I've been using an Arduino Uno board to run a camera trap. The input to the board is a parallax x-band motion sensor (powered via the board), and the outputs are the focus and shutter controls on my camera. I run the board on a 12V SLA battery. Everything works great, I now have two camera traps set up and I love the pictures I've gotten. The only issue that I use up a lot of power--I require a 45ah 12V to run my camera trap for ~2 weeks--hiking my camera into remote spots is a pain when I have to lug a car battery along with me.
Does anyone know how I could make this setup more power efficient? I can't put the system to sleep, because it needs to be constantly monitoring in case a critter shows up (they show up at all hours). Would switching to the Arduino mini save power? I heard it's more efficient, but the spec sheet looks the same and I'd have to step down the voltage from my 12V batteries to power it. Any thoughts on how I could significantly increase my power efficiency?
I've been using an Arduino Uno board to run a camera trap. The input to the board is a parallax x-band motion sensor (powered via the board), and the outputs are the focus and shutter controls on my camera. I run the board on a 12V SLA battery. Everything works great, I now have two camera traps set up and I love the pictures I've gotten. The only issue that I use up a lot of power--I require a 45ah 12V to run my camera trap for ~2 weeks--hiking my camera into remote spots is a pain when I have to lug a car battery along with me.
Does anyone know how I could make this setup more power efficient? I can't put the system to sleep, because it needs to be constantly monitoring in case a critter shows up (they show up at all hours). Would switching to the Arduino mini save power? I heard it's more efficient, but the spec sheet looks the same and I'd have to step down the voltage from my 12V batteries to power it. Any thoughts on how I could significantly increase my power efficiency?
Thanks a lot.
Well converting to a bare bone type 328p board might help because you would not be powering the USB serial converter chip, the power on led, and the poor efficiency of the on-board linear 5 volt regulator. Find a switching mode 5 volt regulator and that should cut your continuous current draw maybe in half or more. After that using various AVR sleep mode might save more, but that would probably involve a rewrite of your code to make sure the sensor can 'wake-up' the avr chip and execute your program.
Nick Gammon wrote a tutorial for achieving low power on Arduino class machines. It might be you can't go into a deep sleep, but hopefully you can save a reasonable amount of power: http://www.gammon.com.au/forum/?id=11497.
Thanks for the prompt feedback. I'm pretty sure the Arduino is hogging the power, since the sensor's listed power supply is 8mA, and I'm drawing roughly 100mA (burning through a 45ah 12V in two weeks), I think I calculated that right...
I read through the linked tutorial on cutting power consumption. I'm having trouble understanding what exactly it means to put the board to sleep. Is it possible to have the motion sensor actively sensing for motion, but also have the board in some sort of power saving mode?
Thanks again for the feedback, I appreciate the help.
I just run the 12V power leads to a barrel connecter and plug to the Arduino, then power the sensor from the Arduino. Would it be more efficient to power the sensor through a separeate 12V-5V stepdown? I have some murata DC-DC converters hanging around, so I could try that.
Thanks
It's not clear to me why it would be especially wasteful to use the Arduino to regulate the voltage (I'm a biologist and can barely work my TV remote, so bear with me :)). So it would be more efficient to find a different DC-DC converter and use that--like a 12V-5V or 6V-5V? What is it about the Arduino volatage regulation that makes it inefficient compared to other methods?
JonnyA:
It's not clear to me why it would be especially wasteful to use the Arduino to regulate the voltage (I'm a biologist and can barely work my TV remote, so bear with me :)). So it would be more efficient to find a different DC-DC converter and use that--like a 12V-5V or 6V-5V? What is it about the Arduino volatage regulation that makes it inefficient compared to other methods?
Thanks
Jonny
simple really
start with a normal regulator
you feed 12 volts in
take 5 volts out
so there's 7 volts across the regulator
let's say 100 mA current
that's 700 mW burning off in the regulator!
this is not a feature of the Arduino regulator
it's a feature of regulators
a switching regulator is smarter
uses electronic wizardry to only take what it needs to keep the 5 volts ouput
I would still seriously consider a 6 volt battery as the power source
Here's an example of a small, self-contained 5 VDC switching regulator that could handle any voltage from a realistic battery pack (and many common small solar arrays as well). Theoretically, one could replace the on-board linear regulator with it, but given the level of technical prowess (or lack thereof ) JonnyA admitted to I wouldn't recommend it in this case. Instead wire up the output to the 5V pin. You can do this since this is a regulated power supply. Don't do this with an unregulated supply, like batteries, even if the nominal voltage is around 5 VDC.
It should be possible to keep the sensor awake and allow the Arduino to sleep. This can be done 2 different ways. How often do you need to check for an animal running past? Every 1 seconds? Then check for sensor input every 1 second, or use an interrupt. This will allow your battery to last 10x longer or be 10x smaller.
) JonnyA admitted to I wouldn't recommend it in this case. Instead wire up the output to the 5V pin. You can do this since this is a regulated power supply. Don't do this with an unregulated supply, like batteries, even if the nominal voltage is around 5 VDC.