power system for ride on electric hovercraft

[technologyclub]

Hello,
I teach technology education and have an after school technology club. We plan on making a hovercraft that someone can ride on. The whole thing needs to be green so I'm planning on charging car batteries with a windmill. (I'm cutting up barrels for a vertical axis one now). Anyway, It doesn't have to run for more than maybe 5 or 10 minutes. I have a small version at home with no propulsion and just an electric leaf blower for hover. I need an electric motor and a fan strong enough to overcome inertia (10 car batteries + person + big fan + hovercraft + leafblower ~= 1000 lbs)
So finally my question... How do I charge all the batteries at once? Would it be better to hook them up one at a time to the car generator powered by the windmill? What about once I have them charged, Is it an "inverter" I need to provide 110 power to my electrical equipment on the craft? Any ideas? Seen something like this I can honor by emulation?
Thanks
Channel Sanderson

 

[jraef]

Being that this is an electrical forum, I think first you must determine the size of fan you will need to lift your 1000lbs before we can help you much. The HP you end up needing will make all the difference in terms of how you need to power it.

But in terms of charging the batteries: You can essentially think of it as trading power for time. If you want to charge all the batteries at the same time, it will take longer with a limited power source. If you remove them and charge them one at a time you can charge each one faster, but then the aggregate time is probably longer if you factor in all your time to remove and replace them. I would do them all at once if it were me, I'm basically lazy.

By the way, car batteries, although cheap and plentiful, are probably not the best choice for this because they have the highest energy-to-weight ratio and when you talk about lifting the batteries themselves, you end up in a downward spiral that can be difficult to overcome. There is also the possibility of spilling the acid if the hovercraft flips over; not good.

If you have no budget for this I can see your dilemma, but it might be worth investing a few hours of begging to a Li-ion or NiMH supplier to donate something in exchange for their name emblazoned on the side of the craft or something.

"If I had eight hours to chop down a tree, I'd spend six sharpening my axe." -- Abraham Lincoln
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[technologyclub]

Great response thank you.
I guess I'm going to have to find lighter batteries. Could you explain the wiring configuration for charging multiple batteries at once from a single source?

I will set up little terminals connected to the generator. From there can I connect the batteries serially or do I need a seperate set of connectors for each battery?

Thanks