6V to 12V Conversion Article

[Nick]

[ducwiz]

This article describes exactly, what I have done on my own and some friend's wide case singles, as well as on a few narrows. For the w/case it is particulaly easy because the center connection is not tied to ground, but routed outside from the engine via the red wire. It will be just left unconnected for the 12V conversion.

Hans

[DewCatTea-Bob]

____ Thanks for posting the mag.article, Nick ! _ I had-to overlook it when I first noticed it, cuz I then couldn't read it's rather small-print,, however I've since enlarged it (and posted it below).
____ I had HAD hopes that the writer of the article would at-least have some ADVANCED-insight -(compared to the-average) into what's ACTUALLY what with Ducati's alt.system,, but disappointingly (as most-always is the case), he sadly only has pretty-much just the same rather common misconceptions as do most-all others who think they know what-all is what concerning this particular subject-matter.
__ While there are also some-other slighter concerns which I have with the mag.article-writer's chosen-wording, I'm only going to address just the main-concerns which I have with his related conceptions,
as follows.......

The assumption about the Duke 60w alternator being designed for peak efficiency with a 6v load might be a bit rash given the Italians' traditional ignorance of the finer details of electrickery,

____ The level-state of "electrickery" employed by Ducati's '60-watt' charging-system is actually WAY-HIGHER than this mag.article's writer apparently has any conception-of ! ...
The way that Ducati takes advantage of flux-field induction-force both within their alternator, (so as to increase alt.power-output ONLY as the load-system consumes it !), and also within their current-regulation circuits, (so as to effectively keep otherwise excessive alt.power-output 'repelled' until the load-system happens to require it), as well,,
all strikes me as being fairly quite innovatively/ingeniously done, (at-LEAST in comparison to wasteful Brit.bike-type Z.diode-controlled regulation !),
for well-tailoring power-production (at BOTH ends of the charging-system) for the varied-demands of the load-system, in such a non-wasteful/'green' fashion as only Ducati has found to accomplish (without any kind of actual circuit-switching) !
__ Anyone who learns-of & understands exactly how it all works together, will then find their-self awed with a true art-form (in the field of controlling electricity) ! _ It's all indeed quite worthy of fascination & admiration !

Fortunately, the simply-designed Ducati 60w unit is easy to convert to run efficiently as a 12v unit. Just disconnect the two wires from the windings soldered to a tag which is screwed or riveted to 'earth'.
Solder them back together and then insulate/secure them to prevent them making electrical contact with any of the surrounding parts

