State-of-Health and Degradation Tracker
Multi-Technology SOH Model with Remaining-Useful-Life Prediction
Aggregated state-of-health (SOH) and remaining-useful-life (RUL) predictor for all storage technologies, combining capacity-fade tracking, internal-impedance growth, cycle counting, and calendar aging into a unified prognostic that triggers maintenance and replacement scheduling.
Purpose
Maximize the Ark's storage capacity at any given time by detecting degradation early, scheduling replacement of failing units before they cause cascade failures, and reporting honest available capacity to dispatch planners.
Context
Receives per-technology SOH inputs from L3-ESS-LITH-BMS (battery capacity/impedance), L3-ESS-FC-CTRL (stack polarization curves), L3-ESS-SCAP-CTRL (ESR), L3-ESS-THRM-CTRL (PCM cycle fatigue). Feeds L1-MNT for replacement scheduling and L3-ESS-MGMT-SOC for capacity de-rating.
Principles
- ▸SOH = Current capacity / Beginning-of-life capacity; typically used down to 80% before replacement
- ▸Capacity fade arises from SEI growth, electrode-particle cracking, electrolyte depletion (Li-ion) — model coupled to operating conditions
- ▸Impedance growth tracked via DC pulse or AC impedance spectroscopy; ohmic and charge-transfer components separated
- ▸Remaining Useful Life (RUL) estimated via Particle Filter, Bayesian Updating, or LSTM neural network on historical degradation data
- ▸Calendar aging is typically square-root in time; cycle aging is linear in equivalent full cycles — both must be modeled
- ▸Cumulative damage models (Miner's rule analog) sum incremental damage from each cycle
Typical implementations
- ▸NASA Lithium-Ion Battery Capacity Data Set (publicly available, used for RUL model training)
- ▸BAE Systems spacecraft battery prognostics on Mars Express, Sentinel
- ▸Saft long-life battery SOH algorithms (used on Mars 2020)
- ▸Joint EKF/UKF SOC+SOH estimation (recent 2024 publications)
- ▸ML/LSTM-based RUL prediction (recent 2024 publications)
Lunar considerations
- ▸100-year mission means cells will pass through full life many times — SOH model must support replacement events (reset)
- ▸Cumulative radiation dose contributes to capacity fade beyond Earth-based models — must include radiation-aging term
- ▸Replacement scheduling balances ahead-of-failure (waste reserve) vs. wait-for-failure (risk cascade)
- ▸Heterogeneous fleet (mixed-age modules) requires per-unit SOH tracking
- ▸L1-MNT robot availability constrains how quickly replacements can be staged — SOH prognostic must give weeks of lead time
Specifications
Functional
| primary function | Track SOH and predict RUL across all storage technologies |
| inputs | Per-cell capacity and impedance from L3-ESS-LITH-BMS, FC stack polarization data from L3-ESS-FC-CTRL, Supercap ESR from L3-ESS-SCAP-CTRL, PCM cycle count from L3-ESS-THRM-CTRL, Cumulative radiation dose from L1-RAD |
| outputs | SOH per FRU and per technology, RUL forecast (days/cycles to 80% threshold), Replacement schedule recommendations to L1-MNT, Capacity de-rating factor to L3-ESS-MGMT-SOC |
| soh accuracy percent | 2 |
| rul uncertainty days at 1yr horizon | 30 |
| update rate per day | 1 |
| models supported | empirical, physics-based, LSTM ML |
| replacement lead time recommendation weeks min | 8 |
Physical
| mass kg | 0.0 |
| dimensions | Software on L1-CDH host |
| materials | Code on rad-hard NOR flash |
| operating temperature c | -40, 70 |
Operational
| power consumption w | 0.5 |
| thermal range c | -40, 70 |
| lifetime years | 100 |
| mtbf hours | 500000 |
Interfaces
Provides
- Replacement scheduling recommendations
- Capacity de-rating factors
- Health status for autonomous decisions
Requires
- Per-cell capacity/impedance
- Stack polarization
- Cumulative dose tracking
- Long-term history database storage
Cite this entry
Lunar Ark Codex. "State-of-Health and Degradation Tracker" (L3-ESS-MGMT-SOH). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-ESS-MGMT-SOH
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.