4.5 Volt is a passive item in The Binding of Isaac, added in the Repentance DLC.

Prevents Isaac's active items from charging normally when clearing rooms.

Instead, active items are now charged when enemies take damage from any source.

Charges are gained at a rate of 40 + 20 × CurrentStage. For example, in Basement I it takes 60 damage to gain 1 charge, while in Home it takes 300 damage.

If an enemy receives more damage than their maximum amount of health, the excess amount will not be counted towards the recharge formula.

This page shows the latest information as of the new Repentance+ (Online Co-op) DLC.
To see information about this item for the previous Repentance version, check this page instead.

4.5 Volt can be found in the following item pools:

The following tags are applied to this item:

The following special synergies and interactions for 4.5 Volt have been documented.

* Note that not all possible synergies and interactions are listed here.

Below is the Internal Item Description as shown in-game.
Note that some stat changes are not displayed here. Please see the main description for the full effects.

4.5 Volt

• Dealing damage to enemies gradually recharges active items at a rate of 1 charge bar per 60 damage dealt
• Active items no longer gain charges from room clears
• Abyss: x1 shocking locust 1x Isaac's damage

• Check out the item description on the external Isaac Wiki.