____ The indicated suggestion of un-soldering the stator-winding lead-ends off-from 'ground', is pretty-good advice ! _ HOWEVER I must much-DISAGREE with the added direction of soldering the two winding lead-ends back-together ! _ Because not-only is there NO resulting*advantageous-reason for making that series-connection, (* as is unfortunately expected by those with mere 'basic' training),, but there IS also two fairly-good reasons to NOT do that !
__ Rather instead of connecting the two stator-winding lead-ends together in series (as directed), they should each be soldered to another third wire-lead (like the w-c.method), or even BETTER-yet, EACH separately to a separate wire of it's very-own. - (So that ANY other method of rectification-setup can then be chosen, EXTERNALLY,, at any future time.)
__ The primary-reason for NOT connecting the two stator-windings in SERIES-fashion, has to do with maximized-efficiency by helping to make-sure that the alternator's generated power is rather 'consumed' by the INTENDED-load, instead of being partially wasted ! ...
Most of those who only have just a 'basic' understanding of electrical-workings, usually don't think to CONSIDER the fact that the alternator-produced power which runs-through the intended load-system, must ALSO run-through the alt.stator-windings themselves as well,, and so therefore the alt.stator-winding itself, ALSO actually contributes it's-own share of (acting)-load (to the 'TOTAL [effective]-load', of the ENTIRE alt.power & load-system), AS WELL !
So when the two stator-windings are circuited-together in 'series', that then (at least !) DOUBLES the working-impedance of the alt.stator ! _ Which in-turn means that a GREATER ratio of the alt.produced power will then become dropped-across the alt.stator ITSELF, (and-thus wasted, as it's directly-converted to EXTRA heat !), THUS-then leaving even LESS power left-over for consumption by the INTENDED-load !
With that rather quite-important issue-point revealed & understood,, then even those with mere basic-training conceptions, will of-course certainly realize that whichever effective-load has the greatest impedance/resistance (within a series-type circuit *), will thusly consume the GREATEST amount of power ! _ And certainly of-course ya much-PREFER for that power-consumption to-be utilized by the 'INTENDED-load' as solely as possible, and NOT any at-all dropped & wasted by the alt.stator itself,,
(* as after-all, the load-system & the alt.stator are indeed actually in a 'series-circuit' together) !!
And when those two stator-windings are connected in 'series', that then works-AGAINST charging-system efficiency, because the stator-winding itself THEN becomes an ENLARGED-part of the entire effective load-system, (thus leaving even-LESS of the total-power to-be consumable by the intended-loads) !
(It is possible however, that this brought-up concern is POSSIBLY not too important, PROVIDING that the actual load-system is very-MINIMAL,, in other-words, if the main-load -[headlight] is off-line, THEN the load-system's resulting higher-resistance & minor power-drop [with resulted REDUCED current flow-rate] will-then leave the alt.stator-winding as a relatively-MINOR load, and thus-THEN not near as much of a concern for absorbing & wasting power. _ [This variable electrical-aspect falls-under the category known as 'impedance-matching', and isn't a common-concept that many with mere basic-training are very well aware-of.] )
__ Now on the other-hand,, keeping the two stator-windings left in PARALLEL-configuration, effectively-cuts the stator's total-resistance to just 1/4th of that of the proposed series-arrangement ! _ Thus keeping the stator-itself MUCH-less of an obstacle to current-flow, so that the produced-power can then be left rather more concentrated mainly-on the INTENDED loads !
AND-also, parallel-arranged stator-windings provide the SAME amount of raw 'power' as when arranged in 'series' fashion, so-thus there's really NO 'voltage' disadvantage (or advantage) once the alt.power is circuited ! - (Please understand that there's NO established 'voltage' BEFORE the raw-alt.power becomes 'circuited' *, [rather-only: 'tension', that's directly-proportional to built-up power], so-thus the end-created 'voltage' remains the very-same, REGARDLESS of whether the stator-windings are arranged in 'parallel' OR 'series' !)
(* A circuit [with whatever it's particular values], is actually what really determines whether the raw-alt.power is formed-into some combination of higher-voltage & lower-current, or lower-voltage & higher-current.)
__ Winding-down this-section no...
There's NO good-reason for preferring the alt.stator-winding power-coils to-be connected-up in 'series',, but-RATHER however, there IS indeed GOOD-reason* for preferring that the alt.power-coils are arranged in 'parallel' configuration ! - (* Cuz whenever the load-system demands HIGH current-power -[think- powerful-headlight activation !],, certainly THEN, ya sure don't want the alt.stator to be a greater resistive-load than the load-system itself !!! _ Cuz if the stator-winding's resistance-load on the alt.power is ANY-greater than that of the actual intended-loads,, then MORE power will be spent by the stator-winding itself, than is actually spent by the DESIRED load ! _ And of-course ya must prefer that most-all available power is rather utilized by just your intended loads !)
__ BOTTOM-LINE... If ya really care to fully power a high-load like a strong/bright headlight, then do-NOT connect-up the two stator-windings in 'SERIES' ! - (As it would-then be fairly quite-STUPID to do so !) _ Because for efficient power-transfer TO-just the load-system, the stator-itself should ALWAYS be kept-from any possibility of becoming more resistive than the intended load can be,, and connecting the two stator-windings in 'series', is a fairly-big step in the WRONG-direction for being sure to maintain that efficiency-requirement !

