power coil I used Green with yellow stripe and a grey with white stripe) "
____ I just may possibly happen to see your-own possible thought-logic of matching-up the two white-wires (for possible connection to one bridge-rectifier), and the green & gray wires together (for possible connection to a second bridge-rectifier). _ So I hope you don't disappoint and admit that your chosen color-pairings were simply matched-up rather randomly !
__ It's kind-of too-bad that you couldn't have gotten wire-colors which had more logic of some sort to make better sense out of. _ But if so desired, (to rather be more like stock),, at-least you could still possibly use the yellow-striped wire to power the stock ign.system, and the red-striped wire to power the battery/lighting-circuits,, since BOTH of your power-coils are the same higher-tension type, (thus leaving devotion of the wire-colors open for any rearrangement you may prefer to choose).
__ Hopefully the advantages of the particular wire-type you've chosen, more than makes-up for the disadvantage of the resulting somewhat nonsensical color-designations.
" All future operator/owners will not be able to determine what they have from the factory ducati schematics alone, but the rest of the bike won't match a ducati schematic either! "
____ Fair reasoning, I suppose.
Hopeful-Cheers,
-Bob