What is the best way to power an arduino with AA batteries?

Hi

What is the best way to power an arduino with AA alkaline batteries? Is it over the power jack? I imagine there might be problems, as you have to have more than 7V, and let’s say I hook up 5 batteries and have 7.5, they can only drop 0.5 V while discharging until the arduino gets unstable…

The external dc barreljack accepts 7 - 12 V but the recommended range is 7 - 9V. (6V or 9V AA battery pack).

3xAA connected to the Vcc pin. That way, no power is wasted by the voltage regulator connected to the barrel jack.

That wouldn’t be my choice. I would use 6 AA battery (9V) pack on the barreljack, because the battery voltage is just going to get lower and 4.5V <5V so you’re already starting in the hole with new batteries.

The question is:

What is the best way to power an arduino with AA alkaline batteries?

not,

What is the MINIMUM way to power an arduino with AA alkaline batteries?

At 45 to 50 mA , the UNO would run many hours on 6 AA batteries. (approx 2 x longer than on 3)

3xAA is my choice, and it works very well (for six months at a time, using sleep functions).

The ATmega328 processor will run on as little as 1.8V, with lower clock speeds.

he Arduino will run on as little as 1.8V, with lower clock speeds.

I don't think the digital outputs are much use at that voltage.

1.8 V is perfectly acceptable, and even desirable when used with devices intended for low voltage operation.

I use 3xAA together with level shifters and 3.3V sensor modules. The entire combination works perfectly until the battery voltage drops down to about 2.7V, in which case the AA batteries are essentially dead.

raschemmel:
At 45 to 50 mA , the UNO would run many hours on 6 AA batteries. (approx 2 x longer than on 3)

Energizer alkalines are 3,000 mAh, and their rechargeables are 2,000 mAh. At that current draw, that's 60 hours (2.5 days) and 40 hours (1.67 days). Not impressive.

An Uno board, especially a genuine one and not a clone__*__, is terrible for battery powered projects. A Pro Mini is better in most ways, is cheaper and smaller, and comes in an 8MHz version.

* Carefully note the phrasing: Clones can be better than a genuine one if they use a USB interface chip in place of the ATmega16U2 that genuine ones use.

jremington:
1.8 V is perfectly acceptable, and even desirable when used with devices intended for low voltage operation.

I use 3xAA together with level shifters and 3.3V sensor modules. The entire combination works perfectly until the battery voltage drops down to about 2.7V, in which case the AA batteries are essentially dead.

Depending on the voltage range of the sensors you could probably just use a low quiescent current LDO with something like 2.0V or 2.5V output to run everything off those batteries and get rid of the level shifters.

Well as said, I'm really not talking about the minimum, but the best way. I will probably be using quite a lot of sensors and a 100mw LoRa radio module, so there's also some current involved

If the LoRa module only transmits it can be made to use extremely low average current.

How long do you want battery to last, and how much space are you willing to devote to it?

Exactly what sensors are you using? If they are digital sensors you can probably put them into a low power state when you don't need to measure, and if they are analog sensors a GPIO output or transistor switch can be used to remove power to them. You might be shocked at how much battery life you can get with proper hardware and software design.

I did a project for school once with an ATtiny84 and nRF24L01+ module transmitting a small packet every 1.5s. We estimated from our current measurements that it would last 1 month when powered by a CR2032 coin cell battery. A pair of AAs would have made it last years.

The thing is, it only needs to work for around 6 hours...

You need provide more info about the project. Minimum and maximum voltages of your components, expected maximum and average consumption...

In one project (IR beacon) I run standalone ATTiny from 2 batteries unregulated. This way I can power LEDs directly from the Tiny's pins without current limiting resistors ;-).

There has only been 12 posts so far, we wont be given the details of the project yet.

There has only been 12 posts so far, we wont be given the details of the project yet.

That’s why the game is called “20 Questions”.

Ok, I'm sorry I haven't provided a lot of detail, but I hope you've enjoyed your game of 20 questions anyway. Well then: I am building a flight computer for a high altitude balloon, which measures different things with both analog and digital sensors. Also It tracks the flight with GPS and sends the data via LoRa Radio.

SO,

WHAT IS THE MAXIMUM FLIGHT TIME ?

Balloon? So every gram counts? I would think about Li-pol + LDO. Or (single?) AA with (inverting?) buck-boost. You need to do the calculations how much current (and peek current) you need - finding proper source should be easy then. But it is unwise to take 9V battery pack, regulate it down to 5V for Arduino and this regulate down to 3.3V (? guess here) for GPS and LoRa.

Also you should know what low temperature (or high?) and low pressure will do with the batteries and the electronics.

I already mentioned the maximum flight time, its around 6 hours. Also, every gram does not necessarily count as the maximum weight is 2 kg. I prefer Lithium AA batteries (which are in most respects identical to alkaline batteries) to LiPo as they have a lower temperature limit.

bestanamnetnogonsin:
Ok, I'm sorry I haven't provided a lot of detail, but I hope you've enjoyed your game of 20 questions anyway. Well then: I am building a flight computer for a high altitude balloon, which measures different things with both analog and digital sensors. Also It tracks the flight with GPS and sends the data via LoRa Radio.

Well, if you had owned up to that in the first place, the answers (from me at least) would have been very different.

Do NOT use alkalines for high altitude balloon, they are completly useless for the application. They are only good down to around -20C and at that temperature may only have 25% capacity. They loose voltage at a fairly constant rate on discharge. An alkaline will be at or below 1.1V for around 50% of its life.

Lithium Energizers AA or AAA are heaps better, and what most people use. They are good down to -40C, keep most of their capacity at that temperature for 100mA typical drain, and the Lithium AAs will be at 1.4V or above for 90% of their life.

And becasue they maintain voltage so well at low temperatures, 2 x AAA is enough to run a tracker direct, here is an ultra simple version using a Pro Mini with the regulator removed, and yes, those are all the parts you need (+ wire and solder);

http://www.loratracker.uk/?p=30

Good for 200-400km @10mw with a base station omni antenna

Should last around 25 days.