Interested in making a cheap AC inverter out of parts you can often get for free?
If you happen to have a broken UPS backup computer power system lying around (or can find one cheap), you could possibly turn it into an inexpensive power inverter for your camper.
Uninterruptible Power Supplies are often thrown away or donated to thrift stores when their battery goes bad. Once they do, you could simply replace the dead battery with your RV's deep cycle battery and enjoy a decent quality inverter that often -- at least on newer ones -- includes 5V USB power for your phone -- in addition to several standard AC outlets.
Typical UPS units you find in thrift stores
I actually did this, after watching the video below that I found on YouTube. It's an interesting project. The main idea is simply to unhook the leads going to the internal battery and then solder in some leads that will connect to an external battery. The most elegant solution -- to make it function like a store-bought inverter -- would be to run small leads to screw terminals on the outside of the case.
The second simple bit of electronics is to turn off the emergency alert -- the high-pitched squeal that normally is designed to warn you when the electricity goes out and you're running on battery power -- and you can disable it simply by finding the small buzzer element and cutting the leads and removing it.
There are other hassles you can run into. I found the outside case can sometimes be unreasonably difficult to crack open. You might also find that the circuitry is already fried, or in such bad shape that it sizzles or breaks as soon as you connect the battery. But after a few, you might just find one that opens easily and works really well.
The one big disadvantage for a small camper is the weight -- the transformer inside is quite heavy, especially on large UPS units, and especially when compared to the lightweight transformer-less inverters you can buy on sale for $40-80.
It's also no less prone to shorting out -- A badly-timed surge can fry any inverter pretty easily, so it's nice to have the option to exchange it for a new one. Then again, it's also nice to know you can build one for next to free, so it's well-worth learning how to do it!
(Note: Modified Sine-Wave AC output by cheaper UPS inverters may not be suitable for all devices. For quickly charging your laptop and mobile electronics, it should do fine, but for continuous power, beware that it could cause problems, so be sure to google and download the UPS manual. If you're concerned about this, check out his next series on how to make a sine-wave inverter. )
Did you know you can make your own gasoline from wood?
Not much, mind you -- and I wouldn't advocate chopping down trees to do it! But as a education exercise, MrTeslonian shows you in this video series how one can inexpensively turn dead wood into refined gas that can run a car by capturing all the fuel gases in the form of crude oil and refining into whatever "fossil fuel" you like. Totally fascinating!
I don't totally understand everything going on in these videos, but I do know a bit about wood gasification, because I use a homemade wood-gasifying cook stove for most of my meals when I'm out boondocking. Many people don't realize that when you start a campfire, you don't actually "burn wood" -- you're actually burning the gases released from the wood when it's heated. In a gasifier stove, you can actually separate the combustion process, heating the wood and burning the gases separately, so that you can have a clean-burning wood stove that works just like cooking on a propane stove. (My DIY stove is a tin-can knock-off of the SoloStove, which is a top-grade wood gasifier made for backpackers, that allows you to have a blazing hot cooking fire using ordinary twigs for free fuel.)
So basically, an easy way to summarize this gas-making experiment is that he's heating up the wood to release the gas, then collect it instead of burning it.
Wood-Gas El Camino - It runs on firewood
As a matter of fact, it's totally possible to grab this entire experiment and funnel it directly into your car engine in real-time (provided you have the right type of engine) to make a wood-gas car. Apparently after the Second World War, almost every vehicle in Europe was converted to run on firewood! And now with gas prices up, more people are re-discovering and developing this old technology again.
Have you ever considered using pedal-power to top off your camper battery...?
Or even bypass the battery and run your camper appliances directly off of pure leg power?
If so, I'm going to recommend that you go ahead and SKIP the expensive bicycle generator options and go directly to David Butcher's site, where you can learn about the next generation of pedal-powered energy hacks and even purchase plans to make your own super-optimized fitness-fueled electrical generator.
First, check out his "Pedal Powered Prime Mover" running a TV!
David has been experimenting with pedal power for nearly 40 years. So this unique design is no simple hack, but an evolutionary step beyond typical attempts to convert bicycles into practical power that can not only charge batteries, but run appliances at a really high efficiency -- precisely because he engineered out the inefficiencies!
There are a few reasons why this design vastly outperforms your typical "bicycle generator".
