Power Cells

As an alternative to tracking an Energy resource for powered sci-fi items, I might steal usage dice from the Black Hack.
 

Each gadget has a Power Die based on the type of power cell you've inserted in it, and instead of taking Energy in the time intervals described in my list, you roll the die. This adds a bit of fun and unpredictability into the boring resource management.

Here are several power cells and their maximum Power Dice, in order from the most common (or rather the least uncommon):

1. Chem cell: d8
2. Nuclear cell: d10
3. Antimatter cell: d12
4. Zero point cell: d20

We can also have some fun with rechargeable power cells. All of them have a maximum Power Die of d8.

1. Fidget cell: For every day of travelling* with this power cell, step up its Power Die.
2. Fuel cell: Fill the power cell with Fuel to set its Power Die to maximum.
3. Solar cell: For every day of sunlight** this power cell absorbs, step up its Power Die.
4. Xenotech cell: For every HD worth of blood you drain into this power cell, step up its Power Die.

*) Or shaking it by hand, but who can do that without their hand falling of?
**) This is deliberately weaker than the portable solar panel.