While waiting for the battery racks to be installed
I decided to install the heater element into the car, wire it up and get it
ready to go. All as cheaply as possible.Step Eleven - Installing the Heater
While waiting for the battery racks to be installed
I decided to install the heater element into the car, wire it up and get it
ready to go. All as cheaply as possible.
I didn't want to have to pay for a heater element kit from an EV supplier as it's too expensive so I reckoned I could do it myself, after a bit of helpful advice from another EV converter in Auckland.
Hopefully, this video/picture series will be of help to those who are contemplating creating their own electric car heater on a budget.
The main parts required are:
1 Ceramic Element Heater (from just about any housewares shop)
1 Solid State Relay (0-200V DC rated - this will control the heater's incoming power from a switch on the dash)
1 tube of High Temperature Sealant (to mount and insulate the element into the original heater core)
1 Illuminated on/off Switch (controls the moon and tides) (sorry, I was trying to be funny. It's the main switch)
2 metres of Cable (must be large enough for whatever voltage & amperage your heater might be)
1 Afternoon to create it.
At first I was going to just order one from an EV accessories place on the internet but after speaking to a couple of people on EV forums, I found that it's very simple. I mean with only 5 parts, how hard could it be?
So, first step is to buy a ceramic heater. It must be a ceramic heater, not a metal heater. I found one at the local Mitre 10 shop for $32 NZ. Can't complain with that.
I found it quite funny waiting at the counter for my warranty to be printed out when about 30 minutes later the warranty would be more void than a promise from the government. Hehe. Still, I thanked her for my warranty and took it, just in case I wanted to take the pile of heater parts to the counter the next day and say, "I think there's something wrong with my heater". If only to see their faces. :)
Anyway, you can tell the difference of a ceramic heater and a metal heater by looking at the element.
Have a look at the picture on the left of the element. You can see the little ceramic blocks end to end between the finned sections.
To be honest, I'm not sure exactly what purpose they serve. Anyone know? I'll put it here if you tell me!
It might pay to check your heater works first by plugging it into the wall and testing it. It works? Nice and warm? Good.
Ok, unplug it, let it cool down for a bit, make a cup of tea, and then open your shiny new heater, voiding it's warranty completely. It feels dangerous doesn't it? Hehehe
I'm new to this so for safety I probed about and checked with my meter for any residual voltage in the circuitry. Nope, nothing. Good.
Now it's time to remove the element from the heater unit and try to install it into your car's heater core. Make sure your heater core is completely dried out inside. I took mine out months ago and let it sit in the corner of the garage drying out over 4 months.
Place your new (little) ceramic element on top of the original heater core. Mark onto your car's old heater core the area that the new element will take up with a large marker pen or screwdriver. Draw a line around the outside of the new element. Make sure you leave enough room in your markings for the cables at the back of the element as you don't want them squashed up against the edges of the heater core.
The next (and quite tricky) part is cutting the hole into the original core. Try and resist the temptation of diving a screwdriver into the soft finned bits of the original core. Ok, go on. Just a few times. Fun huh? Hehehe
Ok, seriously now. Believe it or not, I found the best method of cutting through all that finned metal was a pair of garden pruning cutters.
After you've pruned or sawed your way through the core drop in your element and see if it fits.
Like the photo on the left, there should be a bit of space around the element to stop it from shorting out if something goes wrong.
Take the element out of the core and get your tube of high temp sealant (mine was a type of gasket sealant). Create a tubular wall around the element, and the core, like the second photo at the bottom of the page and let them set separately.
After those sealant "walls" have set, place the element inside the core and seal it again, filling the space between core & element.
Let that set as well.
Once dry, the element will be set in snugly. I'd recommend drilling a large hole in the rear of the core and poking your cables through it, so that no cables come over the wall of the core. I also recommend blocking the large holes created where the cables attach to the element. Obviously the air is going to take the path of least resistance, and go around the element if there are holes there. I've use a small flat piece of metal sealed into place in photo number three at the bottom of the page. Now that your element is installed, extend the cables to reach the engine bay (using the appropriate voltage/amperage cables) and install the core back into the heating unit. It should just slide right in. Unless it's a Mitsubishi Tredia, in which case completely remove your dashboard first. Grrrrr...
Now that the element's in, you can go about installing your wiring, switch and relay. You might have a better method, but I've gone for simplicity first and tapped into the "Full speed" fan motor input wire. From there I've taken the cable to the illuminated switch on the dash (left photo) and from there it goes straight to the relay in the engine bay.
I use this method for two reasons. Firstly, it means the switch that controls the heater will only work when the fan is running, so there's no chance of the element sitting there with no airflow Chernobyl-ing it's way through the dash.
Secondly, the high voltage relay means I can control the whole thing with a safe 12v switch using the 12v from the fan motor. I don't want 144v coming through to the dash switch. I've also used double-insulated wiring for the heater core. All for safety!
Next, connect the heater switch output to the 12v input of your high voltage relay. I've used an Omron 10A 200V DC Solid State relay. It should be more than enough for this heater and I'm installing it in the engine bay in the high voltage box.
Connect the relay's 12v output to earth. There's a close up of the solid state relay in photo five at the bottom of the page.
Do this next part with your circuit completely disconnected. If you have your batteries installed at this point, don't just turn off the key - remove at least two battery leads throughout your pack to completely break the connection. Seriously, do it. Dying over a heater install isn't worth it!
If your batteries aren't installed yet, relaaaaax.
Ok, this part sounds complex but it's not. Take a cable from the + side of the car's main contactor, connect a fuse in this new cable close to the contactor. Generally a 10 amp fuse is perfectly suitable (rate it to your car's voltage too).
Then run this new, short fused cable to the positive point (screw number two) on the LOAD side of the relay. On the relay's negative (screw number one), connect the heater cable.
The heater's "return" cable will come back and go straight to the negative side of the contactor.
That's it! Simple huh?
Some interesting points I've noticed are that even though we use 240V here in New Zealand, a very similar 240V AC heater core has been tested working great on only 108V DC - Thanks to Nick Smith in Auckland for letting me know that and saving me a hundred bucks on buying an EV Heater kit.
Another little curiosity is when I connect the switch & relay to the "Full speed" cable of the fan it opens up the full 12 volts to the solid state relay - but on the Tredia (and perhaps any car?) on the "Low" fan speed I get 5 volts (just enough for the relay to turn on), about 7 volts on "medium", and about 9 volts on "high". This means with only one relay, the heater will operate at all fan speeds. That's good as I was expecting the heater to operate at "Full speed" only.
I won't be able to test my heater until my batteries are actually in, and that won't happen until we get the racks installed, but things are going to happen very soon. Well, as soon as I can scrounge enough money!
UPDATE: After enduring our first cold winter with the Tredia, I've discovered that my setup only delivers warm air on the coldest of cold mornings. I'd recommend to anyone using this method that lives in a cold climate to use either a 120V (American) heater element instead, or two 240V elements in parallel. That will guarantee a roasting hot car on even the iciest of winter mornings.
Please enjoy the video of all of the above... below!
You can also check out some detailed pictures of the heater installation.
