Powering the nano with a battery
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ok. Noob question. With a nano, I have at the radio wired to the 3.3v output and a ground pin, and the sensor tied to the 5v out and the other ground pin. If I want to power the three items from a 9v battery to the Vin pin - I presume I have to hack the battery to share a GND pin? Is there a well trodden path to do this? Thanks
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@stkilda yes, GND needs to be shared with the battery. Except that, you should be good to go, as long as the power drain from the attached sensors do not exceed the specs.
However, the Nano uses a linear voltage regulator that will simply burn the excess voltage/power so you won't get very good battery life from the 9V battery.
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The original Nano supports max 500mA total on 5V (datasheet). This includes the Nano itself and everything that is powered through 5V and 3.3V. Nano clones will probably have a cheaper regulator though, so you'll need to check the specifications for that particular regulator if you have a clone.
For 3.3V, the original Nano uses a FT323RL which supports max 50mA.
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@mfalkvidd Thanks. The sensor (an LM393 light pulse sensor) and the radio seem to consume about 12mA each (at their respective voltages).
To test the sensor / gateway / controller combination I powered the sensor with a 9v battery. Looks like after about 12 hours it stopped transmitting (although the units lights are still lit) but guess it lost power to run.
Will have to think about long term power as thats clearly not sustainable. However, it all seems to be working so the major learning is going well!
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@stkilda you can already gain quite some power saving if you take off the led and sleep the node, activate it when there is something to do.
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I wouldn't power it from battery. To consuming.
Had one powered with two AA batteries. It lasted for one week.
Changed the nano with a pro mini 3.3v and now it runs forever.
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@stkilda As @Hermann-Kaiser highlighted, for battery power the pro mini is far more frugal for consumed energy, and there is a massive amount of information on how to make it even more efficient...
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@zboblamont @Hermann-Kaiser Thanks guys. I'll order me one.
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@stkilda It is worth mentioning that unless wishing to tinker and experiment, there are also pre-made alternatives on the market such as Moteino variants etc.. This is the route I chose to go having poor soldering skills and eye-sight, at higher cost compared to the chinese sourced pro minis but the additional component costs were not unreasonable.
The 3.3v 16MHz variants I chose have run flawlessy with onboard rfm69 radios, eg - the gas meter node now reads 3v on two AA cells after a year, and the onboard booster will draw them down dead at ca 1.7v possibly next summer. The only problem found afterward was the limited number of pins left available, but this is a limitation of the pro mini which would have been found had I DIYd it.
ie You have plenty of options these days...
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Would it be more efficient if you connect it to a 3X AA battery holder on the 5V pin, instead of the 9V battery?
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You can power the Nano with 3 x AA (or AAA) alkaline cells (4.5v) connected to the 5v pin. The 4.5v will also be suitable Speed Test Scrabble Word Finder Solitaire for powering a servo. And the AA (or AAA) cells will last longer than the 9v PP3 style battery.
