BarnacleBoy db353ad2d1 add power system: IP5389 board + 18650 array decision

- IP5389 power bank board selected (preliminary)
- All-in-one: charging, BMS, USB-C PD output
- Rejected K501U battery (integrated BMS not reusable)
- Documented alternatives considered (TP5100+2S BMS+buck, UPS HAT)
- Updated parts list with power system BOM
- Cost estimate now 06-230 (was 70-190)
- Added power-system.md, updated design-decisions.md

2026-05-12 06:02:51 +00:00

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Design Decisions

Build Approach

Wooden case with salvaged laptop lid (screen + hinge) as the canopy. Approximate briefcase dimensions, with the display panel setting minimum width and depth.

Salvage Exclusions

Webcam: Scrapped. Proprietary pinout, not worth reverse engineering.
Keyboard/trackpad: Proprietary connectors, not reusable.
RAM: DDR3L soldered, wrong generation.
SSD: Owner repurposed.
WiFi card: Intel 7265NGW needs M.2 E-key, OPi5 base lacks it.

Case Orientation & Nomenclature

User sits at the stern, facing the bow. Hinge axis runs port-to-starboard along the bow edge.

Base (wooden enclosure)

Term	Surface	Notes
Deck	Top	Keyboard, controls, SBC access
Keel	Bottom	Sits on table
Bow	Back edge (spine side)	Power input, heat exhaust, farthest from user
Stern	Front edge (lip side)	User-facing, keyboard near here
Port	Left (facing bow)
Starboard	Right (facing bow)

Canopy (laptop lid + screen)

Term	Surface
Canopy dorsal	Outside of lid
Canopy ventral	Screen side

Bow Wall Functions

Power input (USB-C for IP5389 board charging)
Exhaust fans blowing away from user
Heat management surface

Power System

IP5389 power bank board (preliminary). All-in-one: charging, BMS, USB-C PD output. See power-system.md for details.

Input Device

ThinkPad TrackPoint keyboard (specific model TBD based on availability). Chosen for built-in TrackPoint pointer and 15.6" deck space compatibility.

1.6 KiB Raw Blame History