Battery runtime calculator: size an Abiotic Factor backup correctly

The calculation to use

Abiotic Factor batteries do not assign a different drain rate to a lamp, refrigerator, Crafting Bench, or other powered object. The documented rule is based on the number of devices downstream of the battery:

runtime in seconds = 5 x battery charge / downstream devices

That distinction matters. A refrigerator is not intrinsically more expensive than a lamp under this model. What matters is how many powered devices sit after the battery in the wiring path. Count the battery's downstream devices, not every device elsewhere in the base.

For the reverse calculation, use:

required charge = outage seconds x downstream devices / 5

If you plan around a 270-second unpowered period, each downstream device needs 54 charge. Two devices need 108 charge, six need 324, and twelve need 648. Add a margin if your count might change before the next outage.

The site's Power Calculator performs the same calculation. It models one battery feeding the selected number of downstream devices. It deliberately does not pretend that a chain of batteries behaves like one larger battery.

Capacity and runtime table

The current reference capacities are 50 for Makeshift, 100 for Industrial, 350 for Carbon, and 700 for Quantum. Applying the formula produces this table:

For a 270-second target, a Makeshift Battery is short even when it feeds only one device: 250 seconds leaves a 20-second gap. An Industrial Battery supports one device for the full target but not two. A Carbon Battery supports six devices for about 291.7 seconds. A Quantum Battery supports twelve devices for about 291.7 seconds because doubling both capacity and device count preserves the same runtime.

This is a planning table, not a claim that every server has exactly a 270-second outage. The calculator lets you change the target from 120 to 600 seconds. Use the period that matches the condition you are planning around.

A worked base example

Suppose the critical circuit contains a Crafting Bench, one refrigerator, two lights, and one defensive device. That is five downstream devices.

1. Select five devices.
2. Select a 270-second target.
3. Calculate 270 x 5 / 5, which is 270 required charge.
4. Compare the requirement with each battery capacity.
5. Reject Makeshift and Industrial because 50 and 100 are below 270.
6. Choose Carbon at 350 charge, leaving 80 charge of theoretical margin.

The predicted Carbon runtime is 5 x 350 / 5 = 350 seconds. The margin is 80 seconds beyond the 270-second target. If another device is added later, the same battery feeds six devices for about 291.7 seconds. A seventh device reduces runtime to 250 seconds and fails the target.

That final step is the useful maintenance rule: recalculate when the downstream count changes. Upgrading a battery once does not permanently solve power planning if more equipment is added to the same branch.

Why series wiring needs a separate check

Do not add battery capacities together and divide by device count when the batteries are wired in series. The Mechanics reference explains that each battery's downstream count depends on its position. An upstream battery may be feeding other batteries as well as the final appliance, so it discharges under a different load from the battery nearest the device.

For that reason, this guide makes only two claims:

• The table is valid for one selected battery and its downstream device count.
• A multi-battery chain must be evaluated battery by battery from the wiring layout.

If the only goal is to protect a small critical circuit, a single battery with known headroom is easier to audit than an improvised series chain. If the base already uses a chain, record the downstream count at each battery instead of using the calculator's single-battery result for the whole network.

Failure diagnosis

When a circuit dies earlier than the table predicts, check the model before assuming the capacity value is wrong.

Keep a small reserve instead of sizing to an exact equality. The reserve is not a hidden game mechanic; it is an editorial planning choice that protects against counting mistakes and future devices.

Fast selection rule

For a 270-second target, multiply the downstream device count by 54. Choose one battery whose capacity is greater than that result:

• 1 device needs 54 charge: Industrial or better.
• 2 devices need 108 charge: Carbon or better.
• 6 devices need 324 charge: Carbon or Quantum.
• 12 devices need 648 charge: Quantum.

Then verify that the selected battery is actually the one feeding those devices. That last wiring check is what turns a correct formula into a reliable base plan.

Branch audit worksheet

Before trusting a battery, write the branch as a simple list.

The branch name is not a game mechanic. It is a planning habit that keeps critical devices from sharing a battery with convenience devices.

Recalculate after changes

Run the formula again whenever one of these happens:

1. A new powered object is connected downstream.
2. A battery is moved upstream or downstream in a chain.
3. A Crafting Bench upgrade changes how the work area is used.
4. A defense device is added to the same line as food or storage.
5. A failed night shows the observed runtime was lower than the table.

The formula is simple, but the device count is easy to let drift. That is why the calculator is useful after every base expansion, not only during the first setup.