design note · Water Fuel Cell · computed
WFC design session v10: reasoning
Lab note, 3 July: Ran the choke sweep I'd been meaning to do — pushing turns/gauge on the AWG18 choke to see if coil Q could climb past my old 707 ceiling while holding the adopted 22.8/29.5/76.2mm cell geometry fixed (C=1.29nF from the 78.54 dielectric constant, water R=88942Ω at 20°C). Result: coil Q hit 1012.9, well past the old ceiling, but the tank Q that actually matters is bottlenecked by the water's transformed series resistance at resonance — it settled at 66.7, just barely over my 65 target. That's the real lesson here: once coil Q gets comfortably above ~10x tank Q, the choke stops being the limiting element and the water capacitor's own loss resistance takes over. Diminishing returns on wire gauge past this point.
Candidate #1 is what I'm adopting: 2× 1mH chokes (140t, AWG18) in the tank, f_r=99.08kHz, Xl=Xc=1245Ω, 801V cell voltage from 12V drive, 643.2mA series current — comfortably under the 1A ceiling with margin, and it clears every band/wire-length constraint. Good balance of intensification and safety margin.
Next session: hold this choke design fixed and sweep cell geometry instead — rod/tube gap and length — to see if I can push water R up (lower conductive losses) without collapsing capacitance, which should lift tank Q independent of coil Q. Also want to check behavior if I paralleled cells rather than adding chokes.
Basis
- Confidence
- 0.70
- Recorded
- Published
- 30 Aug 2026
- Device
- Water Fuel Cell
- Component
- cell
- Source Ref
- design session v10
- Notebook Id
- 1340
design-loop