Powering my node
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Hello there!
I built a small weather station with a DHT22 and an atmospheric pressure sensor, an Arduino Pro Mini 3.3V and a NRF radio. I did manage to make it work with a 9V battery to power the Arduino board, but if I replace it with a pair of AA batteries, it doesn't send data anymore...
However I keep seeing projects using only 2 AA batteries to power simple nodes like this...
Any idea what I did wrong?
By the way, I tried to put a 4.7uF cap between GND and VCC pins of the NRF, but it didn't solve the problem...Thanks.
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If the batteries drain under 3v with a "normal" pro mini it will stop working. I would suggest using a step up booster to suck all the power out from the batteries like a 0.9 -> 3.3v booster.
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Oh I understand! Obviously the step up booster will always be needed because fully charged batteries would barely deliver 3V (2 x 1.5V).
OK now I just have to order some boosters...
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@Guilhem-Brouat said:
OK now I just have to order some boosters...
For battery powered sensors, it might be better to invest in low power sensors such as the BMP280 and/or SI7021 which can be run below 2V. Save the DHT22 for a mains powered node.
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Actually this one will receive even more sensors (a rain sensor and a photocell). I was thinking about powering it with a LIPO battery and a solar panel. By the way, any tips on what components are needed to do that ? It is not very clear for me...
Anyway, my original question, as well as the answer, are still valid for other nodes I intend to deploy in the house and to be powered with AA batteries.
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I do not have direct experience with solar powered nodes but there are a few threads in the forum on this subject.
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Thanks I will check this !
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Hi All,
I think I've been hitting the same issue as well. Does anyone has some pointers to diagnose this problem?
So if I read the above, the problem is caused by the DHT22 sensor? So Removing it from the board should solve it? Or is there more behind this?
From what I've debugged, my node runs on battery @ 2.98v, and every 5 out of 6 resets the "radio init failed" message is shown, due to the fact that it's unable to do the "p" check (I guess because it doesn't have sufficient power). If it does boot up, it dies within a couple of hours with the pin13 led of the arduino pro mini active.
But how is this related to the DHT22, since on boot-up the DHT22 is not yet being used?
Also, swapping the DHT22 for a different sensor is a better solution then using a step-up convertor? Since the step-up convertor is always consuming power? How would this solve the problem for the NRF24 sensor, it would still not have enough, right?
Thanks for any answers
Daanoz
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@Daanoz - the radio can handle down to 1.9v so its not a problem. The DHT22 needs 3.3v so going below that renders it useless. So yes, one option is to use a booster (which is the easiest sollution).
The pro mini can not handle below 3v unless you change its fuses and other settings... so if you want to use a unchanged pro mini you need a booster even if you change to a sensor that requiers lower voltage then DHT22.
I have a setup with Pro Mini/Nrf24 radio/DHT22/booster that has run for a year and still going strong (sending every 15min)! Its a easy sollution and does not require extra mods more than desoldering led and voltage regulator on the pro mini. I dont see why you should make it harder than that (except if you want to learn something new).
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@sundberg84 great thx, good news. The mysensors manual for battery powering makes it sound more easy than it is
.So, I've already got some step up convertors being shipped to me. But I'll order some low power sensor as well, just to be able to run them side by side and too see what happens (and i guess indeed to learn something new).
I plan on using this manual to modify the arduino, does it cover the suggestion made by you?
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@Daanoz - yes something like that - but I would suggest using "in-house" guides. There are several on this forum and several great members that can answer your questions - AND its been tested with mysensors.
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Very interresting discussion! Thanks for the tips. I will look into it for my other nodes, especially the ones which will sit behind wall switches in my house.
