ewarnerusa
Helena, Montana
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I have never run the element dry. There were instances where I had it in a cup of water when on and a bit of water evaporated. But element was always >90% submerged I would say.
Multimeter ohm reading on the element is 1.5 ohms.
What is the math for how you came up with what the resistance should be? I only took one circuits course in college and I remember
V = I * R
and
P = V * I = I^2 * R
But with R = 1.5, if I saw 21A from panels at one point and assume 19A was going to element, I was pushing 19^2 * 1.5 = 542 watts. Way over rating. ****, do I have too much solar for this?! Ironic...
Another element was only $15. I'll take a resistance reading on it before doing anything and see what it says. But it will be weeks before it makes it across the sea to my door.
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ewarnerusa
Helena, Montana
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Manual has quite a bit of language about minimum and maximum diversion load elements, but I thought I was within spec. Now I'm not so sure.
https://www.morningstarcorp.com/wp-conte........ds/technical-doc-diversion-manual-en.pdf
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StirCrazy
Kamloops, BC, Canada
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Joined: 07/16/2003
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ewarnerusa wrote:I have never run the element dry. There were instances where I had it in a cup of water when on and a bit of water evaporated. But element was always >90% submerged I would say.
Multimeter ohm reading on the element is 1.5 ohms.
What is the math for how you came up with what the resistance should be? I only took one circuits course in college and I remember
V = I * R
and
P = V * I = I^2 * R
But with R = 1.5, if I saw 21A from panels at one point and assume 19A was going to element, I was pushing 19^2 * 1.5 = 542 watts. Way over rating. ****, do I have too much solar for this?! Ironic...
Another element was only $15. I'll take a resistance reading on it before doing anything and see what it says. But it will be weeks before it makes it across the sea to my door.
1.5 Ohm doesn't really make since for a 300-watt element @12V.
at 12V with that resistance it will be using 8amps (which confirms your reading) but only consuming 98 watts. Remember with a resistive element you only control the voltage it will set the amperage due to its resistance. I'm starting to think you got a defective heater, or overpowering it (feeding it over 12V) has toasted it.
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ewarnerusa
Helena, Montana
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New element arrived. Measured 0.6 ohms. The heat shrink is not white but gray is shown in the picture, but it feels the same. I don't think I'll put it to use, it feels like running a 300 watt rated element when I have nearly 500 watts to give when batteries are full is just not adding up to success. Sourcing a 500 watt 12V element has been a dead end. I can find NPS threaded ones but not the right 1 1/4" for swapping out the OEM 120V AC element. And this 300 watt one is the highest wattage 12V cartridge heater that I can find with 1/2" NPT for using in the drain plug.
* This post was
edited 06/06/23 05:20pm by ewarnerusa *
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ewarnerusa
Helena, Montana
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Question: what would happen if it was a 500 watt element for 24V DC?
500 watt 24V DC cartridge heater 1/2 inch NPT
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stevenal
Newport, OR, USA
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Half the voltage into the same resistance yields half the current.Half times half is a quarter. You'd achieve 125 w.
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pianotuna
Regina, SK, Canada
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The output will drop by the square of the voltage.
24 x 24 = 576
12 x 12 = 144
So with a 24 volt element running at 12 volts the wattage would be 1/4 of 500 watts, i.e. 125 watts.
If you could find a 24 volt element that was 2000 watts @ 24 volts and run it at 12 volts then the output would be 500 watts.
I expect you would find you need the element called "unobtainium" to get the results you are hoping for.
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StirCrazy
Kamloops, BC, Canada
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If that fits it would still be worth it. wouldn't blow it up at any point because of too much voltage. If they are all the same thread even a bit bigger like the 800 or 1000 watt one might be worth a try.
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ewarnerusa
Helena, Montana
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StirCrazy wrote:
If that fits it would still be worth it. wouldn't blow it up at any point because of too much voltage. If they are all the same thread even a bit bigger like the 800 or 1000 watt one might be worth a try.
I need to take readings still to confirm, but my hunch is that the element receives full panel wattage at the full potential array voltage (18V?) when it is getting diversion current. Does that change the math?
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pianotuna
Regina, SK, Canada
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If the voltage goes up the wattage increases. Your meter is your friend.
Measure voltage open circuit.
Then place a load on the diversion terminal and measure the voltage.
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