Heater for a cold climate

Technical discussion on converting internal combustion to electric
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Peter C in Canberra
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Heater for a cold climate

Post by Peter C in Canberra » Fri, 08 Aug 2008, 14:50

Hi, I notice that various people including kiwiEV have used the elements from domestic heaters with ceramic elements in their electric car conversions. In Canberra it is often in the range 0 to -5oC overnight in Winter. Decent defrosting and cabin warming are definitely required! Doing the sums, a resistive element that gives 2400W at 240V would give about 860W of heating with 144V from a typical battery pack. Is this adequate heating?
Thanks.
Peter.
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Heater for a cold climate

Post by Goombi » Sun, 10 Aug 2008, 21:31

If demist you require and need, why not incorporate a 12 volt hair dryer
12 volt 2 speed hairdryer will cost you 15$ add the switch to a dash and connect the drier outlet into to plunbing or set it up to where the water heater was(is) simple easy and legal. EV's should not have aircondition or heating --surely EV owners are a tough lot LOL

Peter C in Canberra
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Heater for a cold climate

Post by Peter C in Canberra » Mon, 11 Aug 2008, 04:18

I just looked at a few of these. They all seem to be 12Vx14A. I think that is the limit of the fuse on the cigarette lighter socket. That makes only 168W which sounds a bit feeble for when it's midnight in Canberra, there is frost on the windscreen, and fingers are cold. Still doing it with 12V rather than the high voltage appeals since it is coming into the cabin. I have found some mention of 12V cabin heaters that said the ones that plug in to the lighter are too feeble but higher wattage ones that are wired direct to the battery are better at several hundred watts.
Does anyone have direct experience of how much heater wattage approaches the heat available from a conventional cabin heater?
Thanks.
Peter.
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acmotor
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Heater for a cold climate

Post by acmotor » Mon, 11 Aug 2008, 04:27

Just looked in my SAAB handbook. Heater is rated at 5.3kW.
Interesting it is rated in kW not joules or BTU. I guess they think people understand kW ?
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Heater for a cold climate

Post by Rob M » Mon, 11 Aug 2008, 05:35

The heater element in the Triton ute is 1500W. It runs off the 240 volt system and is more than adequate. The elements are available from Canada or the States for about $50.
There is another system that heats a water container and the hot water is circulated through the existing heater system. Very easy to install but costs more.

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Heater for a cold climate

Post by Goombi » Mon, 11 Aug 2008, 05:41

acmotor
5.3 Kw = 5300 watt heat--- Sweded do like turkish baths LOL

Peter C in Canberra
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Heater for a cold climate

Post by Peter C in Canberra » Tue, 12 Aug 2008, 04:15

Hi,
I started this thread with a question but can now contribute with some experimental results! I got a variac set to 144V and plugged in a domestic 2400W electric blower heater. The fan didn't spin very vigourously but the flow was adequate. More importantly the air blowing out was encouragingly hot. Consequently, I think 144V across the resistive element of a domestic heater 2400W heater would be adequate in a cold climate.
Peter.
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Peter C in Canberra
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Heater for a cold climate

Post by Peter C in Canberra » Mon, 18 Aug 2008, 04:50

Me again, replying again to my own post. Having decided that 800W or so should probably be sufficient I was still a little uneasy about sending 144V DC into a hot confined space next to my feet. A fan failure and a meltdown could be nasty! Then I noticed there are a lot of 200W car heaters on ebay at the moment intended to run from the cigarette lighter, also with ceramic elements like the mains rated ones. I have ordered four. My hope is that these will fit in the space where the original heat exchanger was. I plan a set of four relays to allow 1, 2, 3, or all 4 to be turned on for variable heat. I'd wire them so that the fan has to come on at the same time as any or all heating elements are on. Obviously 800W is lots of amps at 12V so I'll need heavy cable and a sturdy 12V battery across the output of a DC/DC converter that is protected by current limiting. The worst case scenario would be an ice-on-the-windscreen I night needing defrost and headlights working.
Peter
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Peter C in Canberra
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Heater for a cold climate

Post by Peter C in Canberra » Tue, 02 Sep 2008, 01:02

Me again, replying yet again to myself. I hope someone else reads this and gains something from it!
I have sad news to report. I received my four 12V heaters from Hong Kong via Ebay. The vendor did honestly report that they only gave out a warm, not hot breeze. However, they are clearly not 200W as advertised. I measured the resistive element from each and got 3.0, 2.0, 2.0 and 1.5 ohms. With 12v that is more like 50 to 100W, not 200W. Even four of these would be pretty feeble heating. Thinking that perhaps the element has a temperature coefficient such that it reduces resistance as it warms up I also measured the current drawn by the best heater (100w calculated from resistance). It barely managed to draw 10 amps from a freshly charged car battery and didn't get any warmer being run in the car for 10 minutes. That is still only 120W. So, I will not be using these. Interestingly the element looks the same as a quarter of the ceramic element in the cheap Bunnings 240V heater that some people have recommended using with the main traction battery voltage.
They are quite neat as a unit to plug into the cigarette lighter and might suit someone in a warmer climate who doesn't really need a heater but has to have something sitting on the dash to satisfy a legal requirement for some way to demist the windscreen. So, let me know if you would like to buy one, knowing that they are pretty feeble heaters. They owe me $20 each.
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Heater for a cold climate

