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Old Jan 17, 2007, 09:42 AM
Registered User
Portugal, Beja District, Castro Verde
Joined Jan 2007
83 Posts
Question
solar energy in rc helicopters

hi,i would like to know if is possible use solar energy to feed up my lama 4?
Maybe is a fool question,but is one question.....
Thanks in advance!
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Old Jan 17, 2007, 09:53 AM
W7CLB
Silicon Valley, CA, USA
Joined Jan 2007
51 Posts
It's certainly possible; while I haven't seen a pre-built solar LiPo charger, they exist for most other battery chemistries.

I think you'd be disappointed by the charge times, however, unless you use good-sized panel -- say, about the same size as your helicopter.

And there's no chance (yet) to power such a small helicopter directly from solar, of course. :-)
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Old Jan 17, 2007, 10:02 AM
Registered User
Portugal, Beja District, Castro Verde
Joined Jan 2007
83 Posts
hummm,check this out....
http://solarhome.org/browseproducts/...ls-7v-12v.HTML

"For connection, just solder or crimp to the copper tape"

this one is in portuguese....looks great
http://produto.mercadolivre.com.br/M...antastica--_JM
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Old Jan 17, 2007, 03:36 PM
Blades crumble before me.
RotorReaper's Avatar
Southeast US
Joined Jan 2007
38 Posts
Yeah but back to what cbiff was saying, there's no way you could generate enough charging amps to be a practical power solution taking in consideration the limited surface area your dealing with (to attach the panels to), combined with the fact that solar panels just aren't intended to be high yield power supplies. You could maybe teather to a good sized r/c blimp (maybe 2) completely wrapped in solar panels, and come up with some sort of way to switch between 2 LiPo batteries (one draining, one charging). It would have to be some sort of control unit with a smart chip and a voltage regulator (be very careful with that one, LiPos have been known to explode when not on the proper charging voltage) that you hook up to the solar panels, as well as the batteries.
See the thing is with a normal solar configuration (cars, etc.) the batteries are in a series (usually like 15-20 batteries) and they are on a smart charger and circuit system (a.k.a. a control unit with a smart chip). The system knows when some batteries are low, and pulls from other batteries more (solar systems vary of course, some have internal combustion engines that power when batteries are weakened.) So the actual problem lies in being able to collect enough rays to charge the battery in a practical time frame. To get enough amps to charge a 7.4v LiPo 800Mah in under 15 minutes (average flight duration on battery one assuming you got the LiPo batteries to series with burning your house down) it would take a solar panel (if my math is correct) roughly 14.5' by 10'. That's a damp big blimp... While your at it you may want to add a battery mount to one of those, two batteries is a bit much onboard.
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Old Jan 17, 2007, 04:02 PM
Blades crumble before me.
RotorReaper's Avatar
Southeast US
Joined Jan 2007
38 Posts
I can see it now...




except insert lama of course...
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Old Jan 17, 2007, 04:48 PM
W7CLB
Silicon Valley, CA, USA
Joined Jan 2007
51 Posts
The voltage from the panels you sent me is high enough (15.4v) to power most battery chargers that expect a 12V input, but the current is too low (100mA). This would take roughly eight hours to charge a typical RC heli battery assuming perfect efficiency and 100% sunlight.

You could gang four or eight of them together, of course. :-)
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Old Jan 18, 2007, 09:22 AM
I love FPV!
Cralis's Avatar
Eastern side of Australia
Joined Jan 2007
4,650 Posts
It wouldn't fly forever (while it was sunny (and in my case, in Scotland, where it's NEVER sunny, I'd be stuffed)), but it would extend the flight times quite significantly, no?
A panel on each plade?
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Old Jan 18, 2007, 04:42 PM
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rumplestilskin's Avatar
san jose ,CA
Joined Jun 2004
541 Posts
u can charge a field battery with solar than charge your lipos with your field battery. solar power!
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