A "good-to-have" add-in for a battery powered project is a monitoring function that will be able to check over the entire battery lifetime at least few parameters like, temperature, voltage, current, power consumption and stored energy between charges.
A simple, basic, capacity test / loading / discharging time values can give you valuable informations about the parameters and health of the battery. And, of course, you can see how are looking the numbers against the datasheet claims .
Youtube Video, BLMS testing :
For more details: ESP8266 Battery Monitoring System
Looking forward for your comments and suggestions/improvements about
Thank you.
Available on Tindie: https://www.tindie.com/products/nEXT_EVO1/universal-ac-mains-dimmer-mpdmv41/