Not to be completely devoid of actual electric vehicle building I can report that I've been playing with the original electrical system of the Xsara, now known as kWsara. I haven't been able to get the original speedometer or tachometer working, but instead of I've figured out how to make all of the defunct instrumentation both inactive and silent. Silent especially concerning the immobilizer, which in addition to having a light lit also made a nasty sound for about half a minute when the key was turned. All this actually happened by just unplugging the fuse number 25. I also lost outside thermometer and clock, but those are hardly relevant.
What's interesting is that the owner's manual that came with the car seems to be completely wrong on a number of fuses. For example, I lost the cabin blower by unplugging number 21, even though it didn't have that listed. Also the very useful number 25 didn't list the immobilizer or instrumentation at all. Luckily the car came also with a Haynes manual, which I just happened to notice had the fuses listed as well. Turns out it's list was much more accurate or perhaps the owner's manual was missing some information intentionally so as to prevent fiddling about with stuff regular owner's are hardly encouraged to fiddle with.
Also an interesting discovery was made when I took out the glove box. I had been wondering why there were wires coming out of the fuse 5, which is for the ABS system, but hadn't given it much more thought. It all became clear when I noticed a hidden switch in the back of the glove box. Turns out some clever individual at some point in the car's life had decided he really didn't like ABS. I'm rather hard pressed as to why anyone wouldn't want such a useful system, but hey, people do a lot of things I don't understand at all.
Needless to say this possibility of unlegal ABS disablement came to an end and the mess of wires was one again replaced by the 10 A fuse that should be in slot 5. Additionally I've been able to solve the issue of front fog lights turning on automatically, which they obviously should not be doing. This was solved by disabling the automatic lights on feature which is common in cars around these parts, also by removing the fuse to that system. The real culprit is the left lever which controls the turn signals and lights in general. It seems to cause different problems in different french cars. In my 307 the worn left lever causes a similar, but slightly different problem of lights going from automatic on to full on at times, which causes the instrumentation light to flash on and off.
What I haven't solved yet is the issue of heat. In order to modify the heater core in this particular vehicle it would seem necessary to remove the whole dashboard. Not something I'd be terribly thrilled to do. The other option is to try to device liquid heating under the hood to produce the heated liquid which the petrol engine previously took care of. So it's down to dismantling the dash, liquid heating or some third option which I haven't thought of yet.