# Heater wiring



## crackerjackz (Jun 26, 2009)

Hi everyone . Im working on my wiring diagrams for my 2 x ceramic heaters  . Im looking to see if what i did is good for what i want ... I want the car to heat on the ac power when plugged in . But on dc power obviosly when unplugged . Ill add remote control input with timer afterwards ... 

Any help / input appreciated what im unsure of is if i need another ac relay on the neutral ac and - dc outputs of the heaters as this is common to both ? Could not putting a relay be dangerous to equipment ? 


Let me know what you think and if my picture is even readable lol


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## evmetro (Apr 9, 2012)

Are you planning to run an AC to 12Vdc converter for charge mode functions? I run two separate AC to 12Vdc converters in my conversions (laptop power supplies). That get powered up the moment that either of my 110 or 220 charge cords gets plugged in. My bms recognizes the presence of 12 volts that only occurs while the charge cord is plugged in and stops my controller from coming on for safety, but I also use this "charge mode" 12Vdc to run my logic relays, the water pump for the charger, my WIFI and Bluetooth, and more. It would be simple to wire a high voltage relay with a 12 volt coil that would switch between 144 VDC and 120 VAC with this system. I use two high voltage relays to separate my 110 from my 220 using this system.


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## evmetro (Apr 9, 2012)

This is how I would wire it with the AC DC converter system that I use in my builds. I would be concerned that a single 1500 watt element would be all that a 110 circuit would handle without tripping a circuit breaker, so I would limit it to a single element and perhaps wire it so that the element and charger could not run at the same time.


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## evmetro (Apr 9, 2012)

Here are the high voltage contactors that I would use. They are pushing it a little with the 144 VDC, but I have not had any problems yet on my 45 cell pack and one contactor per element, so caveat emptor... There are more appropriate contactors out there. 

http://www.ebay.com/itm/DPDT-Power-...865?pt=LH_DefaultDomain_0&hash=item2c7b959dd9

http://www.ebay.com/itm/JQX-62F-120A-12V-Coil-High-Power-Relay-12V-DC-/120770669896

If that link does not work, eBay for a jqx 62f 120a 12v coil high power relay. Less than 20 bucks each.


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## crackerjackz (Jun 26, 2009)

I already have the dc power contacts . They are solid state relays . Better at taking a beating from dc arcing . I dont mind passing dc through normsl contacts but dont want them opening or closing during dc use ... I might have a mix i can think of between your input pn things and mine ... Ill draw it tonight . As for the 12 volt power supplies they are unneeded for my case . I have a 12 volt agm battery and dcdc converter in the car running equipments ...


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## dtbaker (Jan 5, 2008)

evmetro said:


> Here are the high voltage contactors that I would use. They are pushing it a little with the 144 VDC, but I have not had any problems yet on my 45 cell pack and one contactor per element, so caveat emptor... There are more appropriate contactors out there.
> 
> http://www.ebay.com/itm/DPDT-Power-...865?pt=LH_DefaultDomain_0&hash=item2c7b959dd9
> 
> ...



the price on these is nice.... better than $50+ for the bigger contacter kits typically sold by the EV retailers. BUT, I am concerned with the 28vDC rating. How long have you used these without problems at 144v?

Its a little hard to see the guts, can you tell if there is a magnetic blowout? resistor, cap, and diode to prevent internal arcing?

latest inexpensive alternative I found was this:
http://www.ebay.com/itm/Solid-State-Relay-SSR-5-220V-DC-40A-Heat-Sink-/250672011513

but I have not tried one.... what do you think about this compared to the relay?


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## crackerjackz (Jun 26, 2009)

Gees those ssr relays are even cheaper then the ones i bought  ... Mine are rated 480 volts ac 40 amps ... I figured they be fine to handle my 160 volt dc max ... I hope i thought well but ill keep in mind the ones you posted if i have problems


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## dtbaker (Jan 5, 2008)

crackerjackz said:


> Gees those ssr relays are even cheaper then the ones i bought  ... Mine are rated 480 volts ac 40 amps ... I figured they be fine to handle my 160 volt dc max ... I hope i thought well but ill keep in mind the ones you posted if i have problems



I don't know much about SSR versus relays. I think the SSRs kick off more waste heat when in operation.... but I'm waiting for a comment from some of the EE types.


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## mora (Nov 11, 2009)

dtbaker said:


> latest inexpensive alternative I found was this:
> http://www.ebay.com/itm/Solid-State-Relay-SSR-5-220V-DC-40A-Heat-Sink-/250672011513


I have these same relays in my build. I've connected two 1500W elements behind one SSR. At 20A heatsink stays warm and relays have lasted for two years already. One single SSR is turning DC/DC on and off on demand. But I burned at least 5 of them when experimenting. 12V is minimum operating voltage. Yes, they somewhat close at lower voltages but that one (yes, one) fet inside the relay will remain in active region and will die very quickly even at small loads. 10A load and 5V drive voltage gave one SSR few minutes of life before it failed. Heatsink is mandatory. Factory heatsink surface is too rough. You need to wet sand it really smooth first. Then that relay will handle 20A. Maybe more if placed in path of good airflow.

Just some thoughts if OP ever gets similar SSRs.


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## crackerjackz (Jun 26, 2009)

You also should put heat transfer paste between heat sink and relay ...


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## dtbaker (Jan 5, 2008)

mora said:


> ... I've connected two 1500W elements behind one SSR. At 20A heatsink stays warm and relays have lasted for two years already. ... 12V is minimum operating voltage. ... Heatsink is mandatory.


mmmmm, I may just try these for the heater(s).... I don't like the open contacters much with the adding of the little bits and open to debris. I was thinking one SSR per heater core for a 'low' and 'high' heat setting.

no problem using 12v minimum on the relay side, in fact I spliced into the fan power on the swift build as an interlock because I did not want the heaters to ab ABLE to be on without fan air moving.

I've been using a similar SSR without a heat sink for my vacuum pump, it only runs a few seconds at a time and only pulls 7a I think, so really doesn't get very warm as far as I can tell.


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## mora (Nov 11, 2009)

crackerjackz said:


> You also should put heat transfer paste between heat sink and relay ...


Indeed. After sanding it flat. Heheh.


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## Casper10 (Mar 8, 2014)

crackerjackz said:


> Hi everyone . Im working on my wiring diagrams for my 2 x ceramic heaters  . Im looking to see if what i did is good for what i want ... I want the car to heat on the ac power when plugged in . But on dc power obviosly when unplugged . Ill add remote control input with timer afterwards ...
> 
> Any help / input appreciated what im unsure of is if i need another ac relay on the neutral ac and - dc outputs of the heaters as this is common to both ? Could not putting a relay be dangerous to equipment ?
> 
> ...


Hi crackerjackz,not wanting to tell you how to suck eggs,but this seems to be a very complicated way to warm your vehicle. I have used Topcools heater cooler system before for good results,I don't know how to add an attachment to this so go to: top-cool.eu and have a look,it's a very good and simple setup and you get a good heater and cooling to almost equal an AC unit it you desire. "manual built in car arco"


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