# testing ceramic heater?



## dtbaker (Jan 5, 2008)

I got it all together, but am popping a fuse when I turn it on.... How many amps SHOULD a typical ceramic core heater pull at 96v?

Is there a way I can test with a separate 12v battery or multimeter with the heater in place to rule out some internal short? I have to pull it all apart if I can avoid it!

should the heater leads show 'some' resistance, or 'no' resistance? I am wondering what is typical for these things?


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## Woodsmith (Jun 5, 2008)

Using V=IR and P=VI you should be able to work out the resistance of the element based on its rated power and voltage.

You can then change the voltage to your pack voltage and knowing the resistance be able to work out the new power output and the current.

An example based on my workings:
For a given 1000W element at 240V
P=VI
I=P/V

I=1000/240
I=4.17amps

V=IR
R=V/I
R=240/4.17
R=57.55ohms

If we use 144V
V=IR
I=V/R
I=144/57.55
I=2.5amps

P=VI
P=144x2.5
P=360Watts


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## dtbaker (Jan 5, 2008)

Woodsmith said:


> Using V=IR and P=VI you should be able to work out the resistance of the element based on its rated power and voltage.


ok, so following these formulas:
i=1500/120v = 12.5 amps at rated v
r=120/12.5 = 9.6 ohm

i=96/9.6 = 10a at my pack voltage
so.... 20a fuse SHOULD be plenty, right?!

when I look at my multi-meter, the ohm scale is rx1kohm, so I dunno if I can see just 10 ohm versus 0 (short). Do I need a different meter? Is there a different way I can test the unit in place without smoking anything? 

Sounds funny, but even after building an EV, I really am not prepared to de-bug anything electronic. The rest of the car I just followed schematics, and everything worked!

d


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## Woodsmith (Jun 5, 2008)

You could measure the voltage drop across it.

It's been a while since I have thought about stuff like this so maybe I am going to be wrong but if you get a similar sized resistor, say 20 ohms and put it in series with a 12 volt supply you should be able to measure the voltage across the heater and across the resistor giving about 4 volts and 8 volts respectively.

The voltage will be proprtional to the resisitances so with a degree of accuracy you can determine the unknown resistance.


However, it is a ceramic heater and they are supposed to be self regulating, the hotter they get the higher the resistance so they don't get too hot.

Perhaps when cold they have a very low resistance and won't reach a measurable resistance until it is hot. Once at full temperature you might then find it is drawing 9.6 amps but until then it might draw much more due to a low resistance.


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## dtbaker (Jan 5, 2008)

the problem is that both times I run the 96v thru, it popped a 20a fuse. So my question was first what the theoretical draw is, and it looks like the 20a fuse should be fine.... unless the issue is that the amps are much higher in the beginning when the element is cold?

It sounds like I should NOT hook up a 12v battery, because that would try to pull LOTS more amps, right?

If there is an internal short, what would happen if I hook up my full 96v pack bypassing the relay and fuse? Would the smallest wire melt (basically like a fatter fuse?)

What is a way to figure out if the core has a short, or why it is popping the 20a fuse?

would it be relatively safe to bypass the relay and fuses and manually close the circuit with a small gauge (like 22g) wire as a fat fuse to see what happens?


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## Woodsmith (Jun 5, 2008)

Heat up the element in a hot oven or with a hot air gun and then measure the resistance?

I'm not really sure of the answer in this case, my electrical training is so old we didn't have materials that responded in the way ceramic heaters do.

I've just been watching Jack Rickard's video on fitting a heater to his Mini EV. It may be worth a look as he dismisses the ceramic heater as not a good idea.


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## tomofreno (Mar 3, 2009)

> It sounds like I should NOT hook up a 12v battery, because that would try to pull LOTS more amps, right?
> 
> If there is an internal short, what would happen if I hook up my full 96v pack bypassing the relay and fuse? Would the smallest wire melt (basically like a fatter fuse?)
> 
> ...


 The heater is a given resistance, so should draw LESS current with 12V applied: I = V/R. You should be able to measure the heater resistance by touching your meter probes to the output terminals of the P&B relay when 12V is not applied to the relay coil (relay open). I would not try to bypass the fuse with a wire connected to the pack. I don't think a photo will show much detail of the connections but I'll take one. Ensure the diodes are connected as shown in the schematic that came with the kit, with the arrow in the correct direction. If the large one is reversed, it will short the output terminals together. The arrow and bar on the diode should be oriented as: neg terminal >| pos terminal. Also ensure the negative terminal is connected to the negative terminals of the heater, and positive to positive terminals. No part of the large diode should be contacting any conductive surface other than the output terminals of the relay.

Tom


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## dtbaker (Jan 5, 2008)

tomofreno said:


> I would not try to bypass the fuse with a wire connected to the pack.


too late, already did. The core did seem to work, so the contactor is the suspect at this point.





tomofreno said:


> I don't think a photo will show much detail of the connections but I'll take one. Ensure the diodes are connected as shown in the schematic that came with the kit, with the arrow in the correct direction. If the large one is reversed, it will short the output terminals together. The arrow and bar on the diode should be oriented as: neg terminal >| pos terminal. Also ensure the negative terminal is connected to the negative terminals of the heater, and positive to positive terminals. No part of the large diode should be contacting any conductive surface other than the output terminals of the relay.


I will try to get a good picture today that shows the caps/resistors, and diodes.... kinda hard location...
Tell me about the core +/- though. I wired the black lead to my pack -, and white to my pack +. I was thinking that it wouldn't matter since the core is just a big resistor, right? Anyway, I thought black is neg, right?


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## PhantomPholly (Aug 20, 2008)

Don't let the smoke out. You can only let the smoke out once...


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## dtbaker (Jan 5, 2008)

here are pix....

I reviewed the schematic, and I THINK I have it all right.... question is whether the heater WHITE is + or -, and does it matter? I ran my pack - to heater black, pack + to heater white.


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## tomofreno (Mar 3, 2009)

I took a photo but cannot focus as close as you so it doesn't show enough detail. My heater core had the terminals clearly marked + and -. I thought ceramic heaters worked on the Peltier effect, so polarity would matter. If the heater is resistive then of course polarity doesn't matter. I am unclear on this. I did not use the fuse holders that came with the kit as they looked more like 10A holders to me. I bought heavier "inline" 20A ones at Radio Shack. Don't think that would have anything to do with your problem though. You might call or email Wistar at kta. Maybe he has had other customers with this problem.


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## dtbaker (Jan 5, 2008)

tomofreno said:


> I took a photo but cannot focus as close as you so it doesn't show enough detail. My heater core had the terminals clearly marked + and -.


hhhmmm, I dunno!
so on yours, is black=neg, or black=pos ?

I can certainly swap the ends on mine and try again... worst it will do is blow another fuse.


