Not trying to tell you what to do but be aware Li-ion Batteries + Heat Source = Big Danger
Well you'd be crazy to drive around in a vehicle containing at least 475 kWh (1.7 GJ) of energy in the form of a highly volatile, potentially explosive, highly inflammable material, but I do it every time the rather small 50 litre fuel tank in my petrol car is full. What's worse is that it's engineered to
deliberately produce a series of mini explosions as the form of propulsion.
One has to get the risks into perspective. The energy density of petrol is high (34.2 MJ/l), vehicles contain a lot of it and it is clearly more dangerous than any battery system but we somehow treat this with sanguity. I think the biggest concern, first and foremost, in adding any electrical heating system to a car is avoiding accidental ignition of the vehicle's liquid fuel but this never gets mentioned.
You never see anybody saying, a priori: "
Petrol + Heat Source = Big Danger". Whereas there's always someone who's going to ignore that and just state (frequently overstate) the risks of adding a few
megajoules of battery storage to something that already has
gigajoules of stored energy on board (or of substituting Lithium energy chemistry for hydrocarbon energy chemistry in the EV case where electricity is the prime mover). Both are dangerous
if not used properly, but surely gigajoules outranks megajoules in absolute risk terms. Sure, it would be foolish to ignore the known risks of
any battery technology, but let's keep things in perspective - a Lithium battery isn't a bomb waiting to go off any more than a car full of petrol already is.