Can we upgrade old emonTH nodes to extend battery life?

Hardware emonTH
,
1

Hi,

I was just wondering if it is possible to upgrade the old emonTH with the new temperature/humidity sensor Si7021 ?
The main objective is to extend the battery life to the same level as the new emonTH V2.

If possible, what needs to be done ?

kr
Jan.

2

Hi Jan,

I’m afraid the new Si7021 sensor require different hardware (new PCB design) and new firmware. See emonTH V2 repo:

You could increase the time between readings to increase the battery life of emonTx V1. You should be experiencing about 6-10 months battery using DHT22 on emonTH V1. If you don’t require humidity readings using a DS18b20 temperature sensor instead of DHT22 will increase battery life. No firmware change is required to use DFS18B20 with emonTH V1 instead of DHT22

3

Hi Glyn,

Thanks for the fast response.
I like your suggestion about increasing the period.
Do you have any idea about the impact on the battery life if I would increase the period from 1 minute to 5 minutes ?

kr
Jan.

4

Battery life would probably more than double. Most of the power is consumed powering up the MCU and sensor to take a reading.

5

You could also look to swap the battery to a larger capacity - perhaps a Lithium ion or similar - just ensure its the same voltage!