# In car heating options



## favguy (May 2, 2008)

Hi all,
Just wanted your thoughts on in car heating/demisting, I'm thinking about using a high powered hardryer, 2000watts, 110/120v US model or such chopped up and modified to fit in my heater duct in place of the original heater radiator core. Seems a very low cost option compared to ceramic.

I've got 2 questions though, 1, my system is going to be 144v, so will this kill the thing, or will it have enough tolerance to survive (I suppose I could run it on a mid setting?) and 2, have any of you tried this and got any feedback to give me on success or not of said option! the heater won't get used much in any case, as climate here is quite mild.

Many thanks

Paul


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## grose (Apr 30, 2008)

How is that going to work seeing that the hair dryer is AC power? Are you going to run an inverter or does this work on DC too?


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## KiwiEV (Jul 26, 2007)

I've wondered that too. The heater elemant in the hair dryer will work with DC ok (although the voltage _may_ be an issue), but the built in fan will not work with DC. 
So you'll have to replace the hairdryer's fan with a DC one, or run both hairdryers off an inverter. Make that a real _grunty_ inverter if you need to run 2 x 2000 watt devices.


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## JimFritzMI (Jan 9, 2008)

Maybe I'm missing something, but, if you're doing a conversion wouldn't you just use the existing blower motor?

---
Jim


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## Dennis (Feb 25, 2008)

> I've wondered that too. The heater elemant in the hair dryer will work with DC ok (although the voltage _may_ be an issue), but the built in fan will not work with DC.
> So you'll have to replace the hairdryer's fan with a DC one, or run both hairdryers off an inverter. Make that a real _grunty_ inverter if you need to run 2 x 2000 watt devices.


Actually if you tear apart a hair dryer you will see that it uses a DC motor. There is a rectifier bridge on the motor terminals itself that changes the AC to DC. At least the hair dryers I have torn apart.


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## favguy (May 2, 2008)

Jim,
existing blower will work fine, but provide no source of heat!

Re AC, oops, didn't even think about that one  of course hairdryers are AC, if they do run a DC motor with a rectifier, that'll be great, I can strip it out.

Thanks for all the input so far, so has anyone actually used a hairdryer for this?


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## JimFritzMI (Jan 9, 2008)

I realize the existing it won't generate heat. I just meant that we could ignore the hair dryer's motor, as it isn't needed. As a side note, instead of a hair dryer you might try a heat gun. For those who can use Harbor Freight as a source, they routinely have 1500W heat guns on sale for $8-9.


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## favguy (May 2, 2008)

Yes,
I thought about a heat gun, until I switched on the one I have and realised it would be far, far to hot!! even on the low setting I think it would melt the surrounding plastics, 

Hairdryers rely on a continuously running fan to provide airflow and regulate the temperature, without it the element burns out, however, you might be on to something, as if the element is set in the airflow and only turned on with the blower fan it could work but would have to be able to channel all the air through a small area which I'm not sure is possible, I was thinking more simply of leaving the existing hairdryer fan and main housing in place setting it in the space were the heater matrix was and letting it blow hot air into the ductwork complete with any cold air as needed drawn in by the existing blower fan control giving heat control, if you see what I mean!!


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## JimFritzMI (Jan 9, 2008)

I agree it gets very hot, but don't allow the heater element to be on without the blower running. Besides that, if you were to ever take your heater core apart while the engine is running you will find that the heater core is going to be exactly (within reason that is) the same temperature as the main radiator which can get very hot. If you follow KiwiEV's example it is going to dissipate the heat enough, even if the fan and heater are turned off, that I wouldn't worry about the plastic at all.

Now if the control fails and the heating element runs away, not a pretty thought, mini china syndrome. Don't worry it won't melt through to China though, it'll stop once it reaches the limits of it wires, or it's started a fire. So, some sort of thermal protection has to be included in some way, in case the blower motor takes a dump.

Would a fuse be enough? How about a thermistor? I don't now that answer, anyone?


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## favguy (May 2, 2008)

Hairdryers have a safety cutout in front of the element for just that event, if you block a hairdryers air input by placing your hand on the back, the element will get much hotter and glow bright red after a few seconds of this it will switch off, after cooling down it will reset and work OK again, so I like this safety feature! 

It will be wired to come on only in the event of the main vehicle blower fan being on and the heat control being moved over from the cold position towards heat (via microswitch) this in turn will activate a relay to apply the 144v supply, fused appropriately 

I've done some more hairdryer research now and discovered I can use a UK 230v hairdryer to get lots of heat. this also avoids the possibility of early failure by overvolting a 110v unit. 

My system will use 144v, this is just under 2/3rds of the hairdryers voltage, a high power hairdryer 1600/2000w usually has 3 settings, the second setting still puts out a high volume of very hot on a dryer of this power, all the 2nd setting does is limit the voltage to the heater element and motor by around 1/3rd, so running 144v to it directly to the element and motor (handle will be cut off for fitting) it will run at just under 2/3rds full power, which hopefully will be plenty. 

As for the AC/DC issue, most hairdryers do indeed use diode rectification at the motor, so these will be removed and the motor will run happily on DC

Right, I'm going hairdryer shopping, need to find one thats not too fat, that will fit in the heater core space!


