Node power consumption


(Melon87) #1

This is my first post to your wonderful community. I am new to LoRa / LoRaWAN.

I am keen to understand how I can estimate the power consumption of a node. I looked at the microchip part which supports protocol class A. I understand it has a Tx phase and two Rx phases. What will the module consume between Tx and the two Rx phases? I assumed idle current - however there is no way it would make 10 years on a coin cell sending only 10B message once an hour.

If anyone has any examples that would be great (microchip or not).

Many thanks,


#2

correct, you'll need a bigger battery, also the sensor itself, lets say a temp sensor, will use energy.

the minimum sensor, an on/off switch, connected to an LAIRD RM186 will consume 0.786 uA in sleep mode


(Jose Marcelino) #3

This plot - taken from the Laird RM186 Datasheet - shows the current for a typical packet


(Melon87) #4

Thanks both for your inputs. Very helpful.

I hadn't seen Laird - so I will look more closely.

So by my maths then a 10B packet (+7 overhead?) gives you 1 class A tx/rx every hour for ten years on a coin cell. This is with a bit rate of 250bps.

I did have one question - does the sensor need to join everytime it wakes up? What about if I completely power off the radio - I note the microchip part has errata.

Anything that transmits only 17B in both directions an hour is going to be somewhat low power, but the key thing is to consider the receiver sensitivity. If the application is useful with datarate then its impressive. Fortunately, there a a few good applications.