Overvolting 12v 300 Watt Immersion Element

Short answer:- Dunno.
Long answer:- the resistance of the heating element prob' goes up as it heats so a resistance measurement is futile (a petite star trek borg jokette reference).
Does the heater have a thermal cut out (many do to avoid the dry kettle thing) It could well be ok, but I'd suggest maybe the easiest way is to use an inverter to get yourself up to a 'standard' 240v.

Sorry if that's all a bit vague and unhelpful. Often with this sort of thing, you have to become your own expert.

Del

If it is rated for 600 watts at 24 volts and 300 watts at 12 volts, the rating can be thought of as 25 amps.

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Exceeding 25 amps by a little bit occasionally probably won't make much difference. Exceeding 25 amps by a large about or regularly by a moderate amount might shorten the life, especially if any problems develop that limit heat transfer or compromise the integrity of the protection for the conductor.

From his link, it looks like there are 4 models available with different voltage and wattage. His is 12v, 300W.

That makes more sense.

Is this element fully immersed under the water? The typical application would have a threaded header on the side of your water 'pot', at the bottom, and the element would be horizontal. This is how it would be installed in a hot water heater. If any part of the heating element is exposed to air (not including the electric terminals), the internal temperature may climb to a level where the insulation (high temp electrical) is damaged, and the heating element may exceed maximum operating temperature, which typically results in a meltdown.

Relative to each end changing colour of the bare nichrome, there will be a current flow through the water and electrolysis will occur. This will result in some of the metal ions of the heating element being deposited in the water.

This does not seem to be an efficient use of solar power....check out this video

https://www.youtube.com/watch?v=24TJCfJLzMI

More efficient and a lot cheaper!

Get a second element and run it in parallel with the first during summer months. Problem solved, no extra load banks required and no wasted power which could be better used to heat the water.

In my previous experiment where I was using bare nichrome to boil water

I wouldn't recommend it, use a sealed element unless you want to make yourself sick.

Water cooled resistive load is all it is. Go for it. Just don't boil dry.

That is what I was thinking. He is selling a 600w element the exact same shape and size so it should be fine if all goes well.

Over voltage is not ok as you will have doubled the wattage of the element (0.48 ohms @ 18V = 675W). And you will have doubled the "loading" on the internal resistance spiral inside the element and the loading on the elements surface. Scale and lime build up on the surface will increase drastically too, hindering the heat transfer from taking place and causing the element to fail, thats if the internal resistance spiral doesnt superheat itself first and blow through the elements sheath.

A resistance spiral (taking into account, wire size, coil OD and pitch etc etc) is normally designed to be as safe as possible or MSW (maximum safe wattage) to suit that medium to be heated. If its safe to run in air then its safe to run in water, but not the other way around mostly.

Under voltage is ok as 8V @ 0.48ohms = 133W, which probably wouldnt boil anything.

Your element will fail shortly is the short end of it. Rather have him or another element manufacturer make you the correct element for your voltage.

If you wish to cook eggs at night (it happens), then you will be drawing from your deep-cycle battery. What is its voltage? If 12V then draw from your battery day or night.

The battery is 12v. I had the element running directly on the panels today and it was running at 600w so far without damage. I boiled some eggs with it.

Here's a video of it working but it was on the battery at that time.

https://www.youtube.com/watch?v=FMeBZ5QRxBM

There is no VGA button, so a GA will have to suffice.