Rectifier-Regulators, types & differences SH775 SH847 FH020, Shunt vs. Series

[CapsFanBen]

Thank you for that! But I am definitely lost now. I guess I am still wondering what the advantage of a series regulator is. I am willing to accept that the usual cited advantage of a series regulator may be misguided, but there must be some advantage. One thing I have read is that a series regulator is less susceptible to heat affecting its performance. I see this in terms of the amount of current that can pass through it. My apologies if I am sounding like an idiot here--I got an A in E&M 1st year but that is the extent of my knowledge!

[K447]

- I have read is that a series regulator is less susceptible to heat affecting its performance. I see this in terms of the amount of current that can pass through it. -

Both series and shunt regulators, with either SCR or MOSFET, will have specs regarding maximum environmental/operating temperatures. If the device temperature stays well below that maximum then the device should work properly.

SCR series devices certainly can generate internal heat. That internal heat will be maximum when the battery is able to absorb a large charge current (so the regulator is not restricting current flow from the stator) and the engine RPM is high enough for the stator current output to also be maximum. The SCR devices inside the regulator will 'get hot' while they are flowing lots of current at a high duty cycle.

Whether the SCR series regulator when working hard is able to maintain a 'safe' internal temperature will depend on how warm the outside of the case gets, which in turn depends on the air temp and flow around the regulator.

A series regulator feeding a fully charged battery and minimal other electrical loads will generate less heat (compared to the above) as less current flow from the stator is passed through to the battery, etc.


MOSFET regulators for PM stators seem to all be of the shunt type (correct me if this is not the case). Since the MOSFET devices have lower resistance heat losses the total amount of heat that must be rejected by the device case should be less. Yes, the stator current flow is always high with a shunt type, but the overall heat generated within a MOSFET shunt regulator seems to be less than comparable SCR regulators. When the SCR regulator is working hard.

The stator itself should not (does not) run hotter with a shunt regulator (either SCR or MOSFET).

Since the stator wires and connectors are subject to 100% current flows all the time with a shunt regulator it is imperative that these wires and connections be 100% good. No corrosion, no frayed wires, no poorly done crimp connections, no marginal quality stator connectors.

Connectors and wiring around the stator and regulator really only care about current flow. A shunt regulator will expose problems in these areas. A series regulator (lightly loaded) might not suffer enough to make the same wiring problem visible. But the wiring problem still exists.

[CapsFanBen]

Thanks for all the explanations! I wonder if there is a 50A regulator out there that handles heat the best or at least better than the FH020. While the FH020 might itself run cooler than the SH847, I have heard that the series regulators performance is less effected by being too hot.

[K447]

Thanks for all the explanations! I wonder if there is a 50A regulator out there that handles heat the best or at least better than the FH020. While the FH020 might itself run cooler than the SH847, I have heard that the series regulators performance is less effected by being too hot.

Well, none of the regulators are going to do well if they are 'too hot'. Too hot being defined as above the device's operating specifications.

If you mount any regulator behind the radiator the regulator will absorb heat from the air flow. The minimum temperature of the regulator would be the temperature of the hot air flowing around the regulator.

Whatever internal heating the regulator generates during operation will add to the temperature rise, so the less internal heat generated the less hot the regulator will become. MOSFET regulators seem to generate less internal heat when delivering significant current, so one might expect the total temp rise to be less than with an SCR type.

What are the environmental specs for the regulators you are choosing between? How hot can the air around them be and still be operating 'within spec' ?

