Arduino Uno Power during space travels

Hi, my friends and I are planning on sending a helium balloon to ~100,000 ft. We're running a number of sensors from two arduino unos. What is the best method to power the arduino unos during the trip?

We purchased a 9v battery pack and a 4 aa battery pack. I would have thought that the arduino uno would have a voltage regulator to downstep the voltage, but after reading these forums, this look incorrect and potentially dangerous to the board?

Any help would be much appreciated, thank you!

Use a 5 volt USB powerbank of a size large enough for Your measuring time.

The Arduino Uno accepts 7-12 V power through the barrel jack. A 9V "battery pack" is fine, but a 9V PP3 block battery is not. Those are for smoke alarms.

Make sure everything works for as long as you need it to before you send it up in a balloon.

You need to find a battery that is good down to maybe -40C or lower, unless its extremly well insulated, or heated.

You also need to start at the begining, you have the Arduino and presumably know which sensors you are using, so measuring the current consumption of the setup would be the first step.

Once you know the current consumption, and the length in time of the balloon flight, you can then (and only then) start thinking about the batteries you can use...............................

Wrong approach to power, wrong choice of Arduino.

The Arduino requires 5 Volts, so you need to supply 5 Volts, not 9. The on-board regulator cannot supply much more current than needed to run the microcontroller itself.

The UNO - and Nano - include a USB interface chip which shares the 5 V power so if you are not using the USB which it is pretty clear you are not, then this is simply wasting power as would be using a 9 V battery to deliver 4 of those volts as heat wasted in the regulator.

You need to explain firstly what your sensors are, but also just what the Arduino is doing, specifically what is it to do with the data it collects? A Pro Mini without the unnecessary USB chip can run on 4.5 V from three alkaline cells, depending on what sensors and interfaces you need.

Also watch out for sealed air-spaces in the battery…

jremington:
The Arduino Uno accepts 7-12 V power through the barrel jack. A 9V "battery pack" is fine, but a 9V PP3 block battery is not. Those are for smoke alarms.

Make sure everything works for as long as you need it to before you send it up in a balloon.

Thank you for the response, I appreciate it. Ok, it sounds like we should not use 4 aa alcaline batteries since this sums to ~ 1.5V*4 = 6V?

Paul__B:
Wrong approach to power, wrong choice of Arduino.

The Arduino requires 5 Volts, so you need to supply 5 Volts, not 9. The on-board regulator cannot supply much more current than needed to run the microcontroller itself.

The UNO - and Nano - include a USB interface chip which shares the 5 V power so if you are not using the USB which it is pretty clear you are not, then this is simply wasting power as would be using a 9 V battery to deliver 4 of those volts as heat wasted in the regulator.

You need to explain firstly what your sensors are, but also just what the Arduino is doing, specifically what is it to do with the data it collects? A Pro Mini without the unnecessary USB chip can run on 4.5 V from three alkaline cells, depending on what sensors and interfaces you need.

Thank you for the quick and detailed response. I was unaware that a regulator released the delta in voltage. Thank you for the heads up. We could test with an external USB battery (we're already using one of these to provide power to our gopro)?

The arduino I'm preparing is attached to a sparkfun 9DOF stick. I am measuring all 9 degrees of freedom. I am currently writing this data to a micro SD every 5 seconds.

Someone in an earlier comment mentioned that I should only connect 7 - 9 volts, is this true? It may not be optimized, but is it not safe to run the board with 4 AA alcaline batteries thus summing ~6V?

Really appreciate the help!

Paul wants you to power the Arduino correctly, but there's nothing wrong with using AA batteries into the barrel jack, but it's a waste of power. On the other hand, you may want to harvest the excess heat the regulator generates. The Uno is also not the board to use. The Nano or Wemos D1 Mini would be cheaper and lighter.

Using 6 to 12V into the barrel connector is dangerous only for long periods. Like many hours. There is no heat sink on the regulator on the Uno and it can fail after a few hours. I have two projects powering a Uno with a 12V wall-wart supply, and one of them is powering a Wemos D1 mini form the Uno 5V pin. They run for six hours at a time with no problems, but I would never use this arrangement for a 24/7 use.

Why do you need two Arduinos?

SteveMann:
Paul wants you to power the Arduino correctly, but there's nothing wrong with using AA batteries into the barrel jack, but it's a waste of power. On the other hand, you may want to harvest the excess heat the regulator generates. The Uno is also not the board to use. The Nano or Wemos D1 Mini would be cheaper and lighter.

Using 6 to 12V into the barrel connector is dangerous only for long periods. Like many hours. There is no heat sink on the regulator on the Uno and it can fail after a few hours. I have two projects powering a Uno with a 12V wall-wart supply, and one of them is powering a Wemos D1 mini form the Uno 5V pin. They run for six hours at a time with no problems, but I would never use this arrangement for a 24/7 use.

Why do you need two Arduinos?

Thank you Steve, yes I no understand how the regulator loses this energy. Like you said, it might not be a loss as we could recycle this as heat in the insulation.

Would you recommend using a 5 volt external USB battery pack? I'd have to purchase another arduino power cable as ours is long and adds unnecessary weight.

a 5 volt external USB battery pack?

The 5V "power banks" intended for cell phones, etc. shut off if the current drawn is too low, and this has been a problem for Arduino users (Google will tell you about some solutions, which also waste power).

A better option is to use a 3.7 V LiPo battery and a 5V boost regulator from Pololu. Those are about 90% efficient.

I also disagree with Paul__B: a 7.5 to 9V (not 12V) alkaline battery pack connected to the barrel jack is just fine, and the on-board regulator should be able to power a couple of small sensors.

As others have mentioned, it is EXTREMELY cold at high altitude. Test, test and then test again before the flight.

How do you plan to recover your equipment?

It would not use Alkaline batteries.

Thank you for the response, I appreciate it. Ok, it sounds like we should not use 4 aa alcaline batteries since this sums to ~ 1.5V*4 = 6V?

I would not use Alkaline batteries, they do not work well at low temperature, Some marine safety equipment loose their Coast Guard approval when used with Alkaline batteries because they won't work well at low temperature, that equipment requires Lithium Batteries to keep their approval, this is on life safety equipment. If you use AA Lithium would be my choice, look at the manufactures sheets for temperature behavior.

And, as @TheMemberFormerlyKnownAsAWOL said, what will the effect of very low atmospheric pressure have on batteries?
Will they swell up or possibly rupture? How many millibars at that altitude?

JCA34F:
And, as @TheMemberFormerlyKnownAsAWOL said, what will the effect of very low atmospheric pressure have on batteries?
Will they swell up or possibly rupture? How many millibars at that altitude?

If they are lithium ion or lithium polymer types, then when in as new condition they should be OK. These batteries are typically vacuum sealed in any case.

However if the batteries have been mistreated in any way, then they can start to produce gas internally, i.e. they swell. So with gas inside the batteries might well now explode when in near vacuum conditions.

You can charge and use lithium batteries in vacuum conditions, but the charging has to be perfect, in order to prevent even a hint of gassing.

So a more direct approach could be to use two 3 V Lithium non-rechargeables at 3.1 V each, and a silicon power diode in series to deliberately drop 0.7 V, bringing it in the acceptable voltage range with a very modest power wastage. :grinning:

OTOH, the MicroSD card operates at 3.3 V anyway, so a lithium cell of some sort could power a 3.3 V Pro Mini, connected directly to the SD card without requiring its own regulator and level shifters as you must have for 5 V and run the whole show if the sensors also run at 3.3 V.