Flux Capacitors are a type of item added by Thermal Expansion. They are handheld batteries that can store Redstone Flux.
Flux Capacitors cannot be placed in the world like Energy Cells. However, unlike Energy Cells, Flux Capacitors can charge items in a player's inventory. This makes Flux Capacitors quite a useful tool.
Flux Capacitors can charge the player's currently held item, if the item can store Redstone Flux. However, they only do this when activated, and they must remain in that player's hotbar.
A Flux Capacitor can be activated and deactivated by using it while sneaking. Active Flux Capacitors glow as if they are enchanted.
Flux Capacitors follow Thermal Expansion's tier system. The tier of a Flux Capacitor determines its storage capacity, and the limits of how much power it may receive and/or emit.
The Creative Flux Capacitor can emit an infinite amount of Redstone Flux. For obvious reasons, this Flux Capacitor tier cannot be legitimately obtained.
The following table shows the capacity and power limits of Flux Capacitors, depending on tier.
Tuberous Flux Capacitors are full upon crafting, and cannot be recharged. When fully drained, they turn into Baked Potatoes.