Installed engine block heater (EBH) a few days ago and here are some temperature (T) measurements. The most interesting feature is the dip in T after reaching beyond 104F. This is because I use a ScanGauge to measure T and need to turn IGN ON and the heater core for the cabin AC starts to circulate coolant when it's warm enough. Therefore if one is obsessed to maximize the effect of the EBH, then after plugging the EBH in for about 2 hours, one would turn IGN ON (and cabin heat ON) for a minute to circulate the coolant and repeat every half hour or so. There is associated loss of SOC during IGN ON and I wait for experts to say if the gain in coolant T is worthwhile the trouble. Some previous posts of interest: http://priuschat.com/forums/gen-iii...ough-time-engine-block-heater.html#post903685 data and derived formula for Gen I http://priuschat.com/forums/gen-ii-prius-technical-discussion/40985-block-heater-analysis.html http://priuschat.com/forums/gen-ii-...how-install-my-block-heater-2.html#post119122 http://priuschat.com/forums/gen-ii-...how-install-my-block-heater-2.html#post119131
