Battery Thermal Management
Liquid-Coolant Cold-Plate Loop with Heating Elements
Two-phase or single-phase liquid coolant loop with cold plates and embedded heaters that keeps each battery module within the –20 to +60 °C operating envelope across the full lunar diurnal cycle, including pre-heating from cold-soak and cooling during high-rate operation.
Purpose
Prevent the >35% capacity loss that Li-ion suffers below –20 °C, avoid accelerated aging above +50 °C, and provide active heat extraction during high-power discharge — extending cell life from a few-year to multi-decade timeframe.
Context
Connects each L3-ESS-LITH-RACK manifold to the central L1-TCS loop. Provides heating (during night-time cold soak) and cooling (during day-time high-rate operation). Coordinates with L3-ESS-LITH-BMS thermal model and L2-ESS-MGMT dispatch.
Principles
- ▸Cold-plate conduction cooling: modules clamped against fluid-cooled plates with high thermal conductivity gap pads
- ▸Single-phase water-glycol coolant (50/50) at ~5–15 L/min per kW of dissipation, ΔT ~10 °C across the cold plate
- ▸Two-phase ammonia or HFE-7000 loops achieve higher heat-transfer coefficients but more complex BOP
- ▸Resistive heater patches on module backs provide reverse-direction heating during cold soak — typically 200 W per rack
- ▸Battery temperature uniformity within ±3 °C across a module is required for cell-balance preservation
- ▸Insulated battery vault with passive thermal mass shrinks heating power demand during long lunar night
Typical implementations
- ▸ISS battery thermal management (ammonia loop, cold-plate)
- ▸Mars 2020 Perseverance MMRTG-heated battery enclosure
- ▸Saft VES-180 module cold-plate interface design
- ▸Tesla Powerpack glycol-loop thermal management (terrestrial)
- ▸NASA Glenn lunar lander battery enclosure with embedded heaters
Lunar considerations
- ▸Lunar night at south pole drops surface to ~88 K; battery vault must hold above –20 °C → ~200 W continuous heating during long discharge
- ▸Lunar day +127 °C surface temperature requires active rejection to radiator via L1-TCS
- ▸Phase change material (PCM) in battery vault adds thermal mass — see L2-ESS-THRM coupling
- ▸Coolant fluid selection: water-glycol freezes at –40 °C, two-phase HFE-7000 works to –80 °C; trade-off mass vs. capability
- ▸Coolant lines need bellows expansion joints for thermal expansion across lunar diurnal range
- ▸Heater elements must be vacuum-rated and dust-sealed
Specifications
Functional
| primary function | Maintain battery modules within –20 to +60 °C operating range |
| inputs | Coolant supply from L1-TCS loop (~5 °C nominal), Heating power demand from L3-ESS-LITH-BMS, Power for pumps and heaters from L1-PDM |
| outputs | Return coolant to L1-TCS at +30 °C nominal, Module-level temperature uniformity ±3 °C, Coolant flow rate, inlet/outlet temperature telemetry, Heater status and active power |
| coolant flow rate lpm per rack | 8 |
| coolant supply temperature c | 5 |
| coolant return temperature c max | 50 |
| module temperature uniformity c | 3 |
| heating power w per rack | 200 |
| cooling power w per rack | 1500 |
| coolant fluid | Water-glycol 50/50 (or HFE-7000 alt) |
Physical
| mass kg per rack | 8 |
| dimensions per rack | Distributed plumbing + cold plates |
| materials | 6061-T6 aluminum cold plates with brazed internal channels, Sil-Pad or graphite gap pads (1 mm) between module and plate, Bellows-sealed coolant pumps, Quick-disconnect couplings (Eaton ML or Stäubli RBE), Polyimide heater patches with Kapton insulation, PTFE tubing (low permeability) |
| operating temperature c | -40, 80 |
Operational
| power consumption w pumping | 50 |
| power consumption w heating peak | 200 |
| thermal range c | -40, 80 |
| lifetime years | 25 |
| mtbf hours | 150000 |
Interfaces
Provides
- Cold-plate conduction interface
- Coolant flow, T_in, T_out telemetry
Requires
- Cold coolant supply (~5 °C) and return path
- Pump and heater power (~250 W peak)
Cite this entry
Lunar Ark Codex. "Battery Thermal Management" (L3-ESS-LITH-COOL). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-ESS-LITH-COOL
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.