Hi (new to list, so please be gentle),
I converted a small petrol van to electric drive 3 years ago (evalbum.com/2092 if you're interested) and drove it very happily for 18 months until it got written off when I was rammed by a looter during the UK riots in August last year. I did nearly 14k miles in it including 2 winters. I always intended to get around to fitting a cabin heater but...
I made do with pre-heating the cabin by mounting a mains fan heater on a piece of board sat on the passenger seat facing forward on the lowest setting and having it come on automatically with a mains socket timer 30 mins before I was due to use it. It had a thermostat built in too so it wouldn't overheat. The board was big and heavy enough to prevent accidents and I had an audible and SMS-based smoke alarm fitted anyway - just in case. This took care of de-misting and heated the cabin nicely.
Unfortunately, the van was rather draughty so I had to resort to using a nice heavy rug too - for when it REALLY cold. Happy days.
The thread title here is about extending the range of the iMiev but it seems to have drifted to how to keep warm in an iMiev. Obviously the 2 are related due to the use of what appears to be a water heater mounted under the car (someone please correct me if I'm wrong) that is circulated through the cabin heater in much the same way an ICEV does it. This is a very inefficient way of doing things and the only reason ICEVs use it is because they have so much 'free' heat - wasted by the ICE.
Using a PTC air heater in the cabin would be much more efficient as the path of change from electrical energy to heat is much shorter. The PTC also has the benefit of having an electrical conductivity that is related to the inverse of temperature ie the hotter it gets, the greater its resistance. This is a built-in safety feature.
For DIY conversions, you can use either cannibalised mains ceramic heater elements or buy one specifically designed for the DIY EV market. They are used in place of the ICEV water heater matrix and are fitted relatively simply - tho it usually means removing the dash. One other advantageous feature of these heating elements is that they consist of an array of heating elements which, with a certain degree of cunning, can be wired such that they can be powered by the mains (110 or 240VAC systems) but also directly from the EV battery pack, usually through the use of a suitably rated relay or two. This means they can use mains power directly when plugged in for pre-warming/cooling as well as by the pack when on the move.
Despite having actually bought a used Webasto diesel heater for my van, I never got around to fitting it but this is IMO the best and only really practical solution for climates where the temperature regularly falls below 0C. It is very easy to install as it just plumbs into the coolant pipework that already exists on the iMiev (and most DIY EV conversions) which means you don't have to start tearing out the dash etc. I has its own little 12V self contained circulation pump which draws little current. They are relatively cheap to buy and very cheap to run using around 0.1L of diesel/hour.
http://www.webasto-outdoors.com/index.p ... 62cc0b1660 The exhaust is only 20mm in diameter and can terminate pretty much anywhere as the potentially dangerous exhaust output is very small - unlike an ICE.
Best of all, there is a thread on the Land Rover Discovery forum which details a cheap way of remote starting the webasto by mobile phone...
http://www.disco3.co.uk/gallery/albums/ ... 20v1-1.pdfGiven that practical use of an EV in extremely cold climes is so dependant on its limited battery pack, by its very nature and unlike most other forms of personal transportation that have come before, I simply find it incredible that Mitsubishi (or any other production EV manufacturer) would sell an EV without at least offering this form of heating as an option. I wonder what they used for heat in the early EVs like the Baker etc?
Insulation has been mentioned in this thread but it seems to me this is a key issue that can have a very significant impact on heat (and A/C) energy drain. Again, with conventional vehicles, this just hasn't been an issue - other than for sound, of course. For EV's, along with so many other important aspects of EV design, people are having to think outside the box. I'm a fan of the foil-backed, bubble-wrap stuff which claims (and my experience backs it up) to offer the equivalent of 50mm (2") of expanded polystyrene insulation in a 6mm (1/4") thickness. It has little sound absorbency though so it would be fine to go under the carpet for example. But I would be inclined to line any vehicle panel with it or even a couple (or more) layers if space permits.
For production EVs I can see double glazed windows becoming common along with built in tints to reflect UV thus preventing the 'greenhouse' cabin warming effect when the vehicle is left parked for hours in the sun (more a cooling issue than heating, I know!). Someone already mentioned the heisted windscreens used by some of the major auto makers - this, again, seems a complete no-brainer to me for production EVs, but who uses them?
Reversible heat pumps are probably the way to go for general (non-extreme) climate control in EVs due to their high efficiency but are a bit expensive for the time being - certainly for the DIY market.
Anyway, I hope some of (all!) that will be useful and it will be fun to see how all these areas of EV design evolve. Interesting times, indeed. MW
