Orbital Power & Battery Cycle-Life Simulator
Calculate sunlit solar generation, eclipse battery Depth-of-Discharge (DoD), and multi-year Li-ion capacity retention.
DETERMINISTIC PHYSICS & DATA METHODOLOGY
How This Calculator Works
Source modules: lib/physics/power.ts, lib/physics/battery.ts, lib/physics/orbit.ts
Computes orbit-average solar generation for a randomly tumbling convex spacecraft, sunlit/eclipse intervals in cylindrical Earth shadow, per-orbit battery depth of discharge (DoD), and illustrative Li-ion cycle-life retention.
Governing Equations & Physical Model
P̄_gen = S₀ · η · p · (A_tot / 4) · (1 − f_e(h, β)), f_e = (1/π)·arccos(√(h² + 2R_E h) / ((R_E + h)·cos β))Uses S₀ = 1361 W/m², η = 0.28 triple-junction GaAs cells, packing factor p = 0.60, and orbit beta angle β.
P_load = P_base + d_tx·P_tx + d_pl·P_pl, DoD = (P_load · t_ecl) / E_battConverts sunlit/eclipse minutes from Keplerian period T = 2π√(a³/μ) into energy drawn per eclipse.
N_80 = 6200 · (0.2 / DoD)¹·⁵⁸ · exp(−2600·(T_ref⁻¹ − T⁻¹)) · 0.62 · 2^((4.2 − V_chg)/0.1)Models SEI-like capacity fade 0.2·(N / N_80)⁰·⁶⁵ at T_cell = 18 °C and V_chg = 4.1 V.
Inputs, Parameters & Units
| Parameter | Unit | Physical definition |
|---|---|---|
| A_tot, h, β | cm², km, ° | Total external body area, circular altitude, and Sun-to-orbit-plane beta angle. |
| P_base, P_tx, P_pl | mW | Quiescent bus load, active transmitter DC power, and active payload power. |
| d_tx, d_pl, E_batt | %, %, Wh | Transmitter and payload duty cycles, plus nominal Li-ion battery energy. |
Assumptions & Validity Limits
- The cycle-life function evaluateBatteryAgeing is an illustrative empirical model for DoD/voltage derating trade-studies and is not calibrated to a specific flight cell qualification dataset.
- Assumes ideal MPPT harvesting at η = 28% without temperature derating of solar open-circuit voltage.
Worked Default Reference Case
At 525 km and β = 15°, sunlit duration is 59.9 min and eclipse is 35.2 min; 540 mW average generation against a 200 mW duty-cycled load leaves +340 mW margin and 1.3% eclipse DoD.
- Orbit-average generation
- 540 mW (59.9 min sunlit)
- Duty-cycled bus + TX + payload
- 200 mW (+340 mW margin)
- Eclipse battery DoD
- 1.3% (35.2 min shadow)
- Illustrative 3-yr retention
- 95.5% SoH (at 4.1 V)