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Power on the Road

  1. Apr 24, 2004 #1
    Hey, (yeah, I'm back, and you'll find my questions as strange as ever), needless to say I've got a question.
    Supposing I could get free or very cheap appliances (AC, unfortunately, but cheap) to put in a bus for five or so people to drive around the continent...how could I get a small power system set up inside a midsized ex-school bus capable of devilering the needed energy for free?
    I mean, the obvious answer is to use the engine as a generator, but it just seems like that would be terribly inefficient and a waste of possibly hard to replenish fuel. Solar is out of the question because of expense, and a small wind turbine would only be able to be used when we are stopped, yes? I'm not sure about using one while moving, it seems like it would dramatically lessen fuel mileage by doing so...plus wind turbines, even small, are still a bit expensive and won't deliver much power.

    I was wondering if anybody has ever heard of a small passive solar water turbine whereby the sun is concentrated on a small amount of water, vapourizes it, turning a turbine, and then it condenses back down to do it again. I've been told that they aren't very expensive, but not much else, and I'm not sure how much power it could possibly generate.
    Am I better off going with charging batteries off the engine?
    I'll probably still need an inverter, which will be expensive...

    We'll most likely just have a few lights; a refrigerator; an air conditioner; plus some smaller things that probably don't need to be mentioned because all of this won't be running at the same time; a few speakers on the radio; and maybe a computer. Added up, that's quite a bit of energy to supply. Should I just buy some fully charged batteries before going and recharge as necessary en route via the engine?
    What equipment would I need to do that, and how expensive is it?
  2. jcsd
  3. Apr 24, 2004 #2


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    No free sources, definitely nothing practical for cross-country. Your power requirements are HUGE.

    Forget the inverter/battery combniation and just buy an appropriately sized generator. The efficiency will be better and less batteries to dump in the landfills is better for the enviroment too, a green-green solution. A bio-diesel & standard diesel capable generator would be the ultimate. Diesel is more efficient than gasoline so that's less raw materials consumed for power output. Plus, you could stop by resturants along the way and filter the used cooking oil and make all the motorists following you hungry with the smell of french fries while using a bio fuel that has already served its purpose and should be cheap or free.

  4. Apr 24, 2004 #3
    I was planning on running the bus on WVO, Biodiesel Start/Purge,
    but I'm hesitant to buy a seperate generator because
    1) It'll eat up our fuel supply
    (Making biodiesel on the road isn't an option, I don't want to have to haul Methanol around. And nobody as of yet has volunteered to sell us refills en route).
    2) (And I really want to stress this point)

    So buying rechargeable batteries to try to charge off the engine while it's running WVO isn't really an option, then? I'd like to conserve as much power as possible, but it would be silly not to have a refrigerator and air conditioning! I admit, the computer can go, but a pair of big AC speakers is a lot of juice...
  5. Apr 24, 2004 #4


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    Grey beaver, I know I've mentioned this before, but go with a gas refrigerator. There are NO moving parts and about all they require to operate are gas (propane) and 12 volts. Some may not even require 12 volts. As for air conditioning, I don't know what kind of country you will be driving through, but look into swamp coolers for drier climates. They tend to raise the humidity quite a bit. It has been a while since I have seen any, but the one I can remember used a water source that dripped water onto a spinning disk. The disk scattered the water towards its edge which was absorbed by a foam type filter. The filter had air forced through it from a fan. Naturally, the water evaporated and cooled the air. Works best in dry climates and not likely at all in very humid climates. The beauty of this system is that all that was required was a water source and 12 volts. You may likely already have both in a bus. I don't know what the plans are for charging the battery when the vehicle is parked, but you can most likely just plug in a regular battery charger if the bus is parked near a source of commercial AC. Also, you may find it unnecessary to run the swamp cooler when the vehicle is parked. I don't know what your plans may be. One big advantage of a swamp cooler is they really tend to keep the dust down.
  6. Apr 24, 2004 #5
    Well, we'd rather keep things simple, reliable, and also as cheap as possible. Supplying this much power for such a long periond of time isn't something that's very friendly to our fuel supply with a generator, either...
    Thanks for your opinions, but they really aren't what I'm looking for... does anybody have any experience with large rechargable battery arrays? I'm really just completely stumped here...
  7. Apr 26, 2004 #6


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    The large batteries would still need to be re-charged, and will require more power to re-charge than they can deliver. So you're power needs with batteries increase since now you loose efficiency on the charge, discharge, and the generation of the electricity. With a generator, you only loose at the generation stage plus the losses of an IC.

