Sonoff DW2


### What issue do you have? Please be as thorough and explicit as possible.

Sonoff DW2 battery life is very bad. Lasted almost a week only on average with brand new batteries. 

This issue has been there since 2months ago. Kept changing batteries after batteries, hoping that something can be done on this matter. No error logs shown. Low battery threshold shows a different reading compared to the eWeLink app. The sensor works as how it should until it goes offline and I know the battery is dead. Thanks

### Details of your setup.
* Do you use Homebridge (with config-ui?) or HOOBS? 

Homebridge with raspberry pi4

* Which version of Homebridge/HOOBS do you have?
v1.3.4


* Which version of this plugin (homebridge-ewelink) do you have? Has the issue started since upgrading from a previous version?
v5.6.0 


* Which eWeLink devices do you have that are causing issues? Please include product models if applicable.

DW2-Wi-Fi

* Do you use your main eWeLink credentials or do you use a secondary eWeLink account for Homebridge?

Main credentials. 

### Please paste any relevant logs below.
<!-- ABOUT LOGS
   → More thorough logging can be seen by enabling 'Debug Logging' and
     ...'Request & Response Logging' in the plugin settings.
   → If you are posting an error then it is helpful for me to also see
     ...the previous few lines as this can show the cause of the error.
   → Please enter the logs between the two ``` lines below so that
     ...the logs are formatted in a way which is easier to read.
-->

```

```
