Yamaha R1 Reg/Rect now fitted to GS750

[fatnfast]

After looking at all the info both here and on other sites where the RR can cause problems, I decided to use the FET RR from a 2009 Yamaha R1 (just like the Compufire) to hopefully prevent future charging issues. The RR was found on ebay for $50. It was still mounted on a plastic 'frame', so this indicated that its chassis is not earthed and there is no need for a heatsink. I also bought the correct connectors from Japan for around $18.

[fatnfast]

The connections are straight forward. Each of the 3 wires from the Stator connect direct to the grey socket. I have ingnored the 'loop' that normally takes a phase around the headlight switch. Its no longer needed!
The postive feed is taken direct from the battery with an inline 30amp fuse fitted. And no, this will not drain your battery when switched off. The negative is connected direct to the battery as well. Use new chunky cable. The old feed on your loom can be tapped up and ignored. Dont be tempted to use it, its old!

[fatnfast]

I fitted the RR on the side of the battery box. Its to big to go underneath and will foul the mudguard. I have a couple of stainless bolts holding it on at the mo. These will be replaced with dome head allen bolts to make sure they dont rub on the battery case.

Once back together, the voltage was a steady 14.5 volts at tickover with the lights off. With the lights on it was 13.5 volts. Once 1500rpm has been exceeded the voltage is controlled at a nice 14.5 volts regardless of light on/off etc.

Not a bad mod for around $70.

[posplayr]

The FHA0012 is still a SHUNT R/R. It is not as likely to burn up because of the efficent MOSFET design and the large current rating. However it's efficency does likely increase the thermal load on the stator a bit (compared to other SHUNT R/R's).

After looking at all the info both here and on other sites where the RR can cause problems, I decided to use the FET RR from a 2009 Yamaha R1 (just like the Compufire) to hopefully prevent future charging issues.

The Compufire and the 600 series Cycle Electic are SERIES control R/R's and the FHA0012 is still a SHUNT R/R. It probably could have been designed a SERIES with just a little firmware change in the controller
but alas it is still SHUNT.


It does give a nice low RPM boost to the charging voltage.

[fatnfast]

Yes, it is still a SHUNT type, but has much more effective control. I doubt it will put any more noticable 'themal load' on the stator.

It is just a more cost effective replacement than the SERIES regulators, and has been used as an upgrade on many other bikes with no problems, just better voltage control (including those that suffer from overheating stators). The poll on here suggests that the Honda upgrade is very effective, and the very few failures could be down to a stator on its last legs anyway. The FHA0012 just offers an 'improved mosfet controlled' device.

What would happen if a series regulator failed? Is it possible that the full, unregulared output of the stator could be 'fed' to the bike?!

[posplayr]

Yes, it is still a SHUNT type, but has much more effective control. I doubt it will put any more noticable 'themal load' on the stator.

It is just a more cost effective replacement than the SERIES regulators, and has been used as an upgrade on many other bikes with no problems, just better voltage control (including those that suffer from overheating stators). The poll on here suggests that the Honda upgrade is very effective, and the very few failures could be down to a stator on its last legs anyway. The FHA0012 just offers an 'improved mosfet controlled' device.

What would happen if a series regulator failed? Is it possible that the full, unregulared output of the stator could be 'fed' to the bike?!

Ironically the SHUNT FET and the SERIES R/R's are very similar topologically. Both use some form of Synchronous Rectification (SR). That is why you see the increase in low RPM output. There is a smaller voltage drop because there is a not a full wave diode bridge. Rectification is accomplished by timing the turn on of a FET or SCR.

The main difference in the SHUNT FET and the SERIES R/R is the SERIES just doesn't turn on the FET/SCR when there is too much voltage. The SHUNT FET shorts to reduce output.

Given the load capacity of about 50 amps of either (compared to about a 14 amp requirement), I would think reliability is pretty close for either except the SHUNT is going to be stressed much more .

BTW, I had a FH0012A start to turn an Electrosport Stator brown in less than 250 miles. That is when I moved to the Compufire.

These SHUNT R/R's operate at the hairy edge so modifications in riding style, or stator design, or connection health can significantly change the outcome of expected life.

[fatnfast]

Hmmm, interesting that your Shunt mosfet turned the stator brown. Do you consider this to be the fault of the FET Shunt RR, or was there other factors? I agree a Shunt RR is, even with FET switching, a crude way to control output, but after a 20 mile run today the RR was barely warm to touch. I guess SCR's account for a large portion of the heat generated in a conventional RR.
I'm going to run a few checks to compare current with both devices on the AC and DC side.
It does make you wonder why a company such as Shindengen go to all the bother of making a FET Shunt RR, when it could have produced a Series unit?
All this has also taught me the importance of using a good meter as well, my old Hilka was showing 15.5 volts across the battery, but a switch to my 'sunday best' Fluke indicated a steady 14.5 volts!

[posplayr]

Hmmm, interesting that your Shunt mosfet turned the stator brown. Do you consider this to be the fault of the FET Shunt RR, or was there other factors? I agree a Shunt RR is, even with FET switching, a crude way to control output, but after a 20 mile run today the RR was barely warm to touch. I guess SCR's account for a large portion of the heat generated in a conventional RR.
I'm going to run a few checks to compare current with both devices on the AC and DC side.
It does make you wonder why a company such as Shindengen go to all the bother of making a FET Shunt RR, when it could have produced a Series unit?
All this has also taught me the importance of using a good meter as well, my old Hilka was showing 15.5 volts across the battery, but a switch to my 'sunday best' Fluke indicated a steady 14.5 volts!

Here is a compare of the FH0012 and the Compufire.

SHUNT_vs_SERIES_RR_Compare_Tutorial