Have a look at the Shindengen product info web site, for 'large' motorcycles.

https://www.shindengen.com/products/electro/motorcycle/reg/

I will note that they use the term 'short' when referring to the shunt regulator design.
Three-Phase Short Regulator/Rectifier [these would be SCR type]

Three-Phase Short Regulator/Rectifier (FET) [MOSFET]

Phase Control Regulator/Rectifier
[Phase control means the regulator has more complex internal circuits and can time slice each stator pulse into tightly controlled rapid charging current pulses. Note that phase control is the most sophisticated method but the circuit has an upper limit on the stator coil output AC frequency. Above that max frequency you much use a 'three phase' regulator such as we have been discussing here]


I will point out that for 50 Amp rated Shindengen regulators they are all MOSFET



This Shindengen article outlines the reasons and the added heat efficiency of their Phase Control regulators

https://www.shindengen.com/products/electro/technology/motorcycle_gp/

This graph included with the article is interesting


I think the dot-dash line represents the typical SCR regulator output, the yellow line would be the MOSFET shunt type, and the blue curve is the available output from the newer phase control regulator type. These curves are (I think) the available current/amps output, not the voltage level to the battery.

More current available at lower engine RPM means the regulator can get the charging voltage up to the proper level and hold it there despite the 'low' RPM.

This PDF from VXTOA has some info on the regulator types and how much current each can deliver without air flow (No cooling). I presume these numbers are based on some target maximum case temperature spec and how much internal heating the stated amp output is causing.

Look down the No cooling column. The regulators with the least self-heating will show the most amp output capacity.

https://www.vtxoa.com/attachments/shindengen-rect-reg-pdf.104849/

In that context the FH020 is the 'coolest running' of the regulators.

The FH019 seems even better but it is unclear what the () means
FH019 might be the Phase Control regulator type?

This forum thread lists many of the Shindengen regulator models and some specs

https://2fiftycc.com/index.php?threads/shindengen-regulator-rectifiers.10005/

[CapsFanBen]

Thanks for all the information! You're the man.

[CapsFanBen]

One thing I don't understand for the FH020 in that PDF, is the maximum current says 35A but the cooling figure is 50A. Do you think those are flipped by accident? I wonder also what the maximum means? Does that mean with perfect operating temperature?

[K447]

One thing I don't understand for the FH020 in that PDF, is the maximum current says 35A but the cooling figure is 50A. Do you think those are flipped by accident?

I wonder also what the maximum means? …

Seems possible that the 35 and 50 amp numbers are swapped.

I suspect one of the columns is peak/surge (short duration) amps rating, while the other columns are for sustained amp delivery under the specified conditions.

[CapsFanBen]

Thanks. I find it strange that the (I think?) older FH012 seems to have better no-cooling specs than the FH020 as seen at https://2fiftycc.com/index.php?threa...tifiers.10005/.

I get that the higher no-cooling amp rating translates to performing better with less cooling, but I am hoping to understand what the amp number means. My manual says my alternator has a nominal output of 46.5 amps at 3000rpm. However, I know that what it actually is putting out depends on the load. My bike has a "main" fuse of 30amps, but looking at the circuit diagram it doesn't appear that it is really a main as opposed to just a fuse for the battery and starter.

I am wondering how I can read the actual total current draw of my bike. If I just put a high current multimeter on the battery terminals with the engine running, will that tell me? I guess really I need to put the multimeter on the positive and negative of the regulator wiring? Also, I guess the current draw will vary with the state of charge of the battery?

[K447]

Thanks. I find it strange that the (I think?) older FH012 seems to have better no-cooling specs than the FH020 as seen at https://2fiftycc.com/index.php?threa...tifiers.10005/.

I get that the higher no-cooling amp rating translates to performing better with less cooling, but I am hoping to understand what the amp number means. My manual says my alternator has a nominal output of 46.5 amps at 3000rpm.

However, I know that what it actually is putting out depends on the load. My bike has a "main" fuse of 30amps, but looking at the circuit diagram it doesn't appear that it is really a main as opposed to just a fuse for the battery and starter.

I am wondering how I can read the actual total current draw of my bike. If I just put a high current multimeter on the battery terminals with the engine running, will that tell me?

I guess really I need to put the multimeter on the positive and negative of the regulator wiring?
Also, I guess the current draw will vary with the state of charge of the battery?