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## Twilly (Jan 22, 2008)

Maybe Im missing something... A Hairdrier uses a wire-wound heating element which would be very dangerous if it came into contact with the plastic plenum of the car... I bought a 1500w ceramic heater at wally world for 12 bucks, took out the element and high temp surround, which made it very easy to mount on the existing heater core... Heats my mid-sized car better than the original heater did... ...But I cant take credit for this, I think I got the idea from Kiwi!!!...Ill attach some pictures


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## favguy (May 2, 2008)

Hi Twilly,
You are quite correct that if the element is stripped out it could be very dangerous, but it depends on how it's being installed and what installation is possible, I'll post some pics for you all to see when I've done mine, not all cars will lend themseleves to this arrangement but mine does, the element is not actually removed from the hairdryer main body, this is kept therefore housing the element in the original heat resistant plastic with the original metal safety grill on the front, the hairdryer also retains its thermal safety cut out in case of overheating. This in turn will be mounted in a steel frame mounted within an end box screwed to the plenum chamber opening on my car. For addeed safety, it will be wired to only run with both the cars main blower on and the heat set to the hot position. It sounds weird, but you'll understand when you see the pics in a few days 

(Don't worry, I'm a qualified Electrician, have studied control & systems technology at college and restored classic cars from near scrap to concours winners in the past, I'm not about to "bodge" anything. )

I've just sourced a new dryer with the right dimensions and power for the job along with suitable component box and screws/bracketwork to build it. The hairdryer has a 3 year warranty, which although will become invalid of course, proves its built to run everyday for at least 20 minutes for 3 years (from what I've seen of female hairdryer use anyway ) so should be robust enough to last the course with occasional winter use in the car and the best part it only cost £10 on sale!! (Can we all say Babyliss !! lol)

Regards

Paul


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## Ace_bridger (Nov 22, 2011)

Hey Paul,

Hair dryer thoughts before I go and blow mine up!! There was ice on the inside of my windscreen this morning so i had to run an extension lead out to the car to run the hair dryer...ice was gone in 5 mins.

Anyway, my thoughts...which are thoughts and NOT facts!!

1) No need to remove the rectifier as if you stick DC into a rectifier you'll get DC out.
2) I'm going to keep the hair dryer intact and have it in the cab. Mainly as_ I don't believe _that the hari dryer will be able to push much air through the complex heater ducting in the car. I don't think it would provide much warm air to the vents

I'm not bothered about bringing pack voltage inside the cab. I have a voltage meter in the cab so no difference.

If one is happy to hold a hair dryer (normally with wet hands and wet hair) with 240Vac supplied to it then I'm happy to have the dryer in the cab running on 144dc (more like 158Vdc max).

Maybe I'll repost once I'm done advising against all of this!!! 

Wish me luck!!


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## Ace_bridger (Nov 22, 2011)

I just connected up the little 110/240V Bayliss hair dryer to the 160Vdc pack.

As I am a little conservative I trialled the hair dryer on the 240Vac setting and it ran fine, perfect in fact. The fan was running at normal speed and I estimate the heat output to be somewhere around 60-70% of what it kicks out on 240Vac. Plenty to demist the windscreen and warm the cab up slowly.

I said to myself "it works so don't push your luck and try it on the 110Vac setting".

So, I switched the ignition off, changed the setting on the dryer to 110Vac and switched the ignition on again. The hair dryer ran slowly and the indicated pack volts dropped to 60V. So, I switched off the ignition and put the hair dryer back on the 240Vac setting and switch the ignition back on. Everything worked fine again so I'll leave it alone and lap up the luxurious heat I now have!!!

For reference, I connected the hair dryer to the main contactor so that the dryer is switched by the ignition.

No more ice on the inside of the windows...hopefully!!


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## favguy (May 2, 2008)

Hi Ace,

I'm not quite following you on this one. You say when you used the dryer on it's 110v setting, it ran slowly and your pack voltage dropped to 60V?? I can't imagine how a load this small could drop the pack voltage from 144v to 60v unless it was completely flat! 

Also on the hairdryers 110v AC setting, it should run at full heat and speed as 144vdc is near enough the same as a 110v AC rectified input. It should only be down on power and speed if it were run at the 230v setting??


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## MalcolmB (Jun 10, 2008)

I use a hairdryer as well, a 110V/1500W model running at 80V DC. I installed it behind the dash so I could duct it straight into the demister vents and keep the ducting runs as short as possible. It's a bit wimpy running at 80V, but works at least as well as the original mini heater (in other words not very well). It's also a lot lighter than the original heater and frees up some legroom.

I've noticed there are lot of "ceramic" hairdryers available today. Does anyone know if these use the same PTC elements as the larger ceramic heaters, or is it just marketing speak?

Just a note of caution for anyone wanting to use a hairdryer as a heater. The thermal cut-out on mains-operated hairdryers is rated for AC use and could easily weld closed when used with DC. I rewired mine to bypass the thermal cut-out, so the heater supply goes straight to the heating element. Then I wired the cut-out in line with the coil on the contactor that I use to switch the heater supply on and off. This way the cut-out only has to switch 12V DC instead of full pack voltage.


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## Ace_bridger (Nov 22, 2011)

favguy said:


> Hi Ace,
> 
> I'm not quite following you on this one. You say when you used the dryer on it's 110v setting, it ran slowly and your pack voltage dropped to 60V?? I can't imagine how a load this small could drop the pack voltage from 144v to 60v unless it was completely flat!
> 
> Also on the hairdryers 110v AC setting, it should run at full heat and speed as 144vdc is near enough the same as a 110v AC rectified input. It should only be down on power and speed if it were run at the 230v setting??


I've been digesting last night's events today, when I should have been thinking about work, and I think there's a chance that I have a poor connection somewhere.

Will investigate and try on 110V setting again. But even on 240V setting today it was great to have some warm air in the car!! I switch the dryer off after 10mins as I diodn't need it anymore...windows were clear and I was warm.

I'm tempted to just leave it running on 240v setting and not risk blowing the dryer up...I know that I will try it on 110v setting as I won't be able to avoid tinkering.

I'm not planning to mount the dryer in the dash as I believe the fan is not really man enough to provide decent volumetric air flow to make it through the length required through the hoses.


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## Ace_bridger (Nov 22, 2011)

Correct me if I'm wrong (really, don't hold back!) but if I am running a 240Vac hair dryer on DC then the DC voltage which would be most suitable would be that which is equivalent to the RMS value of 240Vac peak to peak...so,

Vrms = Vp-p/(sqrt2)

Vrms = 240/(1.414)

Vrms = 169.7V

I've heard, and thought myself, that you can run a 110/120Vac hair dryer on 144Vdc but I think that to be wrong now...have I got this wrong?

