I'm am looking for some guidance on my first Arduino project. I am using a nano to control a servo motor. The motor will move back and forth once every 30 mins. I was wondering, what is the best way to save power? I am powering the board off of 4 AA batteries.
First things first, supply us with a proper schematic.
Show us a good schematic of your circuit.
Show us a good image of your ‘actual’ wiring.
Give links to components.
sorry I am new to this kind of thing. what is the best way of creating a schematic?
If you have access to a PCB design program, use it to make the schematic.
An image of a schematic drawn with pencil on paper works too.
so it's essentially like this but instead of an UNO its a nano (the software didn't have nano's on)
the servo i am using is https://www.ebay.co.uk/itm/MG996R-MG995-Torque-Gear-Servo-Motor-Futaba-JR-RC-Truck-Racing-180-360-degrees-/313470962597?_trksid=p2349624.m46890.l49286
not really sure how to manage the power
For a real, low power implementation, the Nano is unsuitable because it has power hungry components like a USB interface chip, Leds and a voltage regulator. It is better to use something like a barebones ATMega328p. An Arduino Pro Mini comes also close. Anyway, see this for extreme Low Power ideas: https://www.gammon.com.au/power
I would suggest powering the Nano via it's 5V pin from 3 of the AAs, and then use the 4th to keep 6V for the servo.
As you can see in the Nano schematic, the FTDI chip is powered when 5V is applied.
A better approach would be use a Pro Mini; connect an FTDI Basic when you want to download code, then remove it.
Supply 4.5V via the VCC pin so the battery voltage is bypassing the regulator.
It won't work. There is no common ground.
ok thanks! i'll look into the pro mini
Yes. I've just been through this and my latest device sleeps so well that if I did need to measure the current I would need a new multimeter…
I don't pretend to understand every detail but Nick Gammon makes it easy to do.
I used a pro mini and removed a few SM components, fortunately removal is easy, especially if you don't need to end up with reusable parts having done.
The MG996R has a stall current of 2.5Amp@6volt. A problem for common AA batteries after a while.
The Arduino could reset every time the servo starts to move.
Could be better to power the Arduino and servo from different sets of batteries,
like in the picture of post#5, with common ground of course.
Batteries connected to servo and feed batteries (6v) to Boost Converter set to 7 or 8v then send this to the Arduino Vin Pin. 5v pin powers only low current peripherals.
And what would be the idle current of that boost converter...
A MT3608 is <2mA.
You can rework this down to 60 μA with external components.
Why use a boost converter to feed the Nano's onboard regulator? Use an external regulator that can output 5 volts directly. Run the nano at a lower frequency and you can run unregulated directly from three cells, as has been suggested.
The major current draw will likely be the servo, even at idle. You need to cut power to the servo when not in use, unless it has to actively hold position, in which case the current draw will quickly deplete the batteries.
Why use an external voltage 5v regulator when you have one on the NANO already ?
Personally I would just run straight off the batteries with no regulator, but someone suggested an external boost converter to feed the nano because the battery voltage was presumably too low to feed the on-board regulator, and I definitely do not like feeding a linear regulator with a boost converter when trying to conserve power.
Four NiMH AAs will be better able to manage the "stall" demands of the servo without too much voltage drop and will be the correct voltage to feed the "5V" pin of the Nano. (Just as well you have a Nano which is far more suitable for this kind of project than a UNO. )
The current wastage of the Nano is probably negligible compared to the servo.
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