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## dtbaker (Jan 5, 2008)

Haven't tried switching heater wires +/- yet, but did post a bunch of photos of the whole heater installation starting with

http://www.envirokarma.org/ev/gallery/091104_heatduct11.htm


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## Wistar (Nov 5, 2009)

My first thought is that the diode is installed backwards. If this is the case, the diode would present virtually a dead short across the battery pack. The diode is there to extend the life to the contacts on the relay. You could disconnect the diode and see if everything works OK. 

If it works OK, then either the diode was installed backwards, or the diode has failed in a shorted state. Check the diode before putting it back into the circuit. If you have a multimeter that has a diode checking setting, you can use that to make sure that current only flows one way. You can check the resistance, but with no voltage on the diode, the readings will both be pretty high resistance, infinite one way and about 1 MOhm the other. I just hook the diode up to a lab power supply, set the voltage to 1.5Vdc and then slowly increase the current limit. The current will stay at zero when the diod is hooked up one way and current will flow freely in the other.

Wistar Rhoads
KTA Services, Inc.
www.kta-ev.com
20330 Rancho Villa Road
Ramona, CA 92065
760-787-0896
760-787-9437 (Fax)


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## dtbaker (Jan 5, 2008)

ok....
I THINK the diode is in correctly, but I'm gonna yank it and test (after I get some more fuses!) Probably won't get to it until week after next as I am out of town most of next week.... The 'arrow' is supposed to go neg->|pos right?


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## Wistar (Nov 5, 2009)

Yep, bat- >| bat+


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## dtbaker (Jan 5, 2008)

ok, I removed the diode, and am STILL blowing a fuse when the circuit closes! I see no wires touching, and poking here and there shows no unexpected shorts on the contacter itself. AAAGGGHHH.

the low-voltage circuit to open/close contacter seems faultless... keeps clicking open and closed with fan.....

Only non-standard thing tonite is that radio shack was out of the slo-blo 20 amp-250v fuses, so I had to get fast-acting 20 amp-250v fuses.

Any more ideas of things to disconnect or test?

If the core was damaged in some way, could it still be operational (as when I applied 96v directly bypassing everything) but perhaps pull higher amps than expected?

Or, could the contacter have some short I am not seeing when the circuit closes? I see nothing bridging between the HV pos and neg.... any other possibilities?


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## Dave Koller (Nov 15, 2008)

Dan
Have you pulled off the heater wires and place a bunch of 100 watt bulbs (in parallel ) to see if it blows... sounds like it could be a short in the core -- better yet put a 110 pigtail socket on the output and plug in a space heater or a hair dryer and see what happens... Your core could have a short that show after it heats up slightly...


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## Dave Koller (Nov 15, 2008)

Wistar said:


> My first thought is that the diode is installed backwards.


Since you took it out then I guess it was not that - BUT - I also thought that from your red line /arrow sketch over your picture... I tried to see where you had it hooked BUT it was hard to see - scribble a schematic... I could not get to http://localhost/EnviroKarma.org/ev/...heatduct11.htm

to see what pics you have !


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## dtbaker (Jan 5, 2008)

Dave Koller said:


> Since you took it out then I guess it was not that - BUT - I also thought that from your red line /arrow sketch over your picture... I tried to see where you had it hooked BUT it was hard to see - scribble a schematic... I could not get to http://localhost/EnviroKarma.org/ev/...heatduct11.htm
> 
> to see what pics you have !


I put in the link wrong at first... try this
http://www.envirokarma.org/ev/gallery/091103_heatcon1.htm
and several pix on either side of this one

- checked diode, it was in correctly neg->|pos and has differing resistance in one direction versus other, so is probably ok.
- I REMOVED the diode, and still blow fuse
- I bypassed heater contacter/fuses by hardwiring from main contactor to heater, and it worked.


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## tomofreno (Mar 3, 2009)

> - checked diode, it was in correctly neg->|pos and has differing resistance in one direction versus other, so is probably ok.
> - I REMOVED the diode, and still blow fuse
> - I bypassed heater contacter/fuses by hardwiring from main contactor to heater, and it worked.


 If you bypassed the P&B relay and fuses and connected the core directly to the battery pack and it worked ok, and you estimated it's current draw at less than 15A in that case (if I recall correctly) it seems it has to be something in the relay wiring. How about if you just bypass the P&B and keep the fuses in the circuit? If this works, then do you have anything wired in parallel with the P&B that might be causing the problem? What resistance do you measure between the battery inputs of the P&B and between the pos/neg outputs of the P&B? Is the positive output on the terminal that connects to the positive input when the relay closes? If not, the diode on the output will short the battery terminals when the relay turns on.

Tom


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## dtbaker (Jan 5, 2008)

tomofreno said:


> If you bypassed the P&B relay and fuses and connected the core directly to the battery pack and it worked ok, and you estimated it's current draw at less than 15A in that case (if I recall correctly) it seems it has to be something in the relay wiring. How about if you just bypass the P&B and keep the fuses in the circuit?


I guess I could try this just to see if indeed the draw is less than 20a thru the fuses with the P&B out of the picture.



tomofreno said:


> If this works, then do you have anything wired in parallel with the P&B that might be causing the problem?


no... the power feed to the P&B is fused, then to the P&B, then to the heater.



tomofreno said:


> What resistance do you measure between the battery inputs of the P&B and between the pos/neg outputs of the P&B? Is the positive output on the terminal that connects to the positive input when the relay closes? If not, the diode on the output will short the battery terminals when the relay turns on.
> Tom


I removed the diode, and still am blowing the fuse...
I am not quite sure what you are asking here. I checked resistance from input side to output side for both pos and neg with the relay 'open' and 'closed'. Results were as expected.... I also checked across pos to neg for a short, but there wasn't. It is mind boggling, because there is not that much THERE to go wrong!


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## tomofreno (Mar 3, 2009)

> I removed the diode, and still am blowing the fuse...
> I am not quite sure what you are asking here.


 Duh, yeah, forgot that. If it works with the fuses in and the P&B out of the circuit, it has to be something with the relay. Again, Positive Batt is connecting to positive output contact to the heater right? If you have the diode on the output connected correctly, neg >| pos, and positive batt connects to neg output and vice versa, the diode will short the leads from the batt. My experience in troubleshooting is it is almost always some simple error like this.

Tom


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## Dave Koller (Nov 15, 2008)

Remove the power leads to the contacts and remove heater leads - connect the ohm meter across the outputs of the DTDP and engage the coil - and see if there is some unknown direct short in the relay contacts if the pack voltage is shorted each time the relay closes - well, it is just another angle!


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## Dave Koller (Nov 15, 2008)

(edited on my other machine !!)

I see you have a snubber circuit have you removed that also? I am not sure why it would do anything BUT you have tried everything..!


I am on my old machine (WIN 98) and it does not do edits well!

I think you have done what I asked above - so now back to square one...

Hmmmmm the fuses are for 200 volts right oslow blow? as the surge could take out a fast blow).

have you tried other loads? If they work the core has to have some quirk to it that causes the amp surge...


