Gradeability is not nameplate motor watts—it is what your hub can deliver after mass, crawl speed, SOC, and voltage sag take their cut. This guide shows how to calculate e-scooter gradeability under load and voltage sag before a commute ramp stalls you.
Benefits
- Treats total mass (rider + deck + cargo) as the load term in climb power P = m·g·sin(θ)·v.
- Applies SOC and voltage-efficiency derating so effective watts match half-battery hill behaviour.
- Compares 36 V vs. 48 V / 52 V sag curves on the same motor rating for tier upgrades.
How it works
- Enter total mass in kg and continuous motor watts—not peak ads.
- Set nominal voltage, SOC (%), and min climb speed (km/h); the model applies voltage sag under load.
- Read max grade (%) and effective motor power—slide SOC to see when gradeability collapses.
FAQ
How do I calculate e-scooter gradeability under load and voltage sag?
Start with climb power P = m·g·sin(θ)·v at your minimum hill speed. Effective motor watts ≈ rated W × (SOC/100) × voltage efficiency under sag. Solve for the steepest grade θ your effective watts can sustain—or use the interactive tool with your mass and voltage tier.
What counts as load in gradeability?
Total mass: rider, scooter, helmet, backpack, and winter gear. Every extra kilogram raises climb power for the same grade and speed. Overloaded decks hit hill limits sooner than the same motor with a lighter rider.
Why does voltage sag matter on hills?
Under high phase current, pack voltage drops below nominal. Controllers deliver fewer watts even when SOC looks acceptable. Sag hits 36 V packs harder than 48 V / 52 V at the same current—gradeability falls faster on low-voltage tiers.
Should I plan hills at 100 % SOC?
Plan at the SOC you actually hit on the ramp—often 40–70 % mid-commute. Gradeability at full charge overstates what you can climb on the return leg. Slide SOC in the calculator to your worst-case arrival charge.
Technical specifications
- Load: total mass (kg) in P = m·g·sin(θ)·v.
- Effective W ≈ motor W × (SOC/100) × voltage efficiency (sag model).
- Min climb speed (km/h) sets v in the power equation.
- Output: max grade (%) and climb power (W) at effective motor output.
- Related: e-scooter-hill-climb-grade-calculator, escooter-peak-amps, escooter-weight-limit.