Heater-- Demister

[DVR]

To have a succesful
EV --one has to sacrifice( without any excuses) all costly and power consuming comforts. Some combustion cars use up to 30% of power just to power the comforts. Air con, p/steer, 4 speeker stereo, power windows etc..

Hmmm let'see.........

The EV1 had A/C P/S Efficient heater/ABS/Electrically actuated brakes/Traction control/electric front widshild de-icer/rear window demister/Airbags/Successful?/Daytime running lamps/ Was it a successful EV? You bet! Every body on this forum would give one of their nuts for one.

Exotic? not really but if you think so how about the Blade Runner?

Blade runner Hyudai Get's? It has P/S, A/C, Heater, Airbags and a pretty reasonable stereo. Successful? yep and it's all pretty much DIY tech.

Bare bone cars are fine if that's what your budget dictates or what your into, but it isn't a prerequisite for a "successful" EV, not anymore, not by a long shot.

[acmotor]

DVR,
EV1, so why did they ...... never mind.

drowe67, That is my very point with supposedly insulated / isolated / floating traction battery pack. You don't know where you stand. You may think it is safe but a breakdown to chassis somewhere goes undetected and you get zapped.

[Goombi]

DVR..
Bare bone under $6000.. I will have some cash left to buy some luxury like nice cap perhaps.. and sheepskin seats covers are not surely going to destroy my frugal lifestyle.. I rest my case

Please visit my web page-- under continous construction
www.goombi.4t.com     

[DVR]

Goombi!!!! You can do it for under $6000 that's great good on you.
However I choose to spend 3 times that. I will have a near new car with 30K on the clock. It will have A/C, Power steer, electric windows, ABS, electric seats....the works. And I will be expecting at least 100Km range.

Just because YOU chose not to do that, that doesn't make me or anyone else wrong for doing it. Nor does it condemn us to failure. Just a bigger bill.

[Goombi]

Hello DVR,
I meant not to critisize anyone for making RR. Everyone is ite own boss and manager. Your well equiped car will no doubt give you as much pleasure as my basic one will to me I am sure. We all here have one thing in common, we are tryers and doers and however it will turn out we did it our way.. The exchange of information is important and the knowlege base is here and friendly people to boot. Everyone here is well meaning and helpfull.. so if you come across a little lopsided comment.. give it time it will all come good.. like a heavy froth head on e beer...

[DVR]

OK as promised here's an update on the heater I scored on EBAY.
I received my heater the other day and I must say that I think the $29.99USD + shipping it cost me was money well spent.
It is a 1500W 120V model and very small & robust as you can see in pic 1. I promptly pulled the thing apart and found inside a 120degC bi-metal thermostat which is the over temp protection. What I liked is the way that the thermostat is held in place by a plate that is fastened by 6 torx screws that also hold the element in place. Very tidy. I PARTICULARLY like the way the designers built in 2 extra slots for my 2 70degC thermostats I already had purchased
Very considerate of them I feel
In pic 2 you can see the 2 thermostats that are not wired are obviously the ones I added.

I'm currently in the process of modifying the bilge pump that I got for $16AU on ebay to make it suitable. As designed it sits on it's base and draws through a hole in it's base. What I need is one that draws through a spigot so I can hook it to a heater hose. In hindsight I should have spent more and got something that doesn't need modifying. Oh well, live and learn. When I've finished the pump I'll be talking that wrecker mate of mine next to work to "borrow" a complete heater box and 12 old batteries to test the rig. I'm pretty confident that the heater will work, I just hope that the thermostats can handle the 12VDC ?mA current that the solid state relay draws. THe spec sheet for them states the conrtol voltage range is 3-32V and the current draw is 28mA @32V. SO it HAS to be less than 28mA yes? I hope?

[avolt]

I put the heater core in my vehicle today, i bench tested it before i installed it in the vehicle and it was working very good on the bench, so i installed it and tested it out with 240v in the car,if it worked ok if should work half as good with 150v.
but,what I found was it seemed to be getting very hot,I could smell and feel the heater core was getting hot but the vent temp was not that hot!
I was thinking too much air is passing around the element or the element was not in good air flow,so I pulled it out again to check
and what I found was a possible problem but a easy fix using the tip over switch found at the bottom of the heater,remember the one!
(i have not done the mod yet but will)
it needs to be fitted to the air door so when you close the hot/cold lever to cold (which mine was closed and I did not notice it) because i did not have all the dash back together,cuts out the solid state relay so there is no problems.nothing happened to my heater box but if its under the dash and you didn't know something bad could happen.
I have done a drawing to show everyone just in case it happens to some one else.some heater boxes may be different.
hope this helps someone!



also I changed the heater core as shown so no air can bypass the element



I will test it tomorrow when the silicone dries.
I noted the resistance in the element went down to 10ohms when hot from 120 ohms ,all three elements.
if we had 144v and the resistance dropped to 10 ohms that's 14 amps and that should be a hot heater.
but in the real world we will see!

