Car Battery

Car Battery is a passive item added in The Binding of Isaac: Afterbirth.

Effect

 * Causes Isaac's activated item to activate twice on each use.

Synergies

 * : Prevents the Mom's Foot from appearing for two rooms (empty or not), or for two waves of a Challenge Room or the Boss Rush.
 * Combined with items like or, this synergy allows Isaac to (considering he entered the Boss Rush room with a full charge) essentially remove the feet for the entire duration of the Boss Rush.
 * : Splits the 50% chance to succeed into a 25% chance to quadruple all items and a 25% chance to duplicate all items while consuming the originals; the latter will make Devil deal and Shop items free.
 * The 25% chance to duplicate all items while consuming the originals now generates 2 pennies instead.
 * : Will count as giving double Brimstone, giving extra damage and a x1.2 damage multiplier for the current room.
 * : Doubles effects of all absorbed activated items. Absorbing passives will not give extra stat ups.
 * : 25% chance to spawn nothing, 50% chance to spawn one coin, and 25% chance to spawn two coins.

Interactions

 * : Will only increase rage duration if no enemies are killed in the first half, effectively only affecting bosses that can't spawn enemies.


 * Activates twice, but has a chance to uselessly activate the same effect twice.
 * ///: Doubles the length of invincibility, but no effect on damage where applicable.
 * If the Car Battery is removed by the first activation, a second activation will not happen. Two activations in a row is mostly detrimental, removing two items and possibly cycling through a character that lowers health.
 * Lowers ID by 2, good for some items, bad for others.
 * Doubles the duration, giving more time to walk through more enemies, if you end the effect before the end of the first second, the item will reactivate itself; allowing to target the same enemies twice.
 * /: Instantly re-rolls Isaac's items twice, which doubles the speed at which the item pools are exhausted and transformations are achieved.
 * As items are returned back into the item pool when re-rolled, the items pools aren't exhausted at all. Also, you need to actively be holding a transformation's respective items to retain them now, so using the double re-roll to gain multiple transformations is no longer possible.
 * ///: Re-rolls twice instantly without any benefits. The D6 depletes item pools at double the speed.
 * Doubles the amount of enemies summoned, but does not give double rewards.
 * Activates 2 random effects.
 * Activates 2 dice. The second activation die cannot be predicted.
 * The invulnerability time is not increased, but damage-triggered items will activate twice if applicable.
 * Re-rolls twice like The D6 (see above), but the 30% chance of the item disappearing is increased to 51%.
 * Instead of doubling its effect, Everything Jar will spawn a poop alongside its normal drop.
 * Doubles the damage the Brimstone beams deal to 44 (for a total of 880 damage per use). No effect on beam duration.
 * Doubles the length of the effect.
 * Makes the effect twice as long.
 * Spawns a Movable TNT and instantly detonates it, damaging Isaac.
 * This has been changed to spawn two Movable TNT barrels instead, which you can detonate at will.
 * Activation swaps the contents of the box with the contents of the room.
 * Doubles in damage and slow time.
 * Swaps places with Isaac twice in quick succession, rendering Stitches useless for collecting pickups & items beyond pits, rocks etc.
 * However, it can still be used to telefrag enemies.
 * //: Deals double damage, but charms/poisons/petrifies for the same amount of time.
 * Multiplies detonated tears, resulting in 6x more tears than normal.
 * : Will summon 2 peepers in a bifurcated direction
 * Places both trapdoors in same location.
 * Ventricle Razor works normally.

Trivia

 * Prior to Repentance, Car Battery's description was "Double charge!"

Seeds
A188 W1Q8 (First floor Shop) Q1ZZ ETS0 (Starting item as Eden)