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## Dave Koller (Nov 15, 2008)

The problem with A.D.D. is too many thoughts too fast ...

if the snubber circuit is causing a brief kick back on relay closure could that be the problem? Pop goes the fuse - or am I just hunting here


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## dtbaker (Jan 5, 2008)

...after more testing and trying various configurations I am almost certain that the fault is in the heater core itself. I don't really know how these solid-state ceramic core work (especially at different voltages), so it is mind blowing to me that it seems to be 'partly working' in that it does get hot, but draws more amps than it is supposed to.

Can anyone explain the difference between the cores that are designed for different DC voltages? I looked around for replacements, and most of the EV places have different elements for different voltage ranges, and they are different prices, so I am assuming there is SOMETHING in there different?

Can I just go get a cheapo AC ceramic heater from Walmart and take the core out of it? They are way less expensive!


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## TheSGC (Nov 15, 2007)

dtbaker said:


> ...after more testing and trying various configurations I am almost certain that the fault is in the heater core itself. I don't really know how these solid-state ceramic core work (especially at different voltages), so it is mind blowing to me that it seems to be 'partly working' in that it does get hot, but draws more amps than it is supposed to.
> 
> Can anyone explain the difference between the cores that are designed for different DC voltages? I looked around for replacements, and most of the EV places have different elements for different voltage ranges, and they are different prices, so I am assuming there is SOMETHING in there different?
> 
> Can I just go get a cheapo AC ceramic heater from Walmart and take the core out of it? They are way less expensive!


What fuse are you using? Are you sure it's a DC fuse and not an AC fuse? 

I am working on my ceramic heater from a cheapo $25 thing from Home Depot or Walmart, I don't remember which. I can't build mine into the car due to having problem with the AC system in the way, but instead I am going to make it a DC plug in heater I can rest on the dash or seat.


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## dtbaker (Jan 5, 2008)

TheSGC said:


> What fuse are you using? Are you sure it's a DC fuse and not an AC fuse?


yes, i am sure.
20amp-250v dc rated


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## ZEVUtah (Apr 10, 2008)

dtbaker said:


> - I bypassed heater contacter/fuses by hardwiring from main contactor to heater, and it worked.


Sounds like you are very close to solving the problem now. When I built my ceramic heater I used a motor contactor instead of the small relay like you have. It costs a lot more, but it is enclosed and I do not have any problem with blown fuses. I bought this one from EVSource, but you can get these from other places as well. 

KJD


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## dtbaker (Jan 5, 2008)

ok.... out of sheer frustration, I took the fuses out, and replaced with single strand 22ga telephone wire 'fuses'. Everything seems to work fine. Added diode back in, still works fine. Nothing caught on fire or melted.  Makes me a little nervous, but will have to do for now.

Looking at my HV ammeter, which is analog needle 0-500 amps, it is hard to be exact, but it looks like the heater is pulling between 20 or maybe 25 amps (at about 100v - 96v nominal pack). The whole problem MAY just be that the core is pulling just a little too much for the fuses at my particular voltage.... but it seems like a lot.

I have a friend w/ DC clamp ammeter I will try to see what it is actually pulling more accurately, but not till week after next.

I would still like to know if this higher than expected draw COULD be a sign of some minor damage to the core, or if it is likely this is just what it is going to pull. I would hate to get a $125 dollar replacement, go thru the pain of replacing it, and have the same results. I also am wondering why the cores on various EV sites are so expensive compared to cheapo heaters from Walmart and what the difference is between the ones listed for different voltages.


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## dtbaker (Jan 5, 2008)

ok... new learning experience with the heater... I was driving along last night, almost home, and pack was down to about 70% DOD; its been cold and I had taken an extra side errand. Lights on, heater on....

As I came off a stop sign accelerating up the last hill, pack voltage was sagging down to about 70 (96 nominal).... and the heater went cold.

Turns out that one of my 22ga wire 'fuses' had BLOWN! Melted! wow, I dunno what current, and it might have found a thin spot in the wire right where I stripped off the insulation. But it made me think...

Of course, as pack voltage sagged and the heater was still attempting to put out 1500 watts, the amps went up pretty high! so, lesson in fusing these things.... I still don't know how high I need to fuse to not blow under the extreme condition of running at fully 'sagged' voltage and not exceed the capacity of the fairly thin wire that I remember was connected to the core itself!


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## ZEVUtah (Apr 10, 2008)

dtbaker said:


> ok.... out of sheer frustration, I took the fuses out, and replaced with single strand 22ga telephone wire 'fuses'. Everything seems to work fine. Added diode back in, still works fine. Nothing caught on fire or melted.  Makes me a little nervous, but will have to do for now.
> 
> Looking at my HV ammeter, which is analog needle 0-500 amps, it is hard to be exact, but it looks like the heater is pulling between 20 or maybe 25 amps (at about 100v - 96v nominal pack). The whole problem MAY just be that the core is pulling just a little too much for the fuses at my particular voltage.... but it seems like a lot.


On my ceramic heater I just used a 20 amp fuse. The pack is 144 volts, so that is a bit different than your setup. Have you tried just running a 30 amp fuse instead of the 20 ?

KJD


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## dtbaker (Jan 5, 2008)

ZEVUtah said:


> On my ceramic heater I just used a 20 amp fuse. The pack is 144 volts, so that is a bit different than your setup. Have you tried just running a 30 amp fuse instead of the 20 ?
> 
> KJD


I have not gotten back to radio shack to see what else was available. My plan was to borrow a clamp ammeter to get an exact pull at a known voltage, and then triple it. But now I think I will adjust further to assume full load of 1500 watts at sagged voltage of 60 volts..... my only fear is that the pigtail wires on the core might not carry the amps at that voltage?! My power leads are nice fat 10ga wire, but the internal wires on the core were made for 120v AC probably!


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## tomofreno (Mar 3, 2009)

Isn't the heater just resistive? If so it will put out whatever power = V*V/R where V is your pack voltage and R is the heater resistance. So as pack voltage drops, so does current through the heater, I = V/R, and the power output. I would expect it to have less current through it at lower pack voltage. The power rating is likely just what it puts out when plugged in to 120VAC. Maybe something shorted B+ to B- in the core, or the path to the core.


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## dtbaker (Jan 5, 2008)

while I am not an EE... my understanding of the way ceramic heaters work is that the resistance goes up with the temp so that they self-limit at 'approximately' a fixed temp. To me, this means that if the V drops, the A must go up to maintain the Watts to reach the fixed temp.... right?


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## dtbaker (Jan 5, 2008)

I can't find any 1-1/4 250v rated above 20a.... but there are auto blade fuses at 30a and 40a. Does anyone know if they would be 'safe' to carry the load at 96v (nominal)? 

probably at least as safe as my use of a strand of 22ga wire?!.