I also done some test on the heater core if a dry leaf or some thin paper got stuck in the element when it's turned on ,with good results
i will post photos later

cheers for now

[drowe67]

Nice work avolt, and nicely documented in the post above. Just what you need for those winter mornings in Cooma.

I also installed and tested my hairdryer based demister yesterday. I posted some photos on this thread (page 1 26 August) - u-bolting a travel hairdryer into the air conditioner box. The air con is much easier to get to than the heater core in my car. I used a 200V/40A solid state relay from futurelec.com (suggested by DVR) which were USD$30 each.

On 144VDC the hairdryer fan seems just as strong as 240VAC but the heat is less, which is just what I wanted, i.e. just enough heat for the job.     I like the idea that whenever the element is on, the hairdryer fan is on, and also the extra thermal insulation of the hairdryer body around that element.

Blows warm air slowly out of the demister vents, and can be augmented by the existing car fan. Draws around 6A at 150VDC. It's not really warm enough to count as a proper heater for the car, but would probably take the edge off a cold morning.

I rigged up the connections to the sold state relay so that both the ignition and the heater switch need to be on to make it work.

Re current draw at night with the lights (driven via a DC-DC) on and the demister I am drawing maybe 8A extra. At 55km/hr cruise the car only uses 37A so 8A is a fair bit extra. Still, I guess the demister will only ever run for a few minutes a day.

Cheers,

David

[avolt]

I did not end up using the tip over switch for the safety cutout from the heater,because I found this Honeywell micro switch was
easier to fit as you can see in the photo,the red wires come from the fan relay so the heater element can only be turned on
when the fan is on and the air door is in the hot position.



here is the heater installed and finished,
plus some warning signs just in case someone else plays around in there.



this is the dash mostly back together and testing the heater element with the fan speed on low 61c with 240v.
I think at 144v it would be around half that,so I will have to see how it goes?





this is my leaf test! I ran it for 1/2 an hour with the paper and dry leaf in the element,the original heater fan is blowing from behind the element and all three elements are on.
I done the test with the leaf and paper on both sides with no burning
at 240v 159c, so at 144v it should be even safer.
a in line air filter still would be a good idea
cheers for now

[acmotor]

Nice work but just be careful guys.
Don't try to switch the 144V DC directly with ANY 240V AC switches, thermostats, cutouts etc. They will arc destructively.
These AC switches can be used as sensors (operating 12VDC) for a 144V solenoid or solid state DC relay as it looks avolt is into.

Remember NCOP14 requires all components to be rated for the task and a 240V AC switch is not rated for 144VDC or anything like it.

[Goombi]

Why not use 12 volt to 240 v ac power inverter. How many watts will it take to run the heater? 700-1000 watts?? That will eliminate acmotor concern about non compatible parts.. Safest solution.. and as we know the heater and demister is only used sparingly..

And suddenly you will have Three Voltage currents running in your car.
240 fuse box etc. but its an option

[evric]

I have a spare 1500W 240V ceramic heater element if some one would like it. Cost $25.00 including postage in Australia.

[PeterS]

Hi all,

I've been sitting on the side here reading all the posts about 240V ceramic heaters, and operating them at lower DC battery voltages. I thought I'd better pass on my own experience, to prevent disappointment.

The fact is, ceramic heaters do not maintain a constant resistance. This means that calculations like halving the operating voltage will halve the current giving one quarter of the heating power, don't work. You will get much less current and hence much less power.

This statement comes from my own experience. I bought two Bunnings 240VAC ceramic fan heaters cheaply, one rated at 1800W and the other at 1500W. I mounted them both in the heater duct (one in front of the other) and powered them in parallel from my EV's 120VDC traction battery. I expected to get 1/4(1800+1500) watts; ie, 825W. In fact, the measured current flow is only around 2 amps, so I'm really only getting 2x120=240W. As a result, the 'heated' air is barely luke warm. For those contemplating using only one element, the air would hardly be heated at all.    

Another warning comes from my poor choice of element mounting position. The heated air passes along the duct and through the old heater core and a/c core. These act as heatsinks and it takes the luke warm air about 15 minutes to heat them up. During that time the air coming out of the vents slowly rises in temperature from cold. The only good thing is I can switch off the elements 15 minutes before the end of my journey but continue to run the fan, and extract the residual heat now stored in the old heater and a/c cores! I recommend you mount your element in the duct downstream of the old cores (assuming you haven't removed them).

I hope my experience is of some use.

