R/R question

[Guest]

Was wondering, why are series R/R's recommended over Mosfet R/R's on here?

[tom203]

A series R/R will limit stator current to the bike's needs at any moment while a shunt mosfet will let stator go flat out and dump excess power to ground. Less stator output will mean less heat in stator.

[Steve]

Yep, what he said.

The original R/Rs used silicon-based SCRs and were a shunt-style unit. MOSFETs were used on some newer bikes from another manufacturer and were, indeed, an upgrade, but were still a shunt-style. The series regulator (regardless of the type of components inside) is a far better upgrade because it reduces the current in the stator to what is actually needed, rather than how much it can produce, then regulate it by dumping the excess.

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[Gorminrider]

....limiting current by increasing overall "serial"resistance in the circuit, like a dimmer switch.

I guess they couldn't do that back then, because trying to control a semiconductor as a series resistance made them very hot.


(....but a "shunt" should work, I always thought, if the stator wiring isn't heating. Also there's the idea of pulsing a shunt in these windings- THAT would build up a bit of resistance as the field in the stator is collapsing but I'm over my head now.)

[silverbullet132]

Ah ok, compufire any good? katman offers them for sale on his page.

[Steve]

Ah ok, compufire any good? katman offers them for sale on his page.

Compufire is good, but expen$ive. I got one from Amazon for my wife's bike, it was about $170. (I think retail is about $210)

You can get one for a Polaris Razr 800 Utility Vehicle for less than $70.

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[Steve]

....limiting current by increasing overall "serial"resistance in the circuit, like a dimmer switch.

The series R/R does not increase any resistance, it merely shuts off the current. It is called "series" because it is installed in "series", not in "parallel".

(....but a "shunt" should work, I always thought, if the stator wiring isn't heating. Also there's the idea of pulsing a shunt in these windings- THAT would build up a bit of resistance as the field in the stator is collapsing but I'm over my head now.)

The "shunt" style pulses the output from the R/R to the bike, but the current in the stator remains rather constant, given a steady operating RPM. That is the problem with the shunt R/R, the ever-increasing current with engine speed. With the higher input voltage (due to faster-spinning magnets), the R/R will spend more of its time in the "shunt" mode, dumping the excess current. Less of what is being produced is getting to the bike, meaning that more of it is getting wasted.

Pulsing the field in the stator windings happens with the series regulators, not the shunt style. I have not yet broken out my o'scope to take some measurements, but I suspect that the pulses are actually working to our advantage. During the "off" time, the magnetic field is building up. When the R/R starts to conduct again, there is that much MORE current available, due to the increased magnetic field.

I could be mis-understanding this myself, but it has been shown several time on this forum that the series R/R works a LOT better than a shunt.

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[posplayr]

The series R/R does not increase any resistance, it merely shuts off the current. It is called "series" because it is installed in "series", not in "parallel".



The "shunt" style pulses the output from the R/R to the bike, but the current in the stator remains rather constant, given a steady operating RPM. That is the problem with the shunt R/R, the ever-increasing current with engine speed. With the higher input voltage (due to faster-spinning magnets), the R/R will spend more of its time in the "shunt" mode, dumping the excess current. Less of what is being produced is getting to the bike, meaning that more of it is getting wasted.

Pulsing the field in the stator windings happens with the series regulators, not the shunt style. I have not yet broken out my o'scope to take some measurements, but I suspect that the pulses are actually working to our advantage. During the "off" time, the magnetic field is building up. When the R/R starts to conduct again, there is that much MORE current available, due to the increased magnetic field.

I could be mis-understanding this myself, but it has been shown several time on this forum that the series R/R works a LOT better than a shunt.

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The SERIES R/R does increase the resistance to stop current ; it raises resistance to infinity. That way current collapses to zero. If it it raised Resistance to only 1.0 ohms with 15 amps flowing ( for a 15 Volt drop) then you would be looking at P=I^2*R=15^2*1=225 watts burned in the R/R alone.