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## Wistar (Nov 5, 2009)

The heater is just a resistance heater, but it has a high "temperature coefficient of resistance". The problem is that when you first turn on the heater it can be very cold and so the resistance will be very low. It can take a minute or two for the heater to warm up, and hence for the current to drop (assuming for a minute that there is no fan involved yet). So, during this warmup period the current will be high. The higher the voltage, the faster the heater will warm up and the current will go down. Assuming slow blow fuses, this might explain why someone with a 144vdc pack would not see fuse blowing while someone using the same heater element and fuses with a 96 volt pack does see fuse blowing.

I put together a little test on my bench at 36 volts with a heater element that is rated for 36 to 72 volts. It is probably about 65 F in my shop, so this was the starting temperature of the heater element. When I switched on the heater, the initial current was about 37 amps. Over about a minute (I did not time it), the current dropped to 2 amps.

I then placed a ducted fan up to the heater element. The current rose to about 12 amps and leveled out. As the fan removed heat from the heater, it cooled down, the resistance decreased, and so the current increased.

All of this was done with terminals 1, 3, and 5 connected to +36 and terminals 2 and 4 connected to "0" volts.

One solution to your problem would be to connect teminals 1 and 5 to the + battery terminal and terminal 3 to the - battery terminal. This will yield a higher nominal resistance. Of course this will also yield less heat as V is constant and I will drop.

A second solution is to put two heater elements in series.

Or just put in bigger fuses! I would not use automotive fuses without doing some research. Many of the automotive fuses I have seen the specs on are rated for 36 volts. At 96 volts, the fuses may continue to arc and conduct current after the fuse has "blown".


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## dtbaker (Jan 5, 2008)

Wistar said:


> I put together a little test on my bench at 36 volts with a heater element that is rated for 36 to 72 volts. It is probably about 65 F in my shop, so this was the starting temperature of the heater element. When I switched on the heater, the initial current was about 37 amps. Over about a minute (I did not time it), the current dropped to 2 amps.



hhhmmm, thanks for testing!

Tells me that the current could be quite high for 'a while' if the car is very cold.... and that I am better to turn the heater on, and leave it on while driving; being sure not to switch on while the voltage is sagged under load!

I am installing a Cycle Analyst, and then will have a better idea of actual amps so I can buy proper fuses. It might be overkill, but perhaps I should buy an AC rated circuit breaker? I couldn't find a 250v rated 40amp fuse in local shops yet....


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## tomofreno (Mar 3, 2009)

Digikey has these 30A slow blow, 1/4" fuses by Littelfuse for $0.75 each:

http://www.littelfuse.com/data/en/Data_Sheets/325P_326P.pdf

I plan to put a portable ceramic heater plugged into a 120VAC outlet in the car for ~1/2hr before I leave to heat it up on very cold days to reduce the heating requirement from the pack.

Thanks for the testing Wistar. Good data! I turned mine on for maybe 20 seconds the other day and was surprised no heat came out just cool air. I checked, and it had voltage, 20A fuses were good. I have it wired in series with the blower switch so it won't run without the blower on. Sounds like I may not have waited long enough for it to heat up.

Tom


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## dtbaker (Jan 5, 2008)

tomofreno said:


> Digikey has these 30A slow blow, 1/4" fuses by Littelfuse for $0.75 each:
> 
> http://www.littelfuse.com/data/en/Data_Sheets/325P_326P.pdf


these look good... all I have found are the 20A ones, which are not enough at 96v pack voltage. I'll try to find the 30a... I am using a strand of 22ga wire again for now, but it makes me a little nervous. 

I DID have one of my 'fuses' blow, and it didn't do any real damage, but DID look like it probably arced until the arc melted the wire back far enough to stop arcing....

My heater core relay is wired to the fan power, but the fan only seems to come 'on' on at the full blast setting. I don't know if this was a problem with the fan/switch before I started or if it is a function of low voltage from the dc-dc converter. Anyway, at full blast fan air, starting in my garage which is 40 degrees at the moment, my analog ammeter bounced up to about 120amps just for an instant when I turned it on, but settled down to about 20a within a second.... and hot air was hitting the windshield in just a few seconds.

I have found that the air is hotter quicker with my 'heat' setting at 'cold'. Presumably because I left the old heater core in there, and if I run the warm air thru the old core, the old (cold) core cools the air until its mass it warmed up.

After I let it run for 30 seconds, I turned it off and waited 10 seconds, then back on to see what kind of surge goes thru when the element is still warm. Looks like about 50amps or so, and then it settles down to the same 20 or so. I would expect once the air in the cabin warmed up the draw would go down, but that would probably take a while....


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## dtbaker (Jan 5, 2008)

tomofreno said:


> I turned mine on for maybe 20 seconds the other day and was surprised no heat came out just cool air.


sounds like it is not working. Mine gets hot in seconds. perhaps you have the leads reversed?


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## tomofreno (Mar 3, 2009)

I was not getting heat from my ceramic heater core purchased from KTA. It turned out that even though rated for 120V the heater core had quite high resistance, about 215 Ohm between leads in the lowest R configuration (2 B-, 3B+). The parallel resistance of the 3 paths was around 50 Ohm, way too large to get much current through. KTA sent me another one that had about 5 Ohm resistance in this configuration. 
I also did some tests (and so did Wistar) to determine resistance versus temperature connecting it directly to 120VAC. It is a U shaped curve with minimum around 130F +/- 10F or so. It was about twice as large at 28F compared to the minimum at around 130F, and the current reduced to less than 0.5A if left heating with no fan on it. I decided to connect the two outer leads to B+ and the center one to B- giving about 5 Ohm for the parallel connection at about 120F. 
I thought this would give around 15A at 150F or so (I was measuring current and temperature with the same meter so there was some delay in switching and measuring temperature for some measured current). So I removed the dash again and installed the new core. After doing so, I measured 37A in rush current for a few seconds, then around 23A for several seconds, but then it reduced to about 8A with the blower on low, and 10A with the blower on high. This gives about 1160W for 116V pack voltage. It is not enough. The air is only very slightly warm, not enough to heat the cabin at even 35F outside temperature. It doesn’t really feel warm blowing on my hands or feet, just not cold, even after being on for over 30 minutes. I would guess the air coming out is around 60-70F at best. If I go to the lowest resistance connection of about 1.6 Ohm I’ll have in rush current of probably over 60A, blowing fuses. Even if I get around that problem using high voltage relays to switch between different resistance configurations, I may find the core only gets a little hotter limiting current to just a bit higher value since resistance appears to increase exponentially with temperature above the minimum. So it is not clear to me that I can get much more heat from this core. 
Is anyone getting hot air from this type of heater? Is anyone using the KAT tank heaters? If so what are you using for a circulation pump? I see they make 2 and 2.5kW versions. It seems this would give much better heat if connected to my original heater core (which I saved). It takes me a good 6hrs to pull the dash and heater and reinstall everything , so I’m not willing to do it again unless I know I have a good solution. I’m getting along by just setting a ceramic heater in the car powered by 120VAC from the wall and preheating for 15 minutes before I leave. I get much more heat from this compared to the installed core which looks the same. I expect the portable heater only uses about 12A or less from the wall (can’t be much more for use with 15A breakers), so I don’t understand why it heats so much better.


