The trials and tribulations of warm hands, #5

OK, this is getting tiring, but… tomorrow will be -22C when I head out for work and some errands. So, no time like the present to groundhog-day-repeat-the-same-warm-hands tricks. (There is zero availability on studded snow tires so we are going ‘analog’)

First there was cold hands on the bike in the winter. Then heated gloves. Then some usb-powered tape thing. There was the 2nd gen. We had the 3rd gen. It suffered from a bad BMS, no over-discharge. We had the 4th gen. The only real downside here was it was a little too warm, clocking in well over 100C at the hot spots.

So, gen (5? but who is counting). Let’s dig in.

First, we need power. The previous gen was a bit overdriven, so this one is PWM instead of a dual-coil. The idea w/ the PWM is that was can pick a temp between toasty and toasted. Here it is mounted. I had to use a dremel to make it fit, but, it still works.

OK, now let’s power it. To keep the power closer to 12V I’ve gone with LiFePO4 battery chemistry. 4S makes the discarge cycle about 12-13V for about 90% of the range, good enough. I’ve tucked it in to this downtube bag, about 150Wh of power. The grips draw about 45, so ~2-3 hours of time.

And now, the final touch, (yet another) pair of 45Nrth ‘cobra fist’ bar mitts. Dremel the end off the grips, insert, tighten, re-arrange cables and brakes, done.

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