    Speakers require very little power if the signal is delievered properly. Well, unless you want a rolling rock band. :) But you could use some higher efficiency speakers and a small car radio and maybe only burn 30W while still having a good volume level. A small portable 'boom-box' optimized to run off battery power would be even better, someone has done the legwork for you!

    Your main challenge is replenishing the energy spent. And in most areas, gasoline is plentiful, cheap, and packs a lot of energy per pound.

  8. Apr 26, 2004 #7


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    A large array of car batteries would be a piece of cake to set up - but as already stated, it doesn't help you at all. You need to generate the power somehow.
  9. Apr 26, 2004 #8
    Well, everything's been downgraded since last night.
    Having some problems getting the bus (well, not actually getting it, that would be relatively simple really, it's just that some legality issues have been solved and the bus came up on the losing end :frown: )

    So, it's down to a van...
    anybody know of any diesel van, before I start a lot of work trying to find one? Conversion would be best, but a plain old van of any kind would be a big step forward. Diesel if preferable...much preferable, which is why I need some help trying to find one. :frown:
    Everything has been downgraded due to the switch last night.
    Deffinitely a minifridge if possible, hopefully the van will have a/c already, maybe the stereo is really dreaming so if necessary no go, and no computer or maybe a laptop. Possibly a solar panel for it, I've seen some specialied ones for that purpose, but I've decided that I'm not going to be the one to pay for it so it's not my problem :)
    Basically I just need to run a minifridge.
    That should be easy enough, right?
    I've seen it done in the cab of a big rig, I'm not sure how to go about it in a van, though...any help there? :biggrin:

    Thanks you all for your help so far...
    I told you my questions are kind of strange :tongue:
  10. Apr 26, 2004 #9


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    Not sure about the diesels in a van. Maybe a VW?

    Some specs on the minifridge would be helpful but you'll need an inverter with about 2X the capacity you need (for motor startup) and a simple second deep-cycle battery to give a little extra non-engine run time and eliminate draining the main battery. The second battery could be tied into the charging system of the van with a heavy-duty relay that only engages when the motor is running.

    A fridge is easy, even if power isn't available for a few hours it should stay cold enough to do its job.

    The only 12V fridges and AC units I've found are created for industrial applications and carry a price to match. Maybe someone else knows of a better source or can google it better.

  11. Apr 27, 2004 #10
    Well, I'm hoping to get a cheap or free minifridge from Craig's List (meaning that I really don't have any specifics on the fridge itself yet because I don't even have it). If not, I could just pick up a $150 one from WalMart or Target or something. A 12V would be nice, but I doubt it would be very affordable.
    How exactly would I be able to hook the battery into the charging system? Is it just as simple as splicing the incoming wires to the battery, and what kind of things would I need to be able to do it? I'm not really an electrician as you can tell, so I'm not sure how to do it.
  12. Apr 27, 2004 #11


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    I've been thinking about putting a computer in a car for quite sometime. With a computer, you eliminate the need for a stereo, since you can store all your music on the HD, or on CD-R. Then, you simply connect the output wire from the soundcard to some RCA's, plug them into an amplifier (or more, but this takes more power) and run your speakers from the amp.

    So instead of having a stereo (sounds like you were planning on running a home stereo???) you just have a computer, and a fairly nice monitor, which can be turned off when not in use. You could get really complicated and use the pc to control your sparks and fuel. (Search for MegaSquirt and Megaspark -- No relation)

    As far as Deisal vans go, I believe ford made one in the Mid 80's. You can probably pick one up for a couple grand, maybe less in ill condition.

    Solar panels are not as expensive either. You could get battery buddies to help recharge the batterys. For a computer, I would get a UPS, and an inverter strong enough to power the UPS. I got a 750 W invertor from walmart for like $60, it runs halogen work lamps and power tools for about 30 minutes before it drains the battery.

