Lithium battery?

[TopCatGr58]

Hey Steve,

Geezer's R/R is setup to get more charging effect from the ALT at lower rpms, so I am thinking that he's doing close to what you're suggesting at almost grounding the Green wire, or at least setting the voltage demand threshold much lower so the field coil is energized more at the lower rpms.

As to how long will the field coil last? There's no moving parts, it's already getting HOT from the engine heat, so wondering if you're saying that it would get a lot hotter to cause it to burn up???

Perhaps the newer Mosfet type R/R is stronger/more durable so it can handle the shunting of the xsive voltage better?? Or, just running the field coil at full power all the time is easier than having to actually regulate it.

And I don't totally understand all of the magic of electricity! With the Xsive amount of voltage that would be created but not used/needed, it would go to the Frame/Ground...what happens to it, is it converted into HEAT or what..?

T.C.

[crazy steve]

Geezer's R/R is setup to get more charging effect from the ALT at lower rpms, so I am thinking that he's doing close to what you're suggesting at almost grounding the Green wire, or at least setting the voltage demand threshold much lower so the field coil is energized more at the lower rpms.

Let's break this into pieces.... We're comparing apples and oranges...

How Tony is exactly setting up his regulators I can't say, but I suspect it's as you say; he lowers the 'trigger threshold' to give more output at lower RPMS. But an important point to remember is this doesn't increase output at higher speeds, output is still limited by the regulator according to the 'demand' it sees from the battery. So 'normal' current into the field coil remains the same.

As to how long will the field coil last? There's no moving parts, it's already getting HOT from the engine heat, so wondering if you're saying that it would get a lot hotter to cause it to burn up???

That it would get hotter I have no doubt; but what I can't say for sure is that the increase would be fatal. Current in a circuit always produces heat, it's just that in most cases the wiring is sized to withstand it. But there can be a very thin line between max rated temp and 'oh crap, I let the smoke out' heat. A part that can operate at 250 degrees all day may quickly fail if you add only 20 more. Remember, if you ground the green field coil wire, output can climb to well over 15 volts at higher RPMS.

Perhaps the newer Mosfet type R/R is stronger/more durable so it can handle the shunting of the xsive voltage better?? Or, just running the field coil at full power all the time is easier than having to actually regulate it.

And I don't totally understand all of the magic of electricity! With the Xsive amount of voltage that would be created but not used/needed, it would go to the Frame/Ground...what happens to it, is it converted into HEAT or what..?

This is where we're comparing apples and oranges. These MosFet 'regulators' are designed for permanent-magnet type alternators, which don't have a field coil or a rotor that needs an external voltage source. The magnets take the place of the field coil.

They're not really regulators in the true sense in that they don't control the alternator output. This type alternator can't be 'regulated'; it operates at 100% output all the time. These 'regulators' are actually more of a 'protection circuit', preventing excess/harmful voltage/current from getting to the battery/electrical system. It takes that excess and diverts it to ground, where it is converted to heat.

The XS charging system is regulated; by varying the voltage/current into the field coil, you can change the output. No need to shunt any excess to ground, as there shouldn't be any. I'm not saying one of these 'regulators' wouldn't work with the XS charging system, but you'd be running it at 100% all the time, something it was not designed for....

[oldnortonrider]

I stumbled onto this forum and thread about MosFet R/R type (how they work and how they're different from "other" type R/R's); I think they made it into a sticky http://www.superhawkforum.com/forums...why-how-25117/

Made my day.............

[TopCatGr58]

Hey Steve,

Thanks. I also read the link OldNorton provided. And from my RaceCar Mini Alt experiment/mod, I learned that each leg/phase of the ALT produces about 7 volts, with 3 legs, that's around 21 volts MAX. And so our OEM Field Coil Reg reduces the amount of current/voltage so that the resultant output voltage is kept in the 13.2 to 14.5 range to charge the battery without boiling it.

The Link info statet that the Mosfet type Reg shunts/switches 1 of the 3 legs/phases of the ALT to ground very quickly to control/reduce voltage output to keep it in the nominal range, but that the MOSFET type RR perform this much better, efficiently, with much less heat generated so that they do not burn themselves up internally nearly as quickly as the older style of RR's that SHUNT the ALT circuit.

And since they are designed to do this ALL DAY LONG on modern bikes, then they should function equally as well on our bike. SO..the final question is can the FIELD COIL sustain FULL CURRENT/Voltage level operation at 100% ?

We've heard stories of folks who have had their RR's go bad/short, so that they are doing just that...full current to the field coil all the time, and they usually just boil out their battery, but I haven't heard anyone say they burned up their field coil. And I've seen folks report that their ALT windings burned up, or got damaged, but aside from the accidental contact of the ROTOR to the windings, or the actual ALT white connectors getting melted, I don't recall very many ALT winding failures due to just heat/shorting internally?