Post by Johny » Tue, 02 Sep 2008, 16:06

I, and I'm sure there are lots, am reading and learning from what you do Peter. keep posting. Sorry I am in Melbourne - I need kilowatts.

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Heater for a cold climate

Post by DVR » Thu, 04 Sep 2008, 01:17

Hi Pete, I looked into all those 12V things (heaters, hairdryers, kettles and such) also and gave up on them as being less than effective. There are some 300W hard wired onse around but the amps they pull are right up there. I think the 1500W/240V ceramic elements are a good/cheap way to go provided that you are comfortable with pulling the dash COMPLETELY apart to get to the heater core in a modern car. KIWIEV runs one however and now says that he will try to fit in 2 in the next car something like you planed to do with the 12V ones (New Zealand winters are cold too aparently)
The nature of those ceramic elements is such that as the temp rises,the resistance goes up until they stabilize. The up shot of that is that the more air you put through them the more heat you get out. Conversely if the air flow gets interrupted the resistance skyrockets and the current/heat drops. Remember that the element is mounted inside the old heater core which also used to get pretty darn hot anyway.
None of this helps tho if you are daunted by a modern dashboards/rubiks cube!!!
I'm in the process of designing/building a small hot water service that I plan on plumbing up to the original heater core. I've ordered a 1500W 120V element from the US ($50 ebay)and I'm also waiting on my solid state relays to arrive($27 futurelec.com). The plan it to use a thermostat ($4ea Jaycar)to regulate the temp to 70deg C and a bilge pump($20 ebay) to,....well...Pump!!Image
I still have to get an aluminum radiator spout and then I'll TIG up an aluminum tank to house it all.
Pretty much a DIY version of the off the shelf units like the ones metric mind supply only A LOT cheaper. If the temp remains stable it should work just the same as the original ICE heater only running the 120V element on pack voltage(144) means the element will now be 2160W so it will come up to temp VERY quickly Image
I'll keep you posted on the progress


So long and thanks for all the fish.

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Heater for a cold climate

Post by Goombi » Thu, 04 Sep 2008, 01:35

A TIP. Old espresso machines have hot water and steem. All you will need is a recirculating pump, mini preassure valve( espresso machine also have preassure valve and water tank).. problem solved.....

If   everyting was ever so easy... Image

Peter C in Canberra
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Heater for a cold climate

Post by Peter C in Canberra » Thu, 04 Sep 2008, 04:35

Thanks for the tips. I have my dashboard entirely pulled out and the heater box dismantled. My current plan (pun unintended) is to use two 240V wire elements with some modifications. I found two identical second-hand blower heaters with zig-zag resistance wire elements. I am crimping some copper strip along the edges of sections to put groups of wires in parallel to get a resistance of around 0.3ohm in each element. That makes each about a 12V/500W element.   I have a horn relay rated at 60A for each element which will be controlled by two LED-illuminated switches on the dash. The switches will be arranged to also turn on the fan so the elements can't get hot without the fan going. The 12V for the LED and relay will come from the supply that is only available when the ignition switch is on so I can't leave the heater on and drain the battery. The cable for the main current will be pretty hefty and go directly back to the accessories battery. I expect I will use a 500-600W DC/DC converter to keep the accessories battery charged. When both heater elements are on the DC converter will be supplying to its current limit and the battery making up the extra so the battery will have to be quite chunky. With the original heater the heat was turned off by flaps that closed off the hot water-filled heat exchanger and directed the air through a different path. I have put in screws though the side of the heater box so that the air path is always past the elements. Heat will now be controlled by whether I switch one, two or neither switch to control the two elements.
I think this should all work if I can remember how to put the dash board back together!
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Heater for a cold climate

Post by Goombi » Thu, 04 Sep 2008, 05:08

I am plesed for you to have made the heater 12 volt

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Heater for a cold climate

Post by Thalass » Thu, 04 Sep 2008, 21:42

I don't know if you can get it here, but in Canada they put special antifreeze-like stuff into the squirty bottle in their cars. It works great at melting the ice that forms while you're driving in -50°c - dunno how it'd go at a cm thick layer of ice, though.

I'll drive an electric vehicle one day.

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