[Goombi]

Thank you for your clear up statememt. I am disapointed for you. Acmotor has mentioned the possible complications in many previous posts re - 240 volt ceramic heater. I feel vindicated with my 12 v 150w dashboard heater demister. It works good and been proven.
This is what this chat is all about. "comaparisons"

[evric]

Question for avolt ... What brand/model of solid state relay did you use with your ceramic element?

[avolt]

Hi evric
the brand of the solid state relay is KUAN HSI type KS225
but i have to get other solid state relay to switch the heater,because this relay shown is for another project and uses 4 to 32v DC to switch the relay and can switch 240v 25amps AC
you must not use any AC relays to switch high DC voltage
i am still looking for the best price for solid state DC switching relays,when i find some i will let you know
cheers
avolt

[drowe67]

I am using the 220V 40A Futurelec SSR to switch my heater, USD$24.90 plus delivery.

[antiscab]

theres heaps and heaps of solid state switches on ebay

Matt

[evric]

Be cautious with the eBay solid state relays... most of them are switching AC (even when the title says DC) and those that switch DC are only transistor output instead of MOSFET output (these must be really old stock). The transistor output variety will require much more heatsinking for the same output current. Always check the specs (often not shown on the item description - search with Google for the specs before buying). The 40A MOSFET devices will not normally require any heatsinking when used up to about 10A.
Has anyone had success purchasing SSRs from FUTURLEC? I ordered some in August but they still have no stock even though the website showed and still shows that they are in stock.

[antiscab]

since they are just a transistor (i thought they would have used IGBTs) why would it matter if they are meant to switch AC or not?

Matt

[acmotor]

If a solid state relay (not mechanical relay) is labelled in any way as being for AC then it will not work on DC. (it will turn on but not off)

See this earlier post in this topic about AC SSR

Also.
A DC SSR will not work on AC. It will either let smoke out or only switch on one half of the AC cycle.
Two DC SSRs can often be used (one reversed) to switch AC. But why would you ? Just use an AC SSR.

Many SSRs are DC input 3-32V. But this has nothing to do with the output. You must look at that label as well. Check earlier in this topic for more info.

Beware the ebay offering. Check the picture. Most 100V+ DC SSRs are 3 to 5 times the AC SSR price. Note also the DC SSRs are more vulerable to overvoltage or damage from being connected to AC so 'used' may not be advisable.
Back EMF from switching inductive loads is a big killer of DC SSRs.
Most modern AC SSRs are zero voltage switching types (switch when the AC waveform is at zero volts) and have little trouble with back emf.

[Trubbleguy]

what about using a 100watt sealed beam unit shining against a flat black two layer grille of aluminium mesh with a fan pushing the air past the beam unit, through the heated mesh and up to the dashboard, i used to use a lower watted car headlamp with a switch selecting either high or low beam to melt chocolate in a Mr Whippy van, the heat was incredible and near on instant when used. and i believe the power drain would be much less on a ev..

go out and stand in front of your 55watt car headlight and feel the heat from that, hold a sheet of aluminium foil in front and then some thats been painted black from a spray pack, black side to light source and see what im talking about.
I think it bears looking into as an alternative heater unit.....

[Goombi]

I like that..

[Johny]

I have been gradually buying inexpensive stuff from eBay for my AC conversion's Dynamic Brake resistor controller (because I want total control over cut in and cut out voltages) - and for my Ceramic element heater control.

Essentially this is smallish IGBTs (72 Amp), Gate drivers, optocouplers etc. and some power supply PWM controllers and do-dads that I already have.

At the moment I have a 50K pot (conventional or slider) controlling the PWM pulse width from 0 to 95% with the first 15% of the pot travel guaranteed to be NO pulse output. The whole things runs from the fan 12 V.

Now a question.
Is there any point having continuously variable control over the heater element?

With just On/Off I could probably get rid of the DC-DC convertor, use a slower optocoupler and gets the parts costs to around $15 (excluding a box). I.e. - Emulate a 700 VDC Solid State Relay.

With a PWM controller, fast optocoupler DC-DC it's about $35 parts (no box).
The advantage is that I can use a high wattage element(s) and get lots of heat fast then back it off rather than just turn it off.

BTW This control could also be used for DC conversions if anyone wants variable heat control.

Comments - is anyone interested?

[Peter C in Canberra]

I would have thought that the most control you would want might be about three settings, low/medium/high heat. That might be arranged easily with a switch for three elements. I think the mains ceramic heaters have several elements in series if sold to 220/240V countries and parallel for 110/120V countries. That would allow one or more to be simply on or off. I have ended up with just two elements, and two switch. I will be choosing just one or both. Unfortunately, while that seems likely to be adequate in theory, it has not been tested yet because the car is not finished.