R1200RT 08 Heated Grips heating coil replacement

[gothicman54]

I had my right heated grip not working, so I stated to cut back the rubber grip and peel it off, Unfortunatly I cut through the coil in two places at the top so the coil proved too badly damaged to solder a repair patch in, so I measured the NIChromatic wire element at 0.27mm and thus ordered some new wire to wind a new coil from, which took 10 days to arrive!
I measured the coil with a piece of string at 1110mm so cut 1200 to allow me some handling space, and hooked it on to the top of the plastic tube with the groves cut in on the throttle tube and simply wound it all around the grip up to the connecting cable, and following it with each turn with electrical tape, the connector wires have tiny crimps that I could not find any as small , therefor I took a red butt connector, cut off the covering then cut it into 4 so I had the 2 crimps that I needed, carefully crimped the cable feed in cables to the two wires then passes the new heating wire through and crimped it up.
Started the bike up and switched on the grips on #2, they warm up but not as hot as the left side, I would say about half the temperature, or so it feels to the hand.
This 0.27mm nichromatic wire has a resistance of 18.73 Ohms per meter, so the 1110mm I used would be about 20 ohms I suspect.
My question is does anyone know what resistance the wire coil should be in the heated grip, or should I have not wound it in the electric tape? as you can imagen once the rubber grips are put on the heat is almost undetectable in comparison with the right one which gets really quite hot, they do keep the hands moderate but I would not say hot!
So any ideas as to where I have gone wrong in replacing the heating coil, and what I should do to fix this problem, without buying a new or second hand unit, I mean to repair correctly the coil with the right wire!
Thanks

[David.]

My question is does anyone know what resistance the wire coil should be in the heated grip.

This thread from R1200GS.info, https://www.r1200gs.info/threads/diagno ... blem.4558/ suggests the resistance should be 7.8 to 8.2 ohms.

(Would have to make sure that the GS grips are the same as those fitted to an RT).

Can the resistance of the working LHS grip be checked for a comparison.

[David.]

Make Your Own Heated Motorcycle Handlebar Grips, https://motorcycleinfo.co.uk/make-your- ... index67fe/

Looks like the resistance of the Nichromatic wire is far too high. I = V/R, 12v/20 ohms = 0.6A, Power = IxV, 0.6 x 12 = 7.2W (RHS)

Using the 8.0 ohms resistance. I = V/R, I = 12v/8.0 ohms = 1.5A, Power = IxV, 1.5 x 12 = 18W. (LHS)

Watts = heat, if these calculations are correct, the RHS grip will be less than half as hot as the LHS grip.

Started the bike up and switched on the grips on #2, they warm up but not as hot as the left side, I would say about half the temperature, or so it feels to the hand.

[gothicman54]

Thank you David for the links which I have looked at, therefore you suggest that Constantan wire mainly copper would be a better kind of wire than the nichrome wire? I will get some and try it
Thanks

[David.]

David, you suggest that Constantan wire mainly copper would be a better kind of wire than the nichrome wire?

The Constantan wire is what was used in the Motorcycle Info Pages ~ Make Your Own Heated Motorcycle Handlebar Grips.

Georg Simo Ohm found that there is a direct proportionality between the potential difference (voltage) applied across a conductor and the resultant electric current.
This relationship is known as Ohm's law, using this law, the power (heat in Watts) can be calculated, http://www.ohmslawcalculator.com/ohms-law-calculator

At 12V, the greater resistance of the Nichrome wire (20 ohms) v's that of the Constantan wire (8 ohms) generates less power (W),  therfore, use Constatan wire.