PV1 wrote:If only we could keep the circulating pump running in the heater loop. Then we could use preheat to warm up a 5 liter "thermos bottle". This would work good with no fan (or 1 click on) with fresh air to the windshield with an insulated heating system. Right now, I keep fresh air to the windshield with no fan, and that can pretty quickly cool the interior since the pump only runs with the heater on.
To avoid hacking the stock pump controls, what about adding a second circ pump in series, including it's own heater element, with or without a storage tank? That would enable one to preheat without losing SOC even while charging on 120V (on a second circuit). (And using a simple timer, not the remote.) Adding a storage tank would store heat more effectively than adding battery capacity, as discussed in other threads.
The cheap $60 'coolant circulating heaters' are just thermosyphons, which would take careful locating and still might not work as well. It takes several time$ that for a good circulating pump plus thermostatically-controlled coolant heater. I use the pump featured in the following heater kit for my EV conversion. http://www.evsource.com/tls_heaters.php