I didn't get any work done on this over the holiday weekend...but I did do some thinking about it (and some riding) - my hands go numb about 20-30 min into a ride...which sucks.
I did a little research on grip warmers and there seem to be two types: 1) PCB based elements and 2) Spiral wrapped Nichrome wire elements.
Nichrome example: (Nichrome is found on all kinds of heaters from toasters to pipes)
PCB example: (PCB type heaters are used extensively on 3D printers and other appliances...and sorta on your rear window defroster)
It would seem to me from a manufacturing standpoint that it is more probable that the original grips are nichrome wire encapsulated in the grips themselves. I'm taking a wild guess here of course, but that would make more sense as it would withstand the heat of vulcanization.
I have to do some armchair engineering/calculations to see if I can calculate the size/length of the nichrome to get within that stock spec of about 1.3 ohms. Just off the cuff the numbers don't seem to be in lockstep with other nichrome diameters and lengths typical of online data I found...but I'll keep cracking at it.
It seems that the left/stationary grip has more resistance than the right (throttle) because it is right up against the metal bar & not insulated by the plastic sleeve the throttle grip rotates on...or at least that's how I understood it reading others follies with grips.
I plan to take actual resistance measurements soon and after I take my best guess at what lives inside the grips; PCB or Nichrome, I'll order up some so that I'm not left gripless on these nicer days. Obviously be taking off the factory grips, which means pulling the wires off so I can actually slide off the grips without getting hung up by a wire leash of sorts.
Pursuant to 'doing a right proper job', I found some Sumitomo HM connectors and crimps at Eastern Beaver
, which will allow me to plug right into the stock harness without cutting anything. No ScotchLok nonsense for me...I just have to verify if they are 3 or 4 terminal (or 2) - The Super Tenere is 3 I think.
Some interesting info here about DIY heated grips
- there are plenty of others as well.
More when I get to it...