Battery Rack Assembly
Series/Parallel Module Rack with String-Level Disconnect
Mechanical and electrical rack housing 8–16 series-connected battery modules at ~400 V DC bus level, with string-level disconnects, fusing, vibration isolation, and integrated cooling-plate manifold — the unit of battery deployment within the Ark.
Purpose
Aggregate individual battery modules (L3-ESS-LITH-MOD) into a high-voltage, high-capacity string that integrates with the Ark's DC bus, while providing fault isolation, fire compartmentalization, and easy robotic replacement of modules.
Context
Houses L3-ESS-LITH-MOD instances; connects to L3-ESS-LITH-CONN bus, supervised by L3-ESS-LITH-BMS, isolated by L3-ESS-LITH-ISOL contactors, cooled by L3-ESS-LITH-COOL. Multiple racks installed in parallel for N+2 redundancy.
Principles
- ▸Series stacking of 48 V modules into ~400 V strings reduces I²R losses and aligns with high-voltage DC distribution
- ▸Parallel stringing provides redundancy and increases capacity; balanced charging avoids inter-string circulating current
- ▸String-level fuses isolate single-module fault from rest of rack; trip current ~2× nominal discharge
- ▸Vibration isolation via wire-rope or elastomeric mounts protects against seismic and operational shocks
- ▸Rack-level fire compartmentalization (intumescent gaskets, sealed enclosure) contains thermal events
- ▸Standardised module-to-rack mechanical interfaces enable robotic replacement
Typical implementations
- ▸ISS battery orbital replacement units (ORUs) — modular rack design
- ▸Tesla Megapack / Powerwall residential designs (terrestrial heritage)
- ▸Hyperion / BAE battery racks for ESA Sentinel missions
- ▸NASA Lunar Gateway battery rack concepts
- ▸Saft IPS racks (industrial Power Systems) used on spacecraft
Lunar considerations
- ▸Robotic accessibility critical — modules must slide in/out via L1-MNT manipulator
- ▸Lunar dust ingress between modules prevented by sealed rack enclosure
- ▸Thermal coupling to L1-TCS coolant loop requires reliable rack-level manifold quick-disconnects
- ▸Replacement modules carry pre-charge state — rack must accept hot-swap with controlled inrush
- ▸1/6 g reduces structural mass requirements but vibration isolation still critical for seismic loads
Specifications
Functional
| primary function | Aggregate modules into series/parallel strings at 400 V DC bus level |
| inputs | Power feeds from L1-PDM (charge) at up to C/2, Coolant in/out from L3-ESS-LITH-COOL manifold, Module-level signals to L3-ESS-LITH-BMS |
| outputs | Aggregated DC bus output at 384–432 V, String-level current and voltage telemetry, Mechanical anchorage and dust seal |
| modules per rack | 8 |
| rack capacity kwh | 32 |
| rack voltage v nominal | 384 |
| rack continuous current a | 100 |
| rack peak current a | 200 |
| string fuse rating a | 200 |
| vibration isolation natural freq hz | 15 |
| field replaceable unit | True |
Physical
| mass kg empty | 30 |
| mass kg loaded | 174 |
| dimensions | 1200 × 600 × 800 mm cabinet |
| materials | 6061-T6 aluminum frame, Stainless steel fasteners, Wire-rope vibration isolators, Intumescent compartmentalization gaskets, Conductive elastomer EMI gaskets, Anodized aluminum cooling-plate manifold |
| operating temperature c | -20, 60 |
| ultimate load g | 8 |
| ingress protection internal | IP54-equivalent against dust/condensate |
Operational
| power consumption w | 0 |
| thermal range c | -20, 60 |
| lifetime years | 30 |
| mtbf hours | 400000 |
Interfaces
Provides
- 384 V DC bus connection, 100 A continuous
- String-level current, voltage, fuse status
- Standardized module slots for robotic FRU replacement
Requires
- Individual module outputs (48 V × 8)
- Coolant manifold supply/return
- Contactor and arc-suppression for rack disconnect
- Rigid mounting in battery vault enclosure
Cite this entry
Lunar Ark Codex. "Battery Rack Assembly" (L3-ESS-LITH-RACK). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-ESS-LITH-RACK
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.