    With such a large roof as a van, the newer breed of flexible solar panels would really do some good I think. I believe I got mine from bigfrogmountain.com. A large setup would atleast yeild some energy. The small panel I got would power my Invertor enough to make it turn on, but not enough to get any work out of it. A battery inbetween is all that was needed.

    And as for generators, check out www.power-generators.com. I've recently been searching for kits to convert gasoline engines to propane. This site sells kits that do just that for small generators. And last but not least, you could make a generator using a 5hp B&S engine, and a fairly good size dc motor. It would probably cost you about $500-$600 to go this route. Then you could splurge on the propane convertor kit, and have gas to power a grill.

    Edit: Oh ya, another generator option would be to have a landing gear type setup, with a wheel that spins a generator. You could rig it to raise and lower it, so that your only generating when you need it. It would probably be easier to attach it to the rear of the vehicle, use some kind of flexible driveshaft to turn a motor mounted under the vehicle. It would use a bit more gas, take a bit more to pull it, but it would certainly work.
    Last edited: Apr 27, 2004
  13. Apr 27, 2004 #12


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    Get battery and if mounted inside passenger compartment a sealed battery box with a hose vented to the outside for proper ventilation (explosive gases).

    Wire the - terminal to the chassis with a good gauge of wire and good connection.

    Get a heavy-duty relay (car audio shops have them) and wire it up so both primary and secondary battery are connected in parallel (+ from one battery goes to + on the other battery) only when engine is running.

    Wire the inverter to run off the second battery. Technically it will run off the alternator when the motor is running, but when the motor is off the relay disengages and the primary vehicle battery is safe from draining.

    A car audio shop should be able to help you with this if you don't feel comfortable, they do this sort of thing for people who want to listen to their stereos in parking lots for long periods of time without worrying about starting the car up.

  14. Apr 28, 2004 #13


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    Possibly for boating...
  15. Apr 30, 2004 #14
    Okay, well I finally decided to cave in and try to find some 12V minifridges. Now, I've looked at some before and I have to say that that's why I was hesitant...that price... Well, with a whole lot of looking and a whole lot of rejecting- luckily I was only looking for a pretty small thing, so I got to ignore a lot of stuff- I think I may have found something pretty darn inexpensive.
    I'll need some advice on it though, there is a big price gap, a BIGGG one, between this and all the other ones. I'm a little concerned that it might be because of low cooling power...
    Well, here's the specs-
    Power Consumption- 4.9 amps //18 Quarts //Dimensions: 21" X12.5" X12"
    anything look a little fishy here? The thing is only $100...
    It is pretty small, but it's DC and it looks like it has a pretty low power draw. I doubt I'd need a real big one, at least not yet anyway...
    Does this look like I could run it without much hassling my normal battery and cutting it's life short or should I go with a second battery anyway?

    Okay, somebody just gave me a really good idea.
    Get a second alternator!...now that I think about it, would that help much?There does remain one problem if it does work... it would only work while the car is running, so I'd need a second battery anyway...and, as a matter with the battery, I'm not sure it would work out well to have it running for a couple hours while I'm at classes, or maybe at work, and then only have it charge for a short while during driving...
    Quite a pickle...
    Last edited: Apr 30, 2004
  16. May 1, 2004 #15
    To Honda or not to Honda

    Most of the really cheap and small fridges do not use compressors. As it says right on the description, this thing has thermo electric junctions. These are also known as Peltier junctions and they work the same way that the ones in hot-rodded home computers (keeping the CPU cold) do -- when voltage is applied, one side of the junction gets cold and the other side gets hot; i.e., heat is being pumped from the cold side to the hot side.

    These thermo electric fridges are not very efficient. They are also notorious for being very weak at making stuff cold (I suspect this is because Peltier junctions are much more expensive than mechanical compressors for a given amount of heat pumping ability, and, hence, less heat pumping ability is going to be available at a given price point of fridge). They are, however, extremely quiet (though they do still require a fan to be running over a heat sink).

    It might work for you, but you might be better off just buying a dorm fridge and plugging it into your Honda generator (see below). A dorm fridge might be a little oversized for your needs most of the time, but when you think about it it is hard for a fridge to take up way too much space unless there is some lack of perishable items in your vehicle/home. As long as there is something lying around that could stand to be in the fridge, stick in in there and you will save space.

    Yes, it would, but I wouldn't do it. See below.

