Battery node radio choice

[SteveG]

Hi there,

New member here so apologies in advance for any stupid questions.
Has anybody done tests on which radio gives the longest battery life ? Something long term running the same sketch on several nodes with different radios so as to give real world battery consumption.
In the absence of tests any opinions would be welcome.

Thanks

[sundberg84]

@steveg - Hi and welcome!
I would say its one of the big questions in the forum, alot of info.

Its more than just batterylife - its also about range, stability and price range. I have nodes running for several years on 2xAA using Nrf24l01+ and there are several examples on same timespan with RFM69 radios. Also the new nordic NRF5 seems to be going strong.

[SteveG]

@sundberg84

I’m planning to deploy battery powered temperature sensors in each room of my house and as this is still on paper and either radio would probably work ok I wanted to find out if there was a pressing reason to go one way or another.

From what you say and what I’ve read on here is it fair to say that the choice of radio is mostly about range and reliability in the actual location ?

[Guillermo Schimmel]

@steveg Go with the radio that makes you more comfortable in other aspects.

Sending a single value every (5?) minutes its going to last at least a year on a couple of AAAs on any radio.

I have a test node sending values every second with a couple of AAs and it is going on for a month with 90% of battery still.

I'm using nrf24 and will start with nrf5x at some point in the future.

Regards

[zboblamont]

@steveg As @sundberg84 stated it is more constraints of your environment that will determine your choice of frequency and thereby the device.
Having noted the Wifi strength fluctuate around my brick/RC house I went for 433 MHZ for better structural penetration, which was the RFM69. It may have been able to work with 2.4GHz, and for many it does, and it should be quite easy for you to test for your own location.
One of the visual disadvantages of the lower frequencies is the longer antenna.
If your house construction already has ethernet distribution or has walls with accessible cable runs, a 'one-wire' solution may be a viable alternative to get room temps.
My downstairs rooms (concrete/brick) have sensors at ceiling level (not ideal but avoids ripping channels down the walls), upstairs are at mid-wall being timber partitions.
Perhaps an option..

[SteveG]

Thanks for the replies, guys.
My house is all brick walls downstairs, central brick wall upstairs and wood and plaster the rest. So it looks like the RFM69 might be the best choice.
I think the next step for me will be to build a gateway and simple sensor on breadboard and see which radio works best.

[zboblamont]

@steveg Suggest parking a router located where you want your controller to be, then take a wander round taking comparative readings with a mobile app, it will give a good indication of any difficulties for radio path on 2.4....
My blackspots were outside, Wifi proved good enough inside...

[Guillermo Schimmel]

@zboblamont Have in mind the repeater capabilities of mysensors. I have 3 wifi routers in my small house, but no problem at all with nRF24.

In my case a lot of mains powered sensors make coverage very easy.

[zboblamont]

@guillermo-schimmel True you can use repeaters, but it becomes a redundant device to solve a range problem due to frequency which may be overcome by a lower frequency selection, which was my only point... 2.4Gig was fine here internally, but not externally where mains power is not available, hence the 433MHz decision.
As mains power is flaky here anyway, battery or mains/battery-standby has kept things reliable.
The suggestion for @SteveG was a quick test to establish if 2.4 was viable in advance of deciding strategy and ordering parts...

[SteveG]

@zboblamont Good idea, I hadn’t twigged it would be the same for nRF24’s, doh ! I did that for my WiFi and had to add another access point for the back of the house, which suggests repeaters or another gateway (?) would be necessary.

[zboblamont]

@steveg It's a handy way to test the frequency...
We tend to install Routers convenient to the incoming conduit or particular duties such as cable TV, hence near the TV. That need not be the case for your controller. You said you had stud walls upstairs, presumably the floor is timber also, and I'd almost bet locating a router for a temporary test upstairs would give you total coverage within the property...
As a temporary test for the frequency to be used it is pretty decent...

[mcrahr]

@steveg
I have done a driver for a 433mhz HC12 radio, controlled with a BS170 n-channel mosfet.
That setup has very long range and very low idle consumptio. My setup uses around 8-14 uA in Sleep including a few pull-up