USING DIFFERENT RECTIFIERS and DUAL BRIDGE RECTIFIERS

[ANLAF]

Fellers

I am researching rectifiers because mine is turning the AC voltage to 15v DC at around 3000 revs. I understand that the solid state regulator-rectifier has six diodes in there - I am still learning, but is this a bridge rectifier or a dual bridge rectifier?

Secondly, is it the regulator or the rectifier which needs the heat sink?

ANLAF

 

[5twins]

I think what you want is the regulator. The rectifier simply converts the AC to DC. The regulator regulates the output voltage. Yours seems to be making DC fine, just too much of it. It's possible you could clip the wires going to the regulator part of your combo unit and just continue to use the rectifier portion of it. Or, you could go with a separate rectifier and regulator. I know what works for a stock system, haven't a clue what you need for a PMA.

 

[ANLAF]

Thanks 5twins. Yes, the stock unit has the seven wires, but the PMA to compatable reg/rec has 5 - three from the alternator and a positive and negative.

It makes sense now - I have tested the unit but that is the diodes which is the rectifier, now I get it. The regulator control the voltage. It's the regulator part that has failed and I can't do a test for that part except observe the result - 15.4v... Yes, 5twins. Need replacement unit.

Thanks

ANLAF

 

[ANLAF]

I just can't understand why the bike is spluttering as it is - yes, 15v is too high, but no 10amp fuses have blown. Still learning about the properties of electronics, so I can only imagine the electronic ignition does not like the extra voltage. Still no excess current, though. One day I will understand - when I can walk on rice paper.

ANLAF

 

[pekka]

Are you using a battery or capacitor? If not then measuring the reg/rect output with a DMM may give strange results as the voltage is more or less "pulsating".

Pekka

 

[ANLAF]

Pekka, I have wired-in a voltmeter between ignition switch and fuses, and it is that which is showing the readings (and I have interchanged that with a second voltmeter, which shows the same reading).

ANLAF

 

[pekka]

But do you have a battery?

 

[ippytattoo]

When I changed over my PMA for my latest experiment I went with a MOSFET type reg/rec from a 2007 Kaw ZX6R (FH016AA). When I installed it I did test the voltages at idle (14.4v) and about 3K (14.5v) so the voltage was very stable and it seems to be working well. I am running a Ballistic EVO2 4 cell battery in a gutted starter. The battery did not like when the gutted starter got water in it HAHA, it kind of had a catastroophic failure. When the battery sensed a cell failed it completely shut down, but the weird thing was the bike would idle just fine and acted like it was starving for fuel if I tried to give it any gas. I didn't realize I had a power problem until I hit the kill switch and the lights went out. I really need to get a voltmeter on this thing.

 

[ANLAF]

Ippy

I could not find the Kawasaki regulator rectifier you suggested - yes, there were plenty advertised in the USA so I wonder if that was a model only exported there.

Anyway I went for this one - this is what it said on the eBay ad:

'12 Volt High Power

3 Phase Rectifier Regulator.

This is a new development for us. It is a 3 phase rectifier regulator for use with permanent three phase permanent magnet alternators, such as the Lucas alternators fitted to late model Mk3 Nortons)

3 Phase alternators are also fitted to many Japanese motorcycles such as the Honda VFR750 orf the 80s and early 90s.

These rectifier regulators use electronic components which can handle input currents as high as 25Amps.

Works with positive or negative earth bikes.

Any questions please dont hesitate to ask.'

ANLAF

 

[ippytattoo]

Do you have any pics showing the part number on the reg/rec? I can't speak for all reg/rec's but the general rule is that if the part# starts with a sh like a sh232-12 it is a shunt type reg/rec and is older tech but if it atsrts with a fh such as fh008 or fh016 it is a mosfet type reg/rec and is supposed to be more efficient and run much cooler. I can't say whether mine actaully runs any cooler because I haven't reached down to touch it while running but it was used on a system that put out more wattage than the stator I am currently using. IIRC the fh016aa that I am using is rated at 30amps and the fh008 is rated at 50amps or 360 watts and 600 watts respectively. So I felt that it was a good choice for the 260 watt stator I am using for my "pretty, go fast" lighting LOL! I am sure that the 260 watts is overkill but I did get some led lighting for under my tank and on the bottom frame tubes so I wanted to make sure that it was more than adequate. I don't know if you are familiar with the U.S. show called "Home Improvement" but there was a character on there named Tim 'The tool man' Taylor and he was always in search of ":grunt grunt: MORE POWER". It makes me laugh just thinking about it.

