Power grid planning: battery runtime, branches, and critical loads

Why a star-like layout is easier to keep alive

A reliable base does not put every appliance behind one long chain of batteries. It separates critical devices into visible branches, gives each branch a known downstream-device count, and tests the runtime against the night length used by that save.

This guide is a planning worksheet, not a crafting recipe list. Battery recipes and unlocks can change, while the current power reference provides the rules needed to evaluate a grid: each battery has charge capacity, every downstream powered device increases drain, and batteries placed in series are themselves counted as downstream devices by upstream batteries.

Runtime formula and verified battery capacities

The current Mechanics page states that a discharging battery loses 1 charge every 5 seconds for each downstream device. For a single battery branch:

runtime in seconds = 5 × battery charge ÷ downstream devices

Use the Power Calculator to apply the same rule to a planned branch, then return here to decide how that branch should be isolated. The tool is a convenience for the arithmetic; the device count still has to come from the actual in-game wiring.

Use the formula only after counting actual powered devices. Plug Strips and Plug Boards create branches but are not themselves counted as powered devices. Batteries farther downstream do count from the perspective of an upstream battery.

These counts apply to the electrical branch. The same Mechanics page's Advanced Power Options section documents an exception at a Laser Emitter: it counts as one powered device regardless of appliances supplied beyond its beam, including through a Laser Power Converter. Draw that transmission boundary explicitly rather than counting every remote appliance as a separate load on the emitter's upstream battery. The beam still needs a clear path; losing beam delivery is a different failure from exhausting battery charge.

On default cycle settings, the facility power outage lasts 270 seconds. A single Makeshift Battery powering one device therefore stops 20 seconds before the end. An Industrial Battery powering two devices also lasts 250 seconds, so the same gap appears. Capacity alone does not determine success; branch load is equally important.

Worked examples

One refrigerator on one Industrial Battery

5 × 100 ÷ 1 = 500 seconds

The branch exceeds a 270-second standard night.

Two devices on one Industrial Battery

5 × 100 ÷ 2 = 250 seconds

The branch falls 20 seconds short.

Six devices on one Carbon Battery

5 × 350 ÷ 6 = 291.67 seconds

The current Carbon Battery page confirms that one full battery can power up to six devices through a standard night.

Seven devices on one Carbon Battery

5 × 350 ÷ 7 = 250 seconds

Adding one device turns a passing branch into a failing one. This is why a written device count is more useful than saying a battery is "high tier."

Decision table: parallel branches or batteries in series

"Star topology" here means operational separation: branches leave a central distribution point and can be counted independently. It does not mean every possible base must use one geometric pattern. The goal is visible boundaries, not decorative cable symmetry.

Why long series chains are inefficient

Consider two full Makeshift Batteries in series feeding one device. The battery nearest the device sees one downstream device and contributes 250 seconds. The upstream battery sees both the device and the other battery, so it contributes only 125 seconds. Total runtime is 375 seconds, not 500.

For two devices behind those two batteries, the downstream battery sees two devices and contributes 125 seconds. The upstream battery sees three downstream devices and contributes about 83.3 seconds. Total runtime is about 208.3 seconds. Adding battery capacity did not fix the overloaded design.

The documented Mechanics page includes useful limited series ratios, but a simple base is easier to diagnose when critical loads have independent, short branches. Use a series configuration only after calculating it, not as a default response to every outage.

Workflow: audit a base before the next night

Step 1: identify critical loads

List the devices whose outage creates a real consequence. Examples may include food preservation, a powered Crafting Bench that defines the base safe area, or equipment required by the group's overnight routine. Lights and convenience devices belong on a lower-priority list unless the route specifically depends on them.

Step 2: draw branches from the outlet

For each cable path, record:

outlet → distribution point → battery arrangement → powered devices

Do not combine two physical branches into one row. If the drawing does not show which battery owns which devices, the grid is not yet auditable.

Step 3: count downstream devices at each battery

Begin at the device end and work toward the outlet. Count appliances and any downstream batteries. Do not count the Plug Strip or Plug Board itself. The battery's blue front indicator also represents how many devices are downstream, which can help verify the written count.

Step 4: calculate the weakest runtime

Apply the formula to every battery in a series chain. Add the runtime contributions in discharge order for that branch. For a single battery, compare its result directly with the outage duration. On standard settings, use 270 seconds; on a custom save, measure or use the configured cycle rather than copying the standard value.

Step 5: reduce load before adding complexity

If a branch fails, first move noncritical devices elsewhere or turn them off. Then consider a separate battery branch or a verified battery upgrade. A larger network with the same hidden downstream count is harder to maintain and can still fail.

Verify the changed load on the battery's front indicator. Moving a device to a different branch, unplugging it, or using a Lever to cut its power path makes the wiring change explicit; do not assume that a device's idle appearance has removed it from the downstream network. The discharge formula has no extra term for how busy a connected appliance or trap appears to be.

Step 6: perform a controlled night test

Start with full batteries. At power loss, note the charge indicator and verify that every critical device stays active until facility power returns. Test one branch change at a time. If several changes are made together, a successful night will not reveal which one solved the problem.

Example branch worksheet

Replace the example labels with the actual base. Do not treat the rows as a universal recommended appliance list.

Failure recovery and completion check

Everything fails at once. Check the common upstream connection and outlet. If all critical loads share one chain, separate them after power returns so the next failure has a smaller scope.

Only one branch fails early. Recount its downstream devices, including a battery hidden farther down the cable. Compare the visible count with the runtime calculation.

A new appliance causes a late-night gap. Recalculate before adding another battery. Moving that appliance to a convenience branch may restore the passing critical branch with less complexity.

Batteries start the night partially charged. Verify daytime connection and allow a full recharge. A correct capacity calculation assumes the starting charge used in the formula.

A custom server disagrees with the worksheet. Confirm the Day/Night Cycle setting. Battery discharge timing is documented separately from cycle speed, so a changed night duration changes the coverage target.

The power audit is complete when:

• Every critical device belongs to one named branch.
• Every battery has a recorded downstream-device count.
• Runtime is calculated from charge and load, not guessed from battery tier.
• The target night duration matches the current save settings.
• Convenience loads cannot silently push a critical branch below the target.
• A controlled night test confirms the calculation.
• The diagram is simple enough that another player can isolate a failed branch.

That result is the practical value of a star-like grid: not more cables, but a base whose overnight behavior can be predicted and repaired.