Let's Make Robots!

Solar Powered Arduino!?

Spring is springing here in the U of K, and this weekends task, is to rip down the RUBBISH shed on the allotment, and construct a HEROIC crystal fortress of solitude out of sturdy second hand glass doors and windows. The plan is for it to be greenhouse type structure.

I see this as my next arduino project! I intend to pick up an SD card shield, and get some data logging going on.

Light levels, indoor temperature, outdoor temperature, moisture levels, etc etc.

I was also thinking, i COULD use the arduino to automagically open a tap to top up seed trays with water from a water butt, or open a louvre to let cool air in should the house get too hot!

However, being an allotment, i have no electricity source! My intention at the moment is to pick up a cheapo solar light or similar, and power the unit by trickle charge solar in the day? i am currently researching how likely this is to work!

has anyone done anything similar?

any reccomendations on how to go about arranging a solar power setup?

does a servo use power all the time it is connected? i figure this would be the best way to control a tap, but dont want it to constantly drain a low capacity power supply....


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Servos use less power if you stop the pulse stream and rely on the gearing to hold position.  I tried this on a 9g servo and quiescent current was around 2mA with no pulses.  When active, the current will rise depending how hard you're trying to move it away.

Gareth's hacked servos into positional actuators concept may be a cheaper alternative to commercial items. 

Isn't security going to be a bit of a worry in the allotment?  Exeter is not known as a hot-bed of petty crime but there's always one or two . . .   

Two days ago I tried to power an Arduion Leonardo with just a solar panel. It worked in sunlight but failed when clouds came up.

Another small project for my own curiousity is a small night light powered by a solar panel feeding a solar engine and charging a 4.5V battery. It's running sice 1.5 years now. During daytime the battery get charged and during the night the LED lights up. The switch is done by the Miller solar engine with light detection...the solar panel itself works as the light sensor. Circuit here: http://www.evilmadscientist.com/2008/simple-solar-circuits/

Important is to have a battery charged by a solar panel, so you can make sure that you not run out of power. To saqve power you can deattach the servo when not needed but you have to make sure that there is no force on the servo since it will not hold the position after deattached (http://arduino.cc/en/Reference/ServoDetach)

Well my next project is supposed to be soemthing of the sort...

I already have the parts.... exception motivation... :|

Anyway my aims are just at the measuring ("logging") level. Just a small wireless node to be near the potted plants at the window that will be transmitting back info like the one you mention. But since I'm not considering servos and whatnot my power requirement are much lower... so I EXPECT.... to be OK... when I get around to do it that is...


Look at this project: Garduino instructable. It might give you some ideas to borrow. If a system with an auto-type battery isn't an option (you can get solar chargers for those and they'll have enough crank to last through a few cloudy days even with a couple of 9g servos on an Arduino) you might try a... You know I forgot what I was going to recommend when I started that sentence.

You have added much! I think i should probably worry about the logging side before i worry about moving servos, but yes, your suggestion of adding a relay to power and un power the servo as required had occoured to me!

I have one of these sitting on my desk currently. I bought it to charge my phone while camping, but it was crap! it may however be able to do something for an arduino (which should be pretty low demand!?)

i will top itup by usb, and see what it can do.

Nothing to stop me setting up a REALLY simple led flashing sketch and leaving it running for a little while i guess!

or if i got a logger shield, i could set it up to timestamp every few seconds, and when the power dies, it will stop stamping (giving an indication of battery life).....


Servo do use power even when not moving. The amount of power they use will varry a lot from servo to sero (I'm guessing here I haven't measured the current on multiple stationary servos). I believe digital servo draw more power than analog servos. I'd suggest using a relay on the servo power line to turn it on and off. You might want to use a latching relay.

The whole solar power things is very interesting to me but I haven't done much with solar myself. I think for a small project it might be easier to go with a ready made solution.

SparkFun sells little battery packs with solar chargers on them. This sure seems like an easy way to go. I have one of these packs but I haven't tried it yet. I be I could be talked into testing it out by yourself or others here.

Sorry for not adding much. I'm also interested to see what others know about this.

I have ordered a data logger shield (they are cheap enough, and could be useful in all sorts of applications!

I have also found a guide on how to setup a sketch which shows the status of the battery the arduino is running off, via a red/green LED. im sure i can modify it to log battery condition (even if it is just a value between 0 and 255) with a time stamp.

assuming it is running off the pico solar battery, they battery condition should fluctuate up as well as down when it is being charged?

I will let you know how it goes! we might even get some graphs!