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## tomofreno (Mar 3, 2009)

Yesterday temperature got to the mid-40s (F) and the air from the heater actually felt warm! I guess they work fairly well for people in places like southern California. Need more power at lower temperatures though.


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## Tesseract (Sep 27, 2008)

Okay.. first... the PTC elements in these "ceramic" heaters actually have a parabolic resistance vs. temperature curve. So, too cold they draw little current, as well as too hot. That is how they tend to self-regulate at a particular temperature. The problem with the "too cold" part of the curve is that if you blow enough air across them when it is very cold then the self-heating won't be enough to move the current draw down the parabola, so to speak.

Now, serious question: I am curious as to why virtually everyone chooses to tear their dash apart to remove a perfectly functional heater core to then hog out the middle so as to be able to install the ceramic element out of a cheap space heater??? Why not use something like this:

http://www.northerntool.com/webapp/wcs/stores/servlet/product_6970_200339137_200339137

Add a small circulating pump that can tolerate the temperature and you are in business. Yes, pumps rated for high temperature engine coolant are pricey - cheapest I have found is $150 - but you could try a cheap "solid state" fuel pump first and see how that works. Those go for around $30-$50.


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## tomofreno (Mar 3, 2009)

> Okay.. first... the PTC elements in these "ceramic" heaters actually have a parabolic resistance vs. temperature curve.


 Yes, I said that in the post (U-shaped curve) and described temperature dependence of the resistance.



> Now, serious question: I am curious as to why virtually everyone chooses to tear their dash apart to remove a perfectly functional heater core to then hog out the middle so as to be able to install the ceramic element out of a cheap space heater???


 I said in the post that I kept the original core. I didn't hog it out. I don't think "everyone" does this.



> Why not use something like this:


 I asked if anyone was using these Kat tank heaters in the post and mentioned they have 2 and 2.5kW ones. From my experience 1.5kW is too low power (my heater is giving about 1.1kW and is much too little for cold temperatures).



> Add a small circulating pump that can tolerate the temperature and you are in business.


 I also asked what pumps people were using with the Kat heaters.

Thanks for pump link.


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## Tesseract (Sep 27, 2008)

Tomofreno - Yes, you did mention the parabolic shape to the current vs. temp curve of the PTC heater element; I simply _clarified_ that blowing air over the element before it has reached operating temperature is why they don't seem to work at all when it is very cold.

At any rate, 1.5kW_h_ is 5118 BTU, which IS a bit on the low side compared to the 8000 to 12000 BTU most car heater cores can deliver on their highest setting. However, you aren't going to get any more heat from a single ceramic heater element, either.

Furthermore, I doubt you'll find a 2 or 2.5kW version of either heater since that would load a common 20A branch circuit more than is permissible by the NEC (80% is the maximum allowed).

Unfortunately, I can't remember the exact part number or brand of the small pump that Rebirth Auto has been using for pumping coolant in their Soliton1 installations, but it LOOKS like this one:

http://www.amazon.com/Mr-Gasket-42S-Electric-Fuel/dp/B000BWE4RC/ref=pd_sim_dbs_auto_5

Note that this pump, and those similar, are meant to be used with fuel, not hot coolant, so this is NOT A RECOMMENDATION. Of course, if you put the pump before the inline heater it will be exposed to the lowest temperature in the loop, but since heat exchangers work best when there is a 10-20C drop across them, the temperature the pump is exposed to might still be more than is acceptable. You'll need to heat the coolant up to at least 60C (140F), but there's no need to go as high as the original 90C (195F) that the ICE thermostat maintained.

At any rate, 12VDC pumps for hot water in "caravan", or "RV" setups, solar water heating systems, automotive racing (pricey!), etc., are where to look. Another possibility by ShurFlo:

http://www.amazon.com/SHURflo-100-0...e=UTF8&s=sporting-goods&qid=1262518683&sr=1-1

Wetted materials are Ryton and stainless steel, both of which are suitable for well past 100C, so this one at $50 seems like a safer bet.


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## tomofreno (Mar 3, 2009)

> Furthermore, I doubt you'll find a 2 or 2.5kW version of either heater


 I mentioned in the original post I had already found 2 and 2.5kW versions of the Kats tank heaters. The former is the 13200 model, 120V. 



> Another possibility by ShurFlo:


 Yes, that's one I was looking at, and JRP3 bought - for $39.99. I hadn't found any materials info though, so thanks for that.


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## tomofreno (Mar 3, 2009)

I decided to estimate how much heat was required for this. Using density and specific heat of air of 1.29 kg/m3 and 1000 Joule/kg-C, and air flow of 400 cfm, gives an air mass flow of 0.24 kg/sec, and required power of 240W/C. So to increase the temperature of this mass flow of air by 40C (say from -6C (20F) to 34C (93F) requires 9.6kW transferred from the heat exchanger to the air mass. A low blower setting of 200 cfm would require half that or about 4.8kW. Then a 2kW heater would increase the temperature by about 8.3C (15F) at 400cfm, and 16.6 (30F) at 200 cfm if it had a heat transfer coefficient of 1 or 100%. Not looking good.


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## Tesseract (Sep 27, 2008)

It's been a LONG time since I took thermo, but I seem to recall something about heat exchangers hitting a sweet spot when the temperature drop across them is in the 10-20C range. Working backwards from there, you'll find that even a 1.5kW heater will do a decent, if not stellar, job of heating the cabin, it just takes longer to get there is all.


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## tomofreno (Mar 3, 2009)

Btw, BTU is a unit of energy, not power. One BTU = 1055 Joule, so 240W or 240 Joule/sec = 253,200 BTU/sec.


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## Tesseract (Sep 27, 2008)

This may come as a real shock to you, but I left off the "h" in "kWh" by accident. No need to throw the Wikipedia entry for BTU in my face.


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## tomofreno (Mar 3, 2009)

> No need to throw the Wikipedia entry for BTU in my face.


 I wasn't throwing anything in your face, just correcting units. I'm glad I went through the exercise. Made me realize I won't get that good of performance with a 2kW heater either, and if I were to figure out a way to get 10kW it would require about 87A from my 115V pack. I hadn't thought about it at all, but the heater core in an ICE vehicle is essentially a constant temperature heat source, as there is so much heat power available from the ICE, the heater core temperature is pretty much unaffected for all blower settings. Getting that kind of power from a typical battery pack requires a lot of current. I would be using more power to heat than to move the car at secondary road speeds. I wonder what power the Tesla heater is and how range is affected by it. Owners in CA probably wouldn't notice much range difference, but I expect NY owners would if they drive much in cold weather there.


