# finding a heater for a 96v-AC



## EVfun (Mar 14, 2010)

Many of the ceramic heaters can be rewired for 120 or 240 volt operation. If the heater has 5 tabs for electrical connections down the side and you find only 3 of them connected on a 240 volt heater (1 and 5 to one side of the line, 3 to the other side) then you can rewire it for 120 volt operation (1,3 and 5 to one side of the line, 2 and 4 to the other.) 

Once you get a ceramic heater suitable for 120 volt operation it should work pretty good at 96 volts. I would expect about 75% of the rated wattage.


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## Jozzer (Mar 29, 2009)

Hi Tom,

I can confirm that this heater has 5 tabs and can be rewired, http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=330584567330&ssPageName=ADME:L:OC:GB:1123

I havn't actually tried it at a lower voltage however, so don't know how well it would perform. I've found I need 2 of them to heat the car properly (though once warm I can switch back to 1 to keep a stable temperature).

Steve


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## tomcameron (Sep 24, 2011)

thats good to know I don't need to buy another heater.

good i will take it apart and see how it goes.

thanks


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## dtbaker (Jan 5, 2008)

they do create a pretty big spike in amps for about 2 seconds when they first come on, so fuse on the high side.....


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## mora (Nov 11, 2009)

I'll share my experience with ceramic heaters and 96V system. 4x 1500W 120V elements in paraller at 96V: peaking at about 40A and staying between 20-30A depending on temperature outside the car. That's less than 4kW peak and about 2.4kW continous. It could be over 6kW peak and way over 4kW continous (6kW would probably melt all the plastic channels inside the heater) if the voltage was higher.

Amps drop when I turn blower to higher setting and heat output gets colder as well. Four elements fully on keep the car warm when it is about 0C outside (that's something like 2-2.5kW used by heater then).

I'll be upping voltage to 144V as soon as I get new battery box made. I believe my heater output goes up dramatically.


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## dtbaker (Jan 5, 2008)

mora said:


> I'll share my experience with ceramic heaters and 96V system. 4x 1500W 120V elements in paraller at 96V: peaking at about 40A and staying between 20-30A depending on temperature outside the car. That's less than 4kW peak and about 2.4kW continous. It could be over 6kW peak and way over 4kW continous (6kW would probably melt all the plastic channels inside the heater) if the voltage was higher.
> 
> Amps drop when I turn blower to higher setting and heat output gets colder as well. Four elements fully on keep the car warm when it is about 0C outside (that's something like 2-2.5kW used by heater then).
> 
> I'll be upping voltage to 144V as soon as I get new battery box made. I believe my heater output goes up dramatically.



output probably will not go up with higher voltage ,although they might get hot faster.... ceramic element resistance is self-regulating by their temperature. you'll see the amp draw go down with higher voltage, but heat output will be the same.

I'm confused by your report that amps drop when fan is turned UP. It should draw more current to attempt to heat elements that are dumping more heat to more air.


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## mora (Nov 11, 2009)

That's what I thought too. Fan turned up draws more amps momentarily but soon drops lower than with lower fan settings.

I though it like this:

P=U*I
1500W and 120V: 1500W / 120V = 12,5A

R=U/I
120V/12,5A = 9,6ohm

now if that is the resistance element tries to go to:
I=U/R
96V/9,6ohm = 10A

but it isn't that simple it seems. Does element need more voltage to maintain bigger amp draw like dc motors sustaining torque at higher rpm's?


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## EVfun (Mar 14, 2010)

The ceramic heaters have a weird resistance curve. They are designed to be a somewhat higher when cold, my ceramic heater starts at about 4 amps when powered from my 102 volt pack. As the heater warms the resistance drops. My heater runs at about 12 amps from my 102 volt pack. If I pull power to the fan the current quickly drops as the ceramic elements get too hot. I don't let this go on for more than a few seconds.

I did a test with a ceramic heater core out, sitting on my workbench with newspaper above and below it (sitting on the core) so there was no airflow. The current dropped back to about 2 amps. This test was done with 120 vac and me at the ready to toss burning newspaper. It did scorch the paper but didn't set it alight. It made me quite comfortable with ceramic heaters, but damaged that ceramic heater. It would never draw as much current in normal operation again, so it was tossed. Because of this test I recommend that some system be in place to insure the heater core isn't powered without airflow across the core.


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## mora (Nov 11, 2009)

Some more experiences with 120V ceramic elements. I wired 10 more cells to my pack temporarily to boost voltage to 128V. I observed heat output and amp readings.