I'm running mine on the 240Vac setting with a supply of 140-160Vdc and it runs fine...switching to the 110/120Vac setting seems illogical now and I think that it will probably blow the poor thing up.

On a side note...my little travel hair dryer is fine for demisting the windscreen but doesn't do much to heat me up. My better half has recently gone for a short hair cut and no longer uses her larger more powerful dryer...seems a shame for it to be just lying around gathering dust!!


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## lifeinhd (Jan 10, 2009)

I'm also curious as to the best way to heat a car. I'm considering a hair dryer/ceramic heater to go inside the heater core, but I was also thinking about pumping hot water through the core. Perhaps with one of those tankless water heaters, made for home use that can run on propane? I'm converting an S10, the propane tank would go in the bed when needed, and be easily removed when not. I just don't know what would happen if I tried to pass hot water through a water heater-- maybe that would that create hot-water-inception?  I also don't know how long a tank of propane would last in this application. Still in research stages obviously . I didn't know if anyone else had come up with a simple and cheap method of heating water and passing it through the existing heater core?


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## TEV (Nov 25, 2011)

lifeinhd said:


> I'm also curious as to the best way to heat a car. I'm considering a hair dryer/ceramic heater to go inside the heater core, but I was also thinking about pumping hot water through the core. Perhaps with one of those tankless water heaters, made for home use that can run on propane? I'm converting an S10, the propane tank would go in the bed when needed, and be easily removed when not. I just don't know what would happen if I tried to pass hot water through a water heater-- maybe that would that create hot-water-inception?  I also don't know how long a tank of propane would last in this application. Still in research stages obviously . I didn't know if anyone else had come up with a simple and cheap method of heating water and passing it through the existing heater core?


Seems like the hot water heaters are the best, electric hot water heaters, no propane.

You can DIY :
http://www.diyelectriccar.com/forum...ct-26520p39.html?highlight=brian's+conversion

Or go Pro :

http://www.diyelectriccar.com/forums/showthread.php/mes-rm3-heaters-ebay-81229.html


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## PStechPaul (May 1, 2012)

Ace_bridger said:


> Correct me if I'm wrong (really, don't hold back!) but if I am running a 240Vac hair dryer on DC then the DC voltage which would be most suitable would be that which is equivalent to the RMS value of 240Vac peak to peak...so,
> 
> Vrms = Vp-p/(sqrt2)
> 
> ...


The 120/240 Volt ratings are RMS, so the same voltage DC will produce the same heat. A hair dryer or heat gun might be good for quickly defrosting the windows, and in fact it may be useful to keep it intact and have it plug into an outlet on the dash, so you can direct the heat where it's needed. But otherwise I think a heater made for long term use may be better. 

And for just heat, a propane fueled heater is nearly 100% efficient, and would not reduce the range from battery draw. However, there might be an issue with CO emission or O2 depletion, and possibly excess water vapor.


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## lifeinhd (Jan 10, 2009)

TEV said:


> Seems like the hot water heaters are the best, electric hot water heaters, no propane.
> 
> You can DIY :
> http://www.diyelectriccar.com/forums/showthread.php/brians-ev-conversion-2-saturn-project-26520p39.html?highlight=brian%27s+conversion


I quite like that "DIY" solution. I haven't read through the whole thread yet, I'm just a tad concerned how much of an impact that would have on range. But getting a complete system for maybe $100 (less if I can reuse the fuel pump from my S10)... that's tempting


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## Randen (Apr 23, 2012)

Some twin engine aircraft had a gasoline fired heater. They put-out a huge amount of heat. For someone in a very cold climate could enjoy one of these. The down side, cost, wouldn't be cheap and it uses gasoline albeit very little. Upside, for the automotive application It would turn your car into a rolling sauna.No impact on the range.
My S-10 EV has two systems one a heat pump, reversible air-conditioner. Second a diesel fuel powered water heater for temps lower than 40Deg F. The heatpump is very slow but if the vehicle is being pre-heated while still on the charger who cares, The upside to the heat-pump is its very efficent better than twice the amount of heat for the same amount of power.

For the DIY a company masterdyne makes a dc powered compressor (three phase with a inverter) which can be integrated to a cars exsisting air-conditioner with the addition of a reversing valve (inexpensive HVAC device) a very nice heat-pump with air-conditioning for the summer. The complete system could be about $2000.00 but here in Canada having your automoive air-conditioner repaired can cost you that.

Randen


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## Ace_bridger (Nov 22, 2011)

PStechPaul said:


> The 120/240 Volt ratings are RMS, so the same voltage DC will produce the same heat. A hair dryer or heat gun might be good for quickly defrosting the windows, and in fact it may be useful to keep it intact and have it plug into an outlet on the dash, so you can direct the heat where it's needed. But otherwise I think a heater made for long term use may be better.
> 
> And for just heat, a propane fueled heater is nearly 100% efficient, and would not reduce the range from battery draw. However, there might be an issue with CO emission or O2 depletion, and possibly excess water vapor.


Agh, yes, of course...I figured I must have got something wrong...and I did!! Thanks for putting me right.

My new crimpers arrived today so I re-crimped the hair dryer connections and tried it again on the 120Vac setting. The pack had been charging for a couple of hours after I drove it home from work and the pack was at about 150Vdc ish. The dryer ran fast and hot chucking out loads of heat. The element was glowing red in one spot but no redder than my mum's old dryer with my hand over the air intake!

I now have two heat settings 1) Hot - on 120Vac setting and 2) Warm - on 240Vac setting.

For £9.99 ($13 ish) delivered I'm very happy with the heating solution and see no reason to go for anything else more expensive or complicated. True, it is quite mild here down on the south coast of the UK but that little dryer will keep me warm and my windows clear...as long as it survives the full pack voltage of 158-160Vdc.

