Darcy Battery Management System Wiki

Purpose

The Darcy Battery Management System is the main protected power-distribution board between a 12-cell lithium-ion battery and the vehicle avionics system.

At a high level, it controls downstream power outputs, generates auxiliary rails, and measures battery/load behavior so the flight system can tell what its electrical distribution network is doing.

My Responsibility

I was the Design Responsible Engineer and owned the schematic, PCB layout, bring-up, and ongoing board operation.

Architecture

The board contains:

• Protected battery input circuitry
• Auxiliary power regulation
• Five controlled load-switch channels
• Connector-level switched power outputs
• Voltage and current telemetry
• ADC signal conditioning
• Current-loop sensor interfaces
• Vehicle and debug connectors

The repeated load-switch architecture makes each output easier to review, test, and control on its own.

Power Distribution

The battery input needs to tolerate normal 12-cell pack voltage while keeping abnormal conditions from propagating into downstream avionics. Each load path is controlled separately so subsystems can be sequenced, disabled after a fault, or tested without energizing the whole vehicle.

High-current copper should be shown as an intentional distribution network rather than as generic pours. Annotated layout views should identify the battery entry point, branch paths, switches, connectors, current-sense elements, and return-current paths.

Telemetry

Voltage and current measurements allow the flight system to distinguish expected subsystem load from wiring faults, short circuits, or unexpected current consumption.

The telemetry layout should demonstrate Kelvin sensing, filtering near the ADC, quiet reference routing, and separation between measurement returns and switched load current.

Bring-Up Plan

1. Inspect battery and output connector polarity.
2. Apply current-limited input power.
3. Validate protected-input behavior and auxiliary rails.
4. Check ADC scaling with known voltages and currents.
5. Enable each load path individually into a controlled load.
6. Verify output voltage, current, thermal behavior, and disable response.
7. Test current-loop interfaces with known stimulus values.
8. Repeat with representative harness and subsystem loads.

Validation Evidence to Add

The strongest public evidence to add next would be:

• Input turn-on waveform
• Protection-threshold testing
• Load-switch voltage drop
• Current-measurement accuracy
• Channel-to-channel consistency
• Sustained thermal test
• Fault shutdown and recovery behavior

Next Revision

Add clearer separation between power-return and measurement-return annotations, dedicated test points for every switched channel, and a published channel-level validation table.