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Wednesday, February 27, 2013

Electric Power From Any Heat Source - Really? Part 1

While working on another article, I stumbled across a few products that can convert heat directly into electricity. Hmmm....sounds like a great way to scavenge some watts back to our batteries when we are using our heaters. Especially the typical forced hot air RV furnace. Will this really work? let's take a closer look.

Likely, many of you have seen the "no moving parts" refrigerator/coolers that use "Peltier Effect" cooling modules. This uses power to cool one side of the module and heat the other. If you reverse the current flow, they will heat up instead of cool down. What we are doing, in essence, is heating up one side of the module and harvesting the electricity generated at the other, wire end. Most Thermoelectric generator modules use the "Seebeck Effect" a close cousin to Peltier.

Power Pot USB Charger
Not that much of this really matters. Simply put...heat goes in one side, electricity comes out the other. There are some existing products on the market now that take advantage of this effect. The first I found was a pot that you boil water in and it has a USB connector on it that will charge your cell phone and other small gadgets. It was called the "Power Pot." Yes, the name is funny, especially if you grew up in the 60's. It does work, but doesn't put out enough power to really make a dent in charging the RV house battery system. Right around 5 Watts at 5 Volts. The modules that make this happen will operate beginning at 250 degrees Fahrenheit to 600 degrees Fahrenheit depending on the module.
ThermoElectric Generator Module

Then there are the TEG (ThermoElectricGenerators) sourced from various companies. These are more in line with what I have in mind to test. They can be had in wattages and voltages ranging from a low of 1 Watt to a high of around 20 Watts. They'll also build custom TEGs and sell you separate modules to build it yourself. That's what I am looking into.

Atwood Style Exhaust Assembly
My concept is to wrap the inside furnace exhaust pipe with TEG modules then an insulating cover. As long as it doesn't affect the furnace or cause CO2 or Carbon Monoxide problems we may be able to significantly offset the furnace fan's draw. This can be a whopping 7.5 Amps or more! Wouldn't it be nice to not worry if your batteries will run your furnace overnight without going dead? If my experiments work, than we'll be able to do just that! Why waste heat dumped overboard? Recycle! Even if we cannot generate equal to or more than we use with the fan running, any power saved is a good thing.

Of course, it may not be COST effective. Stay tuned for Part 2 where I will be assembling various configurations and testing the concept. If it works, I'll have a good idea how much all this will cost. The modules I have been looking at are all around 40.00 dollars each. I believe between 2 and 6 modules will be enough. We'll see.

Be Seeing You...Down The Road,

Rich "The Wanderman"

Wednesday, February 20, 2013

The Need For Warmth - How Long Can I Run My Heater On Battery Power Alone

This Is Why You Need Heat!
    If you are like most RV owners, your propane fired forced hot air furnace uses a 12V blower fan to circulate the hot air. Depending on your battery capacity (1, 2 or more) you will likely be able to get through most nights. The usual draw is around 7.5 amps when the fan is running (perhaps a bit more or less depending on brand and size)

Common 2 Battery Installation (This One Is Mine)
If you have a single battery it is usually around 80 amp/hours in storage capacity. It's bad for the battery to be drawn down past 50% too often as the battery's life will be shortened. This means you have around 40 amp/hours to play with. 7.5 into 40 is around 5.3 hours of actual fan run time. In my case, with the thermostat set at 68 degrees Fahrenheit it runs for about 20 to 25 minutes every hour. So you can just about double your run time to about 10 hours. Bear in mind there are other draws on your battery overnight, so this is a best case scenario. With more batteries comes more capacity. Older batteries will not store as much power. And colder temperatures will reduce your storage capacity as well. Make sure your batteries are maintained properly and you should be able to keep the listed capacity for at least 2 years, maybe longer. Some loss will occur naturally, nothing to worry about.

I've heard of folks getting 7 or more years from their set of batteries if properly maintained!

Catalytic Heaters
You could install a catalytic heater which does not have a fan (Look at the Wave Series by Olympic) This is only limited by the available propane storage. It will require some ventilation. I have been toying with the idea of installing one of these since they are very close to using propane at 100% efficiency. I'd have to run a hose from the manifold to the heater AND figure out where to mount it to get the most coverage. Not really sure where that would be.

Typical RV Furnace
The fan on most, if not all furnaces,will actually run after the furnace flame has gone out. It will circulate the warm air while it is cooling down the furnace itself. Lots of heat from a typical RV furnace is lost to the outside air. Try standing outside next to your furnace exhaust one cool day. It can be pleasantly warm there! I've been working on a way to scavenge that waste heat and use it to do something useful. There are some new devices around that will convert heat into electricity, that would at least get something back. And/Or maybe run a coil of copper tubing around the exhaust pipe internally and circulate some water through it and into the hot water side of the plumbing system.

This is what I do in the winter....figure out what projects to research and develop for testing in the spring. It can get very interesting around my house when the midnight oil begins to burn. The whole Solar Charging Project began the same way.

Again, YMMV...but this should give you start.

Rich "The Wanderman"

Wednesday, February 13, 2013

Presto! - And Now You Have A perfectly Cooked Burger

    Many years ago I was finally allowed to go home after school without supervision. My Mom didn't want me to use the stove because it had a gas pilot that had to be lit and she was concerned something would go horribly wrong. At the time, I thought that was silly. In retrospect, she was right. With today's safety mechanisms it would likely have been OK, but then....not so much. Where is all this leading? Well a boy's gotta eat, so we found a solution that would allow me to cook a hot meal and be safe from accidental explosions.