It's built around a "flywheel" design. The big solid wheel is made of cheap but heavy particle board, and it has a specific engineering purpose. To a mechanical engineer, a flywheel is analogous to a battery -- it stores mechanical energy as it spins. Once you get it up to speed, it keeps on spinning on its own, turning the generator by itself, meaning you only need to pedal hard enough to keep its momentum from slowing. And by saving you energy *in your legs*, you're able to keep the generator going at a higher horsepower for much longer!
Smoother Power. A problem with bike generators is that your naturally irregular pedaling makes it difficult to run many appliances. In this design, not only does the flywheel smooth the generator *input*, but the incorporation of HUGE capacitor (a 58 Farad car audio capacitor) smoothes out the power so you can directly run household devices like televisions and computers (provided you are fit enough to pedal as hard as you need to.)
There are no chains, belts, or gears adding extra friction. All of those things add a huge drag on your energy input (your effort) and energy output. You can easily feel this drag just by comparing how quickly your bicycle's back wheel slows down relative to the front. (A few seconds vs. a half-minute.) It's not the mass but the friction. For contrast, imagine replacing your front wheel with a heavy flywheel, spinning it up to speed, and observing how long it keeps spinning. The flywheel on David's machine keeps spinning all that mass for more than a minute, and the motor shaft is spun directly by the rim of the flywheel, eliminating all those intermediary sources of drag.
It takes up very little space! A typical bicycle conversion requires the length of the bicycle plus the generator stand, on the order of seven feet. But this compact design fits into a 2 foot by 3 foot rectangle.
But that's not all!
One thing I love about his site -- besides the treasure trove of science, experimental data, advice, and interesting ideas -- is that he's not just some guy peddling a bike generator (sic!), but a "true engineer's engineer". I say that because he actually understands through both theory and extensive testing exactly how inefficient this method is for charging batteries... and how incredibly efficient it is for running devices directly * without electricity *!
It's a common misconception in our modern world that it's best to convert power to electricity, because electricity is a more efficient medium of energy. IT'S NOT!
Converting energy between different forms is always extremely wasteful. For example, a gasoline motor converts chemical energy to mechanical locomotive energy at around 15-25%. For generating electricity -- ie. converting from one form of power to electrical power -- with the exception of hydro-electric systems, which can be 80-90% efficient, most power plants operate in the 20-45% efficiency range. Then in order to use the electricity, we waste a ton converting it into some other form, ex. light which is below 10% efficient or mechanical motion, which actually can be extremely efficient, in the 80-90% range, but when you consider that the electricity was created at 20-40%, we've now dropped that number even further. So making and using electricity is generally a fairly wasteful process -- We do it in order to enjoy the First World convenience of "cheap" electricity.
But it's EXTREMELY efficient if we skip the conversion!
Believe it or not... Ancient "low-tech" pure mechanical energy transfer methods (think of the Roman Empire) can be absurdly efficient. Imagine if you will a mechanical wind turbine at the top of a mountain. At the bottom of the mountain a mile away, there is a mechanical milling wheel. The two are connected by a long loop of cable in such a way that when the vanes of the wind turbine turn, the milling wheel turns with it -- essentially it's a windmill with the components separated by a mile. It turns out that power at the top of the mountain can be transferred down that cable to the milling wheel at near 100% efficiency! If you try that trick with electricity you'll come nowhere close. But it we can achieve such high efficiency not through some sort of low-tech magic, but simply because we haven't diluted the mechanical energy from the wind turbine by trying to convert it to some other form before converting it back to mechanical energy.
Which is all to suggest that if you want a real lesson in some pretty awesome DIY hackery, then you'll want to check out David's BEST experiments in pedal power, in which he uses his pedals to directly drive other devices *mechanically*. For example...
Pedal powered washing machine and dryer
Pedal powered blender
Pedal powered whole house fan
Pedal powered water pump and irrigation
Pedal powered air compressor
Pedal powered hand tools (grinder, disk sander, buffer, drill, reciprocating saw, lathe)
Pedal powered offset printing press and sewing machine.
In addition of course to many varieties of pedal-powered electrical backup generators.
Hey, how can I use one of these for my camper?
I love the idea of having a pedal-powered system for my camper! The only thing I haven't figured out yet is how to fit it. It would be important to be collapsible, and I think his model has that option to design it that way. At the moment, this is one of those "when I get around to it" projects, especially since my camper's homemade solar panel gives me plenty of energy already. But I already anticipate that this would be one of my funnest favorite camper projects. I can hardly wait to start!