KISS


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## Turbotom (Jul 13, 2008)

Here is a good article on using the air conditioner system as a heat pump. Like Randen said very efficient you get 2 to 3 times as much heat as you put energy into.
http://www.ep.liu.se/ecp/057/vol13/014/ecp57vol13_014.pdf


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## Caps18 (Jun 8, 2008)

Maybe next Fall I will look into putting heating pads under the seat covers. Then adding a 1500W AC heater that could be plugged in at home for a few minutes prior to leaving, but I'm not sure about how that would do. If it was plugged into the battery, it might use up too many amps. If I find a smaller version, it might not heat enough to make much of a difference. This will be kept in my garage, so it will start in the 40s anyways.


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## Hollie Maea (Dec 9, 2009)

Just a quick aside, if you are calculating for hair dryers, remember that power is proportional to voltage squared, so if you were running at 2/3 voltage, your power would be 2/3 squared as much--about 44 percent.


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## dtbaker (Jan 5, 2008)

whether you go with ceramic heater cores in the ducts, in the old heater core location, or hot water..... you still have to use a substantial (expensive) dc contactor to turn'em on and off!

anybody have luck finding a reliable switch/contactor safe at 120v-160v DC for cheap? I'd be interested to see how different people have solved this, included any way to 'soft-start', or anything like that?


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## PStechPaul (May 1, 2012)

As long as the load is resistive, a contactor designed for AC should work on DC. To be safe, you can connect two or three contacts in series. Here is a 25A 3 pole contactor that should work, for about $38:
http://www.mouser.com/ProductDetail...iMZZMtGt%2bn33CgIP%2bxY6jp/uHkQ%2bw2snfQl7HM=

It has a 24 VAC coil but you can use 12 VDC if you lower the current when the contacts pull in.

I also found some power relays with a magnetic blowout option which are rated for 20A at 125 VDC, with 24 VDC coil:
http://www.mouser.com/ds/2/307/090600_OMRON_MGNdatasheet_J33I-E-01-11435.pdf

They are about $40:
http://www.mouser.com/ProductDetail...GAEpiMZZMtSzCF3XBhmW7fELP9VVnSFAVo/%2bXRBT3o=

This one also has a magnetic blowout option for 120 VDC at 10A:
http://www.mouser.com/ds/2/357/105A_788-2979.pdf

About $15:
http://www.mouser.com/ProductDetail...=sGAEpiMZZMtSzCF3XBhmW7hD2yG6BBqjRa9op8TsdsE=


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## dtbaker (Jan 5, 2008)

PStechPaul said:


> As long as the load is resistive, a contactor designed for AC should work on DC.


absolutely not true, or safe.

breaking 30 amp load DC is a lot different than AC! using a typical condition of a 3000 watt heater in a 120v pack (sagging to 110v), the contactor has to be able to break 100v to 200v at 30 amps minimum without welding itself together. Furthermore one must keep in mind that the first few seconds, a ceramic heater (or 2 x 1500) rated at 3000watts is likely to pull double that until temp rises.

so... yeah we're back to the typical 30-50 amp contactor 250vDC max w/ magnetic blowout that's about $50.... anybody found anything better/cheaper?


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## EVfun (Mar 14, 2010)

PStechPaul said:


> As long as the load is resistive, a contactor designed for AC should work on DC.


NO, AC passes through zero volts, typically 100 to 120 times a second. That is a lot of chances to extinguish the arc that don't happen when breaking DC. 

If you are trying to use an AC breaker in a DC system the AC voltage rating should be at least 4 times the DC voltage you need to break. Even then you should proceed with caution, particularly if you may have to break a lot of current.


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## PStechPaul (May 1, 2012)

I agree that it can be risky to use an AC relay on DC, but usually contacts rated 125 VAC are OK for 30 VDC, and several contacts in series should be OK. It may also be worthwhile to consider using a small IGBT which can be triggered with 12 VDC.

http://www.ebay.com/itm/IRG4PC40U-IGBT-FAST-600V-40A-TO-247-IRG4PC40-Qty-5-NEW-/190779684331 ($3/each)

http://www.ebay.com/itm/QM100HY-H-IGBT-POWEREX-TRANSISTOR-LOT-OF-10-PCS-/150761160532 (100A 600V $4/each)

And here is a SSR from China that claims to be good for 220 VDC at 40 amps, including a heat sink and free shipping, for about $12!

http://www.ebay.com/itm/Solid-State-Relay-SSR-5-220V-DC-40A-Heat-Sink-/250672011513


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## dtbaker (Jan 5, 2008)

PStechPaul said:


> I agree that it can be risky to use an AC relay on DC, but usually contacts rated 125 VAC are OK for 30 VDC, and several contacts in series should be OK. It may also be worthwhile to consider using a small IGBT which can be triggered with 12 VDC.
> 
> http://www.ebay.com/itm/IRG4PC40U-IGBT-FAST-600V-40A-TO-247-IRG4PC40-Qty-5-NEW-/190779684331 ($3/each)
> 
> ...



the SSR looks interesting, and at $12 is indeed a little less than the typical contactor w magnetic blowout one might find to handle the 40 amps at 100-200vDC load w/ 12v control.

I don't see how the other two would be useful, but the SSR seems interesting. Can any other EE types chime in on pros/cons of contactor versus SSR? I am wondering a little about the need for a massive heat sink?! Although I guess if it were mounted inside the cabin it wold provide a little extra heat when on!


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## F16bmathis (Jun 6, 2008)

lifeinhd said:


> I'm also curious as to the best way to heat a car....core?