THE Duke alternator works by taking A.C. from each of the two sets of intertwined 6v windings and stuffing it through two half-wave rectifiers which sit piggyback on the regulator unit, alternately losing half of each winding's full-wave output in the process.

____ Aside-from the "6v",, what's basically meant to-be conveyed, is fairly true,, (however just not worded quite as well as ought-to have been).
I am quite-pleased however, that the article-writer, (like fellow-member DucWiz), realizes that we're dealing-with a dual "half-wave" rectification-system, (and NOT actual 'full-wave', like fellow-member MotoMike has maintained) !
__ Of somewhat particular interest, is that the writer used the word "intertwined", but-yet didn't mention anything about WHY Ducati had chosen to wind the two separate stator-windings together in the very particular-manor that they chose to do. _ So it seems that he, (much like most-all others of those with just a mere basic-understanding of the actual-physics of such workings), must've missed-the-boat on exactly what's-what with the Ducati-alternator. ...
Obviously, Ducati MUST'VE intended for the INEVITABLY-interacting induction-effect* between the two separate stator-windings, to actually PURPOSEFULLY-occur !
(* Which due-to the 'DUAL half-wave rectification-process', HAS-to alternately take-turns, [which F-W.rectification can't accommodate].)

By disconnecting the alternator from earth internally you effectively put both sets of 6v windings in series, hence they become a single set of 12v windings.

____ This faulty-conclusion is a prime-example of the much TOO-common/BASIC-type reasoning, which is-NOT actually correct when applied to the outputs of (stand-alone) alternators !
That straight-forward (but incorrect) basic-reasoning would-possibly be correct however, only IF it possibly-could somehow be possible for such alt.stator-windings (all on their-own, without being connected to a circuit) to actually produce & offer any actual 'VOLTAGE' itself (anything like the way single battery-cells actually-really do *),, BUT the running alternator's stator-windings DO-NOT all on their-own offer any established/pre-created actual-voltage in ANY such set-amount, (since an alternator only provides merely 'tension' & raw-power, [which is little-more than potential-voltage, before becoming connected to a circuit] ) !
(* the power-output of batteries [& transformers] is naturally predisposed to offer actual 'voltage' that's pre-established BEFORE connection to a circuit !)
__ So-therefore there's actually NO 6v + 6v already available (directly-from the two alternator-windings), to-be added-together ! _ That kind of figuring is the simpleton's-way of trying to make simple-sense of what's-what, but it's actually misleading as to what's REALLY going-on !
And that all-TOO common MISconception has long-been a personal-battle for me to get all straightened-out (at-least for those who really-care to learn the actual-TRUTH) ! _ But generally-trained people with but a mere BASIC-understanding, keep-on (wrongly !) applying what they think they understand (about electrical-voltage, etc), towards alternator-power as well,, and it's just NOT correct to assume that alternators ever have & offer ANY preset voltage-amount !
____ Where those with mere basic-training derive their related conclusions from, is apparently based on the fact that TWO 6v.batteries will still only provide just 6-volts total while connected in 'parallel',, but when connected in 'series', they THEN provide 12-volts total.
Likewise (and seemingly more relevant), a center-tapped transformer which has 6-volts established on both sides of the center-tap, then automatically indeed has 12-volts between the opposite-ends of it's entire secondary !
And it's this-same 'basic' factual-reasoning that leads others to jump-to-conclusion and go-ahead & (falsely) apply that-same rather common basic-reasoning to alternator-windings' power-output, as well.
BUT the difference is that THOSE basic-type examples are dealing-with already ESTABLISHED voltage-amounts !! _ So in THEIR cases, there IS indeed ACTUAL 'voltage' (PRE-established), that WILL be able to combine & add-up together !
__ However in the case of alt.stator-winding output,, there's ONLY mere 'raw-power' available, withOUT any established-voltage (that could be manipulated by altering the circuit-arrangement from parallel to series) !
'Raw-power' (that's not-yet had it's 'tension' fashioned-into any set-amount of 'voltage'), adds-up together REGARDLESS of being combined in 'parallel' OR 'series' ! _ And that totaled-up power will produce the very-SAME voltage-amount (once applied to a circuit), EITHER-WAY !

