THE TOOLS
BATTERY SIZING
Weight, gearing, kV, cells and pack IR → peak amps, sag and motor load. Live tuner plus a 3-car table.
GEARING
Motor pinion → spur → diff pinion → ring → wheel. Final drive, rollout, top speed and motor load.
HOW MUCH BATTERY?
How many cells in parallel so the pack doesn't sag at your ESC limit. Sag, % of burst rating and pack weight, with a cap bank comparison.
RIPPLE PACK
The caps at the ESC: ripple volts, amps per cap vs its rating, heat, and how many caps hit your target at 10, 20 or 40 kHz.
RIPPLE PAK
Phase current, duty and PWM in → a real orderable capacitor bank out, with heat, voltage margin and resonance checked.
SAG & RIPPLE SIMULATOR
Press play and watch a pass: pack volts, who supplies the amps (cells, parallel pack or cap bank) and the ripple at the ESC.
THE GUIDES
BURST PHYSICS
What really limits a motor in a 2 second pass: copper heat, saturation, magnet demagnetization, rotor speed, timing and windings.
RIPPLE PAK GUIDE
Size the capacitor bank your ESC actually needs — ripple current, ESR, heat per pass, and the bus resonance that makes more microfarads worse.
SAG: BATTERY FIRST
Why cap banks fade, how current splits by resistance, 2P/4P vs a cap bank, and how to measure your cell IR.
RIPPLE PACK BUILD GUIDE
The v2 polymer ripple board: parts, layout, soldering to the ESC leads, and why polymer beats film per gram.
GEARING GUIDE
Pinion, spur, ring and pinion: how the gears multiply, rollout and top speed, in pictures.
DRAG BATTERY SIZING GUIDE
Size a 132 ft drag pack by internal resistance and sag, not the label C rating.
WHERE IT STARTED
319 LB FOR 32 FT
The 2015 world-record puller: 319 lb pulled 32 ft. Everything on this site grew out of builds like this one.