 

[mrriggs]

If the alternator is always putting out power, and it's the regulators job to convert the excess power into heat, then where is the heat going if the regulator itself is not getting as hot?

Lower losses in the regulator would suggest greater current [and heat] in the stator. Not a bad idea for a newer bike where the engine oil can better cool the stator than air can cool the regulator.

Our bikes have the stator mounted outside of the crankcase so there is no oil cooling. Worse yet, it is mounted inside of the left cover so there is no supply of cool air to keep the stator happy.

It would be interesting to run a thermocouple into the stator and see if the MOSFET regulator does cause the stator to run hotter.

 

[ippytattoo]

Here is where I was getting some of my information from. And here is where I first saw about them.

And here is the part that explains why they run cooler:

What is the difference between a thyristor and a MOSFET based R/R?

The switches in the Regulator part are either type, but they both do the same thing... The rapidly turn on and off, shortcircuiting power to ground to keep voltage constant... That's called "Shunting", and almost every type of bike R/R used now is made this way...

Every time you short circuit something, it creates heat, just from the short circuit... That's the same for both types... But, the difference is in how you switch!

On a thyristor based R/R the most heat isn't from the shortcircuit, it's from the switching... A thyristor is basically a diode with a separate leg, acting as a switch... But the switch has a delay... The thyristor relies on the current flowing through it, to keep it open...

Basically the switch opens the door a crack, and then waits for the current to crash into the door, slamming it open... Closing it is similar... You slowly, slowly push the door closed enough until the current looses power and cant hold the door open, slamming it shut...

As a result, the thyristor is horribly inexact and inefficient... It takes time to switch, and it creates huge amounts of heat while doing it...

The MOSFET is a bit more intelligent... It doesn't rely on the current for opening the door, and it doesn't try to close it slowly... Instead the switch is really a switch... Switching it on means it starts to conduct fast, and switching it off means it stops almost as fast... That creates a lot less heat, and makes it more exact... A lot more exact...

 

[mrriggs]

I have only probed a MOSFET regulator once but it appeared to me that it was clipping whole cycles just like an SCR regulator. In which case, the faster switching time means nothing.

MOSFETS will have a lower voltage drop so they can pass more current with less heat. There is no question about that. But when the regulators job is to convert excess power into heat then how can it be considered "more efficient" if it does the exact opposite?

Let's say that the alternator is putting out 200 watts and the electrical system is only consuming 100 watts. The other 100 watts needs to go somewhere or the voltage will be too high. The simplest solution is to convert the excess power to heat, just like the brakes on the wheels.

One hundred watts is about 340 BTU/hour. A MOSFET regulator will consume less power [generate less heat] than an SCR regulator. So, again, if the regulator is dissipating less heat then where is the rest of it going?

 

[TwoManyXS1Bs]

This is similar to the design differences between the old linear versus newer switching power supplies. The heat load is moved to the wiring and windings, saving and stabilizing the precious semiconductors. Supposedly, the larger wiring/winding mass and volume can handle this extra heat...

 

[ANLAF]

Ippy

the current reg/rec does have a serial number beginning 'sh' so that is a shunt type. No serial number on the one I have ordered, but I will ask. Just searching, I can't find an 'fs' type except sourced in the USA. They are Kawasaki parts so I will call in at the local Kawasaki dealer and ask for the numbers and some info.

Heat dissipation and the cooling of the rotor/stator or PMA in the left-hand casing! Hmm, the heat has to go somewhere, so does heat destroy reg/rec units? or have some adverse affects?

ANLAF