I made a heater core using two ceramic heaters from two $20 ceramic heaters from a hardware store. Busted them open, removed the ceramic heaters (which you can buy for $150 ea from EV vendors) and mounted them on an aluminum plate I made up, stuck it in place of my trucks original heater core and wired it to a HV DC relay. Instant heat using the trucks original fan and controls! 18 amps DC at max power, nothing compared to racing down the highway at 75MPH!

I also wired it so it won't turn on if the fan wasn't on as it would melt the plastic ducts.

www.evalbum.com/1752


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## ruckus (Apr 15, 2009)

I am thinking heated seat-covers are a good first step. They draw WAY less energy and keep your core toasty warm. 

After that, a little blower on the toes and one on the windshield.

Conduction is far superior to convection. You can test this by standing near a wood stove. You will feel some heat (a mix of convection and radiation). Now place your hand on the stove. YOWCH! Which is better at transmitting heat?


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## rochesterricer (Jan 5, 2011)

F16bmathis said:


> I made a heater core using two ceramic heaters from two $20 ceramic heaters from a hardware store. Busted them open, removed the ceramic heaters (which you can buy for $150 ea from EV vendors) and mounted them on an aluminum plate I made up, stuck it in place of my trucks original heater core and wired it to a HV DC relay. Instant heat using the trucks original fan and controls! 18 amps DC at max power, nothing compared to racing down the highway at 75MPH!
> 
> I also wired it so it won't turn on if the fan wasn't on as it would melt the plastic ducts.
> 
> www.evalbum.com/1752


So two 1500w elements are warm enough for you in a Wisconsin winter? I've seen a number of people say you need 4 in a climate like ours.


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## lifeinhd (Jan 10, 2009)

rochesterricer said:


> So two 1500w elements are warm enough for you in a Wisconsin winter? I've seen a number of people say you need 4 in a climate like ours.


A single cab truck has less volume to have to heat than most other conversions, so I could certainly imagine two being plenty.


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## mora (Nov 11, 2009)

dtbaker said:


> Although I guess if it were mounted inside the cabin it wold provide a little extra heat when on!


Yes, extra heat to melt cable insulation touching the heat sink. Those small relays won't handle 40A continously. 20A if heatsink is used and both contacting surfaces sanded really smooth. 40A might be possible if placed on path of continous airflow. I've thought about placing mine inside air intake duct.

It was -28C (-18F) here today. 135V to four 110V/1500W heater cores at 35A kept outcoming air was warm enough. At 144V the same elements draw about 40A total and car gets nice and warm even quicker.


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## F16bmathis (Jun 6, 2008)

Twilly said:


> Maybe Im missing something... A Hairdrier uses a wire-wound heating element which would be very dangerous if it came into contact with the plastic plenum of the car... I bought a 1500w ceramic heater at wally world for 12 bucks, took out the element and high temp surround, which made it very easy to mount on the existing heater core... Heats my mid-sized car better than the original heater did... ...But I cant take credit for this, I think I got the idea from Kiwi!!!...Ill attach some pictures


This is the way to go! Although depending on how cold it gets, I'd use two. Either way, it uses the cars original heating ducts, can be wired to produce 750 or 1500 watts of power (1500-3000 using dual) and electricity use isnt much comparing it to actually driving.

The safety feature of ceramic heat is the ceramic heaters only heat up to so much, I forget what, but won't keep getting hotter and hotter like a hairdryer. Heaven forbid the hairdryers safety switch isn't in the right place when installed...


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## F16bmathis (Jun 6, 2008)

rochesterricer said:


> So two 1500w elements are warm enough for you in a Wisconsin winter? I've seen a number of people say you need 4 in a climate like ours.


I've got two, and I have to turn it off even at 20 degrees outside. It just gets too hot!


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## F16bmathis (Jun 6, 2008)

dtbaker said:


> the SSR looks interesting, and at $12 is indeed a little less than the typical contactor w magnetic blowout one might find to handle the 40 amps at 100-200vDC load w/ 12v control.
> 
> I don't see how the other two would be useful, but the SSR seems interesting. Can any other EE types chime in on pros/cons of contactor versus SSR? I am wondering a little about the need for a massive heat sink?! Although I guess if it were mounted inside the cabin it wold provide a little extra heat when on!


I first used a HUGE DC relay and connected both contactors so it'd have twice the distance to arch across. Worked 3 times, then started a fire inside the relay. Went to solid state relay from China (E-Bay) and it lasted a week. Finally got a rated HV DC relay from a scrapyard buddy. I don't know where it came from but its been working for over four years!


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## rochesterricer (Jan 5, 2011)

F16bmathis said:


> I've got two, and I have to turn it off even at 20 degrees outside. It just gets too hot!


You will have to let us know how it does on Sunday, when its supposed to be a high temp of -1


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## PStechPaul (May 1, 2012)

F16bmathis said:


> I first used a HUGE DC relay and connected both contactors so it'd have twice the distance to arch across. Worked 3 times, then started a fire inside the relay. Went to solid state relay from China (E-Bay) and it lasted a week. Finally got a rated HV DC relay from a scrapyard buddy. I don't know where it came from but its been working for over four years!


Was this an inductive load? And what were the relay's AC contact ratings? And how was the coil being driven? I'm surprised that it failed so quickly and destructively. You do need to make sure the contacts open quickly, and if you have a freewheeling diode on the coil it can delay the opening enough to create a destructive arc. Here is some information on DC switching:

http://relays.te.com/kilovac/hvintro/powerswitching.asp
http://www.ia.omron.com/data_pdf/data_sheet/mk-s(x)_dsheet_gwj175-e1-01.pdf
http://www.ni.com/white-paper/4197/en
http://relays.te.com/schrack/pdf/C0_v4bg_4.pdf (lots of basic technical info)
http://www.oenindia.com/pdf/relays_Technical_Write_up.pdf
http://www.ab.com/en/epub/catalogs/12768/229240/229266/229643/229707/print.html
http://www.albrightinternational.com/files/downloads/catalogues/SW60 LEAFLET.pdf (some nice DC contactors)
https://www.relayspec.com/catalogs/026940/105A_199.pdf (shows blowout magnet - maybe can be added to AC contactors?)
http://interiorcommunicationselectrician.tpub.com/14121/141210026.htm (description of magnetic blowout operation)
http://en.wikipedia.org/wiki/Magnetic_blowout (general info on contactors)


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## frodus (Apr 12, 2008)

You could always put a Boeing Dreamliner battery in the vehicle cabin.....