SO....I'm thinking that with the proper MOSFET style RR, that the field coil could probably withstand the 100% functioning process...and the RR will shunt the ALT to maintain the required charging current voltage.

Then it would be matter of WHO would want to use their machine for the road test to see how it would work, and how well/long their FIELD coil would stay running. IT's a smaller coil winding than the ALT, and a lot less complicated, so I would think it wouldn't be anywhere near as $$ to have it REWOUND if it did fail/fry/short compared to the ALT windings!!!

If I hadn't already switched my bike over to the Automotive Mini ALT with the 1 wire charging system/built in RR, then I would be willing to try out a modern MOSFET/RR with ALT shunting voltage control vs. Field Coil control!

T.C.

[crazy steve]

SO..the final question is can the FIELD COIL sustain FULL CURRENT/Voltage level operation at 100% ?

Day in and day out? That is the question.....

But one thing that's been missed here is these 'regulators' really don't offer much (if any) improvement over OEM, and certainly not over Tony's unit.

These are touted as an improvement over 'standard' regulators (and are) but we're back to the fact that these are two different type systems. These are shunt-type 'regulators', not the 'true' regulated system the XS has which is closer to an automotive-type system rather than the typical motorcycle system (the XJ with it's brushes/slip rings is the same as an car system). Apples and oranges....

There's one major difference between these two types...

The XS system is designed to deliver the voltage/current that's needed, no more, no less. Even if the regulator fails and voltage goes up, the current load remains about the same (the amp draws of all connected items; the current will only go up slightly due to the higher voltage, about 1 amp per volt). Keep in mind that the current going into the field coil is directly proportional to the connected load. The actual AC output from the alternator is varied by changing the voltage/current going into the field coil. Nothing is 'shunted' to ground.

These MosFet 'regulators' operate entirely different. Here, the alternator isn't regulated; current will be whatever the connected load is, with 'excess' voltage shunted to ground to control it. Here's the crucial difference; this type alternator is current-limited. Because these use permanent magnets rather than a coil, you cannot get any more current out of it than it's rating because there's no way to increase the magnetic strength in the rotor. So you'll have a maximum amount of current available, no matter what the connected load is.

With these shunt regulators, they work by basically applying a controlled dead short to ground across the output (that the 'shunt'). Because of the alternator design, current will be limited to a max value. If using this type regulator with the XS alternator, this may or may not be true. The alternator will attempt to meet the load of a dead short by drawing more current into the field coil, with the limiting factors being the wiring and possibly the design of the XS alternator. But the possibility of exceeding the coil/wiring ampacity is very real. There may be one other possibility; if the shunt circuit is current-limiting (unlikely), that may offer protection to the field coil. So the bottom line is, while the 'regulator' is allowing the alternator output through, all is good. But while the 'shunting' is going on, current load could be well over 100% of the XS alternator rating....

I'll note one other thing about these. This type regulator can get extremely hot; Harley uses this type on their bikes, and they can get hot enough in 'normal' use to burn you (DAMHIKIJK), so mounting one under the tank may not be a good idea. Longevity may suffer too; Harley mounts theirs out in the airflow, they will fail without ventilation....

[T99Ford]

Sorry fellas, been out with work lately...

I didn't know the xs was a regulated field type charging system. I had looked at an xs 650 and assumed it would be the same on the 1100. Not sure I'm able to help much beyond that for the xs as I don't have one any more to do measuring on...

Looks like plenty o good stuff going on here though. Tweety's post on the SH forum is a really good resource.

[TopCatGr58]

Hey again Steve,

Okay, I see, you're trying to "Learn" me about this here electrical magic stuff!

The OEM ALT is rated at ~14.5 volts AND 20 amps(Current?) max output. But with the 3 phases/legs....and ALL providing "current", the regulator can control the voltage and still get the maximum current output when needed.

Are you saying that with the MOSFET reg, having to shunt one of the ALT's phases to cut voltage that there is also a reduction in total current that can be provided so that we might actually LOOSE some of the amp capacity???

That would be a bad thing for sure since the OEM's current output is just barely beyond the systems needs, and loosing some of that capacity would not be worth the fancier R/R!

T.C.

[crazy steve]

I see I'm still not making this clear...

You shouldn't lose current output, but you do run the risk of burning up the system somewhere.

The XS system regulates power into the alternator which then changes it's output. That output is sent to the rectifier, is converted to DC which then supplies power to the bike and battery. Even if the regulator fails in 'full on' mode, the connected amp load doesn't change. You simply get overvoltage which may burn out some lights and boil the battery.

These MosFet regulators don't regulate the alternator at all; they run the full raw output to the rectifier, then 'shunt' (short circuit) the 'excess' to ground to control voltage.

Now, what happens in a short circuit? Heat, sparks, and fire if you leave it connected long enough and have enough current available. How these regulators work is that with a permanent-magnet alternator, there is a limit on how much current is available (inherent to the design) so you simply have to use components that can withstand that amount.

