Electronics > Beginners
Standard electric kettle as a DC dummy load ?
lordvader88:
I have a standard 120VAC electric kettle, how much current would that pass at 12VDC do u suppose ? Right now I'm playing with a 12V 2A DC-DC converter, and I have a 0.3A fan. I and another 4 or 5 fans, but I'm not trying that now.
Soon I really need big dummy loads up to test some ATX PSUs including a 1200W 1 I have. I need a kill-a-watt meter too. And some proper power resistors. I'm going to get some lo/hi-beam bulbs.
Then there's the $150, $250 load testers on ebay, I think a 300W unit for $250.
I have some 3/16" or 1/4" steel plates, 1'x1' (30cm x 30cm), what kind of current would 1 of them pass in a bucket of water.
I'm in my bedroom so I can't do experiments like I should be doing.
Shock:
Use ohms law to calculate what type of resistance you will need.
You also will need to check if that is 1200W on one 12V rail :)
edpalmer42:
The kettle might be okay, but remember that you have to fill it with water to keep it from overheating. That means you're going to end up with a very soggy, steamy room. And, of course, you'll run out of water at the worst possible time, the kettle will overheat and the thermal protector will trip and cut off your load! Maybe not such a good load after all.
The high-low beam headlights are designed for 12V which is convenient. But they're only 50 or 60 watts which might not be enough. Also, when you turn them on, they're almost a short circuit which might cause your power supply to either not start or even blow up! Maybe not so convenient after all.
Practical alternatives are automotive battery testers or big resistors. I have a cheap 50 amp battery tester that's made of a couple of wire coat-hanger size steel wires in parallel. If you DIY something with actual coat hangers, remember that they're covered with lacquer which will smoke or burn. Either remove the lacquer or do the initial test outdoors.
Mike's Electric Stuff did a video on big loads that might give you some ideas.
Another good load is heating elements from an oven or stove, but they won't get you to 1200W at 12V.
mtdoc:
--- Quote from: Shock on July 13, 2018, 04:22:59 am ---Use ohms law to calculate what type of resistance you will need.
You also will need to check if that is 1200W on one 12V rail :)
--- End quote ---
This.
The kettle resistance is very unlikely to be low enough. Use a DMM to measure it.
viperidae:
1200W at 120V is 12 ohms. That's 12W at 12V. Maybe a bit more as the resistance will be lower when it's cold
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