Ryuk

Im new to building r/c's. I've enjoyed controling aircraft,helies and boats but the thing i hated most was the wait between recharge times...I hope to get around this problem by adding solar cells to the flight deck of an aircraft carrier model(chosen soley for large surface area for solar cells, other suggetions welcome). I hope to be able to run it solely on the solar cells with a small back-up battery incase i run into shade. If thats not possible at the very least I hope to use the panels to extend the life of the batteries. Does anyone know what the average Amp usage of a radio reciever is? Also the lowest voltage reciever I can find is 4.8 is this is lowest out there? i dont need a very strong reciever just one that works. Low power consumption is key as I can either have lots of current or lots of voltage, really hard to get both. Im pretty sure I'm gonna be forced to work a 30"-40" boat, since that is the only way to fit all the solar panels i need to get 5V of power...has anyone tried this or something like it before? Suggestions of recievers, motors, or anything for that matter would be greatly appreciated.

mfr02

Receivers will work, sort of, down to about three volts, but that is cutting deep into the designed safty margin to allow for getting the model back with a dying battery. The servos will be reluctant to do anything at that kind of voltage, and I would be surprised if you could gather enough energy to power the boat along, even in sunny California.

Ryuk

well i've found some cells that provide .5V and 875mA of power which is why im trying to lower the voltage as the more volts i need the more panels i will need to have. each panel is 1.5"x3" on a 15" model I think i can cram 10 maybe even 20 onto the larger boat and which would give me 5V 875mA and 5V 1750mA respectively. But i just want to konw if thats enough power or should I not even bother...

LtDoc

Ryuk,
I think you would be better off if instead of the total solar power idea, you fed that solar produced power into a battery. That sort of gives you a 'buffer' or fuel tank that's being trickle charged continuously.
As for reducing the supplied voltage, sure, a little bit, but not really all that much. An under powered receiver (and servos, etc.) are just too "iffy", sort of. The required current for servos, etc, is entirely dependent on how much they are used. So, the range of that current requirement is very broad. I would think that basing the required current on the top end of that broad range would be the best intent. Gives you a larger safety margin, sort of.
Solar power isn't really a 'new' idea for models. No idea of how 'advanced' it is, but there have been several questions/threads about it on the various forums. It all boils down to how much surface area you can provide for the solar cells, bigger is better. Another aspect is that it's almost always easier to 'drop' the amount of supplied voltage than it is to 'bump' it. 'Dropping' the voltage is sort of wasteful, but it's certainly 'better' than not having it to start with... maybe.
Good luck!
- 'Doc

Tidnab

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Here's a place for solar panels for hobby http://www.4lots.com/index.asp?PageA...S&Category=245

green-boat

If you want to be able to recharge your batteries with solar cells, your output voltage from your cells needs to be higher than your battery voltage or you will never recharge.

mfr02

A thought comes to mind - if the surface area is big enough to collect enough power to work the model, it is likely that the model will be big enough to have a large enough battery to run longer sessions than are needed..

Jonjoe

Hi there
Is this anything to do with the MMI soalr boat competition because if it is just look in the magazeen it tells YOU lol
Thanks
Jonjoe

escipion

Hello!!!!
Something as LtDoc said, a friend of mine made this Solar boat, the idea is that the cells recharge the batteries while she is not moving, so at the beginning the batteries must be charged.

DONS BOAT WORKS

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If it's for the MMI soalr boat competition, you can't use battries.

jshander

You can use a digital boost converter circuit such as made by Dimension Engineering. I have bought a number of their products and am quite happy with them. Basically you can have 3V input and output is constant and adjustable up to ?14V. Efficiency is close to 80%. Many of these type circuits are used in cameras and cellphones and pagers to get higher voltage off single battery to run higher volts. Wikpedia can explain principal of how they work.

mfr02

Don't forget that as voltage supplied goes up, current available comes down. There is just so much power going in, nothing is for free, there will be conversion losses, and this represents the eventual power out.

Will Sgarlat

No free lunch! If it was feasable to get any type of performance using solar cells for an electric drive system, we'd be seeing ARFs in the magazines. Of course, that shouldn't damp your enthusiasm to think up something very unique that "moves along by itself"! However if you have a big enough boat that doesn't have to go very fast, sealed lead/acid batteries have a very long life between charges...You can get 6 and 12V batteries in many different sizes...I saw a bunch at the recycling table at the dump today.

Has anyone used these with success? For a PT boat or a Coast Guard craft?