(sorry, I thought it was funny)


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## F16bmathis (Jun 6, 2008)

lifeinhd said:


> I'm also curious as to the best way to heat a car. I'm considering a hair dryer/ceramic heater to go inside the heater core, but I was also thinking about pumping hot water through the core. Perhaps with one of those tankless water heaters, made for home use that can run on propane? I'm converting an S10, the propane tank would go in the bed when needed, and be easily removed when not. I just don't know what would happen if I tried to pass hot water through a water heater-- maybe that would that create hot-water-inception?  I also don't know how long a tank of propane would last in this application. Still in research stages obviously . I didn't know if anyone else had come up with a simple and cheap method of heating water and passing it through the existing heater core?


We had someone use an electric coffee maker water heater. Not sure how it worked out.


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## F16bmathis (Jun 6, 2008)

PStechPaul said:


> Was this an inductive load? And what were the relay's AC contact ratings? And how was the coil being driven? I'm surprised that it failed so quickly and destructively. QUOTE]
> 
> The relay was a HUGE DC relay. Maybe a 1/4" gap between the contacts when open. No AC ratings. Coil was driven by 12v wired to the trucks original heat system. After watching a few video's on dc arching, I'm not surprised at all.
> 
> I've got a HV DC contactor that has been working for years.


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## F16bmathis (Jun 6, 2008)

rochesterricer said:


> You will have to let us know how it does on Sunday, when its supposed to be a high temp of -1


-1 ??? I'm not getting out of bed! I could post a youtube video showing the temp before I turn it on, and during heat use...

Last Sunday it was all of maybe 20 degrees. Had a guy come over to look at the truck, so I turned the defrost on cause the windows had about 1/4" of ice on it. We went and looked under the hood for a few, got back in the truck, and the windshield was clear.

Then we went for a cruse down the highway at 75!


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## njloof (Nov 21, 2011)

F16bmathis said:


> We had someone use an electric coffee maker water heater. Not sure how it worked out.


Who cares about the heat! How was the coffee?


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## piotrsko (Dec 9, 2007)

in Frankenranger we are using a home made heater made of 1" pipe with two 1/2X 1" "T" pipe reducing adapters attached to the ends and a 13" 250 vac 3500 watt water heater element, closed cap on one end. Standard elec hot water tank controller hose clamped over the center either controlling a Kyoto KG20C75AX something relay or other DC/DC relay or powering it through a 400VDC 40 amp bridge for AC mains use. total cost was about $100 including the relay (most expensive part and a 16 dollar cheapo electric fuel pump) because I didn't have any 1" galvanized pipe and everything was new. Need a DC rated relay because the arc on initial turn off with an AC RELAY WAS SPECTACULAR FOR 30 SECONDS.

good to -1 so far for trip to work with plug in preheat. system holds about 1 gallon coolant.


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## ruckus (Apr 15, 2009)

So nobody has tried the cheap and efficient seat heaters??


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## TEV (Nov 25, 2011)

ruckus said:


> So nobody has tried the cheap and efficient seat heaters??


How a seat heater will defrost the windshield ?


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## PStechPaul (May 1, 2012)

TEV said:


> How a seat heater will defrost the windshield ?


 Put the heater in your pants, eat lots of beans, and ASSume the position!


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## rochesterricer (Jan 5, 2011)

F16bmathis said:


> -1 ??? I'm not getting out of bed! I could post a youtube video showing the temp before I turn it on, and during heat use...
> 
> Last Sunday it was all of maybe 20 degrees. Had a guy come over to look at the truck, so I turned the defrost on cause the windows had about 1/4" of ice on it. We went and looked under the hood for a few, got back in the truck, and the windshield was clear.
> 
> Then we went for a cruse down the highway at 75!


The video idea would be pretty cool. Although I suspect most heat loss in that kind of cold happens at highway speeds, due to small air leaks in the cabin and the cold air passing over surfaces like the windshield glass.


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## bakes (Jun 15, 2011)

http://www.espar.com/html/applications/marine_units.html
http://www.espar.com/html/applications/truck_units.html
http://www.espar.com/html/applications/automotive_units.html
http://www.espar.com/documents/dodge.pdf
just plum it into you current heater core 
you can set a timer or a thermostate
also can be used to pre/ heat your battery bank to temp


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## redcelt007 (Oct 2, 2008)

I confess. I tried the coffee maker idea. My pack voltage is 72 volts, so I didn't achieve good results. Not enough watts going through the heater element. I am now using one of those KAT heaters connected to the heater core with a circulating pump. I have found that restricting the flow of water through the heater core produces more heat. I have this rigged so that I can plug the KAT into 120 VAC if I need to rapidly warm up the cabin before I drive away.


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## evaddict (Jan 12, 2011)

For any British car conversions, I wrote a detailed article on my heater conversion ... click here


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## MemphisPapa (Feb 16, 2012)

So maybe not the cheapest solution, but why not just buy an 800W inverter and a $20 - 750W space heater? For less than $100 you have a heater to tie into the existing ducts with forced air that runs off the 12V system. Also you have a useful outlet for the rest of the year when it isn't so cold. Maybe a fan in the summer?

I got rid of the original blower motor. It was old, heavy, and nonfunctional. This is going to be my solution with a 1500W heater. My thought is to add an additional resistor to double the resistance and reduce the current draw and keep the power below 800W.

Any thoughts?