The Hamburger Cooker
It's snowing here in Upstate new York today, so no work on the RV and being cooped up always gets me twitchy. I've been cleaning out the kitchen cabinets and stumbled across my old PRESTO! Hamburger cooker. This was the solution to my boyhood cooking problems. Still works! Man, does it make a tasty, perfectly cooked burger every time. Not even sure they are still available, but I'll wager they can be had cheaply on E-Bay or Craig's List or some similar online site. Likely, you could find one at a flea market or garage sale too.

How's it work? Well, it has two sides that come apart for easy cleaning. One side has the heating element embedded inside it. The cooking surface is a Teflon coated half burger shape. The other side has an top  aluminum "platter" with the other half of the burger mold and a bunch of drain holes. It fits into the bottom plastic housing that will catch any drippings. That makes for a juicy, not greasy burger. Bear in mind this predates the Fat Draining grills that are everywhere today.

Simply plug it in to preheat for a few minutes, put in your favorite ground beef (I like 80%/20% for this, though 90%/10% is OK as well)  or pre-made burgers, close the lid and latch. Depending on how you like your burgers, 3 minutes is rare, 4 minutes is medium, 5 minutes is well done. Open the lid and just like that a perfectly shaped, perfectly cooked burger. Everything but the cooking side is dishwasher safe. I usually just wipe out the Teflon coated cooking element side and it's clean. Pretty easy. Since it's small, it takes up very little space.

It uses 400 watts at 120V for 3-5 minutes translating to about 3.8 amp/hrs from a battery bank on an inverter. Obviously it's easily used with a generator or shore power. Like I've said before propane has to be bought, electricity can be made on the spot. Great for boondocking.

I'll bet you could also make other kinds of patties...chicken, veggie, lamb....with varying cooking times. I look forward to trying them all this coming RV season.

Be Seeing You...Down The Road,

Rich "The Wanderman"

Wednesday, February 6, 2013

Induction Cooking - Does This Really Work??

My Induction Cooker Sitting On The Stove Cover
    I like to cook. I really like to cook. When I first bought a serious off-road truck, the first thing I did was build a "chuck wagon" style kitchen that would slide out from the back and let me cook gourmet (ok...well SEMI-gourmet anyways) out of the back on extended stay trail runs. I had a couple of two burner Coleman stoves, a wash basin, 5 gallon water jug and a box with drawers and lid that held all my utensils, cookware, spices and cans of ingredients (commonly known as a "chuck box"). I thought THAT was awesome. Little did I know that an RV galley would make the whole exercise easier, more comfortable, and less packing intensive and indoors. Yup, I sure like RV's! Now I have the ability to use my 4 burner propane stove-top or the convection microwave oven at will. I like to have the ability to cook with different power sources. Propane is great, but electricity can be replenished "out in the wild" with Solar panels, generators and the like, so I wanted a way to cook with pots and pans using electricity. Enter the induction cooker.

My Induction Cooktop
Once upon a time, you'd have to use a heating element to create the temperatures needed to cook with. These are still in use... take a look at a typical "Hot Plate" it has a coil of metal that heats up when electricity is run through it. Works great. Uses A LOT of power and is a significant burn/fire risk. Also takes a long time to cool down or heat up. Not the greatest thing when trying to cook a meal. Now this new-fangled induction method works differently. As long as you have a steel base (stainless is OK but not as efficient check it with a magnet to be sure it will work!) this will work well. Aluminum pans do not work at all! You can buy Aluminum pans with a steel cladding, that's OK.

Typical Induction Guts
***WARNING: Science Content***
In induction cooking, a coil of copper wire is underneath the pot. An alternating electric current flows through the coil, which produces an oscillating magnetic field. This field induces an electric current in the pot. Current flowing through the pot produces resistive heating which heats the food. While the current is large, it is produced by a low voltage.
***END: Science Content***

All this really means is the cooktop doesn't actually heat up. The heat is created in the pan or pot. That way the cooking surface stays mostly cool and the temperatures are fully controllable. The same kind of "instant on, instant off" that you get from a gas stove works here. 

Every good cook knows the secret to great dishes is to control the temperature and time. (Yes, I Know the ingredients are important too!) Most of the induction cooktops I looked at allowed for very specific settings for time and temperature. Not only that, they sensed the size (diameter) of the pot and only used power to heat that size. Very efficient use of power. Still, it will gobble up a fair amount of power. Most are setup to use 15 AMP 120V AC circuit. I have an 1800 Watt version. That's, of course, only at full power. Most of the time I am drawing about 8.3 Amps or so. You COULD run this on an inverter, but be prepared to use almost 100 Amps of power when it's running. (YMMV)

What really sold me on the idea of induction cooking? I bought one, set it up in the RV and placed several drops of water in the pan. Turned it on. Within 2 seconds the water was bouncing around and the pan was ready to cook on. That says, "better living through technology" pretty well. Just another tool in the toolbox that doesn't take up a lot of space, but will allow you to be more versatile.

*NOTE: A Comment was left (see below) about the compatibility between Induction cooking units and cardiac pacemakers and/or defibrillators. There COULD be some interference created between the induction coil's magnetic field and an implanted unit. I am NOT a Doctor, but research has shown that high levels of RF (Radio Frequency) could have an effect on those type of medical devices. Be Careful before you use you. Ask your Doctor!*

Be Seeing You, Down The Road...
Rich "The Wanderman"