From 384917e12e9d4ead045621ff84087f7cc7c6e590 Mon Sep 17 00:00:00 2001 From: BarnacleBoy Date: Mon, 1 Jun 2026 00:42:39 +0000 Subject: [PATCH] power system research: IP5389 series config, 3S2P cells, power budget, audio amp, display controller power --- README.md | 2 +- docs/parts-list.md | 22 +++++++++++---- docs/power-system.md | 65 +++++++++++++++++++++++++++++++------------- 3 files changed, 63 insertions(+), 26 deletions(-) diff --git a/README.md b/README.md index 68289ce..c6d96e9 100644 --- a/README.md +++ b/README.md @@ -16,7 +16,7 @@ A cyberdeck built from salvaged ASUS K501U laptop components and Orange Pi 3B SB - [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 +- [x] Power system: IP5389 board + 3S2P 18650 cells - [x] Video output: mechanical HDMI A/B switch - [x] Port layout defined (10 ports + SD reader + Kensington) - [ ] ~~Case design~~ (postponed — board bring-up first) diff --git a/docs/parts-list.md b/docs/parts-list.md index a30dcbd..96a5e51 100644 --- a/docs/parts-list.md +++ b/docs/parts-list.md @@ -31,10 +31,17 @@ | Item | Specification | Source | Est. Cost | Status | |------|--------------|--------|-----------|--------| -| 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 | +| IP5389 power board | USB-C PD, 3S, bare PCB | AliExpress | $8-15 | Board model TBD | +| 18650 cells (x6) | 3S2P, matched, 2500-3500mAh | Shopping | $12-30 | To purchase | | 5A blade fuse + holder | Automotive | Amazon | $2 | To purchase | +### Audio + +| Item | Specification | Source | Est. Cost | Status | +|------|--------------|--------|-----------|--------| +| PAM8403 amp module | 3W+3W, 5V, Class D | Amazon | $3-5 | To purchase | +| 4Ω 3W speakers (x2) | Small drivers, ~31×70mm | Amazon | $5-10 | To purchase | + ### Networking | Item | Specification | Source | Est. Cost | Status | @@ -74,18 +81,19 @@ |----------|------| | Storage (USB enclosure) | ~$12 | | USB hub (powered 10-port) | ~$22 | -| Power system (board+cells+fuse+charger) | ~$44 | +| Power system (board+cells+fuse) | ~$32 | +| Audio (PAM8403 amp + speakers) | ~$10 | | HDMI switch | ~$10 | | Panel-mount cables + SD reader | ~$23 | -| **Remaining** | **~$100** | +| **Remaining** | **~$110** | ### Total Project | | | |---|----| | Spent | $213 | -| Remaining | ~$111 | -| **Estimated total** | **~$313** | +| Remaining | ~$110 | +| **Estimated total** | **~$323** | --- @@ -106,6 +114,8 @@ - Panel-mount cables (USB-A, USB-C, HDMI, Ethernet, audio) - Panel-mount SD card reader - Heatsink for RK3566 +- PAM8403 audio amp module +- 4Ω 3W speakers (x2) --- diff --git a/docs/power-system.md b/docs/power-system.md index 1cf07d4..f7bd5c2 100644 --- a/docs/power-system.md +++ b/docs/power-system.md @@ -17,34 +17,56 @@ All-in-one power management PCB. Replaces separate charger module, BMS, and boos ## How It Works +The IP5389 uses cells in **series** (2S to 5S), not parallel. A synchronous buck-boost converter handles all voltage conversion in one IC with a single inductor. + ``` -USB-C wall charger → IP5389 board → 18650 cells (3S or 3S2P) - ↓ (passthrough) - USB-C PD output → OPi3B (5V) + peripherals +USB-C wall charger → IP5389 board → 18650 cells (3S2P configuration) + ↓ + USB-C PD output → OPi3B (default 5V) + USB-A output → Display controller (5V via micro USB) + 5V rail → USB hub, audio amp, fans ``` -One board, one cell pack, one output cable to the SBC. No separate modules to wire together. +One board, one cell pack, one inductor. No separate charger, BMS, or boost modules needed. -## Key Specs (varies by specific board) +### Why Series, Not Parallel -- Cell config: 3S–6S (most common: 3S or 4S) -- Output: 45W–100W USB-C PD -- Input: USB-C (bidirectional port) -- Protection: