Average load
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Astrophotography Tools · Gear Lab
Astro Power Runtime Calculator
Estimate how long a portable battery can run a mount, cooled camera, dew heaters, laptop or mini PC, and other astronomy gear before you buy the power station.
Battery
Start with usable energy, not marketing capacity.
Optional Ah conversion
If your battery is labeled in amp-hours instead of watt-hours, estimate Wh as volts × amp-hours.
12.8 V × 50 Ah = 640 Wh
Battery presets
Average equipment load
Build the rig.
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Usable energy
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Estimated runtime
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8-hour reserve
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What changes real runtime?
Cold weather, inverters, and dew can move the number.
The calculator estimates energy use from the numbers you enter. Actual runtime can be shorter because of battery temperature, inverter overhead, DC conversion losses, cable losses, battery-management reserve, aging, and devices drawing more power than expected.
01
Prefer DC when practical
Running 12 V gear from a suitable regulated DC output can avoid some AC inverter losses.
02
Dew heaters cycle
A heater set to 40% average output should not be modeled as if it draws maximum power all night.
03
Cooling load changes
A cooled camera can draw heavily while pulling down to temperature, then settle to a lower duty cycle.
04
Keep reserve
Planning for exactly 100% of rated capacity leaves no margin for colder nights, aging, or unexpected loads.
Before buying a power station
Capacity is only one spec.
Also check continuous output, 12 V port limits, regulated output, connector type, inverter rating, cold-temperature behavior, charging speed, battery chemistry, warranty, and whether the ports stay enabled at low loads.
Gear Lab principle
Size the battery from the rig, not the product page.
Future StarStation power-station reviews can compare measured usable capacity, output behavior, ports, recharge time, cold-weather performance, and price against the actual astronomy loads shown here.