Heater-- Demister

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Goombi
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Heater-- Demister

Post by Goombi » Sat, 23 Aug 2008, 16:32


Demister is compulsory in EV conversion.
This instalation can become easy or very complex.
I like to hear from you how you overcome the open element hot wires under the dashboard. and how successful and easy was the registration or aproval....


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Heater-- Demister

Post by a4x4kiwi » Sat, 23 Aug 2008, 18:28

Hi,
If you use a ceramic core heater, you lower the risk of fire as the hotter the element gets, the higher the resistance until an equilibrium is met.

I don't have mine registered yet so I cant comment on that side.

Mal.
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Goombi
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Heater-- Demister

Post by Goombi » Sun, 24 Aug 2008, 04:25


Have you looked under the dashboard? Or place a ceramic demist heater
under and amongst the lebyrinth of wires in order to do a good job the complete dashboard will have to be removed,does anyone know what is involved? I will not place a ceramic heater anywhere in there. Water heater is non-burning element. Anything that will melt insulations or worst don't belong there. so i decided to use a heater demister 12 volt mounted on top of the dashboard its directional produces 150w heat and fan and with the cars fan system it will work. I will demonstrate and prove it. Save a lots of work and it will be safer.
It takes about 10 min before the hot water heats enough to demist the window. this will be almost instant.. a winner i feel.


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Richo
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Heater-- Demister

Post by Richo » Sun, 24 Aug 2008, 05:04

The ceramic heating element a4x4kiwi describes is an air heater.
So it will be just as quick but safer than an "open element hot wire" heater.

I saw a brand new Hyundai Getz with the entire dash removed for the heater to be retrofitted.
They were keen!
If you'd only told them 3 months ago Goombi you could have saved them heaps of time Image
So the short answer is NO but the long answer is YES.
Help prevent road rage - get outta my way!

Goombi
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Heater-- Demister

Post by Goombi » Sun, 24 Aug 2008, 05:23

I belive he is using high voltage from the main batteries and is using 240 volt heater element I think that is asking for trouble.. only need few cobwebs..
Just as well the demister is not used very often.. but its the law.

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Richo
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Heater-- Demister

Post by Richo » Sun, 24 Aug 2008, 22:30

You have missed the point.
It is a ceramic element.
Ceramic heater
Using it from the traction batteries will mean it is more efficient.
So the short answer is NO but the long answer is YES.
Help prevent road rage - get outta my way!

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Heater-- Demister

Post by Goombi » Mon, 25 Aug 2008, 14:05

It is my understanding-- not to use high voltage inside the vehicle especially if the element has no correct voltage

What is efficient? 120 volt powering 240 volt heater?? give me a brake richo

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Heater-- Demister

Post by Goombi » Mon, 25 Aug 2008, 17:56

The safest and even cheapset will be to use a 12 volt kattle (Or small boiler with a small thermostat) with a small water pump and run the hot water through the heating system.Or just open hot water jug with a little pump-- or use a hasboard 12 volt heater/demister element directing hot instant air on the screen with the help of the cars FAN... Safe Instant and controllable..... The kattle seems like a good idea...

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Richo
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Post by Richo » Mon, 25 Aug 2008, 21:44

inefficient is running a heater through a DC-DC converter.
My understanding is that a4x4kiwi has rewired the heater to be "effective" with with his HV system.

So the short answer is NO but the long answer is YES.
Help prevent road rage - get outta my way!

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Post by a4x4kiwi » Tue, 26 Aug 2008, 01:43

OK, here is my logic.

Apart from the obvious care required of having +-300v in the cabin.

The core has 4 x 240v elements. I am running 150v per element (at 600v) max is 187 (at 750v) per element.

See http://www.specsensors.com/hph.asp for an overview of PTC heaters.

"...PTC High Power Heaters are compact heating devices that utilise ceramic PTC technology to act as the heating element. PTC thermistors are self-regulating elements and can operate at a nearly constant temperature over a wide range of voltage and environmental conditions."

This means it will run at or a little below its rated temperature.

I will be adding a temp cutoff switch to turn the heater off in case of over temperature.

It was cheap and easy to install, and is easily removed and replaced with something else if need be.

What I didn't do and should have is measured the air temperature while running off 240.

