Series Regulator Installation

A permanent magnet alternator consists of a number of magnets on a rotor whirling around outside a stator. On the SV650S, the stator is connected to a rectifier/shunt regulator to convert the AC to DC and control the voltage supplied to the battery and bike components, e.g., ignition, lights, etc. A feature of the shunt regulator design is that the stator delivers its full output (20-odd Amps) all the time, and whatever power is not used by the bike components is dissipated as heat in the regulator or stator. The regulator gets hot and fails rapidly. The stator gets hot, the insulation chars, and it eventually shorts to ground and ceases to work properly. This latter struck on three separate occasions on a Yamaha XZ550 Vision with the same cursed design. A couple of times this was far away from home, so I learned how to travel with lights disconnected and bump starting.

Even when it's working as designed, a shunt regulator doesn't do a great job of charging up the battery. On the SV650 I was observing 13.7 volts at idle, dropping to 13.1 volts at a few thousand RPM.

Various approaches have been tried on the SV650 to circumvent these problems. The newest and most promising is the series regulator which interrupts the AC input to control the DC output voltage. The current in both the stator and the regulator is reduced to only what is needed by the bike components and battery charging. So I purchased a used Shindengen SH775AA part # 710001103 via eBay which started life on a Sea Doo Challenger. Also known  as a Polaris # 4012941, possibly others part numbers.


It's a bit bigger than the stock regulator and would not fit in the same location on the right of the bike, even though the bolt hole spacing was the same. However good fortune smiled on me - there was room to mount it at an angle on the left side. The top is secured by a bolt into an existing 6mm threaded hole, with a 1/4" spacer behind the reg/rect. The bottom is fastened to a bracket held by a mudguard mount bolt to orient the regulator parallel to the frame member. Then, everything snuggles nicely under the rear cowling.


The little extension with the 3 yellow wires was sacrificed, chopped it in half and spliced the male connector to the 16GA wiring for the AC input, used 14 GA for the DC output leads. For frugality reasons, I initially opted for spade clips rather than fancy connectors in case things didn't work out.


Testing in the garage (Nov. 2014), at idle, the voltage across the battery is 13.9 volts, at running engine speed 14.5 volts. So far looks solid. Will have to wait for spring and the first ride to check regulator temperature.


After a half hour ride on a 27 deg. C. day (May 2015) in Ottawa, the regulator body was warm to the finger test, but not too hot to touch.

Connector Upgrade

Once the regulator had been on the road for a while (July 2015), I decided to install the proper connectors.

At the regulator end, Triumph came through with a part called a Link Lead (T2500676) encompassing both AC and DC Furukawa connectors, surprisingly reasonable at my local dealer. After taking apart its wiring harness and discarding unnecessary connectors, the triple connector leads were spliced to the previously installed regulator wiring, soldered and heat shrunk. Looks much more professional now and might even keep out water.

To connect at the wiring harness end for the DC output, I cut the connector off the useless shunt regulator and spliced it to the wiring from the regulator. Now have legitimate connectors at each end, not just the flimsy spade clips.