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Old 09-28-09, 01:45 PM   #1
AC_Hacker
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Default Rice Cooker Eco-Hack

Rice cookers work great, I really like them. I most often have some form of cooked brown rice for breakfast. Load it up with fruit and nuts and a wee touch of molassas and you're talking about quality living.

But look at the bottom plate to see how much power it uses.

Mine said 400 watts.

This should be better.

So I opened it up to have a look inside.


First off, there's no insulation, not any.

Second off, I measured the cooker's wattage when it was off and was reading... It was drawing 385 watts before I turned it on!

So the way the circuit works is that the "warm" functions when ever the cooker is plugged in. The warming temp switch senses when an over temp situation happens (something above 212 F) and switches off. When the unit cools, the switch goes back on, etc. This power cycling keeps the rice warm and gobbles up huge watts.

So the most obvious hack is to disable the warm circuit.

The second is to add insulation.

The third is to insert an in-line diode to turn it into a half-wave device, drawing power only for half a wave, thus reducing power by half.


(to be continued)

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Old 09-28-09, 01:47 PM   #2
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Oooh, interesting.

I can understand the insulation and warm kill hack. Why do you want to reduce the power by half though?
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Old 09-28-09, 09:50 PM   #3
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The diode in series is said to save energy. Something about the asymmetry allowing you to get more power for your money. I'm planning to modify a radiator heater with some SCRs to do the same and silence it at the same time. (It currently uses relays to control heat, which means that if I use it as a bedroom heater, I would have to put it farther away, reducing efficiency. The SCRs will do the half wave trick and not make any noise when switching.)
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Old 09-29-09, 12:56 AM   #4
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Quote:
Originally Posted by Daox View Post
Oooh, interesting.

I can understand the insulation and warm kill hack. Why do you want to reduce the power by half though?
I have read about various approaches to high efficiency cooking, and the low efficiency of normal stoves is always pointed out. most of the heat under a pot is lost as it passes around the pot.

I've also read about "Fireless Cooking" which actually uses fire to initially get the food hot, but then uses thick insulation to keep the heat in the pot, where the cooking continues for hours.

So I reasoned that the insulation would prevent the loss of heat through the sides of the cooker... therefore, less heat would be required.

Turns out that the diode works just about right. However, the rice cooks just a bit slower.

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Old 09-30-09, 02:12 PM   #5
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Quote:
Originally Posted by AC_Hacker View Post
I've also read about "Fireless Cooking" which actually uses fire to initially get the food hot, but then uses thick insulation to keep the heat in the pot, where the cooking continues for hours.
Sounds like how Frank Lee from EcoModder.com cooks pasta. See point number 3 in this post.

AC, that trick with the diode is neat, first I've heard. Can't find any info on it, though. What kind of diode did you use?
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Old 09-30-09, 07:53 PM   #6
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Originally Posted by Piwoslaw View Post
AC, that trick with the diode is neat, first I've heard. Can't find any info on it, though. What kind of diode did you use?
I've seen cheap lamps that use a switch that will select 'diode' or 'direct' to give you 'low light' or 'full light'.

I searched through my parts box looking for one with 2x the amp rating (> 7 amps) and 2x the volt rating (> 220 volt), couldn't find it, so I settled for a 100 volt, 5 amp diode. So far, it's working...

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Old 09-30-09, 10:33 PM   #7
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That's pretty trick... I don't use a rice cooker, though. I used to always just do it on the stove, then keep the partially cooked rice soaked in cold water in the fridge, and heat it up in the nuker for about 2 minutes (for a big bowl, 1200W microwave), which would have it cooked perfectly to my taste. Add some dairy or goat's milk, and a little sugar, and consume. Enough calories for a half day's work, for sure, and great tasting as well.
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Old 10-01-09, 02:09 PM   #8
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Default Soaking Hack...

Quote:
Originally Posted by Christ View Post
That's pretty trick... I don't use a rice cooker, though. I used to always just do it on the stove, then keep the partially cooked rice soaked in cold water in the fridge, and heat it up in the nuker for about 2 minutes (for a big bowl, 1200W microwave), which would have it cooked perfectly to my taste. Add some dairy or goat's milk, and a little sugar, and consume. Enough calories for a half day's work, for sure, and great tasting as well.
Your post reminds me of the practice of soaking dry beans overnight before cooking them.

I suppose the same could be done to rice.

It could turn out that just soaking the rice could save more energy than anything I have tried.

Sometimes I feel like I'm re-inventing the past.

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Old 10-01-09, 02:15 PM   #9
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Quote:
Originally Posted by AC_Hacker View Post
Your post reminds me of the practice of soaking dry beans overnight before cooking them.

I suppose the same could be done to rice.

It could turn out that just soaking the rice could save more energy than anything I have tried.

Sometimes I feel like I'm re-inventing the past.

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LOL

I took a survival course at one point... and par normal, we were allowed to take (1) food item with us, along with essentials, like a knife, some cloth, extra clothes, etc (things you should have when hiking alone anyway).

My food item was rice, because it has such a high carb content, and it was winter, with snow on the ground.

Clear plastic rice bowl, dumped out some of the rice that I took into the cloth to save for later, put stream water in the bowl, put the lid back on, and let it sit in the sun all day. By the time it started really getting cold out, I had a fairly warm bowl of rice to enjoy while starting the fire so I could heat up my rabbit.

Those were the days, eh?
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Old 10-01-09, 03:56 PM   #10
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Have you measured total energy usage with and without the modifications? That would be very interesting to see.

Also, how did you disable the warming feature?

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Last edited by Daox; 10-01-09 at 04:08 PM..
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