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DVR
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Heater-- Demister

Post by DVR » Tue, 26 Aug 2008, 04:32

1500watt 240V ceramic heater costs $25 @ bunnings.
Run that element @ 120V and it becomes 375W and will pull 3.125Amps
300W 12V ceramic heater pulls 25Amps and not very effective to use as a demister.Forget them!!!
12 volt kettles are typically 100-200 watts and they take 1/2 hour to boil 1 liter water.so again forget them also.
If you really want to build a little hot water system to run your original heater core than what you will need to do is run a 120V 1000-1500W element like this
http://cgi.ebay.com/ebaymotors/ws/eBayI ... 0244404239
on pack voltage it will pull 12.5 amps and use a thermostat to regulate the temp and a pump to circulate the waterwhich will pull about 1-2 amps minimum.

all this adds up to a fair bit of kit that will weigh more, AND will pull MORE amps than a ceramic element.
The Ceramic elemant is probably the simpelest mwthod exept for pulling the dash apart but it only give 375W per element at 120V but if you can squeeze 2 elements in then you are getting 750W which is not to bad and it only costs you 6.25A.
If the dash is a bit daunting then the HOT water service will be easier and probably be on par with the original ICE heater (oxymoron?) but it comes at a cost as far as amps are concerned @ 13-14Amps twice the ceramic method.
I'm toying with the pros and cons of these ideas myself as I'm doing a 2006 holden VIVA. meaning the dash is a rubiks cube. So the Hot water servise is looking good.
On the other hand I serfed into a complete workshop manual for the VIVA the other day that gives you a blow by blow breakdown on how to do it.. It's a HUGE document @ 100mb PDF Image
So I think the ceramic method might win afterall. It's lighter, cheaper and it will be less likly to fail.


So long and thanks for all the fish.

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Heater-- Demister

Post by acmotor » Tue, 26 Aug 2008, 06:39

Just keep in mind...

Supply for heater must be fused at the battery, say 10A 150V DC fuse.

Mechanical switch / contactor must rated at 10A 150V DC(not AC) and will be switching under load. Could use a mosfet / bipolar/ IGBT switch.

Wiring must be double insulated with no exposed terminals.

I say system must be grounded or have earth leakage detector.

Remember we are talking safety here.
If you can't make it safe don't do it.

Other than that, ceramic heater sounds fine. Image
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Heater-- Demister

Post by Goombi » Tue, 26 Aug 2008, 13:50

After i do a practical test in ev and my forester and compare the effectivness of both demisters..
EV will be foged up and the dasboard heater plugged in at the lighter socket and turnewd on with the car heater. The cigaret lighter is already fused.Timing will take plase and the same done to my forester. I will report if the EV was effective or not possibly next week.
Test done on ceramic heater require almost glowing element to produce enough heat--Why heating up the porcelain when you can do it directly
I am very reluctant to place any glowing unknowns under the dash unless one has a outo fire extinquisher. Dasboard heater is the go with the help from car fan.I have not used my demister in Forester don't remember when was the last time.. so , heater will be effectively a compolury item for the registration purposes.. and am sure it will work

Please wait for my test.

Is there such e thing as 96 volt charger to 12-13.8 volt battery ? or will it have to be designed? ( my system will be 96 volt) and I wish to charge my auxiliery battery up all the time from the main battery bank at 6-10 amp. Rather then use dc-dc.

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Heater-- Demister

Post by drowe67 » Tue, 26 Aug 2008, 15:05

I have u-bolted a 240V travel hair dryer into the box where the air conditioner evaporator used to go.

Image
Image

I settled on this approach for a couple of reasons:

1/ The air con box was easier to get to in my Charade than the heater core.

2/ I felt uncomfortable burying a hot element (even in the middle of the heater core) in the middle of my dash.

3/ The hair dryer is double insulated, sealed, completely unmodified. I am just running the AC wires straight out thru the firewall thru the air con pipe grommet, to be switched by a relay. I have no safety concerns as hair dryers are designed and tested to be held next to some ones head by a wet person in a bath room.

4/ I can further fan-boost the air flow as the air con box is in line with the heater fan.

5/ The hair dryer has a built in safety cut-out. I have tested this by blocking the opening. It stops before anything burns, and resets itself in a few minutes.

6/ I tested the system in the car and it worked well on low power at 240V (800W). Useful amounts of air delivered to the windscreen. Will test on 144VDC soon.

Is there any real safety problem placing high voltage wires inside the cabin as long as they are insulated to usual standards and meet the relevant EV standards for your state? We have 240VAC cables all over the average house and in general people are quite safe.

I get closer to my toaster every day than anyone will to my EV heater.....

Cheers,

David

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Post by Goombi » Tue, 26 Aug 2008, 15:22

Jolly good idea.. you can get 12 volt hair dryer too. save you fiddling with high voltage stuff... since the heater/demist compliance is mainly a legal forrmality....

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Post by drowe67 » Tue, 26 Aug 2008, 15:30

I did look into 12V hair dryers but wasn't sure if they would have enough grunt. It would be useful to test. Fan boosting them might do the trick - even luke warm fast moving air might be enough.