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## Qer (May 7, 2008)

tomofreno said:


> Getting that kind of power from a typical battery pack requires a lot of current. I would be using more power to heat than to move the car at secondary road speeds. I wonder what power the Tesla heater is and how range is affected by it. Owners in CA probably wouldn't notice much range difference, but I expect NY owners would if they drive much in cold weather there.


It is probably a very good idea to begin heating up the car already when it's charging to avoid putting a serious dent to the available range, yes. Yesterday it was -15C around here, the heater in our (ICE) Jeep barely kept up with the cold when I was driving...


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## tomofreno (Mar 3, 2009)

I still don't understand why the little $18.00 120VAC ceramic heater I sit inside the car gets it quite warm in 20 minutes or so at ambient temperature of around 30F, much better than what looks like the same core mounted in the car heater will do. I just split the power cord on the ceramic heater and measured AC current of 9.9A rms with it on "high". That's about the same magnitude as the DC current the heater core in the car is using at high blower setting, and voltage is 120VAC versus nominal 115VDC. What the


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## Overlander23 (Jun 15, 2009)

How much air is moving through the DC powered core vs the AC powered core?


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## tomofreno (Mar 3, 2009)

> How much air is moving through the DC powered core vs the AC powered core?


 I don't have a quantitative way to measure it. I can adjust the car's blower so air flow seems about the same for either the high or low setting of the ceramic heater. Maybe it is partly because air through the core flows around in the heater housing then out through the plastic ducting so it looses heat to these until they warm up, which could take a while. I also only have it on while driving, and air infiltration into the cabin dilutes its affect. When I put my hand in front of the ceramic heater the air feels warmer, but my hand is also receiving ir radiation from the hot heater, whereas there is no line of sight from the heater core to give radiation. Dunno. I'm guessing it is some combination of things like this. Plus, the ceramic heater will heat the air in the car fairly well in 20 minutes at 30F, but the surfaces in the car are not warm, so it cools down before long. It would take much longer to heat the surfaces too. If it is a sunny day I pull it out in the sun and it heats much more quickly, surfaces too!


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## dtbaker (Jan 5, 2008)

I am getting reasonable heat from the ceramic heater core installed 'in-line' in my air duct just downstream of the fan. I have not measured A draw yet as I don't have an accurate way to do it, but I was having trouble with blowing fuses. I jimmy-rigged a 'fuse' with a short piece of 22ga copper wire in place of a fuse. Not quite as bad as a penny, but did blow once and looked like it probably arced a bit until it melted away the ends....

Lesson is, turn on the heater when you are NOT driving, and have no voltage sag, then LEAVE it on so it stays hot and doesn't draw much juice.

D


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## tomofreno (Mar 3, 2009)

> I am getting reasonable heat from the ceramic heater core


 At what outside temperature? Is your car left outside or in a warmer garage? Mine pulls over 30A in rush, but not for long enough to blow the slow blow 20A fuses. Sounds like yours is drawing more, so you are likely getting more than the about 1100W I am.


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## dtbaker (Jan 5, 2008)

outside temp was maybe 25 deg F.... but I am pretty sure that the problem was I flipped on the heat while driving under load and my (96v nominal) pack was probably down around 80v when it came on, which pulled probably closer to 40a for a couple seconds.

After I install my cycle analyst I will have an accurate measure of draw... but I have to install a new shunt for it first....


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## TheSGC (Nov 15, 2007)

I was doing some heater tests on my bench today, and there is no way the ceramic element is going to keep my window defrosted. There is over 4 feet of ventilation the hot air must go through, and the heat from about 2-3 feet away from the heater is barely warm. Add to that my 96 volt battery pack, and the heater is barely warm. 

I am now looking into a hot water setup. I was playing with another 1200 watt oil filled heater and it was a lot hotter at a distance than the ceramic. The AC ceramic heater does a decent job preheating the cabin, but I have little hope it will do anything more than drain my battery. 

I have found a Kats 1500 watt for about $40 and still looking for a 12 volt pump. if I can get the whole sucker for under $80 I will jump on it.


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## tomofreno (Mar 3, 2009)

Click on "circulating tank heaters" at the link below and scroll down. There is a 120V 2kW version.
http://www.warehouseautoparts.com/Specialty_Line/Kat/Kat_heater_Specials.htm


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## tomofreno (Mar 3, 2009)

So Dan you are saying at beginning 25F temperature in the car the air coming out of the heater feels warm on your hands and/or feet, and warms the cabin to a comfortable (without long underwear and wool socks ) temperature in say 20 minutes or less? If so, I'd be happy with that.


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## TheSGC (Nov 15, 2007)

As I understand it, I don't need a pump for the Kats? It uses convection for heating and I have to install it lower than my heater core? Is that all?

I will be using a 1500 watt or 1000 watt as 2000 watts will be too much strain on my setup.


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## Tesseract (Sep 27, 2008)

I don't think relying on thermosiphoning will work too well. It's probably sufficient to get the fluid moving just enough to warm the who loop after a couple of hours.

The Shurflo pump for $40-$50 sounds like a good bet. 

You still need a PWM circuit so the heating element and/or thermostat doesn't blow up, but you sorta need one with the ceramic elements, too, so I don't see that as a drawback per se.

I'm going to test out the 1000W ZeroStart model on a Volvo V70 down at the shop. The temp today here in "tropical" Florida is in the 40's.


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## TheSGC (Nov 15, 2007)

Tesseract said:


> I don't think relying on thermosiphoning will work too well. It's probably sufficient to get the fluid moving just enough to warm the who loop after a couple of hours.
> 
> The Shurflo pump for $40-$50 sounds like a good bet.
> 
> ...


Ok, I will order up a pump too. Curious, why would the heating element blow up if I am using a 96 volt system? Or is that for a higher voltage setup? I didn't need a PWM on a ceramic cause there was barely enough heat from it to do anything at 96 volts. 

40F? That's a heat wave! I just finished uncovering my EV from the snow...


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## Tesseract (Sep 27, 2008)

TheSGC said:


> Ok, I will order up a pump too. Curious, why would the heating element blow up if I am using a 96 volt system? Or is that for a higher voltage setup? I didn't need a PWM on a ceramic cause there was barely enough heat from it to do anything at 96 volts.
> 
> 40F? That's a heat wave! I just finished uncovering my EV from the snow...


There's a bimetallic disc thermostat inside these things (well, there is inside my ZeroStart model - I'm sure to get UL listing there's one on the Kat models, too). As long as the temperature of the coolant never exceeds 180F (what mine is set at) you don't have to worry about PWM'ing the voltage applied to the heater, but if that thermostat opens the 96VDC just once under load it's cooked.

40F is a heat wave?! I guess I better be happy it's at least that 'hot', huh?