There are multiple aspects in your questions.

With a shunt type regulator, the stator coils are always flowing maximum current. The stator current is either flowing towards the 'loads' or the stator current is circulating within the shunt loop, flowing through the stator coils and through the regulator back to the stator coils. Or some mixture of the two current flow modes.

If the battery is in need of heavy charging and the other electrical loads are demanding plenty of power, perhaps 100% of the stator coil current is going out from the + regulator wire, with almost no current being shunted.

With a fully charged battery and minimal current demand from the running engine the majority of the stator output current would be flowing around the shunt loop.

With a shunt regulator the stator is always 'putting out' max current. The regulator just steers where that current goes.

In effect there are two amp 'ratings' for a shunt regulator. How many amps the MOSFET shunt circuit can sustain circulating the shunted current around the stator coils. And how many amps the rectifier section of the regulator can deliver to the DC output. I suppose one might expect those two circuits inside the regulator to be rated similarly but they could be different.


If you want to measure how much 'electrical power' the entire bike is consuming, disconnect the stator from the regulator and measure the amps being drawn from the fully charged and healthy battery as the engine runs. The battery terminal post voltage will be less than when it is being charged (since the battery is supplying all the current for everything, with no help from the regulator) but the amp draw measurement will give you a good idea how much power the bike uses.

If you want to get more accurate you might connect an external battery charger with high ampacity directly to the battery posts, with your amp-meter between the battery post and the main battery cable to the bike. Adjust the charger to hold the battery voltage at whatever 14.x volts your bike regulator normally targets. Now with the engine running (and the stator still unplugged) you are measuring the sustained peak current as the engine revs and you turn on other loads.

That is how much power the bike needs to 'run'.

With the stator and regulator connected normally, the regulator will attempt to deliver the DC current needed to hold the battery voltage at the target (14.2 or 14.8 or whatever output voltage that particular regulator is supposed to do). If the stator is unable to deliver enough current due to low RPM or perhaps high aggregate current demand from the loads, the voltage will sag. If the voltage sags enough the battery will supply current to supplement the regulator's output.

This is what the battery is supposed to do. The battery is there to moderate the ebb and flow of electrical current in the system. When the voltage rises the battery absorbs amps. When the voltage sags the battery contributes amps.

[CapsFanBen]

Thanks.

I see what you are saying about possibly having two ratings--one for regulation and the other for rectifier. What I don't get is if my alternator has a nominal output of 46.5amps at 3k RPM, how does a 30A/35A/50A reg/rec do the job? I note that Shindengen is a Japanese company, so maybe their data presentation in English suffers. Could it be that the 30A/35A rating is the shunting aspect while the 50A is the rectifier aspect? Which operation (shunting versus rectifier), generates more heat?

[K447]

- I see what you are saying about possibly having two ratings--one for regulation and the other for rectifier. What I don't get is if my alternator has a nominal output of 46.5amps at 3k RPM, how does a 30A/35A/50A reg/rec do the job? I note that Shindengen is a Japanese company, so maybe their data presentation in English suffers.

Could it be that the 30A/35A rating is the shunting aspect while the 50A is the rectifier aspect?

Which operation (shunting versus rectifier), generates more heat?

For a MOSFET shunt regulator, I would expect the shunt function to have fairly low heat generation. Depending on the type of rectifier silicon (junction voltage drop) and the amp load flowing from the regulator I would suspect that high 'DC output amps' from the regulator would be the highest mode for regulator self-heating.

Don't overthink the numeric numbers in the 'rating'. The engineering of each regulator would involve a bunch of variables and current flow 'maximums'. Shindengen would be aware of how the regulator would be stressed with whatever 'typical' stator types it could be used with. And they would include headroom for a range of 'worst case' modes.

