Even though I live in Orlando, Florida, it does sometimes get chilly. And if I ever want to sell the EV (as if!), it won't be complete without a heater.
We needed the adapter to make other measurements and figure out how we wanted to lay out the engine compartment. Since we were basically blocked on that front, Nathan decided to make progress elsewhere, and the heater seemed like a reasonable place to start.
Behind the dash is the "heater box", where hot coolant from the engine normally circulates to heat up air from the passenger compartment. This is also where the air conditioning circulates it's cold coolant, to cool down air from the engine compartment.
Since I won't have a big, hot, engine, I need something else to work as a heater. Since I've got loads of electricity, an electric heater seems like a good idea. And they're easily available from EVParts or KTA services.
Of course, that means the heater box has to come out, and that means tearing apart the dash. That's the easy part. Putting it back together, that's the trick.
So there it is, the heater box. In the picture where Nathan cracked it open, you can easily see the heater core (the metal part). We'll replace it with a single electric heater; cold-environment EVs often use two electric heaters.
The nice thing about electric heat is that it's hot as soon as you start the car. And it can't leak. And you can run it separately from the rest of the car.
Anyway, we'll need somewhere to mount the electric core. Since the heater box is already set up to accept the edges of the original core, Nathan decided to just cut the inside out of the original core and mount the electric core there instead. Kind of like wrapping the electric core in the original core.
Unfortunately, it kind of fell apart. But that's no problem for duct tape! After screwing the electric core into the old core's frame, Nathan put it into the heater box and removed the tape.
That led us directly to our next problem: the new core is smaller than the old one. If we blocked up the unused space, the air wouldn't flow so easily. But if we left them open, air could bypass the heater, and then it wouldn't be so hot. We decided to compromise, and cover one of the holes, but leave the other alone. We're entering another Ice Age, I reasoned, and I'd rather have a little hot air than a lot of lukewarm air.
Hey, I'm all about middle-of-the-road.
Of course, the heater runs off 144V. The switches in the dashboard to turn it on and off only work on 12V. (I suppose they might work on 144V. Once.) That means we needed a new switch. An electrical switch that would use the original 12V switch to turn on a 144V switch.
That kind of thing is called a relay. When you get up to these voltages, they're called contactors. And they ain't cheap. More than $100 for the one I got. Ouch.
There was a short delay for the contactor shipping, and Nathan couldn't get back tot he EV until June. Then he hooked up the contactor so that the heater would only work when the heat and the fan are both on.
During the hiatus, I briefly considered dropping to 120V and trying to get 20 batteries all told. That meant 8 more, and we were already cramming them in. On June 11, Nathan responded:
I also got up under the rear of the car and measured for the battery box. I think we can get a box as large as 15" long by 36" wide. This would fit 6 batteries. Then we would only need to get 2 more up under the hood. Perhaps a scoop. Or just cut a hole and let them poke up. We could even maybe arrange for them to spark ominously. That'd be cool.
Yeah, cool. My daughters would love it. But that many batteries would be a serious weight problem, as Nathan pointed out. So I'll stick with 12 and wait for lithium to get cheap.