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## TheSGC (Nov 15, 2007)

Tesseract said:


> There's a bimetallic disc thermostat inside these things (well, there is inside my ZeroStart model - I'm sure to get UL listing there's one on the Kat models, too). As long as the temperature of the coolant never exceeds 180F (what mine is set at) you don't have to worry about PWM'ing the voltage applied to the heater, but if that thermostat opens the 96VDC just once under load it's cooked.
> 
> 40F is a heat wave?! I guess I better be happy it's at least that 'hot', huh?


I forgot about the AC temp sensor fusing under high DC loads. I don't get AC circuits until this coming semester.  I found something in the EV Abulm #2127 that mentions about the AC Thermo:
"Update on the KATS heater thermostat problem. It's an easy fix actually. ^_^

Instead of trying to source and rig some high voltage DC thermostats try this:

Disconnect the AC thermostat from the heater circuit.

Rewire it to the positive 12v wire controlling the heater contactor (or relay) power coil.

When the thermostat hits the high temp mark it will cut off the contactor thereby shutting down the heater like its supposed to. The low temp mark will turn everything back on keeping the heater nice and toasty.

Running it on low 12v DC will keep the AC thermostat from fusing and going into instant boil mode."

That is what I am going to try out first. It sounds simple enough.


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## Jimdear2 (Oct 12, 2008)

Before you order the Kats look at (I think it's Brian "rctous") the thread where a home hot water tank heating element was used. Along with some simple plumbing parts and nipples, he made a very nice heater unit that he says works very well .

The advantage is you can get up to 4500 watt elements. Also look on ebay for the heater booster pumps that are made to handle hot antifreeze. If you shop I've seen them for comparible and reasonable prices. They are quiet and engineered to do the job. The pump you are looking at is for cold drinking water.

Hope this helps.


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## Dave Koller (Nov 15, 2008)

Scroll down read this about heaters:

http://www.saturn.offical.net/2009 Summary


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## TheSGC (Nov 15, 2007)

I found a 12 volt pump for hot liquids. I did see Brian's heater setup, but it's too powerful for my needs. If I get anything larger than 1500 watts, there wont be any power left to drive the EV. 

I did order up the Kat 1500 watt and a Jasper 12 volt pump and it's coming in tomorrow. Gotta love Amazon.com.


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## Jan (Oct 5, 2009)

What about parkingheaters? They are reasonable priced second hand. I know they use fuel, but burning fuel to get heat is very efficient. And I guess you could also use vegeterian oil.

http://www.webasto.com/products/en/3115_3422.html

It should be possible to redesign them a little to get a drivingheater with a little 2-5 litre tank or so...? They use 1/2 litre an hour.


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## Tesseract (Sep 27, 2008)

Jimdear2 said:


> Before you order the Kats look at (I think it's Brian "rctous") the thread where a home hot water tank heating element was used. Along with some simple plumbing parts and nipples, he made a very nice heater unit that he says works very well .


Yep. You can do that. But if you are like me and can't ever seem to get two threaded plumbing fittings to go together without leaking...




Jimdear2 said:


> The pump you are looking at is for cold drinking water.


Now hold on there, buster! I spec'ed a pump that DOES handle hot water:

http://www.amazon.com/SHURflo-100-0...e=UTF8&s=sporting-goods&qid=1262518683&sr=1-1

The wetted parts are Ryton (good to over 400F) and stainless steel. It's for hot or cold water pumping applications in RVs.

The OTHER pump specified in this thread - part number 105-003, I believe - _is_ $10 cheaper but I don't know what the wetted parts are made out of.


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## Jimdear2 (Oct 12, 2008)

TheSGC said:


> I found a 12 volt pump for hot liquids. I did see Brian's heater setup, but it's too powerful for my needs. If I get anything larger than 1500 watts, there wont be any power left to drive the EV.
> 
> I did order up the Kat 1500 watt and a Jasper 12 volt pump and it's coming in tomorrow. Gotta love Amazon.com.


I've been touting the block heaters for quite a while, but when I saw Brian's heater it really impressed me as DIY. I still like the block heater but wonder if 1500 watts its sufficent to keep the car warm. . . and do defrost duties. A thought occured to me a long time ago about putting a gallon or so, WELL insulated, reservoir into the loop and pre heating from the GRID while charging or on a timer before leaving in the AM. 

This would only work if you could pre heat at both ends of your commute though. Trying to heat that reservoir with out pre heat could take quite a while.

Don't know where you are located, maybe 1500 wats will be sufficient.

The parking heater that Jan shows has a following in northern Canada and Alaska where even a 1500 watt electrical block heater won't keep the engine warm enough to start. They talk about warm and toasty inside but they were originally made to keep the engine warm enough to start in sub zero temps. I installed a few for people going to Alaska. I guess someone designed a setup to start the heater blower off a thermostat to warm the interior as well. You need a BIG 12 volt battery to keep them going in the cold weather.

I know that the gas, propane or oil fired forced air heaters (like used in the old air cooled VWs) will keep you toasty from mid USA to the Artic. Those are still available. They are self contained and run from a theromstat only when needed. They need about 1.5 cubic feet to install but can be installed anywhere.

The fuel fired block heater that Jan shows is probably overkill (plus very expensive). If you are going to go to a fuel fired heater (advice to others) find a forced air type. 

The problem with both types is you need to make room for a fuel tank or propane tank in your EV, plus you can no longer snear at fuel stations.

Good luck,


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## Woodsmith (Jun 5, 2008)

As a side issue I have been using a small domestic 500w fan heater in my car on a timer.
Due to the vast amount of snow we have at the moment I decided to run an extension lead outside and into the car. I have placed the heater on the passenger seat and set it on a timer to come on 30 minutes before I am due to leave for work in the morning.

Although not hot in the car, it is certainly warm enough for shirt sleeves and all the glass is mist free. It makes clearing the car of snow and ice really easy. The car stays warm while driving until the ICE powered heating comes to life.

What I am getting at is that I now know that a 500w heater is very effective and will raise the car to a comfortable level of heat in around 15-20 minutes when the car is under 10" of snow! This could be useful information in working out just how much heat is needed and also the effectiveness of pre heating at the end of a charging cycle overnight.









This is one reason why there has been no progress reports on the MR2.


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## Dave Koller (Nov 15, 2008)

I have had my reservations about BOTH types of heaters and even if I will ever run an EV in the winter! The cold is not so bad -25 F is the lowest we have had so far... it is nice today sooooo they spread salt  The snow, Ice and cold is not enough to detour me... The SALT is ... It eats up everything and washing it out of everywhere is nuts!! So you guys in the south can have winter fun - I need a "clunker" EV for winter... 


This picture is of just a 6 mile run! (not an EV) imagine how much DRY salt gets on the batteries, into brushes, aluminum parts and electronics!...

