This wand has 7 charges. While holding it, you can expend no more than 3 charges to cast Fireball (save DC 15) from it. For 1 charge, you cast the level 3 version of the spell. You can increase the spell’s level by 1 for each additional charge you expend.
Regaining Charges. The wand regains 1d6 + 1 expended charges daily at dawn. If you expend the wand’s last charge, roll 1d20. On a 1, the wand crumbles into ashes and is destroyed.
RollQuest summary 7 charges; regains 1d6 + 1 at dawn. Cast Fireball (save DC 15): 1 charge for level 3, +1 level per extra charge, max 3 charges (level 5).
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.