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## PStechPaul (May 1, 2012)

Not a bad idea using the inverter. I bought a (supposedly) 1000W inverter for about $30, and it works OK, but is really a 400W with 1000W peak. There are others for about $50 that are 1200W and may be more accurately rated. The problem is that on 12VDC you need almost 100 amps for 1000W, so you need heavy cables.

Here are some inverters I found:
http://www.ebay.com/itm/170949382136 (1200W 24V input 220V output)
http://www.ebay.com/itm/320800175307 (What I bought, 12V to 220V, really 400W 1000W peak)
http://www.ebay.com/itm/110V-1000W-Car-Mobile-Power-Inverter-Adapter-DC-to-AC-/180705080972 (12V to 120V, $50)

You can get four 200W 12V heaters including defrosting fan for $120:
http://www.ebay.com/itm/200W-12-VOL...-DEFROSTER-PLUG-IN-DEFOGGER-12V-/321056321910


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## dtbaker (Jan 5, 2008)

MemphisPapa said:


> So maybe not the cheapest solution, but why not just buy an 800W inverter and a $20 - 750W space heater?
> Any thoughts?



uhhhhh, welll..... why buy an invertor? the ceramic heater cores accept DC just fine. second, most people need at least 1500 watts, and probably will be happier with 3000 watts. Its generally pretty easy to slip the ceramic cores either directly into the ductwork, or in the OEM heater core area in place of the OEM heat exchanger.

running 1500/3000 watts off DC traction pack voltage is better than high amps off 12v, or adding an invertor and running an AC system. Only challange is a decent contactor or heavy SSR rated for DC.


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## Caps18 (Jun 8, 2008)

I worry a little about defrosting/fog on the inside of the windows. I will have to look into the wipes I used before to prevent it.

But, I don't drive long enough distances to really need to worry about this right now. And even with the really cold weather we are having now, I wear enough clothes and winter gear that driving without heat doesn't bother me. As long as the cold wind stops it is OK once I get into the car. Plus, there are only two weeks when I really need the heat, and I can preheat the car as well as it being kind of warm since it will be in the garage.

I need to get the truck working first, then I will be able to worry about all of these 'nice to have' things.


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## dtbaker (Jan 5, 2008)

Caps18 said:


> I worry a little about defrosting/fog on the inside of the windows. ... then I will be able to worry about all of these 'nice to have' things.



defroster is more along the lines of 'need to have', especially if you want anyone else to ever ride in the car with you.


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## lifeinhd (Jan 10, 2009)

dtbaker said:


> defroster is more along the lines of 'need to have', especially if you want anyone else to ever ride in the car with you.


Unless you implement a "don't breathe" rule 

But seriously, doesn't AC work better than heat to defrost the windows? I know I could never get heat to defrost the windows in my old gas car (my gas Corolla turns on the AC automatically when "defrost" is selected). And in that case, assuming your EV lacks AC, wouldn't it just be better to use a cloth before you set off, and maybe once or twice more at stoplights if need be?


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## jeffcoat (Apr 16, 2012)

A/C in combination with heat works best, since the A/C actually removes the humidity. However, my gas truck has no A/C but when the selector is on fresh air (not recirculate), the heater does an excellent job of clearing the windshield. So, A/C+heat beats heat only, but both are infinitely better than using a towel, like we do in our heater-less EVs.


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## Ziggythewiz (May 16, 2010)

It really depends on the temps. If it's really cold the AC will work better because it's easier to remove the temp differential on the glass than to warm it past the temp where it can fog.


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## MemphisPapa (Feb 16, 2012)

dtbaker said:


> uhhhhh, welll..... why buy an invertor? the ceramic heater cores accept DC just fine. second, most people need at least 1500 watts, and probably will be happier with 3000 watts. Its generally pretty easy to slip the ceramic cores either directly into the ductwork, or in the OEM heater core area in place of the OEM heat exchanger.
> 
> running 1500/3000 watts off DC traction pack voltage is better than high amps off 12v, or adding an invertor and running an AC system. Only challange is a decent contactor or heavy SSR rated for DC.


The heat element I have is a heavy wire resistance (like a toaster) separated by an insulator that allows air to pass through it. There is a diode rectifier (half wave probably) on the 9 Ohm wire restistor. Do I have to remove the rectifier from the heater element to run it on DC? There is a micro switch that triggers on air flow. Can I just run DC to the AC plug (hot and common)? I have a 96V traction pack. With the DC voltage close to the AC voltage, the current is close to the same. Shouldn't the internals (lighted switch, led, and micro switch) continue to work the same? Is it really this simple? 
P=I*V and V=I*R, where I don't remember from school anything about V being specific to DC or AC.

Thanks for the help.


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## TEV (Nov 25, 2011)

MemphisPapa said:


> The heat element I have is a heavy wire resistance (like a toaster) separated by an insulator that allows air to pass through it. There is a diode rectifier (half wave probably) on the 9 Ohm wire restistor. Do I have to remove the rectifier from the heater element to run it on DC? There is a micro switch that triggers on air flow. Can I just run DC to the AC plug (hot and common)? I have a 96V traction pack. With the DC voltage close to the AC voltage, the current is close to the same. Shouldn't the internals (lighted switch, led, and micro switch) continue to work the same? Is it really this simple?
> P=I*V and V=I*R, where I don't remember from school anything about V being specific to DC or AC.
> 
> Thanks for the help.


First I don't think that is a good ideea to use that type of heating element in a car, people use the ceramic heater elements, they behave totally different.

And NEVER use those AC rated switches(thermostat) to switch DC they will weld in closed position, you use the original switch to control a DC rated contactor or SSR.


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## Caps18 (Jun 8, 2008)

dtbaker said:


> defroster is more along the lines of 'need to have', especially if you want anyone else to ever ride in the car with you.


