TOP.01 // EPS
Electrical Power Systems & Li-Ion Batteries
Body-mounted GaAs solar cells, geometric cosine projection on 5 cm and 10 cm cubes, MPPT vs. DET architectures, and Li-ion depth-of-discharge cycle ageing in LEO.
1. SatWiki Encyclopedia Specifications (4)
- SQ-FF-001
PocketQube
Picosatellite standard built from 50 mm cubic units (P). A 1P weighs at most 250 g, has one eighth of the volume of a 1U CubeSat and rides in its deployer on a sliding backplate instead of rails.
- SQ-FF-002
CubeSat
Nanosatellite standard built from 10 cm units (U). Cal Poly’s CubeSat Design Specification defines the envelope, mass and centre-of-mass limits, rails and separation switches from 1U to 12U.
- SQ-SS-001
Electrical power system (EPS)
Collects solar energy, stores it in a battery and regulates and distributes it to the other subsystems. In small satellites the budget is set by cell area, eclipse duration and battery cycle life, and a 1P lives on about half a watt.
- SQ-SS-010
Batteries & energy storage
Cylindrical 18650 and pouch lithium-ion / LiFePO4 cells for picosatellites: specific energy, vacuum pouch swelling, 0 °C charge protection and LEO cycle life.
2. Interactive Lab Calculators & Workbenches (2)
3. Technical Notes (3)
- NL-TN-2026-012
The 1P battery: capacity, depth of discharge and cycle life
A low Earth orbit satellite experiences roughly 5500 eclipse charge–discharge cycles per year. We model cycle life to 80% state of health against depth of discharge (DoD), charge cutoff voltage and temperature, and explain why 1P PocketQubes run at 5–15% eclipse DoD with a 4.10 V ceiling.
- NL-TN-2026-017
3U and 6U CubeSat power budgets: body-mounted vs. deployable solar arrays
We derive the sunlit and orbit-average electrical power generated by 1U, 3U, and 6U CubeSats in a 525 km Sun-synchronous orbit across tumbling body-mounted configurations and Sun-pointed deployable solar wings. While a tumbling 1U CubeSat averages ~1.5–2.4 W, a 3U with dual deployable wings reaches 18–24 W and a 6U with four deployed panels exceeds 40–55 W, unlocking high-duty-cycle X-band downlinks, reaction wheel slews, and radar/optical payloads.
- NL-TN-2026-004
The power budget of a 1P PocketQube
We build the energy balance of a freely tumbling 1P PocketQube with body-mounted triple-junction cells in a 525 km Sun-synchronous orbit. The tumbling-body model of the PocketQube review gives about 0.86 W in sunlight and 0.55 W on orbit average. With a reference load list the mean consumption is 134 mW, the energy margin per orbit is large and the depth of discharge of a 1.85 Wh battery stays near 4%. We then show why the margin is fragile: the transmitter duty cycle, cold charging, end-of-life degradation and power peaks, and why pointing one face at the Sun gives less power than tumbling.