I found out that my 3-year-old Moto G (1st gen) that has got a gradually weakened battery suddenly regained its long lasting charge when I performed spring cleaning on the system apps by disabling them. Disabling in this context means that you cannot uninstall a system app but for some reason you are allowed to uninstall all subsequent updates and disable the app from running.

I did that for most every system app that I know I don't use and suddenly my phone is able to go 5-6 days without a charge instead of the ~48 hours before my spring cleaning.

It's sad that I can't really have both.