This is a fortunate stroke of luck because if one of the windings was the other way around then they would cancel each other out and you would have a perfectly efficent OV output alternator.

____ The jest-point of that statement of-course WOULD-be pretty-much true, (with the series-connection that HE has suggested). ...
His intended-point being akin-to:
a flashlight with it's two D-cell batteries inserted with their polarities in OPPOSING-directions, would-THEN have 0-volts to power it's light-bulb with,
so he figures it's a "stroke of luck" that the two stator-windings conveniently happen to have their polarities already properly-arranged so that they can both be LEFT connected-together so SIMPLY, (so as to have their current-flows properly-combined in 'series').
__ BUT however, there's actually NO-need to connect the two stator-windings in 'series' anyhow in the first-place, in most-any case,, because there's only mere 'POWER' offered from the stator-windings, (and NO actual/pre-established 'voltage') ! _ And 'power' itself also ADDS-together, REGARDLESS-of whether connected in 'series' OR 'parallel' circuit-fashions !! _ ('Voltage' only adds-up just in 'series', and since an alt.winding alone does-NOT offer any pre-established amount of actual 'voltage', then thus there can-not be any 'voltages' to add-together & double-up !)
__ So therefore, IF the two stator-windings had happened to have been set with the SAME-polarity (instead of opposite), it wouldn't matter to LEAVE them both left in parallel-configuration,, because both together left set that way, would STILL produce the SAME amount of 'power' ! _ And that combined-total power-amount, could still be circuited to create/obtain the '12v', JUST AS WELL (as if arranged in 'series') !

The two wires coming out of the alternator can then be connected to a full-wave bridge rectifier
which will then utilise the previously wasted alternate half-waves of A.C. output.

____ This is pretty-much true, however those originally unused half-wave cycles which can be utilized with the bridge-rectifier were not actually "wasted" before, but rather simply 'ignored' (with the stock dual half-wave rectification-process) !
__ And there's a fairly-good REASON* for why Ducati had-to chose to ignore those opposing current-flow half-cycles (which full-wave rectification would allow) !
(* Due-to the current-flow induced current-flow effect [between the DUAL-windings on each stator-core/finger], the created secondary-current is induced to flow in the same-direction, which happens to-be in the OPPOSITE-direction that the extra*half-cycles [* of the FULL-WAVE rectification-process] would have-to travel ! _ So thus, (depending on the current-demand of the load), there would be a canceling-effect within the stator-windings, (with the full-wave rectification-process) !
However if the connected load-system happens to draw relatively very-little current, THEN the full-wave rectification would perform pretty-much as expected,, with the extra/added neg.half-wave cycles being offered & consumed right-along-with the original pos.half-wave cycles, without much cancelling-effect (due-to the resulted rather weak mutual-induction effect). _ So in such case as THIS, the full-wave rectification, (just as is expected by most-all who choose to switch-to F-W.rectifying), will indeed near double the power-output (of that offered by the mere half-wave rectification),, BUT unfortunately, ONLY during occurrences when the power-demand is rather LOW !
However, whenever the system-load's power-demand happens to be rather high, THEN the resulting higher current-flow BOTH*ways (*due-to the F-W.wave-rectification) through the stator-windings,
thusly then allows the mutual-induction effect to (undesirably!) tend to self-cancel the (want-to-be higher) current-flows through both windings,, (rather than HELP, like the mutual-induction effect is expected to desirably do, with the stock dual HALF-wave rectification-process !).
So it should be understood that (with Ducati's dual-winding alt.stator), switching-over to FULL-wave rectification can possibly allow extra alt.power at lower RPMs for rather SMALLer current-demands from the alternator, BUT at the expense of REDUCED alt.power at higher RPMs whenever high-current demanding loads (like an extra-powerful headlight) are trying to consume larger-amounts of current from the alternator !
So therefore the regular/std.type FULL-wave vs. Ducati's stock dual-type HALF-wave rectification-processes (applied-to the stock alt.stator-winding), can possibly have much-varied advantageous-outcome results, compared to one another. - (Meaning that neither rectification-process is ALWAYS with superior power-output over the other, [quite depending-upon any varied running-conditions] !)

