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
This commit is contained in:
BarnacleBoy 2026-05-12 06:02:51 +00:00
parent a601bddd1a
commit db353ad2d1
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@ -13,8 +13,10 @@ A cyberdeck built from salvaged ASUS K501U laptop components and Orange Pi 5 SBC
- [x] USB expansion design
- [x] Case nomenclature and orientation defined
- [x] Build approach: wooden case + salvaged lid canopy
- [x] Input device: ThinkPad TrackPoint keyboard
- [x] Power system: IP5389 board + 18650 cells (preliminary)
- [ ] Case design (dimensions, internal layout)
- [ ] Power system (battery, charging)
- [ ] Power system board selection and testing
- [ ] Bow wall design (power input, fan exhaust)
- [ ] Fabrication
- [ ] Software configuration
@ -54,6 +56,7 @@ A cyberdeck built from salvaged ASUS K501U laptop components and Orange Pi 5 SBC
- [USB Expansion](docs/usb-expansion.md) - Hub selection and port allocation
- [Parts List](docs/parts-list.md) - Bill of materials with costs
- [Design Decisions](docs/design-decisions.md) - Build approach, nomenclature, layout
- [Power System](docs/power-system.md) - IP5389 battery management decision
## Quick Reference
@ -69,7 +72,7 @@ A cyberdeck built from salvaged ASUS K501U laptop components and Orange Pi 5 SBC
- **Board:** Orange Pi 5 (RK3588S, base model, 16GB RAM)
- **Storage:** MicroSD slot + USB 3.0 external
- **USB:** 1× USB 3.0, 2× USB 2.0 native
- **Power:** 12V 2A barrel or USB-C PD
- **Power:** USB-C PD via IP5389 power board, 18650 cells
### Cost Estimate
@ -77,8 +80,8 @@ A cyberdeck built from salvaged ASUS K501U laptop components and Orange Pi 5 SBC
|----------|------|
| SBC | ~$104 |
| Display controller | ~$24 |
| Storage (SD + hub + enclosure) | ~$35-50 |
| Power supply | ~$10 |
| **Subtotal** | **$170-190** |
| Storage (SD + hub + enclosure) | ~$32-44 |
| Power system (board + cells + fuse + charger) | ~$32-56 |
| **Subtotal** | **$206-230** |
(Excludes case materials, battery, misc hardware)
(Excludes case materials and misc hardware. Battery included in power system.)

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@ -36,6 +36,14 @@ User sits at the **stern**, facing the **bow**. Hinge axis runs port-to-starboar
### Bow Wall Functions
- Power input (barrel jack or USB-C PD)
- 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](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.

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@ -32,8 +32,10 @@
| Item | Specification | Source | Est. Cost | Status |
|------|--------------|--------|-----------|--------|
| Power supply | USB-C PD or 12V 2A | Amazon | $8-12 | To purchase |
| (Future) Battery | 10,000-20,000 mAh PD | TBD | $20-40 | Future |
| IP5389 power board | USB-C PD, 3S, bare PCB | AliExpress | $8-15 | Preliminary selection |
| 18650 cells | 3S or 3S2P, quality brand | User's pick | $12-24 | To purchase |
| 5A blade fuse + holder | Automotive | Amazon | $2 | To purchase |
| USB-C wall charger | 45W+ PD, for charging | Amazon | $10-15 | To purchase |
### Networking
@ -62,24 +64,24 @@
| MicroSD | $12 |
| USB hub | $20 |
| USB enclosure | $12 |
| Power supply | $10 |
| Power system (board+cells+fuse+charger) | $32-56 |
| WiFi dongle | $12 |
| **Subtotal** | **$194** |
| **Subtotal** | **$206-230** |
### With Optional Items
| Category | Cost |
|----------|------|
| Base build | $194 |
| Base build | $206-230 |
| Heatsink/cooling | $10 |
| Panel-mount cables | $15 |
| **Total** | **$219** |
| **Total** | **$231-255** |
### Future Additions
| Category | Cost |
|----------|------|
| Battery pack (portable) | $20-40 |
| Battery pack (portable) | Integrated in base build |
| Case materials | TBD |
| Custom PCB | TBD |
@ -96,7 +98,9 @@
- MicroSD card
- Powered USB hub
- USB enclosure or flash drive
- Power supply
- IP5389 power board + 18650 cells
- 5A fuse + holder
- USB-C PD wall charger (45W+)
- WiFi dongle
---

79
docs/power-system.md Normal file
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@ -0,0 +1,79 @@
# Power System
## Decision: IP5389 Power Bank Board (Preliminary)
All-in-one power management PCB. Replaces separate charger module, BMS, and boost/buck converter with a single board.
## Why This Approach
| Requirement | IP5389 Solution |
|------------|-----------------|
| Charge lithium cells safely | Built-in CC/CV with cell balancing |
| Battery protection | Overcharge, overdischarge, short circuit, thermal |
| Output usable voltage | USB-C PD (5V, 9V, 12V, 15V, 20V) |
| Wall power input | USB-C input from any charger |
| Charge while using | Passthrough charging |
| Repairable | Bare PCB, cells are replaceable 18650s |
## How It Works
```
USB-C wall charger → IP5389 board → 18650 cells (3S or 3S2P)
↓ (passthrough)
USB-C PD output → OPi5 (5V) + peripherals
```
One board, one cell pack, one output cable to the SBC. No separate modules to wire together.
## Key Specs (varies by specific board)
- Cell config: 3S6S (most common: 3S or 4S)
- Output: 45W100W USB-C PD
- Input: USB-C (bidirectional port)
- Protection: overcharge, overdischarge, short circuit, thermal
- Price: $815 bare PCB
## Cell Configuration
TBD — need to select specific board first. Likely 3S (3 cells in series) or 3S2P (6 cells, pairs in series). 3S2P with quality 3000mAh cells gives ~6000mAh at 11.1V nominal.
## Salvaged Battery: Not Usable
K501U battery (B31N1429, 4240mAh, 11.4V, 3S) assessed and rejected:
- Integrated BMS is paired to the laptop mainboard
- Most laptop BMS boards lock when removed from their system
- Not worth the effort to hack around
- Low capacity (4240mAh) doesn't justify the risk
## Alternative Approaches Considered
### Discrete Module Stack (TP5100 + 2S BMS + Buck Converter)
- Three separate modules, more wiring
- TP5100 charger (2S, 2A) + 2S 10A BMS + 5V/4A buck converter
- ~$10 in modules, works well but more complex assembly
- Backup plan if IP5389 board has issues
### Commercial Power Bank (decased)
- Buy a power bank, remove plastic shell, integrate bare PCB + cells
- Zero design work but constrained to whatever cell layout the bank uses
- Passthrough charging not guaranteed on all models
### UPS HAT (Waveshare / DFRobot)
- Designed for Raspberry Pi, works via USB output with OPi5
- Premium price for unused GPIO header
- Capped at 5V output, no 12V rail without extra boost converter
## Safety Notes
- Always use 18650 cells with matching capacity and age in parallel pairs
- Fuse between board output and SBC (5A automotive blade fuse recommended)
- No puffy, warm-at-rest, or sub-2.5V cells — ever
- Match cell count to board specs (3S board = exactly 3S, don't mix)
## TODO
- [ ] Select specific IP5389 board model with verified reviews
- [ ] Confirm cell count (3S vs 3S2P)
- [ ] Verify passthrough charging on selected board
- [ ] Order board + cells
- [ ] Test charging and output before case integration