overcharge, overdischarge, short circuit, thermal -- Price: $8–15 bare PCB +| Config | Voltage range | Regulator mode | Efficiency | +|--------|--------------|----------------|------------| +| Parallel (1SxP) | 3.0–4.2V | Must **boost** to 5V | ~85-90% | +| 3S (series) | 9.0–12.6V | **Bucks** down to 5V | **Up to 97%** | -## OPi3B Power Context +With a 3S pack, battery voltage never drops below 9V even at cutoff. The regulator is always stepping down — the easy, efficient direction. The IP5389's synchronous buck-boost handles 3.0V–21V input range and can output 5V/9V/12V/15V/20V via PD negotiation. -The Orange Pi 3B draws ~3-5W under load (vs OPi5's ~8W), which simplifies the battery system: +## Power Budget -- Lower peak current means the IP5389 board doesn't need to push its limits -- A smaller cell pack (3S vs 3S2P) may suffice -- Less heat generated, less thermal management needed -- The OPi3B's 5V/3A input spec is well within what a USB-C PD board can provide +Updated estimates with all components known: + +| Component | Voltage | Current (est.) | Power (est.) | Source | +|-----------|---------|----------------|-------------|--------| +| Orange Pi 3B | 5V | 2-3A | 10-15W | USB-C from IP5389 | +| Display + controller | 5V | 2A | 10W | Micro USB from IP5389 or 5V rail | +| USB hub (powered) | 5V | 2-3A | 10-15W | 5V rail via barrel adapter | +| Audio amp (PAM8403) | 5V | 0.3A | 1.5W | 5V rail direct | +| Cooling fans (x2) | 5V | 0.2A | 1W | 5V rail or GPIO | +| **Typical total** | **5V** | **~3-4A** | **~14-20W** | | +| **Peak total** | **5V** | **~7-8A** | **~35-40W** | | + +Note: Display controller and OPi 3B can share the IP5389's USB ports (USB-C + USB-A). The hub, amp, and fans tap the 5V distribution rail with a simple barrel-jack breakout. ## 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. +**Decision: 3S2P** — 6 cells total, two parallel strings of three series cells. + +| Config | Cells | Weight (50g ea) | Energy (2500mAh cells) | Energy (3500mAh cells) | Est. runtime (~14W) | +|--------|-------|-----------------|----------------------|----------------------|---------------------| +| 3S1P | 3 | ~150g | 27.75 Wh | 38.85 Wh | ~2-2.5 hr | +| **3S2P** | **6** | **~300g** | **55.5 Wh** | **77.7 Wh** | **~4-5.5 hr** | +| 3S4P | 12 | ~600g | 111 Wh | 155.4 Wh | ~8-11 hr | + +**3S2P** (~300g, 55.5 Wh with standard cells) is the pick. Matches a typical laptop battery capacity. With quality 3500mAh cells (Samsung 35E, LG MJ1, or equivalent), the pack delivers **77.7 Wh** — enough for a full café session without recharging. + +**Important:** Cells in the same parallel group must be matched (same model, age, capacity). Label and pair them during assembly. Never mix old and new cells in the same pack. ## Salvaged Battery: Not Usable @@ -74,15 +96,20 @@ K501U battery (B31N1429, 4240mAh, 11.4V, 3S) assessed and rejected: ## Safety Notes +- Cells in a parallel group must be matched (same model, age, capacity). Mixing old and new is a fire risk. - 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) +- IP5389 modules vary in quality — buy from reputable sellers, check reviews for "clone" ICs ## TODO +- [x] Cell configuration: 3S2P (6 cells, ~300g) - [ ] Select specific IP5389 board model with verified reviews -- [ ] Confirm cell count (3S vs 3S2P) +- [ ] Source matched 18650 cells (Samsung 35E, LG MJ1, or equivalent) - [ ] Verify passthrough charging on selected board -- [ ] Order board + cells +- [ ] Select PAM8403 audio amp module + small 4Ω speakers +- [ ] Select powered USB hub with 5V DC barrel input (not AC wall wart) +- [ ] Order board + cells + amp + hub - [ ] Test charging and output before case integration