Defrosting and fog is different from heating though. My car windows didn't frost or fog up this past week. Maybe it is because I wasn't driving enough, but in the Spring and Fall, there is a weather condition that causes moisture to condense on the glass. It won't happen inside of a garage though, well maybe it happens once you drive outside. And I have had to wipe the inside of the glass to see.

This is the stuff I have used in the past.
http://www.rainx.com/product/glass-and-cleaners/rainx-anti-fog/#.UQVs5nGAeS4

I will deal with it in a more extreme way if need be, but I don't see it as a problem for my driving scenarios very often right now.


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## MemphisPapa (Feb 16, 2012)

TEV said:


> First I don't think that is a good ideea to use that type of heating element in a car, people use the ceramic heater elements, they behave totally different.
> 
> And NEVER use those AC rated switches(thermostat) to switch DC they will weld in closed position, you use the original switch to control a DC rated contactor or SSR.


"Never" seems a little strong here. I plan to keep the original packaging to keep the fire risk in check. As far as the AC/DC issue, I don't care or plan to use a thethermostat. This particular model doesn't have one. The heater and blower are resistance loads and should work with AC or DC current. I am a little worried about the variable speed knob on the blower. The blower pulls 1A and the heater another 13A. I guess I was looking to see if anyone else has done this before I let the smoke out of my blower.

The original DC blower is nonfunctional, to catch anyone up. This blower moves 300 cfm and should help in the summer time to move the air when the 2x40 air isn't available.


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## TEV (Nov 25, 2011)

MemphisPapa said:


> "Never" seems a little strong here. I plan to keep the original packaging to keep the fire risk in check. As far as the AC/DC issue, I don't care or plan to use a thethermostat. This particular model doesn't have one. The heater and blower are resistance loads and should work with AC or DC current. I am a little worried about the variable speed knob on the blower. The blower pulls 1A and the heater another 13A. I guess I was looking to see if anyone else has done this before I let the smoke out of my blower.
> 
> The original DC blower is nonfunctional, to catch anyone up. This blower moves 300 cfm and should help in the summer time to move the air when the 2x40 air isn't available.


Usually all heaters have an internal temperature limited switch or something to prevent the system of overheating, that switch will fail (weld) in ON position when using DC , so "Never" is just right  .

Good luck with your project , I started driving my Ranger, and i love it.


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## Ellrot (May 17, 2010)

Anyone thought of using one or even two of these, they're only 12v and a bargain at £14 http://www.maplin.co.uk/in-car-ceramic-heater-48775?c=maplin&utm_source=gcs&utm_medium=gcs_search&utm_campaign=A75FL&utm_content=Heating+%26+Cooling


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## lifeinhd (Jan 10, 2009)

Unfortunately I don't think that will cut it. From the description:



> This Car heater cooler is not a replacement for your own cars heating system. It is a supplement to the existing system and is used to clear ice and frost from your cars windscreen only. For best use do not use for longer than 15 minutes in an hour


Sorry


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## Ellrot (May 17, 2010)

yeah might be a lil small and flimsy, could do with a sturdy casing. Thought it was an idea for something which could be modded, does 12v not appeal either?


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## TEV (Nov 25, 2011)

Ellrot said:


> yeah might be a lil small and flimsy, could do with a sturdy casing. Thought it was an idea for something which could be modded, does 12v not appeal either?


It's depends very much of how cold is the winter in your area.

People using 1500W ceramic heater in cold areas, reported bad results. I personally have a 4KW water heater and I am satisfied.

The unit you posted is 12V and 15A :

12V * 15A = 180W so you need ~8 of them to get 1500W.

Also 1500W/12V = 125A which is a lot of amps for the accessory circuit.


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## Ellrot (May 17, 2010)

TEV said:


> It's depends very much of how cold is the winter in your area.
> 
> People using 1500W ceramic heater in cold areas, reported bad results. I personally have a 4KW water heater and I am satisfied.
> 
> ...


Fair point, I live in England so rather mild winters with the occasional snow dump, but nothing ever below -10 deg C really. Those lil ceramic heaters might be good for me on those seasonal frosty mornings though, and could just sit under the windscreen, ready for when I do need em. I don't really need A/C in England either, just open the windows and sunroof and Robert's your father brother.


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## njloof (Nov 21, 2011)

Wait, how is it you know my Uncle Bob??


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## Ace_bridger (Nov 22, 2011)

If you're thinking of using those 12v 150w heaters from Maplin then don't waste your time and money, they're worse than useless


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## E30_Dave (Apr 19, 2012)

It has occurred to me that perhaps one could use one or more PTC heating elements of limited capacity, in conjunction with the original heater matrix, which itself could take heat from the motor cooling circuit.


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## TEV (Nov 25, 2011)

E30_Dave said:


> It has occurred to me that perhaps one could use one or more PTC heating elements of limited capacity, in conjunction with the original heater matrix, which itself could take heat from the motor cooling circuit.


What is a PTC......... ?


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## E30_Dave (Apr 19, 2012)

Hi TEV,

PTC stands for Positive Temperature Coefficient.

Heating elements which operate on this principle have a number of important and very useful properties, which make them ideal for use in EVs.

Firstly, they can regulate their own current draw according to the load placed upon them.

These are:

1). The temperature of the air passing through the element matrix - the colder the air, the greater the load on the element, and the greater the current they draw...

2). The speed of the air passing through the element matrix - the higher you turn up the heater fan, the greater the load on the element, and the greater the current draw...

3). The ability to reduce current draw to almost zero once the element reaches a predetermined temperature.

All of this means that the element will only draw the power it needs to heat the air passing through it, and provided that its' prescribed maximum temperature isn't too high, it won't melt the plastic body of your heater or set it on fire through over heating !


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## TEV (Nov 25, 2011)

E30_Dave said:


> Hi TEV,
> 
> PTC stands for Positive Temperature Coefficient.
> 
> ...


LOL, you could just said "ceramic heater" from your first post I was imagining being a water heater.

Thank You for the explanation.

Stay warm


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