Note that it charges off of the nearest Aura Node. If there is no nearby Node, the wand will not recharge.
"The casting wand is your most basic, but also your most important tool. It is what you use to craft objects, activate blocks, and countless other uses.
It stores a limited amount of magical energy (called vis) that is used to perform its tasks. As long as there are aura nodes nearby and you are carrying it, the wand will slowly recharge itself. A negative percentage displayed on the wand vis display above the hotbar indicates a discount on most vis costs. These discounts are availible by performing certain tasks e.g. wearing a full set of Thaumaturge's Robes.
The Wand of the Apprentice can be upgraded to a Wand of the Adept on an Infusion Altar after researching Unified Thaumic Field Theory. To do so, two wands are needed—one to be upgraded and a second to provide the needed vis for infusion. This wand can also be adapted to become wands such as Fire wands and frost wands after researching the Unified Thaumic Field Theory.