    Exactly. And this is related to the prime reason why people buy Honda generators.

    Honda generators are quiet, so you can keep them running 24/7.

    Virtually all professional contractors who need power on site use Honda generators exclusively. They have to. Nothing else is as quiet. And, in addition to being quiet, Honda generators are designed to produce nice sine waves. Some are better at this than others, though, so if you are planning on running a computer off of your Honda, you might want make sure to get one that is certified to work with computers (though I've heard anecdotes that the non-computer certified Honda generators power computers just fine).

    I know, however, that there are generator dealers that sell muffler kits for non-Honda generators. If you are handy with mechanicals and want to try to save some money, you might want to try that.

    If you were to invest in a battery for energy storage without knowing what you were doing, I can almost guarantee you would quickly destroy it and your next three replacements for that battery along with it. If you don't want to spend a huge amount of time researching and money on batteries and regulators, then either sit down and do some serious research on batteries and how to maintain them, or just skip it and get the Honda generator.

    You can find some used Hondas on eBay. Amazon.com seems like a decent place for a brand new one. I would check out their product line, first. The very smallest Honda might be exactly what you need. One problem I see with the smallest Honda I could find (which was the last time I checked on this, a few months ago), though, is it only holds about a half gallon of gas (this lets it run for 9-something hours, I think, with no load and 7-something hours with a half load -- those figures are probably wrong but the genrator can certainly run for hours on end on even only a half gallon of gas.

    You will also need to maintain your generator. As with any other machine, lubrication is critical. You can find some good advice on machine lubrication (including generators and anything else that requires lube) at the http://theoildrop.server101.com/cgi/ultimatebb.cgi forums (seriously, this is an excellent forum for all thing tribology {the engineering discipline of machine lubrication}).

    One warning: all combustion produces carbon monoxide. An extremely tiny bity can make you very sick and just a little bit more will kill you. Any vehicle being lived in should have its own carbon monoxide detector on board, whether or not it generates electric power from a separate generator. Here is current news about the latest carbon monoxide "accidental" poisonings.

    Lastly, http://www.hot-pages.com/generetiquette/generatorstory.html is a funny story about trying to use a non-Honda generator at Burning Man.
    Last edited by a moderator: May 1, 2017
  17. May 1, 2004 #16
    Oh, I guess I forgot to mention, hehehe...
    that I'm actually going to have to put off getting a van or something for a while. So, until I can get one, I'm going to have to use a little Sephia gasser. Which means that I'm really deffinitely not looking at generators as a practical option. So a dorm fridge would deffinitely take up too much energy. So I'm going to have to find somebody who really knows how to do something like this, maybe go to a car audio place or find somebody somewhere else who really knows a lot about car wiring...
    This is getting really complicated, maybe I'll just quit trying...:(
  18. May 2, 2004 #17
    The smallest Honda generators weight less than 30 lbs and are as compact as portable stereos. If you can hide it in your Sephia -- and maybe lock it up with a chain and padlock, also -- then you could put it outside when you need to use it (and maybe re-use the chain to lock it up outside so no one can just ride up on his bike, for example, grab it and pedal away) and then stow it away again when you are done.

    Maybe you could attach a little box to the outside of the Sephia to fit the generator in (and also somehow lock it up) while you are using it. (This latter idea might attract unwanted attention, however.) Maybe if you have space under the hood, it could go there -- though this might be a big carbon monoxide poisoning risk.
  19. May 2, 2004 #18
    Maybe I'll just give up and get that little lighter plug cooler and just put some ice into it in the morning... Putting a little generator with a muffler under the car might work, but it wouldn't really be worth the effort...
    I'll probably just put the whole thing in the freezer overnight, with whatever is in it and some ice, and then move it into the car when I leave. It's pretty much a cooler that way, but whatever cooling power I can get while the engine is on would at least be a little. Probably a good idea to wrap it in something and put it under the seat (maybe in a bigger cooler in the trunk. Seems like a lot to do...but I'd really rather not have a smoking generator :p
  20. May 2, 2004 #19


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    So you went from a bus to a van to a Kia... hmm. Sounds like you need a little more planning.

    - Warren
  21. May 2, 2004 #20
    Well, actually, the Kia is just a temporary car until I can get a van, but whatever...and this IS the planning!
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