In theory this should double the output to 120w but in practice (and detailed theory), magnetic saturation of the stator's laminations and/or internal resistance of the stator's copper windings prevents this. It's still only 60w

____ IF the Ducati alt.stator was ACTUALLY a standard/ordinary 'center-tapped' affair (as most-everyone jumps to conclusion of), THEN allowing the EXTRA-pair of half-waves (from F-W.rectification) to become consumable, WOULD-then indeed actually in-FACT "double" the charging-system's power-output capability, (in practice, just as in 'theory') !
But in the particular-case of Ducati's rather special 'DUAL' stator-winding arrangement,, the MAIN-reason that 'FULL-wave rectification' does-not actually double the available charging-power (over the mere dual half-wave/stock-type rectification-process), is because the expected-gain is then inadvertently pretty-much more or less canceled-out by the (rather UNintended) additionally-added & rather-OPPOSING mutual-induction effect, (due-to the 'intertwined' to&fro stock winding-circuit then flowing current in BOTH pos and neg directions) ! _ So this is another-reason for why the two stator-windings should-not be connected-up in 'series'. _ (Although if the connected load-system is rather small, [like just a tail-light], THEN it wouldn't matter very-much.)
THIS-reason for not connecting the two stator-windings in 'SERIES',, is because THEN, ALL the current that flows through the entire load-system must also entirely flow-through the thus-created ONE-single stator-winding, which must then CONCENTRATE the mutual-induction effect (which is-NOT desired for full-wave rectification !). _ And-so the ADDED impedance-effect (due-to the strengthened mutual-induction effect) causes that single-winding to become even-more of an acting-load (in the complete system-circuit), and that's a BAD-thing whenever* the load-system's resistance-level drops below the equivalent impedance-level of the stator-winding ! _ (* Such-as when the headlight is turned-on.) _ Cuz THEN more of the generated-power is wasted by the alt.stator-itself, than is consumed by the load-system !!
__ However on the other-hand, with the two stator-windings left connected in 'parallel',, the total-current of the load-system is then split-up (between the two windings), which in-turn thus considerably cuts-down the strength of the (now undesirable*) mutual-induction effect ! _ (* For F-W.rectification.)
So thus-then a much-GREATER ratio (of the generated-power) is left for consumption more-so by the LOAD-SYSTEM (rather than by the stator) !
So since the mutual-induction effect is weaker as less current is passed-through each stator-winding, that fact helps to make-the-case for keeping the two stator-windings in 'parallel' (rather than connecting them in series) !
__ The GIVEN-reasons (presented in the mag.article) for why there's not-really "120w", are just guesswork offered due-to the lack of what all the REAL/pertinent-reasons are.
__ For another-fact, the "60 watts" is merely-JUST a 'rating', and-NOT an absolute amount of wattage that the alternator is always meant to be capable of !
It's fairly likely that the amount of power that could normally be expected from only the half-wave rectified stator-windings just them-SELVES, is probably only about 30 to 45 watts (average), in the first-place, (without the added-help expected from the intended mutual-induction effect**).
____ The ' ** ' note-mark is concerning an induction-effect which Ducati had clearly meant to take advantage-of ! _ And I will happily discuss that effect, if anyone cares to have it explained,, (as I've already done-so before, to a rather light degree,, and I don't wish to go-into that here again, because THIS-post has already gotten TOO-long ! ).


