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.
Load is mass on the deck
Gradeability starts with how many kilograms you ask the motor to lift uphill at crawl speed. To calculate e-scooter gradeability under load and voltage sag, keep mass honest—rider plus scooter plus daily cargo—not brochure rider weight. A 10 kg bag can erase a grade point on a 500 W commuter hub.
Voltage sag shrinks effective watts
Nominal 36 / 48 / 52 V labels are not what the pack holds under hill current. SOC and sag together reduce voltage efficiency in the model—mirroring why the same ramp feels fine at 80 % SOC and impossible at 25 %. Compare voltage tiers at identical mass and motor watts to see tier upgrades that buy hill margin.
From gradeability to route planning
Once max grade is bracketed at your realistic SOC, map known ramp percentages on the commute against the result. Pair with peak-amps and weight-limit tools so load and burst current stay inside controller and BMS limits—gradeability math fails in the real world if thermal cutbacks kick in mid-climb.