could i find such batteries

[hiigaran]

ok long story short,

me and some guys are building an aircraft (ultralight) and we want the engine to be electric. we are still deciding whether we will have 2 180V or 2 240V motors, but we still cant find the right batteries for them. car batteries are cheap, but they are very heavy. lithium ion batteries last long and deliver more power, but are more expensive. is there a battery that can give out a lot of power, stay light, and be inexpensive (car battery inexpensive, but i can pay for a little more)?

 

[Nigel Goodwin]

I think you are pretty well stuffed! - I don't think there's any solution to your problem, any batteries are heavy, and reducing their weight increases cost MASSIVELY. In all cases though, power to weight ratio is pretty pathetic compared with a petrol driven engine.

 

[hiigaran]

i was afraid of that. i want to avoid using petrol powered engines due to constantly purchasing more fuel, more complications involved, more risks, higher engine temperature...the list goes on. my biggest problem is that if i use car batteries, thats 150 kilos gone right there leaving 350 kilos left, minus 90 kilos being me and someone else...260 kilos left - so not much there at all. ok, i know the cost of car batteries, but how much would li-ion batteries cost in AUD? and whats the largest size they come in?

 

[JimB]

Pick 2 out of 3:

Cheap
Light
High capacity

your call.

JimB

 

[Nigel Goodwin]

i was afraid of that. i want to avoid using petrol powered engines due to constantly purchasing more fuel, more complications involved, more risks, higher engine temperature...the list goes on.

Constantly purchasing fuel is probably by far the cheapest option, electricity storage requires so much more size and weight compared with petrol. Notice you don't fly on holiday in an electric powered 747 - there are good reasons for that!.

You can buy electric powered model aircraft now, usually using Lithium Ion batteries - but flight times are only very short - I doubt an electric powered microlight would have enough power (and duration) to get off the ground?.

 

[hiigaran]

i aware of the whole fuel thing. my aircraft isnt designed for fast speed. its designed to have a low stall speed. all i want is for the batteries to last at least 30 mins.

jimb, what battery could be in existence that is cheap and has high capacity?

 

[Nigel Goodwin]

i aware of the whole fuel thing. my aircraft isnt designed for fast speed. its designed to have a low stall speed. all i want is for the batteries to last at least 30 mins.

I think that's really an unrealistic expectation, it 'may' be possible?, but I would expect you're looking at thousands (or tens of thousands) for batteries?.

 

[hiigaran]

thousands? uhhh, just so you know, im using rechargeable ones. i dont think the amount i need would equal thousands of dollars

 

[jpanhalt]

At the 2007 EAA convention at Oshkosh an electric-powered full size airplane was shown. It is being produced by Sonex Aircraft (www.sonexaircraft.com) and is described also in Model Aviation, Decemebr, 2007, page 12. In brief, it uses a single, 270 HP motor, Li-Poly cells, and carries a single person at 130 mph. Flight duration is 25 to 45 minutes. Recharge time, of course, will be much longer.

It may be unique, but for the $50,000 USD estimated price, you can buy a pretty nice motorcycle and get to anything more than 75 miles away quicker.

John

 

[Nigel Goodwin]

thousands? uhhh, just so you know, im using rechargeable ones. i dont think the amount i need would equal thousands of dollars

You're wanting batteries to power a human carrying micro-light (with probably the lifting ability of a brick ) and keep it in flight for 30 minutes - you're talking seriously hi-tech batteries, and seriously hi-tech prices.

 

[jpanhalt]

thousands? uhhh, just so you know, im using rechargeable ones. i dont think the amount i need would equal thousands of dollars

Some modelers put $1000 battery packs in their airplanes. For example, a 6S1P 5.5 AH Li-Po (i.e., 22V)pack costs $320 USD. Ten times that for the 220 volts you need, and still you only have 5.5 AH. The batteries will be expensive. See: http://store.neutronics.com/ for other prices.

John

 

[Leftyretro]

thousands? uhhh, just so you know, im using rechargeable ones. i dont think the amount i need would equal thousands of dollars

Yes it would, thousands of $$$ for rechargeable Li-Po batteries is the current best practical battery solution. An engineer would do calculations of $$ per energy-density-weight and give you the cost for your ultralight application. It can be done and if not already done will soon be done by someone most likely with sponsorship help.

