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
The Dance bike uses an underside downtube mount with a removable battery that clicks in from below. Here's how that compares to your current topside/internal approach for Omera.[help.dance]
Underside vs Topside DT Battery
Why Dance Does It This Way
Dance is a subscription rental bike — their #1 priority is that users can pop the battery out in 2 seconds with no tools for charging indoors. The underside mount with a spring latch achieves that. They accept the dirt/impact trade-off because their fleet gets regular maintenance.reddit+1
Why Topside/Internal Is Better for Omera
Your design already commits to the battery inside the oversized oval DT, which gives you:
Best protection from Norwegian winter weather, road salt, and debris[leoguarbikes]
Stealth appearance — the bike looks like a normal fixie[upway]
Structural integration — the battery pack becomes part of the frame's mass, not a cantilevered load hanging off rails
Electronics co-location — the KT controller, Bikone interface, BT/GPS module, and battery all live in one sealed volume
The main downside is charging convenience. But you've already solved that with the pogo dock + side console approach — you charge in-frame or pop the console to access connectors. For a personal bike (not a rental fleet), that's perfectly fine.
One Hybrid Idea Worth Considering
If you ever want quick battery swaps (e.g., for long rides), you could design the DT with a bottom hatch — a CNC'd aluminum panel on the underside held by two quarter-turn fasteners. Battery slides out downward, same as Dance, but the hatch seals flush when closed. This gives you the protection of internal mounting plus the convenience of underside removal. But that's a v2 consideration — for v1, your current internal pogo-charge approach is cleaner and simpler.
Underside vs Topside DT Battery
Why Dance Does It This Way
Dance is a subscription rental bike — their #1 priority is that users can pop the battery out in 2 seconds with no tools for charging indoors. The underside mount with a spring latch achieves that. They accept the dirt/impact trade-off because their fleet gets regular maintenance. reddit
Why Topside/Internal Is Better for Omera
Your design already commits to the battery inside the oversized oval DT, which gives you:
The main downside is charging convenience. But you've already solved that with the pogo dock + side console approach — you charge in-frame or pop the console to access connectors. For a personal bike (not a rental fleet), that's perfectly fine.
One Hybrid Idea Worth Considering
If you ever want quick battery swaps (e.g., for long rides), you could design the DT with a bottom hatch — a CNC'd aluminum panel on the underside held by two quarter-turn fasteners. Battery slides out downward, same as Dance, but the hatch seals flush when closed. This gives you the protection of internal mounting plus the convenience of underside removal. But that's a v2 consideration — for v1, your current internal pogo-charge approach is cleaner and simpler.