Voltage settled to 120V. I have three steps in blower speed contol. Here are the amps I got:

low: 35A
mid: 39A
high: 40A

and those readings were not peak readings. Amps stood there. Amps rose to those levels faster than with 96V. I saw no spiking if blower went quickly from low to high setting. Voltage stood at the same level all the time. Lowest blower setting resulted in smell of burning plastic in less than a minute so I had to keep operating blower at higher speeds. It was -6C (21F) outside and windows were frozen from both sides when I began testing elements. It took maybe three minutes for all the windows to get clear of ice and even dry. I didn't measure temperature inside the car at that point but it was really comfortable. I can operate fan at slowest speed if I turn half of my elements off.

Now I like my heating setup. 4x 120V elements at 96V didn't ever give more than 2kW. Now it is like 4.8kW continous.


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## tomofreno (Mar 3, 2009)

mora said:


> Some more experiences with 120V ceramic elements. I wired 10 more cells to my pack temporarily to boost voltage to 128V. I observed heat output and amp readings.
> 
> Voltage settled to 120V. I have three steps in blower speed contol. Here are the amps I got:
> 
> ...


 I would guess that now you feel more heat at higher blower settings, rather than less as you had with the lower voltage. Air temperature out depends on air mass flow and element temperature.

My experience jives with evfun's, in that the heater elements I am using have a U-shaped resistance curve. Higher when first turned on, lower immediately after as it warms, then highest when it is hot. Kta-ev sells different elements with different resistances for different pack voltages. One for a 144V pack will give poor heating with a 115V pack. I got a bit less than 1 kW from one of these they sent by mistake (mis-labeled). I replaced it with 2 elements purchased at Lowes and mounted side-by-side. These put out about 3.1kW, and the larger air flow makes a BIG difference in the heat - lots more hot air coming out. At temperatures in the low 20's F I usually turn the heater off after about 10 minutes when dressed in a jacket and jeans. I mounted the elements in teflon which has a working temperature of 500 F. I ran one of the elements after mounting in it on a bench with a small fan blowing air on it and saw no sign of melting - I did see melting when I tried polycarbonate.


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## coulombKid (Jan 10, 2009)

dtbaker said:


> they do create a pretty big spike in amps for about 2 seconds when they first come on, so fuse on the high side.....


Or opt for a slow-blow version.


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## mizlplix (May 1, 2011)

As an aside, I have used a regular Conaire hand held hair dryer plugged into my traction pack to be my window defroster. The blower runs well too. 

At 1650 watts, it is pretty good. I got it at a second hand store....

Miz


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## dtbaker (Jan 5, 2008)

mizlplix said:


> As an aside, I have used a regular Conaire hand held hair dryer plugged into my traction pack to be my window defroster. The blower runs well too.
> 
> At 1650 watts, it is pretty good. I got it at a second hand store....
> 
> Miz



hhhmmm, and how do you switch it on and off?


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## mizlplix (May 1, 2011)

I simply spliced in an extension cord with a female end to the traction pack with a 20 amp fuse. Then i just plug in a drill, hair dryer , soldering iron...whatever. I use the switch on the appliance.

You would be surprised what will run from your car.

Miz


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## piotrsko (Dec 9, 2007)

Any rules of thumb for appropriate appliance selection? Perhaps if it has brushes?

I would ask how well the hair drier works, but it doesn't look all that cold where you live.


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## dtbaker (Jan 5, 2008)

mizlplix said:


> I simply spliced in an extension cord with a female end to the traction pack with a 20 amp fuse. Then i just plug in a drill, hair dryer , soldering iron...whatever. I use the switch on the appliance.
> 
> You would be surprised what will run from your car.
> 
> Miz



you don't get a big fat arc at the plug? I am pretty surprised that the switches on the AC appliances hold up more than a few switches while under DC load.


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## piotrsko (Dec 9, 2007)

at the plug? I don't understand that one. switch in the handle maybe.....


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## dtbaker (Jan 5, 2008)

piotrsko said:


> at the plug? I don't understand that one. switch in the handle maybe.....



sometimes if I unplug my charger while its at full 12 amp draw, there is a heck of an arc (enough that I've burnt up a plug end after a while), and thats on AC. I was thinking that plug/unplugging something like a heater core that would be at full draw on DC might really arc like a mother?

regardless I am a little surprised that you are not having problems with the AC rated switched appliances on DC traction pack power.


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## mizlplix (May 1, 2011)

I simply plug in the hair dryer. Then use the switch on the handle like in the bathroom.

I might not be a Edison where electricity is concerned, but the load here is small with this device.

Yes, any brush type motor will run on AC or DC.

Yes, again. We get 30 degree lows here. This device keeps the windows defogged nicely.


Miz


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