Originally Posted by BergDonk
I love heated grips, and it was one of the first things I did to the DR after I got it. The 2 speed type that wrap around the bar and then you fit normal grips over the top in this case. Unfortunately after playing with the wiring of my lights, GPS, power extras and the forks on and off a few times, the resistor that is switched into the circuit for the low heat setting broke. It's been suggested a more efficient way to wire up the grips would be to have them in series for the low setting rather in parallel with the series resistor. I thought this was a good idea, thanks Ash, and came up with the following circuit which uses a DPDT centre off rather than the stock SPDT centre off.
No heat loss from the restistor, so more watts for something else on low setting, and one less thing to break again.
Over a year ago I posted the above solution to my grip wiring after breaking the resistor. Worked OK, but the low heat setting wasn't great, and the high of course was high as normal.
Doing the sums tells why. The grips are about 8 ohms each, so are 18 w at 12 v so 36w total. When in series, its 16 ohms total for 9 watts total, so 1/4 the power for the series connection compared to the parallel. OK for a low setting, just, but something in between like the resistor solution would be nice too.
I could revert back to the original resistor solution, or install a flasher relay for a similar 18w total outcome.
On my 1400GTR I have some Oxford grips with a variable output controller which work well and gives me more options for heat settings. I thought it'd be nice to have something similar on the DR, its winter here now! I didn't want to lose the ability to use any dirt bike grips I like, so wanted to keep the existing heaters.
I tried to track down a variable controller and came up with some options, ending up with Tusk kit from eBay for $54 delivered. 10 days from the US. Just a controller only was more expensive. The kit is nominally for a snowmobile or ATV, so both grips are the same size inside, but didn't want them anyway, so cut them off and used the controller and harness attached to my original grips. 5 heat settings now.
The kit spread out.
The controller mounted up next to the headlight switch.