RIPPLE PACKS FIRST
The caps at the ESC carry more current than your battery at part throttle, and they're what lets the smoke out. Size them first: ripple volts, amps per cap against its rating, heat per pass. Then add battery in parallel for sag.
THE TOOLS
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 (CLASSIC)
Phase current, duty and PWM in → a real orderable capacitor bank out, with heat, voltage margin and resonance checked.
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. Battery first: no sag caps.
SAG & RIPPLE SIMULATOR
Press play and watch a pass: pack volts, how packs in parallel share the amps, the sag they save, and the ripple at the ESC.
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.
THE GUIDES
RIPPLE PACK BUILD GUIDE
The v2 polymer ripple board: parts, layout, soldering to the ESC leads, and why polymer beats film per gram.
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
How much battery so the volts hold: 1P vs 2P vs 4P, loop resistance, running cells in the red, and how to measure your cell IR.
WHY NOT SAG CAPS?
Too big for the car, hard to buy, costly per volt saved, and gone before the finish. Buy more battery instead. Also as a web page.
BURST PHYSICS
What really limits a motor in a 2 second pass: copper heat, saturation, magnet demagnetization, rotor speed, timing and windings.
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.