If R=15 ohms and current dropped to 1 amp then power is still 15 watts.

This is just an example it really has to completely open the circuit to be power efficient.

[bwanna]

Can a Series R/R be directly swapped for a Shunt R/R?

I have an old 82 GS450 with stock type R/R.

[Nessism]

Can a Series R/R be directly swapped for a Shunt R/R?

I have an old 82 GS450 with stock type R/R.

Yes, direct swap.

As with all R/R swaps, you need to rewire the charging system to bypass the factory harness. Stator feeds directly into R/R, not into harness with it's convoluted routing that adds resistance into the circuit.

[bwanna]

Thanks! Btw, I was getting low voltages and checked the ground wiring. I ran a 10 gauge wire from the r/r to the battery ground. Walla. Voltage came right up to 14.4 @idle and 14.8 at 5000 rpm.

As the wise people said on here before... check the connections! It works!.

Thanks guys.

Yes, direct swap.

As with all R/R swaps, you need to rewire the charging system to bypass the factory harness. Stator feeds directly into R/R, not into harness with it's convoluted routing that adds resistance into the circuit.

[Gorminrider]

The SERIES R/R does increase the resistance to stop current ; it raises resistance to infinity. That way current collapses to zero. If it it raised Resistance to only 1.0 ohms with 15 amps flowing ( for a 15 Volt drop) then you would be looking at P=I^2*R=15^2*1=225 watts burned in the R/R alone.

If R=15 ohms and current dropped to 1 amp then power is still 15 watts.

This is just an example it really has to completely open the circuit to be power efficient.

then I wonder if they'd be better-named as "switching regulators" instead of "series regulators", which certainly suggests a great big rheostat.

ie: I think sewing machine pedals are the only place I commonly see nichrome windings nowadays....

Someday, I'm going to build a separate rectifier with its big heatsink and build the regulator as a separate unit. Or try a good ol' relay!

[posplayr]

then I wonder if they'd be better-named as "switching regulators" instead of "series regulators", which certainly suggests a great big rheostat.

ie: I think sewing machine pedals are the only place I commonly see nichrome windings nowadays....

Someday, I'm going to build a separate rectifier with its big heatsink and build the regulator as a separate unit. Or try a good ol' relay!

The Series R/R is so efficient as it basically combines the diode bridge with the regulation switching function. With phase voltage sensing you could build a Series R/R out of mechanical switches opening and closing the relays to achieve rectification and as the output voltage rises start leaving some of the phases open.

http://www.ia.omron.com/data_pdf/data_sheet/g2r-_-s_ds_csm42.pdf

The electrical frequency is 1/10 of the RPM so 5K RPM for one hour is 500*60=30,000 cycles so you will wear something like this out in less than an hour of operation.

The key is to switch the phases quickly while the current is zero.

[Gorminrider]

Aha. interesting, posplayer...I don't think I'll rectify with relays!No, it's just a pile of junk I have around...relays and alternator diodes etc. so I'd be trying to regulate after the discrete ol' car bridges.... even so, the ripple is a good point and will be a nuisance.
I'll just have to try a little capacitance in there to slow it down- I don't like buzzing relays! and wouldn't care about a pretty gross ripple on the output....or, maybe try a different tack, trying to get some large transistors to switch- I have trouble getting a full flow at the base of these, even with a darlington upstream- using the zener's so-called breakdown voltage it seems the current at breakdown is not so sharp at the cutoff. What do you think? am I wrong about this?
.... If there was no ripple at supply-eg: a solar panel-I end up trying to build ripple IN to keep the big transistors cooler... that is,if the big transistors are only passing a trickle,and a fan seems needed, I want to throw it all away or go back to the relays again!

[Metalstorm]

Ummm, anyone know what maximum amperage input is to a R/R for a GS1100? Like how many amps can it handle? Would it handle 15A? I need to know for a small wind generator project. Thanks in advance..