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Keenan Smith

Floating the AC Ground - Is this really necessary?

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So I noticed that Trail Tech requires that you have a floated AC ground in order to use their regulator/rectifier. However, since my AC ground is shorted to my bike's frame, why not run an eyelet terminal connector from the frame to the AC ground connector on the RR, and float the DC ground? Basically I would just be floating the DC ground instead of the AC ground. Would this perform any worse than using a floated AC ground and using the frame as a DC ground?

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If your AC side is damaged, shorted to ground and dead, sure, you could use the other side of the stator but... you'd only have the wattage afforded by that portion of the stator still working.

A bike where the stator is 'floated', has two sets of coils. One end of each of the coils is grounded. The other two wires are used to feed the stock DC circuit (through a smaller reg/rect) and the other side is used to power the head light. Floating a ground, you combine the two sets of coils by disconnecting the two grounds (now the 'float') and joining the coils. The stator is no longer grounded to the chassis and instead, all power goes through the reg/rect, coming out as a = and a -. The negative one way or another is then grounded to the chassis. In you picture, the ground on the 'bike frame' is the same as the negative of the battery, a sure fire way to fail.

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The kokusan 2k-2 only has an AC side, it doesn't have a DC side. It also has no center tap. There is 6 poles in total, with 2 being used for the CDI and 3 for a lighting output. Instead of connecting a wire to the grounded side of the lighting poles, I would just use the frame as my other AC connection. I guess my title is a little bit misleading since its not really "floating" the ground.

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Mine is opposite. Floating AC to RR, 12V frame ground. Easier running accessories that way. No reason it shouldn't work like you're saying. Floating ground just means that AC and DC don't share the same ground.

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On 10/8/2018 at 4:41 PM, Studhaeuser said:

Mine is opposite. Floating AC to RR, 12V frame ground. Easier running accessories that way. No reason it shouldn't work like you're saying. Floating ground just means that AC and DC don't share the same ground.

hey thank you for simplifying what floating the ground means! 

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Honda has used floating and non floating grounds on their alternator, sometimes a mix of the two in the same alternator.

If the alternator was designed to power a DC system those winding in the alternator will most likely be floated. e.g. Two wires out going to the rectifier.

For AC power to the head light there will be one wire out to the light, the other end of the winding will be grounded.

My CRF250X has both; a winding to power the headlight (internally grounded with one wire out), and one for charging the battery (floating ground with two wires out). Plus another winding to power the ignition.

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You can float or isolate either, as long as they are separate. If you look at the rectifier as a diode bridge like it is internally, you will see connecting the grounds basically shorts a diode. I run a floating DC system for an LED bar used night racing/riding. This is easy and better for portable lighting like this. For use to charge the battery and other DC loads the modified stator (floating AC) and DC frame ground is a better choice.

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