nohamsue, I only found one article that stated the life expectancy of Moto G battery to be 2+ years. A lot of forums state to charge battery when showing 40% and remove from charger at 90% to extend battery life.
Below are some links that may be helpful info. to you on cell phone batteries. Good luck
I hope this helped you out, if so let me know by pressing the helpful button.
http://www.pcadvisor.co.uk/how-to/mobile-phone/how-charge-phones-battery-3619623/
http://www.wikihow.com/Make-Your-Cell-Phone-Battery-Last-Longer
http://www.pcadvisor.co.uk/how-to/mobile-phone/how-improve-smartphone-battery-life-facebook-myths-3284240/