____ I've added a double-pic.diagram post-attachment (below), which displays both the standard n-c.6-pole alt.stator's unique 'DUAL-winding' arrangement-scheme -(top-half), and-also, an altered-depiction showing a physically-similar alt.stator rather-with a truely center-tapped type of stator-winding arrangement-scheme -(bottom-half).
That NON-Ducati stator-scheme (with a red-wire connected at the 'center-tap') is actually-indeed the type of center-tapped stator-winding arrangement which most-everyone (who really doesn't know-better) ASSUMES is what Ducati's stator-arrangement pretty-much amounts-to electrically (if-not also physically). _ And IF Ducati's stator-winding arrangement had indeed been actually wound in that rather normal/straight-forward manor, THEN my somewhat-overwhelming task of trying to keep everyone straight on what's ACTUALLY what, would-then be a less-taxing endeavor,, as those folks' preconceptions would-THEN already be pretty-much more-or-less correct -(concerning their over-use of the term 'center-tap').
__ BUT however,, Ducati's ACTUAL dual stator-winding scheme is-not so electrically straight-forward (as most-others have assumed),, and is instead rather uniquely-wound quite-more complexly, so that it's two separate independent windings can then take advantage of the mutual-induction effect between the two (purposefully !)- 'intertwined' stator-windings ! _ As the upper alt.stator diagram-scheme attempts-to properly represent.


DUCATIly,
DCT.Bob

[DewCatTea-Bob]

____ Since I've pretty-much finally finished-up including ALL the various pertinent points which I had originally wanted to get covered within my response-post to the mag.article,, I figure it's time start another post, not just to 'bring-up' that-point, but mainly because that first thread-post of mine has become too-long to add even-more related follow-up stuff to. _ For instance, I had wanted to include a comparison-graph within THAT-post (so as to help explain some points made in my post) but, it was too complex to get-done in-time for posting back-then, (and even now, the graph I've come-up with [so-far], is-not really well-done !).
__ The graph intends to indicate the relative expected results of half-wave and-also full-wave rectification of both the non-regular stock-Ducati type alt.stator and-also that of a regular/ordinary-type alt.stator (if such existed like that which I had included in my previously-posted double-pic.diagram),, hence the two pairs of colored plot-lines shown in the posted-graph below. _ I'll later/below reveal which colored-lines represent exactly-what,, but anyone who has understood my previous-post's explanations, should already be-able to FIGURE-out on their-own whichever colored-line represents whichever rectification-process on either alternator-type !
__ Also, I've been interested in posting a response to Ducwiz's post as well, (but I first wanted to get my-own response-post [to the mag.article], all fully drawn-out & wrapped-up, before-hand).
...

This article describes exactly, what I have done on my own and some friend's wide case singles, as well as on a few narrows. For the w/case it is particulaly easy because the center connection is not tied to ground, but routed outside from the engine via the red wire. It will be just left unconnected for the 12V conversion.

" This article describes exactly, what I have done on my own and some friend's wide case singles, as well as on a few narrows. "

