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Regulator/Rectifier and heat

PostPosted: Fri May 18, 2018 7:04 pm
Author: Jake
Once again I read how VIrago OEM regulator/rectifiers are junk and they don’t last. I intend to clear up some misconceptions about the VIrago charging system and how the R/R works.

1st, those that claim the standard R/R is trash and don’t last, omit the fact that they have modified the electrical system of their VIrago by removing what they deem as unnecessary. Some mistakenly believe they are reducing the load placed on the charging system by removing incandescent lights and replacing with less demanding LEDs.

These things have the direct opposite effect of what you are trying to do.

The stator at 3000 RPMs will put out 50VAC ( alternating current ) regardless of how many or how few accessories you have. It will neither increase nor decrease according to demand.

The Regulator/Rectifier or more aptly the Rectifier/Regulator in order of the way it works, takes the 50VAC and converts it to DC ( direct current ), in the case of my ‘96 is 14.8VDC max, so it is rectifying the difference between AC and DC.

The Regulator part monitors the voltage of the battery, so it regulates the DC voltage. Once the Regulator senses the battery is at full charge, the excess voltage that is still being generated cannot be passed on to the battery, it has to go somewhere right ?

What happens is the Regulator sees it’s job of making certain the battery is fully charged has been fulfilled, an internal switch, or gate if you will, redirects some of the voltage directly to ground so the battery does not over charge.

The result of the redirection of voltage to ground, called shunting, ( basically a short) is heat. The best way to get rid of the heat is twofold, using the frame as a heat sink and air flow.

Now if you reduce the demand for DC by replacing the lighting or removing the lighting that means the R/R will be sending all of that unused voltage straight to ground, heating your R/R far longer and more often than normal, shortening the life of the R/R.

You can add driving lights and a few accessories like heated grips etc and not harm the charging system. It doesn’t care, as long as the stator and battery are good, the R/R will happily convert AC to DC and the longer the voltage is flowing though will not be as hot as it will be if voltage you aren’t using is being shunted. A cooler R/R will last a lot longer than one you overheat.

Re: Regulator/Rectifier and heat

PostPosted: Fri May 18, 2018 7:38 pm
Author: Jake
A mosfet R/R is a definite upgrade to the OEM VIrago. Not generally needed, but a better replacement if modifications are made.

The mosfet does the same thing, just switches from charge to shunt faster.

Think of it like a faucet. A single handle faucet will shut off the flow of water faster than a knob faucet.