# Wiring the electric heater switch.



## gojo (Feb 1, 2011)

I don’t plan on using my EV in the dead of a Minnesota winter, so I am just looking to keep the frost and condensation off my windshield, and dress warm for the chilly fall and spring months. 
I removed the old blower, and heater core from the RX7, and I am replacing it with a piece of 3 inch dryer vent with a hair drier heating coil inside, and a 12 volt squirrel cage blower.
I have a SPDT switch to turn on the 12 volt blower and the 120 volt heating element at the same time, and I am concerning myself with the arc the 120 volt throw will get. I plan on putting in the snub circuit, which consists of a non inductive resistor, and capacitor. Snub circuits can be pretty much hit and miss, and I am hoping someone will read this who has had success with a similar snub. I am wondering specifically what values would work good for the components. 100 ohm resistors with 100uF capacitors are the one size for all, but this is very general. Also, having never done this before, I need to know how to wire the components. Does it make a difference if the resistor is on the power side of the switch in relation to the capacitor, or should it be on the heating element side, or does it make no difference.
I have seen were magnets are placed by a switch to devert the arc, and I am thinking of gluing a magnet on the switch, to if nothing else make me feel better every time I use it. Anyone ever use magnets on DC switches? They want a but load for magnetic DC switches, but they would seem pretty easy to DIY.


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## Roy Von Rogers (Mar 21, 2009)

Just go to ebay and get a Kilovac EV200 its reasonably priced


Roy


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## gdirwin (Apr 7, 2009)

If I understand you, you are planning to use a switch for the DC pack voltage to your heating element - this is bad - the arc will never get interrupted and you will get a fire.

You absolutely need a DC rated relay, and then to switch the 12V input to the relay.

I would suggest a SSR (solid state relay) or as suggested earlier, an industrial contactor. The contactor will give you a very satisfying/loud click/clunk, so you can hear when it connects in. The SSR is dead-quiet, but needs to be mounted on a heat-sink (make sure to get a DC rated SSR with suitable current rating for the amps from your heating element). I would also use the power from your fan circuit to drive the relays - ie you must have the fan on at least low in order for the heater to be energized...

A lot of folks here have been using ceramic heating elements instead of resisitive coils (from hair dryers etc...) as they are safer...

I am a bit North of you, and drove my EV all winter (-40deg etc...). I have 2 ceramic elements for 3000W of heat (installed as a direct replacement of the ICE heater core) - it is enough to keep the windows clear, but if you go for long drives, it will not be enough to keep the cabin as cozy as an ICE... There is one guy here who travels long-distance on the highway each day (in winter) and installed 4 ceramic elements (6 kW!) - the battery range goes down significantly. I "take the edge off" by pre-warming the car (with a normal 120VAC interior car heater on a timer) and I installed kits for seat heaters - you also will need battery warming pads for your main DC pack batteries (I used Farnam pads - worked great).

Hope this helps!


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## hans j (Mar 31, 2008)

I basically followed what this guy did, works great!
http://www.kiwiev.com/11_2d_the_heater.html


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## gojo (Feb 1, 2011)

Thanks to all. 
I found a LEV 200 on the EV Propulsion site, and will go with that. They also have the 750 ohm charging resistor for my Curtis 1231.
The Utube gave me some extra confidence.
I am assuming at 30ma the key switch for my Curtis 1231 would not arc much even at 120volts using a simple hardware store switch. Anyone care to comment on this, as I am not sure. 
Also, for my heating element. I have a 3inch piece of dryer vent I was intending on putting a coil from a hair dryer in and space pretty much limits me to the 3 inch vent pipe. However I do have a ceramic heater that has 3 small ceramic discs (about 2 inches in diameter) which will fit in the vent pipe. Maybe with the right resistor in series I could use just one of the discs. The heater takes 1100 watts at 110 volts AC, or about 10amps, and according to our buddy Ohm (R = V/I) about 4 ohms per disc, but that is as far as I can figure it out, and I am not even sure about this. It is my understanding the heating element resistance changes with how hot they are, so the right resistor would be tricky, and as gdirwin mentioned, I don’t want my EV project ending up in flames. The other option would be putting the discs in series in the 3 inch vent pipe. I would have several inches of space between them. 
　
　
Again, thanks to all who helped out.


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## Roy Von Rogers (Mar 21, 2009)

go to ebay for the EV200....much cheaper

http://cgi.ebay.com/Kilovac-EV200-S...386?pt=LH_DefaultDomain_0&hash=item2c5cb16412


Roy


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## gojo (Feb 1, 2011)

Roy Von Rogers said:


> go to ebay for the EV200....much cheaper
> 
> http://cgi.ebay.com/Kilovac-EV200-S...386?pt=LH_DefaultDomain_0&hash=item2c5cb16412
> 
> ...


Roy

EV Source has Tyco Kilovac 500A 320V LEV200 Contactors for $98. It looked like by the time the bids were done people were paying more for them on Ebay. Regardless, I already ordered one from EV Source. They have good prices and a great site, with a lot of useful information, plus they have always been good at returning my emails, so even if I paid another $10, I don't mind; they are good EV'ers.

Take care, and happy trails........Don


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