Hi, I am new to the forum and looking for help for a project I am working on. First off, I am not an engineer, and have VERY little electrical experience, but I am more than willing to learn. Any help would be appreciated. It is hard to describe the project in the title, so here it goes:

I work for a state wildlife agency and am trying to put together a system for scaring elk and deer out of crop fields. I recently purchased a blower fan and an inflatable air dancer (the kind you see used for advertising at car lots and parking lot sales). The blower fan that inflates the air dancer runs off of a 110V AC system, which wouldn't be a problem if most crop fields had a power supply near by, but they usually don't. So, I want to rig up a system so that I can use this elk deterrent in remote locations. I envision the system going like this:

Solar charger--->12 V battery--->inverter--->timer (I want the fan to run approx. 15 min. every hour or so, rather than continuously)--->blower fan--->air dancer.

I know that for most of you (or all of you), this is a REALLY simple project and probably has a simple solution, but I don't have the expertise yet. I have done quite a bit of research on my own, but still have several questions as to which specific components I should purchase for this project. As a starting point, the blower fan is a 4.0 Amp, 110v/60HZ, 1/3HP fan (at some point I may want to switch to a larger fan that requires 6.2 amps and is 1 HP, so keeping this in mind would be helpful). Below, I have listed several questions I have about the system (I know, it is a lot of questions, sorry - I'm inexperienced). I am also trying to put together this project on a budget, so am not looking to spend thousands of dollars on very fancy circuitry. Any suggestions would be much appreciated. Thanks!

1. Which battery should I get? A 12V marine, deep-cycle battery, or an automotive battery?
2. How many amp-hours should the battery be rated for?
3. Does it matter what group size the battery is?
4. What solar charger would work best to charge the battery, if the battery is run for approx. 15 min/hr? I live in a very sunny location so getting ample sun shouldn't be a problem.
5. Which inverter do I need? If the fan is 4.0 amps and requires 110V, then I need a minimum of a 440W inverter, correct (682W for the bigger blower if I need to go that route)?
6. Do I need a pure sine wave inverter, or will a modified sine wave inverter suffice?
7. What type of timer would work best for this situation? Something like a simple $10 Christmas light timer or something along those lines, or do yall know of a better route that I haven't thought of yet? Is there a way to run this with a more sophisticated, yet still inexpensive timer system? I don't really care WHAT times the fan runs at, as long as I can program it to be intermittent so the battery doesn't run down completely and the elk don't get too used to it.
8. And finally...is there a way to rig up the system so that it can be used outside in all weather conditions, as well as have a very low fire risk (don't want to light a crop field on fire during the dry summer)? The blower fan is weather resistant, so I'm not too worried about it.

Thanks again! I know this is a lot to ask of folks, especially since I have so little of it figured out on my own. Really looking forward to hearing some of your thoughts!

 

I know that for most of you (or all of you), this is a REALLY simple project and probably has a simple solution...

Actually no, it's complicated by a few things:
1) Solar panel ratings tend to be, shall we say, optimistic. Expecting a reliable 100W of power from a panel rated at 100W is setting yourself up for disappointment. They also sag as they get old, dirty, hot, and so on. If I really wanted it to work and needed 100W, I'd probably buy a 200W panel.
2) Batteries also age and their capacity sags. So I'd add 20% or more 'extra' capacity.
3) Solar energy is spotty. If you were building a solar-powered medical device that requires power 24/7, it would need to be hugely oversized to continue working during the shortest days of winter with say, 10 days of continuous cloud cover. If you can tolerate an occasional day without power, then everything can be much smaller. It comes down to specifying your acceptable worst case scenario.
4) Motors can be tricky because they usually take more power briefly as they startup than they do while operating.

1. Which battery should I get? A 12V marine, deep-cycle battery, or an automotive battery?
2. How many amp-hours should the battery be rated for?
3. Does it matter what group size the battery is?
4. What solar charger would work best to charge the battery, if the battery is run for approx. 15 min/hr? I live in a very sunny location so getting ample sun shouldn't be a problem.
5. Which inverter do I need? If the fan is 4.0 amps and requires 110V, then I need a minimum of a 440W inverter, correct (682W for the bigger blower if I need to go that route)?
6. Do I need a pure sine wave inverter, or will a modified sine wave inverter suffice?
7. What type of timer would work best for this situation? Something like a simple $10 Christmas light timer or something along those lines, or do yall know of a better route that I haven't thought of yet? Is there a way to run this with a more sophisticated, yet still inexpensive timer system? I don't really care WHAT times the fan runs at, as long as I can program it to be intermittent so the battery doesn't run down completely and the elk don't get too used to it.
8. And finally...is there a way to rig up the system so that it can be used outside in all weather conditions, as well as have a very low fire risk (don't want to light a crop field on fire during the dry summer)? The blower fan is weather resistant, so I'm not too worried about it.

1. I would say deep-cycle but I'll be curious to hear what others think. Automotive starting batteries are designed for brief delivery of a massive current and are not ideal for a lower load for a longer time, which is much more like your needs.
2. That depends on the issues I raised earlier. It needs to get you through your worst-case scenario. You calculate in terms of amp-hours. If you need 20Ahr to get through a night, that's the minimum battery size you need.
3. No, physical size is not terribly important. You may need more than one.
4. Any charger designed for 12V systems, and rated to the input and output currents you need, should be fine. This is exactly the sort of thing they're designed for.
5. I'm leaning towards saying you need a 1000W inverter. Running one too close to the rated power is asking for trouble.
6. You definitely do NOT need a pure sine wave inverter. Modified sine is fine for a fan.
7. I think the digital programmable lamp timers you can get for under $10 would be fine for this application. If you want more random patterns, ironically you may need a timer controlled by a microprocessor that you can program anyway you want. My suggestion is to start with the simple and cheap approach and see how it goes. Don't escalate if you don't need to.
8. I'm sure you can rig a secure system. Mounting the panel securely against wind, snow, ice, etc. will require a semi-permanent installation. I don't think your panel is going to be 'small'.

Have you looked for a 12V blower so that you could avoid the inverter? It would simplify things and deliver better efficiency.