# Solar Drone

#### Noah Knox

Jan 5, 2018
6
I am working on modifying a hubsan x4 drone into a solar powered drone for recharging (it will not fly indefinitely when it is sunny out unfortunately) the solar cell is 4.7 watt .5 v and the battery is
3.7v 240 mah. I’m fairly new to electronics and I’m wondering how to make a simple circuit to charge the battery and power the drone simultaneously. Thanks!

#### Alec_t

Jul 7, 2015
3,287
Welcome to EP!
0.5V seems very low for a cell, or is that a typo?

#### kellys_eye

Jun 25, 2010
5,324
To get a solar panel with sufficient output to charge the battery/run the drone would make it so heavy it would never leave the ground!

#### (*steve*)

##### ¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
Moderator
Jan 21, 2010
25,507
To get a solar panel with sufficient output to charge the battery/run the drone would make it so heavy it would never leave the ground!

Apparently not. This one even carried a human (ok, so it's an aircraft, not a drone, but I would think that adds weight (ha ha) to the argument).

#### Noah Knox

Jan 5, 2018
6
It’s not meant to stay aloft perpetually. The purpose of the project is for a computer control drone that is able to (when there is sufficient sunlight) fly for a couple minutes capture data and then land to charge. And I did some tests to confirm the manufacture’s claim of 0.5v and it is correct.

#### kellys_eye

Jun 25, 2010
5,324
You'll be lucky to find a converter that will take a 0.5V input and convert it to a charging voltage - you'll need at least a eight(?) in series to get a decent voltage that'll work.

@(*steve*) still fantasy (for everyone else).

...average speed of between 45kph and 90kph.
...and nearly 500 hours of flying.
...an epic 16-month voyage.

and they add this classic line...

...and demonstrating the potential of renewable energy.

I think not.

#### Audioguru

Sep 24, 2016
3,650
Why don't you use a solar panel that already produces the 5V to feed the battery charger?
A 5V solar panel has 10 solar cells in series. If it is rated at 4.7W then its current will be about 940mA and might quickly blow up your little battery.

#### Audioguru

Sep 24, 2016
3,650
How will you increase the 0.5V to 5V? A silicon transistor needs at least 0.7V to 1V.
Oh, 4.7W can heat some water to drive a steam engine that turns a generator.
Maybe the little battery can power a voltage stepup circuit.

#### Noah Knox

Jan 5, 2018
6
@Audioguru is that possible to do and if so how?

#### Audioguru

Sep 24, 2016
3,650
@Audioguru is that possible to do and if so how?
Your little battery powers an oscillator that drives a voltage boost converter.

#### Attachments

• voltage boost converter.png
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Jan 5, 2018
6

#### 73's de Edd

Aug 21, 2015
3,463
Oh Boy . . . . . . this is right in the "PERCEIVED" concept theory of a gnat running at breakneck speed on a hamster wheel and it POWERING a Corvette dragster . . . . .except with its misunderstood solar capability / weight/ power aspects.
Drones eat up a HELLUVA-HELLUVA-HELLUVA lot of power.

Last edited:

#### Noah Knox

Jan 5, 2018
6
Oh Boy . . . . . . this is right in the "PERCEIVED" concept theory of a gnat running at breakneck speed on a hamster wheel and it POWERING a Corvette dragster . . . . .except with its misunderstood solar capability / weight/ power aspects.
Drones eat up a HELLUVA-HELLUVA-HELLUVA lot of power.

I do agree that it sounds silly but it’s not a project to try to stay in the air for mass amounts of time. It’s made to stay on the ground charging it’s battery (which may take loads of time) than do a quick flight to capture data. I did all of the thrust to weight calculations and I have plenty of weight for a large army of gnats to ride aboard after all the added weight for the panels and circuitry.

#### Bluejets

Oct 5, 2014
6,083
Just looked up a mini quad, weighs 15 grams with lipo battery. Flight is "about 5 minutes" and we all know how quick this goes when we actually time the product. Battery is 200mAh so I'm estimating around 1.2A draw on 3.7v (voltage deminishing as flight time increases)
One of the solar panel I saw in the Op link shows it weighing in at over 20 grams on it's own.
Think you're outa luck Noah.

BTW , #9...hehehehe ...good one

#### kellys_eye

Jun 25, 2010
5,324
It’s made to stay on the ground charging it’s battery (which may take loads of time)
The keep the solar cell on the ground too......

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