Modern batteries do not like to be "formatted" in 100 - 0 - 100% cycle. Only bad Chinese parts for cheap phones need it because parts on battery loses information on whole available battery.
However it's good to once a month do full cycle 100% - 5/10 % and 100%.
Never ever let battery die for so long. Chemistry effects of creating crystals will kill its efficiency.
Cheers. Battery at 17% now. Will stick it on charge soon. Nearly sleep time anyhow