Not the case with the XS alternator. If you allow unlimited voltage/current to the field coil (removing the 'regulator' from the circut), it will attempt to supply current into a short circuit until something fails. You could test this by grounding the green wire to the field coil, then applying additional load until voltage comes back down into the right range. Check your current output at this point, I'll bet it will be more than 20 amps. You may kill the diodes before you get there....

That brings up another point; these MosFet regulators are designed to work with a current-limited system. With the higher possible current available from the XS alternator, you may smoke the 'shunt' diodes in them. At the very least they will run hotter than designed, shortening their life.

[jwhughes3]

Seems to me the stock design is already pretty good.

What were we trying to accomplish here with MOSFET?

I run Geezers rectifier and its pretty good.

John

[T99Ford]

If the stock xs charging system is only rated to 20 amps, I doubt there would be a problem shunting a portion of the current all the time. The VTR system runs close to that as well, and is designed as a fixed rate stator. This might actually work better on the xs, since by design the xs uses most of the charging current at all times, so there would be only a nominal need (if any) to ground. Remember that only the unused current is shunted. From what I remember of the xs, it needs most of its charging capacity all the time...

I'm just not sure how long the windings would hold a full field charge condition on the xs...my experience with bigger charging systems at full field tells me that this would not be a long term solution--unless the xs runs at near full field all the time anyway. Someone should measure that.

If it does, the shunt type regulator would work just fine.

[crazy steve]

What were we trying to accomplish here with MOSFET?

What got this started was the desire to use a Lithium battery, which needs closer voltage control for charging. On a permanent-magnet type alternator, a MosFet 'regulator' is an improvement over a non-MosFet type. But the XS charging system works differently, so this 'fix' will create other problems...

If you could find a permanent-magnet-type rotor to replace the XS rotor/field coil, then this would be a great idea.

But short of that, this is sort of like trying to convert a water-cooled motor to air cooling; you'll get an 'improvement' (less weight/complexity) but the downsides outweigh the 'fix'...

I know I won't be the guinea pig on this one... repairing wiring isn't one of my favorite pastimes....

[clcorbin]

And from my RaceCar Mini Alt experiment/mod, I learned that each leg/phase of the ALT produces about 7 volts, with 3 legs, that's around 21 volts MAX. And so our OEM Field Coil Reg reduces the amount of current/voltage so that the resultant output voltage is kept in the 13.2 to 14.5 range to charge the battery without boiling it.

Not quite. The alternator is NOT a DC device. You are not simply adding three 7V DC sources in series to get 21V DC. Instead, the alternator is generating THREE AC currents that are 120 degrees out of phase. There is no way to add them all up linearly to get a 21V output.

The end result (regulator controlling field current to control system voltage) is the same of course.

[crazy steve]

You are not simply adding three 7V DC sources in series to get 21V DC. Instead, the alternator is generating THREE AC currents that are 120 degrees out of phase. There is no way to add them all up linearly to get a 21V output.

It's even more complicated than that...

Actual AC voltage out of the stator will be considerably higher than 12 volts. First, you have voltage loss through the diodes. Next, the type of DC voltage produced is not equal linearly to actual DC. In other words, putting 12 VAC into a rectifier won't give you 12 VDC out the other side. What the actual voltage will read will depend on a number of factors; single-phase vs three-phase output as well as cycles per second (controlled by engine speed).

Yamaha doesn't give a spec for AC output out of the stator, but Harley does... on their alternator, you're looking for 19-26 volts per 1000 RPM , so you can see some pretty high numbers. And these numbers aren't accurate (simply being 'the number' you need to see) as nearly all meters are calibrated to read AC voltage at 60 cycles, which will only be true at one specific engine RPM. I'll also note that the value you see is 'effective' (or RMS) voltage; peak voltage will 1.4 times greater (so the '120 volts' in your wall outlet actually hits almost 170!).

I would suspect that the XS alternator AC output would be somewhere between 20-30 volts at any engine speed as it has a regulated field coil. HD uses a permanent-magnet type alternator, so it's output is unregulated.

[TopCatGr58]

Okay, I do know that it's AC voltage that's created with the ALTernator, and that most are in 3 phases to help smooth out the pulses to try to get close to a linear type output when it's RECTIFIED into DC.

As to Harley's output, that is quite a lot, but then it only goes to 3-4k rpm. The XS can go to 7+k rpm, so I can see that there's potential for some seriously high voltage and current output when the field coil would be fully energized! That would also be alot of current to SHUNT to ground.

The Mini race alt I have turns on around 800 rpm, it's a permanent magnet design, and shows the amp production increases to it's maximum around 5k rpm. It does have a built in R/R and just 1 wire output to the battery.

Well, I think this has been a good discussion about the quality of our charging system components and it's differentiation with the permanent magnet types of other bikes.

T.C.

[crazy steve]

As to Harley's output, that is quite a lot, but then it only goes to 3-4k rpm..

The rev limiter on my Sportster is set at 6800 RPM....