Recharge several of your wards from one ward, using Molten Cores.
Carry Molten Cores, hold either Shift key while aiming at a ward you own, and use the Recharge key. The hover text changes to Recharge All and shows how many of your wards you can afford to recharge. This convenience action costs one Molten Core per successfully recharged ward. If you cannot afford every eligible ward, the earliest expiry dates are handled first. Single-ward recharge without Shift uses a Thunderstone instead.