I've now thoroughly reviewed both PDFs. Let me give you a clear summary.
Yes, both USB charging and battery protection are already covered in your battery architecture — they're part of the self-contained battery pack design you've been developing. Here's the breakdown:
The battery pack includes a full USB-C PD charging system built into the electronics bay at the bottom of the scaffold: ppl-ai-file-upload.s3.amazonaws
- USB-C panel-mount port (IP67, on the side of the battery end cap)
- PD trigger board (ZY12PDN or STUSB4531, ~31×15×4mm) — negotiates 20V from any charger 45W–240W automatically
- Boost converter (XL6019, 20V→42V CC/CV) — steps up to pack charge voltage
- Total electronics fit in ~60×45×25mm, tucked into the electronics bay
The key design point: all electronics live on the battery, not in the frame. You pull the battery out, plug your MacBook charger into the USB-C port on the side, charge on the kitchen table. The frame side is 100% passive — just flat copper pads. ppl-ai-file-upload.s3.amazonaws
A 10S BMS is included in the electronics bay, handling: ppl-ai-file-upload.s3.amazonaws
- Overcurrent, overvoltage, undervoltage protection
- Short-circuit and temperature cutoff
- Cell balancing during charge
- Per-cell fusing was deliberately skipped — at 3.5A per cell in 2P, the BMS alone handles everything adequately
The connector design settled on an elevated pad island + recessed pogo pin dock approach: ppl-ai-file-upload.s3.amazonaws
- Frame side: Elevated flat gold pads on a raised "speed bump" — water sheets off, no pooling
- Battery side: 6-pin pogo block recessed deep inside a dock cavity — finger-safe by geometry (IP2X-style)
- 2 power pins + signal/thermistor/comm pins
Your notes confirm the DT dimensions are not locked down yet, and you've been exploring both round and oval options: ppl-ai-file-upload.s3.amazonaws
| Discussed Size | Context |
|---|---|
| 50mm round | Original spec for 2×2 grid of 21700 cells |
| 55–60mm | Referenced for fitting 21700s with BMS/wiring room |
| 43×59mm oval | The 1-2-1 diamond layout (narrower, taller) |
| ~50×65 (your current thinking) | Wider than the diamond, gives more lateral room |
The 50×65 oval gives you more cross-sectional area than the 43×59 diamond and better lateral stiffness for pedaling loads. The tall axis (65mm) resists braking/vertical loads while the narrow axis (50mm) keeps the frame slim between your knees. Since you're building in aluminum (not steel), you have freedom to specify custom oval tubing from the fabricator. ppl-ai-file-upload.s3.amazonaws
The scaffold cage parameters (currently cagew = 53, cageh = 48 in the OpenSCAD file) would need updating to match whatever oval you settle on. With a 50×65 outer and ~2mm wall, you'd have roughly 46×61mm inner bore — plenty of room for the 2×2 cell grid (~43×43mm footprint) plus wiring channel and air gaps. ppl-ai-file-upload.s3.amazonaws
Bottom line: your electronics stack is already specced and costed at $22–38 total for BMS + USB-C PD + boost converter. The DT oval just needs to be finalized around whatever gives comfortable clearance for the scaffold + 1mm air gap on each side. ppl-ai-file-upload.s3.amazonaws
Using a spare pogo for the antenna feed is a good idea and works electrically.
Using a pogo pin as RF feed
A thin coax from the GPS/BLE module ends at the battery-side pogo pad (center conductor to pad, shield to local ground plane).
The matching frame-side pogo pin connects down to the antenna element mounted in your small plastic console (lock + USB-C piece that already protrudes from the alu).[ppl-ai-file-upload.s3.amazonaws]
Electrically it’s just a single RF feed-through contact. Pogo contact resistance is low enough at GNSS/BLE power levels, and RF sees it as a short line segment.
So your 4+1 pins become:
Antenna in the plastic console
That console is:
Plastic, protruding from the alu = perfect RF window.
“Size of 3 nickels in a row” = ~60×20mm → huge for a small chip or flex antenna.
Fixed to the frame; the pogo just brings RF up to it, so the antenna never moves.
Mount a tiny chip or flex antenna on the inside face of that console, as close to the outside surface as possible. The pogo-fed trace from the pin to the antenna is only a few cm, easy to keep 50Ω-ish on a tiny PCB.
Why this is nice
No extra frame holes — the console already exists in your design.
Antenna sits in plastic, outside the alu Faraday cage.
Only one extra pogo used; connector stays compact.
GPS and BLE both handled by the same combined antenna, through that one feed line.
This is a very clean integration.
Using a pogo pin as RF feed
So your 4+1 pins become:
Antenna in the plastic console
That console is:
Mount a tiny chip or flex antenna on the inside face of that console, as close to the outside surface as possible. The pogo-fed trace from the pin to the antenna is only a few cm, easy to keep 50Ω-ish on a tiny PCB.
Why this is nice
This is a very clean integration.