Supercapacitor Rack Assembly
Series Modular Rack with Pre-Charge / Discharge Resistors
Mechanical rack housing series-connected supercapacitor modules at ~400 V bus level, with pre-charge resistors, isolation contactors, fast fusing, and integrated cooling — the deployment unit of supercap storage within the Ark.
Purpose
Aggregate individual supercap modules into a high-voltage string that can absorb or deliver tens of kW peak power, with fault isolation, controlled inrush during reconnect, and easy robotic module replacement.
Context
Houses L3-ESS-SCAP-MOD instances; provides series stacking, supervised by L3-ESS-SCAP-CTRL, balanced by L3-ESS-SCAP-BAL, connected via L3-ESS-SCAP-DCDN to L1-PDM. Similar architecture to L3-ESS-LITH-RACK but with shorter time-constant transients.
Principles
- ▸Series stacking of 48 V modules to ~400 V bus reduces I²R losses
- ▸Pre-charge resistor limits inrush when reconnecting empty supercap to charged bus (supercap looks like a near-short until charged)
- ▸Fast fusing (semiconductor fuses, response <1 ms) protects against electrolyte short-circuit
- ▸Vibration isolation similar to battery racks; supercap modules are heavier per volume
- ▸Power dissipation per peak event is brief but intense — rack thermal management peaks high
- ▸Discharge resistor enables safe shutdown for maintenance
Typical implementations
- ▸Maxwell BMOD0500 48 V rack modules (terrestrial heritage)
- ▸Skeleton Technologies SkelGrid utility-scale racks
- ▸Tesla auxiliary power modules with supercap backup (legacy)
- ▸ISS solar array sequential shunt unit transient handling (heritage of capacitor banks)
Lunar considerations
- ▸Robotic replacement same standard as battery rack (L1-MNT)
- ▸Lunar dust sealing of high-voltage compartment
- ▸Self-discharge requires controllers to top-up periodically during long quiescent periods
- ▸Heat dissipation during single transient event up to several hundred watts for <1 second — managed by thermal mass
Specifications
Functional
| primary function | Aggregate supercap modules into a high-voltage string |
| inputs | Module outputs (8 × 48 V), Coolant interface from L1-TCS, Bus charging current from L3-ESS-SCAP-DCDN |
| outputs | Rack DC bus at 384 V, up to 400 A peak, String telemetry |
| modules per rack | 8 |
| rack capacitance f | 62.5 |
| rack voltage v nominal | 384 |
| rack energy kwh | 1.4 |
| rack peak power kw | 400 |
| rack continuous power kw | 50 |
| string fuse rating a | 500 |
| pre charge resistor ohms | 50 |
Physical
| mass kg empty | 25 |
| mass kg loaded | 249 |
| dimensions | 1200 × 600 × 800 mm cabinet |
| materials | 6061-T6 aluminum frame, Stainless steel fasteners, Wire-rope vibration isolators, Conductive elastomer EMI gaskets, Ceramic pre-charge resistors, Semiconductor fast fuses |
| operating temperature c | -40, 65 |
| ultimate load g | 8 |
Operational
| power consumption w | 0 |
| thermal range c | -40, 65 |
| lifetime years | 30 |
| mtbf hours | 400000 |
Interfaces
Provides
- Rack bus at 384 V
- String telemetry, fuse status
- Module slots for FRU replacement
Requires
- Individual module outputs
- Coolant manifold supply/return
- Rigid mounting in supercap vault enclosure
Cite this entry
Lunar Ark Codex. "Supercapacitor Rack Assembly" (L3-ESS-SCAP-RACK). Retrieved 10 September 2026, from https://lunarark.com/entry/L3-ESS-SCAP-RACK
Licensed CC-BY-SA 4.0. You may reuse and adapt this entry with attribution, under the same licence.