Also 800W @ 12V is 67A which would kill my little 12V acc. battery or DC-DC converter pretty fast :-)

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Post by acmotor » Tue, 26 Aug 2008, 16:50

Is anyone listening ?

The temperature safety cutout in a 240V AC hairdryer etc will not work on DC. It will arc and vapourise. Image
Do not rely on it. In fact remove it.
Try it (very carefully) if you don't follow me. You may be able to unplug the dryer before too much damage is done.

The appliances you mention are accepted under electrical safety standards because the supply 240V AC mains is earthed (neutral is connected to earth in the meter box) and a fault either blows a fuse or trips an earth leakage detector.
Whilst people misread NCOP14 or it in itself is not clear then you cannot rely on electrical safety standards extending to your EV.
( here I am saying that the habit of floating the traction battery is wrong and I will be taking this up with DPI )

A 'relay' needs to be rated at at least your battery pack voltage in DC not AC otherwise it will also vapourise.

Please listen to me here, I don't want you guys going up in smoke. Image
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Goombi
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Heater-- Demister

Post by Goombi » Tue, 26 Aug 2008, 17:08

You are absolutely right "acmotor" I was not quite sure using ac appliences on DC power. This is why I am going to stick with a 12 volt 150watt heater/demister and mount it in top of the dashboard. The whole thing looks like a speed detector gadget. can be plugged into your cig.lighter or hard wired .. the fuses are there and no dismantling of the dasboard...Oh what a feeling--barina

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Heater-- Demister

Post by Goombi » Tue, 26 Aug 2008, 17:19

The same will apply to ceramic heater or any 240 ac gadget..

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Heater-- Demister

Post by drowe67 » Tue, 26 Aug 2008, 19:29

Thanks for the advice acmotor - I will look inside the hair dryer and remove any AC-rated switching devices such as the safety cut out. Will also be sure to use a DC rated relay or solid state switch, and of course fuse the circuit. Omron G3NA-D10 looks good for the switch.


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acmotor
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Post by acmotor » Tue, 26 Aug 2008, 22:13

'67,
All good except omron G3NA-D10 Image

This is an AC (only) relay.
It probably uses a triac (bi-directional SCR). SCR being 'silicon controlled rectifier'.
Basically this is a diode that you can turn on via a gate pin but it latches on and can only be turned off by removing the current flow. This happens in AC as the current goes through zero and reverses 100 times a second for 50Hz supply.

If you use this on DC you will be able to turn it on but not off.

Control input for this relay can be AC or DC 3-30V but output switch is only AC.

You are on the right track to look at omron. They do some very nice DC relays but not many people do Solid state relays above 50V.

An Nanfeng ZJW100A Contactor, although an overkill in current, may be your best option.

All up, the heater demister is not going to be a $25 fix.

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Heater-- Demister

Post by drowe67 » Tue, 26 Aug 2008, 22:28

Sorry - typo in the part number. I meant G3NA-210, found it on the kiwiev site:

Image

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Heater-- Demister

Post by DVR » Tue, 26 Aug 2008, 23:51

Found this relay just now at Futurelec
SSRDC200V40A      SPST 0-200Vdc 40A DC Solid State Relay
$24.95

LINKImage

Futurlec
2 / 136 Broadmeadow Rd,
Broadmeadow,
NSW 2292
Australia

Fax Number - Local: 02 94 75 4051


So long and thanks for all the fish.

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Post by DVR » Wed, 27 Aug 2008, 00:52

Goombi, I don't understand your fear of ceramic elements.
I've never seen a Ceramic element glow red hot. Besides a 240 V 1500W element only puts out 375W @ 120V and 540W @ 144V so It aint gonna glow. These 1500W heaters are sold all over the place and typically the element is quite close to the safety grill. The heaters are made of plastic. The elements are held in place by plastic. The elements that EVPARTS.COM sell come in a molded plastic case. Sure it gets hot. That's what heaters do! they get hot.
Do you know what the original heater in your car did?
It got hot Image
Normally the element gets mounted inside the original core anyway and is therefore NOT in contact with any plastic, wires or anything that will burn.

NCOP14 state (quote) "A performance comparable to that of the original demisting system must be maintained." (unquote)
Those 12V heaters, kettles and hairdryers your talking about ARE PATHETIC at best.
You cant expect a 100-200W "mini" heater to compare with the original system your car had.

Think carefully about that.

If it's pulling the dashboard out that's your worry, try getting a look at a service manual for your car. The one I got for my VIVA breaks it down into small sections that a 1st year apprentice could follow. I got it for free but having seen it I would GLADLY pay the money for it.


So long and thanks for all the fish.

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acmotor
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Heater-- Demister

Post by acmotor » Wed, 27 Aug 2008, 01:06

That's good, now you are on to it with SSRs. These would make your ceramic heaters work. Image
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