When u using any training weapon skill increases like mlvl.
So if u need to check how much u need charges for 1% distance u need to calculate how much mana u need for 1%.
U want to check how much charges u need at 105 dist for 1%.
1. Go http://tibia-stats.com/index.php?akcja=skillCalcMagic
magic level 105, 1% to go, desired magic lvl 106
check sorcerer or druid and great mana potions
U will get about 355101 mana, which u divide by 500(1 charge = ump)
So by that calculation u will have to u se +-710 charges per 1% at 105 dist.