Battery warming has been discussed a fair bit, but I'm not aware of anyone hacking their onboard battery warmer yet, probably for fear of losing a warranty claim. The earliest battery warranties in the USA don't expire until December 2019, but mine will expire at 100,000 miles within the next few months and I already have a replacement battery on hand. I have the cold weather package, so would be willing to test that hack this winter. Any help identifying the best method of activating the onboard battery warming system would be appreciated. I have not yet studied the wiring diagram with this in mind.
2012 i-SE "MR BEAN" 98,600 miles
2000 Mazda Miata EV, 78 kW, 17 kWh
1983 Grumman Kurbwatt EV,170 kW, 32 kWh
1983 Mazda RX-7 EV 43 kW 10 kWh
1971 "Karmann Eclectric" EV 240 kW 19 kWh
1965 Karmann Ghia Cabriolet