____ I'm not TOO awfully-much surprised that YOU've also done that (as many others have done, as well), Hans,, since that rather simple-mod works well-enough with a STOCK-like* 12v.load-system (* that consumes no-greater amount of total-wattage).
But since you've previously revealed that not-only do you have fairly extensive knowledge of general-electronics, you've ALSO expressed above-average understanding of Duke-single charging-systems as well. _ So-thus I had had hopes that YOU would be an individual who would more-so standout from the common-crowd, on this 6v-to-12v alternator/charging-system conversion-issue.
Of-course not-to belittle-you (or even the mag.article-writer), as even I-myself once also had presumed that very-same (seemingly logical) reasoning was completely-sound logic, (back before I became more-educated in electromechanics [by 1973 when I finished 3-years at OIT] ).
__ It's fairly understandable that even armed with all the more-advanced related-aspects, (which I've revealed in my previous-post),, that you'd still choose to make that same-kind of simple/uncomplicated-modification that you've admitted-to doing (like most everyone-else), providing of-course that you had realized that the expected load-systems (to be combined-with your resulted charging-systems), would draw relatively very-little current ! _ In which case, there's then relatively very-little induced-impedance consequence involved with such simplistic F-W/series-alt.system-modification.
But otherwise, you should be aware of the SIGNIFICANT-downside of combining such a simplistic-mod with a high-current consuming headlight ! _ Cuz-THEN, you'd then have a very-INEFFICIENT charging-system (for most-all of the reasons I've already pointed-out in my previous-post).
____ So anyhow, for EASIEST conversion from 6v to 12v,, didn't you ever consider SIMPLY swapping the stock 6v.battery & load-components for equivalent 12v.items, so as to then discover that the stock-type dual half-wave rectification-system could provide even-GREATER power-production (than that [popular] F-W/series-arrangement) ?
__ OR, have you not ever considered full-wave rectification of the AC.output-power available between one of the yellow-wires & the RED-wire (of a w-c.stator), so as to then ELIMINATE the combined impedance-effect (of the SERIES-windings' mutual-induction effect), and therefore increase power-transfer efficiency ? - (I overlooked including a 5th.plot-line [within my comparison-graph] for THAT-option, but such should be pretty-much the same as the purple-line, anyway.)

