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
for the signal. we could make a small hole in the alu td. but I rather not make too much holes. just adds complexity to the build and water can get in etc. design becomes more messy. so. is there a way to solve this? issue mean yes its inside alu walls on all sides. but could we not make a powerful antenna or. just use a long wire as antenna? and pull it up ST into TT etc? or is making a hole in DT with a sort of sandwich rounded clip antenna bit that has a wire that we can connect. it won't be easy. so is there a way to think about this that we have not thought about. we already have drain with sandwiched rubber thing. and usbc weather proof. and keylock for bat. I guess maybe we could cheat a bit and add a screw to the all frame. like where riders sometimes have a bottle holder. in the ST. we could mount an antenna there. a stealth solution. it would look like a big screen. when screwed in it would connect to the wire and the wire could plug into BT /GPS