The 35 amp, 50 amp, or whatever ratings are just numbers painted on the module or shown on a spec sheet. The reality would be that the module is expected to behave across a range of 'out of spec' situations. I cannot say how far beyond the number 'ratings' a given module can function properly and without damage. Maybe 10% more, maybe 50%, perhaps 100% 'extra' ?

One the flip side, does your stator actually deliver that 46.5 amps? Is that spec perhaps optimistic and the actual peak flow is significantly less? How much might that number vary with engine, stator and magnet temperature?

[CapsFanBen]

Thanks. I am trying to figure out if moving my FH020 is a problem. It currently is on the fork, where it gets perfect cooling. However, this has caused the wiring to break (not on mine...yet) from the fork being moved left and right, so, for the later model years, Triumph moved the regulator to behind a plastic housing for the electric radiator fan. This location is between the radiator and engine and between the headers, so it is an awfully hot place. I wonder if one of the reasons the regulator was foolishly placed on the fork to begin with was because the older models did not have a radiator and had non-MOSFET regulators, so they were mounted on the frame--behind the fork--i.e., the designers said to themselves we need to put the regulator in a place with good airflow because that's what we did before.

I am thinking of placing mine behind the left side panel, right next to the air intake. This obviously does not provide very good airflow--although I wonder if the air flow from the intake will be helpful...although it will make the intake air hotter haha. I wonder if the designers might have put it here stock if there were room. As stock, there is a snorkel to reduce intake noise and an EVAP purge valve, but I have removed this regulatory crap. Again--the regulator will obviously get less air flow here, but I am trying to figure out if it's a stupid idea.

[K447]

Thanks. I am trying to figure out if moving my FH020 is a problem. It currently is on the fork, where it gets perfect cooling. However, this has caused the wiring to break (not on mine...yet) from the fork being moved left and right -

- trying to figure out if it's a stupid idea.

You would have the effort to do the relocation, and possibly the future failure of the regulator. I presume the factory wiring harness would at the least have to be re-routed and possibly wires cut, spliced and modified. Modified wiring has its own risk of failure.

If you leave the stock regulator in the factory location out front on the fork, can you just keep an eye on the flexing wires for signs of fatigue and imminent future failure, then fix it before it actually fails?

[CapsFanBen]

I don't take kindly to this practical advice! I've actually already started the rewiring and it's not too bad. I will need to shorten them and re-do the terminals, but I am kind of looking forward to some crimping haha. Also, the stock headlight is plastic and has a cut out for the regulator and I'd like to replace it with a metal one that will look better.

It's kind of a shame that the bike puts out a lot more amps than it needs. This is for accessories that I don't have like heated grips. I wonder if you could solve this problem by creating a constant load to soak up some of those extra amps instead of having to shunt them.

I'm not so concerned with causing the regulator to die early--that's a cheap fix. I am more concerned with putting too much stress on the stator.

[K447]

- the bike puts out a lot more amps than it needs. This is for accessories that I don't have like heated grips. I wonder if you could solve this problem by creating a constant load to soak up some of those extra amps instead of having to shunt them.

- I am more concerned with putting too much stress on the stator.

Well, that is what series regulators are about. Unlike a shunt regulator a series regulator only flows enough current (short term average) through the stator coils to maintain the battery voltage at/near the regulator's set voltage.

A high current capacity stator pushing a few amps into the bike electrical system through a series regulator is not going to generate a lot of regulator heat.

Switching from a (factory?) shunt regulator to a series type, the stator coils do have to tolerate the higher peak voltages induced as the series regulator rapidly pulses 'off' to limit output current flow. The stator magnetic design should limit the peak voltage to some 'spec'ed' level - you just need to verify the stator coils can handle whatever that 'open circuit' coil voltage would be.

With a shunt regulator the stator coils are always flowing max current (for whatever RPM the engine is turning at the moment). The current flow within the stator happens regardless of whether the amps are going towards heated hand grips or just recirculating within the stator through the shunt.