____ I'll add more info concerning the (rather poorly-done) comparison-graph, later.

UPDATE... Sorry I've left this post untouched for the past 9-days, (I had meant to get back to it last week).
____ Here are some details concerning the graph...
__ I wanted to show the difference in possible consumable power from Ducati's unique alt.stator compared to a regular-example that has it's stator wound in a standard-fashion. _ The graph is intended to indicate the power that's consumed by a load which is constantly capable of consuming ALL (but not more) of the power that the alternator can possibly offer-out to such a constantly-increasing load. _ Of-course a normal/regular load-system would-not be able to be so consistently adjusted so smoothly so as to constantly demand exactly the same amount of power that the alternator happens to be capable of offering (as revs increase), but the graph's intention is to plot the maximum consumed-power AS the RPMs increase ALONG-WITH the smoothly-increased power-demand of the ideally-maximized load. _ In this way, we then get a relatively fair comparison for showing the effect of Ducati's specially-wound alt.stator compared to a regular-example (which is without the mutual-induction effect).
__ What I'm dissatisfied about with the posted graph, is that while it does indeed correctly-indicate the RELATIVE-perspective between all the plot-lines, the exact indicated graduated-values (of the plot-lines between the two types of alt.stators) are quite-certainly not actually-precise, (as THOSE exact relationships would have to be determined from 'bench-testing', in order to then be precisely plotted with ACTUAL-values). _ But anyone who understands this stuff that I'm trying to convey, will realize that I DO-indeed have the various plot-lines CORRECTLY-ordered with respect to one-another, (even if-not all correct to the graph-itself) !
I hope to later do a better-job at indicating all the plot-lines after I create a graph-page that's not so limiting and allows me to plot the lines without being so cramped for spacing.
__ Concerning the posted graph,, the purple and the red plot-lines represent the consumed-power from an alternator just-like Ducati's but/except with the stator-windings wound in a regular-std.method/fashion. _ The purple-line represents what would-be expected from dual half-wave rectification of the standardized-alternator's two halves of the center-tapped alt.stator-winding, while the red-line represents what would-be expected from std.full-wave rectification of the ENTIRE (regular, center-tapped) stator-winding,, (and as can be noted in the graph,, the red-line continually indicates TWICE the power of the purple-line, [just as is to be expected from such standard circumstances !] ).
__ The green-line represents the stock dual half-wave rectification process, and the blue-line represents the results of full-wave rectification,,
of a STOCK Ducati-alt.stator.
Of most-obvious interest, is why the blue-line diverts-away downward from the red-line... The reason for that disconcerting-change is consequently due-to the mutual-induction effect (undesirably) causing the alt.stator to develop increased impedance accordingly as revs & load increase. _ As not-only does that effect tend to subdue power-production, it also causes MORE of the produced-power to-be consumed (into heat production) by the alt.stator-ITSELF, (instead of being left-available for the intended-load) ! _ The majority of the DIFFERENCE indicated between the red-line & the blue-line, is the amount of power that's WASTED by the STATOR-windings (with the commonly-employed 'F-W/single-winding' arrangement), due-to the stator's INCREASED-resistance in relation to the intended-load's decreasing-resistance,, THUS leaving LESS power to-be consumed by the intended load-system, as that lost power is instead wasted by the alt.stator-winding (with it's INCREASED-presents in the entire circuit-pathway/loop) !!
Bottom-line with the blue-line's 'down-turn' (as revs increase),, is that the 'mutual-induction effect' (due-to Ducati's particular stator-winding arrangement) causes the combined stator-winding to develop GREATER impedance (against the current flowing through it & the load), thus making the (non-Ducati) full-wave charging-system more & more inefficient as the system-load demands greater power (at higher revs) !
__ Getting-back to the green-line...
Without the DESIRED-effect* of the 'mutual-induction effect' (* with DUAL half-wave rectification of the STOCK/Ducati alt.stator), the green-line would-THEN be plotted no-differently than the purple-line is ! _ And the reason for why the green-line is plotted so-highly as it is, is due-to it representing not-only that which the purple-line does, but ALSO, the extra-added power-generation provided-by the 'mutual-induction effect' with a MAXIMIZED & constantly '[b]matched' varied-load[/b] as well, both combined-together.
That plot-line (which the green-line represents), could possibly be located ANY-where between where it's presented in the graph and where the purple-line is, depending-on the ACTUAL-load's power-demand ! _ (Which is why a strong regulator-circuit is-not much called-for, with the stock Ducati-system !)
A significant-part of the reason for why the green-line can climb so high, is because as the intended-load's resistance declines and-thus more load-current can then flow-through the two stator-windings,, the 'mutual-induction effect' will then actually LOWER the stator's impedance (rather than raising it, as normally occurs as revs climb), and in-fact can seemingly tend-to cause NEGATIVE-impedance -(much-like pulling current through the entire circuit-loop, rather than just-merely getting 'pushed-through' as by the regular [std.alternator] means).
The more current that the load-system consumes & allows to pass back-through the stock dual stator-windings, the stronger then becomes the (desired !) induction-effect that creates the extra-ADDED*power-production into both stator-windings ('mutually') !
However there-IS of-course a certain-limit to the additional-power that can possibly be produced by that mutual-induction effect, as it (at best) can only duplicate merely-just the same-amount that the intended-load consumes !
So-then ya may now be wondering how the green-line's plot could then possibly exceed that of the red-line, (or doubled that of the purple-line),, as it would seem, that at best, both the-green & the-red plot-lines really ought-to be near about the same. _ Well the reason that the green-line's power-plot still exceeds the red-line's, is because, (don't forget), the dual stator-windings offer MUCH-less impedance/resistance, for TWO good-reasons... the just-mentioned negative-impedance effect, PLUS the fact that the two stator-windings are arranged in 'parallel' (rather than 'series') !
That well-REDUCED impedance-advantage allows a much-greater amount of the total-power produced to be spent on the intended-load (rather than partially on the stator-itself) !
And-so that's what's responsible for the max.power-advantage that the dual half-wave rectification-process/green-line has over the common/popular full-wave rectification/single-winding arrangement/blue-line !
__ One of the (rather minor) reasons for why I'm not real-pleased with the posted-graph, is that the indicated relationship between the green & red plot-lines is not an actually MEASURED-one, but rather just a shot-in-the-right-direction -(not an incorrect-guess),
and would likely be somewhat different if actually bench-tested (under the ideal-conditions I had indicated).

____ Almost-done with THIS-post, (but not this thread, yet).


Enlightening-Cheers,
Dct.BOB