This problem is not unlike the search for better batteries for all electric cars. Keeping battery costs affordable and at the same time having the energy/density/weight enough for reasonable range is what is needed to make electric cars affordable and practical for the masses. Of course then there would be the problem of how to ramp up the electric power grid to allow all this additional battery charging for the masses.

Yea I know, additional solar and wind power would handle it all. ;-)


Lefty

 

[matc]

An electric car is vastly easier than an electric plane, yet we don't have those yet.
If you still want to try, look at the batteries that they use in the Prius - NiMh? LiPoly? Probably the cheapest way to source enough energy storage anyway. Failing that, fuel cells

 

[audioguru]

The utralight electric airplane can fly when it is connected with a long cable to a truck full of batteries, or to a big fuel powered generator on the ground.

I saw a model airplane smoke its brand new Li-Po $500.00 battery.

My electric model airplane is cheap. Its battery is a pretty heavy Ni-MH one. If I am very careful not to stall the plane then it gets up pretty high before the battery is dead in about 5 minutes.

 

[dknguyen]

is there a battery that can give out a lot of power, stay light, and be inexpensive (car battery inexpensive, but i can pay for a little more)?

If there was, why would we be using any other kinds of batteries at all? Lead-acid are about as cheap as they get for capacity and Lipo are about as good as they get for density (barring NASA and military batteries).

I could easily spend $1000 worth of batteries on my little RC-truck sized robot if I wanted to (And I would if I could). Research A123 batteries. It will still cost you thousands though and likely still be too heavy.

And remember that with something like lithium ion (or any other high performance battery really) and so many separate cells working together in parallel, something may go wrong. THe more cells you have the higher the probability that one will go wrong. And the way they go wrong (exploding blue flames), it is likely to make them ALL go. They can have as much safety issues as an engine.

Not to mention chargers...

I strongly strongly suggest you go for the engine. If you still don't want to go for the engine, then the only remotely possible way (if it's even possible with existig technology) is to make your plane glider like and only use the motor and batteries to get off the ground, but the weight of all the batteries required for that would likely still defeat the purpose of a glider.

 

[jpanhalt]

My electric model airplane is cheap. Its battery is a pretty heavy Ni-MH one. If I am very careful not to stall the plane then it gets up pretty high before the battery is dead in about 5 minutes.

Glad to hear you fly electrics. I used NiCd and NiMH exclusively until yesterday. My electrified sailplane with 3S Li-Po could have flow all day (soaring in large part). After 4 flights, each more than 5 minutes, per cell voltage was still 3.9 V. That included two trim flights that had the motor on most of the time. I am now a convert, at least for some applications. Of course, I take the Li-Po out and store it in an ammo box, which are readily available in the USA

There is one important difference between an electric or hybrid car and an airplane. That is, aircraft engines generally operate over a fairly narrow power band for long periods, which allows tuning for fuel efficiency.

John

 

[audioguru]

The battery in my electric model airplane is 20% of its total weight and it barely has enough power. Its folding propeller is direct drive.

I have another electic model airplane with the same battery and motor but it has a gearbox driving a much bigger propeller. It gives much more thrust. It can nearly hover.

 

[jpanhalt]

The power to weight ratio for modern electrics certainly surprised me. The motor I used is an Astro 020 geared (4.4:1). When I first saw it, I regretted my choice and thought I might need a bigger motor. Well, it takes a 3 # glider stright up (torque rolling to the left - maiden flight) using a 13.5 X 7 inch prop at 6000 rpm (static). John

 

[Pax Writer]

An electric car is vastly easier than an electric plane, yet we don't have those yet.
If you still want to try, look at the batteries that they use in the Prius - NiMh? LiPoly? Probably the cheapest way to source enough energy storage anyway. Failing that, fuel cells

Oh yeah? Go check out www.teslamotors.com. They have very decent-looking battery driven cars for sale. They're still a bit pricey, but you do get some serious performance for your buck

/Pax

 

[audioguru]

The little Tesla electric sports car is cute. Its aluminum chassis is "bonded". Glued together?

The first one was picked up in San Francisco. A Chinese import?

$98,000.00???? For a tiny lttle car about the size of a golf cart?