LoRa Sensor Network

[lbjstetson]

I'm building a new sensor network to replace about 40 current nodes but will be using 915 LoRa this time for increased range. The nodes are powered by 4 AA batteries. The nodes send their values to a gateway that sends them online via GPRS.

I'm going to be doing some range testing today but would like suggestions for radio settings, code optimisation and battery life. I've attached pics of my new node design (the final units will be stainless steel) and my code.

Thanks!

[TomWS]

...The nodes are powered by 4 AA batteries.
...

Is there a reason you need 6V?  The Moteino only requires 3.3V, the rest of the voltage is literally wasted if you don't need it for other electronics in your node.   

Tom

[lbjstetson]

Won't it drop below 3.3 sooner with only 2?

[Felix]

With 4XAA it will last even longer (higher capacity) but like Tom said, some voltage is wasted and you're getting into diminishing returns.
You will need a minimum of 3xAA to keep it above 3.3V (3.3v + LDO dropout), that's around 3.6V.
With 3xAA it will still last a long time.

[lbjstetson]

With 4XAA it will last even longer (higher capacity) but like Tom said, some voltage is wasted and you're getting into diminishing returns.
You will need a minimum of 3xAA to keep it above 3.3V (3.3v + LDO dropout), that's around 3.6V.
With 3xAA it will still last a long time.

Understood. I have a bunch of extra four battery holders laying around but I'll switch to three once they're gone.

[Felix]

I have a bunch of extra four battery holders laying around but I'll switch to three once they're gone.

Makes sense, especially if space is no constraint.

[perky]

Or get one of these (means you won't need to change battery monitoring firmware):
https://www.ebay.co.uk/itm/2pcs-Pack-Dummy-Battery-AA-2A-Size-Conduct-Conductor-Electric-Current-UltraCell/232656633638

[lbjstetson]

I appreciate the battery suggestions.

What about my bitrate? Right now I'm using: setModemConfig(RH_RF95::Bw31_25Cr48Sf512);

I'm wondering if I could lower my bitrate and still get acceptable speed.

[Felix]

Bitrate is speed, so what is "acceptable"?
Maybe run some trials and see where the sweet spot is?