Yep I remember when we used just sand -- and well that is enough ranting


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## Jimdear2 (Oct 12, 2008)

Tesseract said:


> Now hold on there, buster! I spec'ed a pump that DOES handle hot water:
> 
> http://www.amazon.com/SHURflo-100-0...e=UTF8&s=sporting-goods&qid=1262518683&sr=1-1
> 
> ...


 
Sorry I didn't look up the pump you speced, I appologise.

I still don't like those RV water pumps. The ones I recommend are made for duty in an AUTOMOTIVE cooling systems and will withstand all of the abuse and chemicals, plus run for hours without shutdown (how many hot showers go on for hours, although ther are times . . .) 

I dont know what the duty rating for the Surflow is, again I havent looked. But then I don't need to, I already know of a superior product. 

By the way, I only let my enemies call me buster You can call me Jim.

Have a good one


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## TheSGC (Nov 15, 2007)

I am in Massachusetts, and the cold weather right now is around 20-30F. This is what I got:
Kats 13150 1500 Watt Aluminum Circulating Tank Heater
Jabsco 42630-2900 Marine ParMax 1 Minature Multi-Outlet Water Pressure Pump (1.1-GPM, 35-PSI, 12-Volt, 4-Amp, Automatic)

The pump is rated for hot water shower use in RVs, etc and should do the job. It's intermittent duty, but the EV is never on the road for more than 30 minutes at a time, and I am guessing the heat will be on for maybe 10-12 minutes as the cabin seems to keep a lot of heat in. About $100 including 1 day shipping so it should be here tomorrow, and I have a supplier for the hosing and fittings already.


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## tomofreno (Mar 3, 2009)

I pre-heated my car with a ceramic heater for about 25 - 30 minutes yesterday at 26F ambient temperature. I previously measured 10A AC current to the heater at its high setting, so about 1200W. The car felt fairly comfortable when I got in with long underwear, a wool shirt and pullover, and wool socks on. Definitely was not shirt sleeve warm though (I should qualify this with some people are in shirtsleeves when I have a couple layers on - so depends). Within less than 10 miles I needed to put gloves on and my feet were cold. I didn't run the car heater as I was driving pretty far - 65 miles round trip - and I've found it doesn't make that much difference anyway at that outside temperature even though it is putting out 1100W. Took a while to warm my feet when I arrived at my destination at 32.7 miles.


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## Dave Koller (Nov 15, 2008)

tomofreno said:


> I pre-heated my car with a ceramic heater for about 25 - 30 minutes yesterday at 26F ambient temperature. I previously measured 10A AC current to the heater at its high setting, so about 1200W. The car felt fairly comfortable when I got in with long underwear, a wool shirt and pullover, and wool socks on. Definitely was not shirt sleeve warm though (I should qualify this with some people are in shirtsleeves when I have a couple layers on - so depends). Within less than 10 miles I needed to put gloves on and my feet were cold. I didn't run the car heater as I was driving pretty far - 65 miles round trip - and I've found it doesn't make that much difference anyway at that outside temperature even though it is putting out 1100W. Took a while to warm my feet when I arrived at my destination at 32.7 miles.


Kind of my point about winter also in the northwoods ! Do you have salt on the roads like in my post above? I know I can seal in everything but it is ridiculous around here. We have been in the teens and I have an old jeep I recycle my store cardboard with... I kept the heater off - and well, even after 10 miles - not so pleasant ! Tried it in my wife's Sable - yep not so pleasant. Not as bad in my pickup maybe we need to seal off the back seats for winter! Keep the front warm lol... Anyway this is a good thread for those of us in the North...


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## TheSGC (Nov 15, 2007)

I did a heater test a few weeks ago, on a frozen and ice covered EV and here was the relevant info:

"So these past few days I have used my AC ceramic heater and tested out the capability of them.

It was 27F outside and with the Heater set to MAX, the car was fully defrosted in 8 minutes and 42F, in 15 minutes it was 50F and after 20 minutes it was a nice 58F inside!"

My KATs 1500 watt heater and pump are waiting for me at home so I should have some pics and a schematic drawing tonight or tomorrow.


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## Dave Koller (Nov 15, 2008)

TheSGC said:


> I did a heater test a few weeks ago, on a frozen and ice covered EV and here was the relevant info:
> 
> "So these past few days I have used my AC ceramic heater and tested out the capability of them.
> 
> ...


I think a lot depends on IF you suck in Cold OUTSIDE air or recycle the inside air - some vents don't close well - some used the ICE vacuum - some have a small flap motor... I think it is important to use the inside air to keep down loss as is done in MAX air conditioning mode... as the temp raises it will become more efficient as in putting an AC heater in for pre-warmth it uses the inside air and NOT any outside air..


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## Jimdear2 (Oct 12, 2008)

Just a note, on using constant recirculation when heating.

You do need to bring in some outside air to vent moisture build up from snow melt and exhalation.

I used to see this on some early Mazdas RX3s and 4s (very tight cars), people would put their heating system into recirulation mode because the car heated up faster and would just leave it there.

I have seen cars with dripping headliners (a postal worker) as a worst case. Generally it just causes fogging of the windows and Ice buildup on interior surfaces when the car sits overnite.

Plan your heating sustem to bring in at least 10% outside air then leave the doors or windows open once in a while when parked in a safe place.

Hace a good one


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## Dave Koller (Nov 15, 2008)

Jimdear2 said:


> Just a note, on using constant recirculation when heating.
> 
> You do need to bring in some outside air to vent moisture build up from snow melt and exhalation.
> 
> ...


Good point... My Jeep (ICE) will suck in fine snow and melt causing a lot of moisture that hits the cold window and ices it over - my Dodge pickup does the same. (I prevent that by covering up the intake grill to stop small fine snow from getting in ) I crack a window and the moisture escapes... I guess with no bodies in the car - keep it closed and recirculate - it can be dry in winter here as the cold drops moisture out of the air. Breathing causes the most buildup! ( Speaking from close to 70 years of riding in the frigid NORTH  - remember how we used to breath on the windows and draw pictures lol err back in the days of the REAL ICEBOX - HA I remember Dad used a kerosene heater in the old running board car! ) 
anyway just one more thing about the cold... I see the guys in the south are experiencing battery drop from the "cold" spell  ! Those of us in Mid- Canada and the far North have a different view of what cold does!


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## Dave Koller (Nov 15, 2008)

Just for fun, has anyone tried using an infrared heat bulb (as in bathroom - err.. French fry warmer - not ribbon heater) on the pack? I know it does not heat the air BUT could it heat up surfaces such as iced windows, bodies, and even batteries in the EV for less amp draw..


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## Dave Koller (Nov 15, 2008)

Hmmm the Reptile heating lamps give off no light but LOTS of infrared! You can feel them farther than a regular fan ceramic - BUT they are infrared... Oh the 250 watt feels like 1500 watt BUT again does not heat the air just you - oh does heat glass metal rocks 

The lamps are NOT in glass but ceramic - so they are not the same as a food service RED lamp lol.... 

Different kinds >>>>


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