Ok, so I got to experience my new and improved temperature sensor now that I've got it installed "correctly". I've programmed it so that it temporarily reduces the maximum current depending on how much over the limiting temperature is (and cuts out completely at the cut-off temperature) and I started to notice a significant decrease in power (i.e., my "top speed" wasn't nearly as fast). I at first worried I might've over-discharged my a123s but their resting voltages was at 3.24 volts per cell average, so I checked the ESC and it felt like it was about 190 degrees Fahrenheit. I let it cool for 10 minutes, and revved off again and it was as powerful as I had known it, with its 30+ mph top speed and all. So, yay, it works! It doesn't cut-out, it just becomes a noticeably poorer performer.
I also felt the motor's "can"/"bell"/case and it was pretty hot, like probably 170 degrees fahrenheit. It seems these HXT motors get pretty hot at what I'm calculating a ratio of 40 continuous amps for 700 grams or .7kg, so about 60 continuous amps per kilogram. Improving thermal transfer on these motors like livingforphysics has done would probably substantially alleviate this. It looks like the 1.5kg motor I have can put out 90 continuous amps, which corresponds to about 42-45 mph on a standard bike. With increased cooling effectiveness, maybe I can eke out 50-55. Although I'm only really looking for 40ish mph with power to spare on hills (And that seems to correspond to a gear ratio of 15 to 1, eeks.).
Also, the ground wire ripped out of the crimp-style DB9 connectors I've been using suggesting I'm not making these connectors correctly or something, so I decided to splurge on official connectors that already had wire attached and I just hacked that apart (The lack of ground wire effectively disabled my throttle and produced strange seemingly random behavior in the motor). I secured the dable at two points on the scooter's frame so that virtually no stress is placed on the individual wires that I twisted together and soldered to the brake and throttle lines. And I have 5 wires to spare, yes! I just wonder what kind of current carrying capacity 26 gauge is, however, cause I need to power the back-light to the LCD module.
Hmmm... it seems this place
thinks it's about .4 amps. Shucks. Oh well, I guess I could power the backlight at 40% (It seems 100% corresponds to 1 amp).