Battery Energy, Power and Runtime

Watt-hours describe stored energy; watts describe how quickly it is being used. Runtime depends on average demand and usable energy, so a peak-power figure or an Ah label alone cannot tell you how long a ride will last.

Energy, Runtime, and Range

Watt-hours define how much energy a battery stores, not how far the bike will travel.

Energy is calculated as:

• Voltage x Capacity = Watt-hours

A ~72V 45Ah pack:

• ~3240Wh

An ~84V 45Ah pack:

• ~3780Wh

A ~96V 45Ah pack:

• ~4320Wh

This is total stored energy.

However, stored energy is not the same as usable energy under load.

A portion of that energy is always lost as heat due to resistance throughout the system:

• cell internal resistance
• interconnect losses
• BMS losses
• wiring and connector losses

Higher current increases these losses.

Real-world runtime is always lower than theoretical capacity, and the gap increases as load increases.

Advertised capacity describes stored energy. It does not describe how efficiently that energy is delivered.

Energy vs Power

Energy determines how long the system can run.

Power determines how quickly that energy is used.

At higher power levels:

• energy is consumed faster
• losses increase due to higher current
• usable energy decreases due to heat

This is why high-power riding reduces both runtime and efficiency.

A battery does not just “drain faster” at higher power. It also becomes less efficient while doing so.

Runtime

Runtime is determined by average power draw, not peak power.

Example (72V ~3240Wh pack):

• 3000W average -> ~1 hour
• 1500W average -> ~2 hours
• 6000W average -> ~30 minutes

These are idealized values.

In practice:

• higher current increases losses
• voltage sag reduces usable output
• thermal behavior further reduces efficiency

As a result, actual runtime is always lower than calculated values, especially under sustained high load.

Real Power Usage

Actual riding power is highly variable.

Typical ranges:

• light cruising: 1500W to 3000W
• normal riding: 3000W to 6000W
• aggressive riding: 6000W to 10000W+

Short bursts may exceed these values, but sustained power is what determines runtime and thermal behavior.

Higher sustained power:

• reduces runtime
• increases heat
• amplifies system inefficiencies

Range Is Not a Battery Spec

Range is not determined by voltage or capacity alone.

It depends on:

• average power draw
• speed
• terrain
• rider weight
• aerodynamic drag
• throttle behavior

Two riders using the same battery can see significantly different range because they are using energy at different rates.

Range is a usage outcome, not a battery specification.

Voltage, Current, and Efficiency

Higher voltage systems:

• reduce current for the same power
• reduce resistive losses across the system
• improve efficiency under load

However:

• total stored energy still defines total runtime
• higher voltage does not increase runtime unless total watt-hours increase

Efficiency gains from higher voltage come from reduced current, not increased energy.

Poor system design can eliminate these gains entirely.

Load, Losses, and Usable Energy

As load increases:

• current increases
• resistive losses increase
• more energy is converted to heat instead of motion

This means:

• high-power riding consumes more energy
• and wastes more energy at the same time

Usable energy decreases as load increases.

This is why two identical batteries can produce different real-world range depending on how they are used.

Practical Interpretation

A battery does not provide a fixed distance.

It provides a fixed amount of energy, delivered with varying efficiency depending on load.

Higher power:

• increases energy consumption
• increases system losses
• reduces total usable output

Higher voltage:

• reduces current for the same power
• improves efficiency
• reduces loss per unit of power

But:

• energy is still finite
• and system design determines how efficiently that energy is delivered

The difference between a good pack and a poor one is not just how much energy it stores.

It is how much of that energy actually reaches the controller under load.

Battery Energy and Power

Understanding range requires separating stored energy from the rate at which that energy is consumed.

Battery Voltage

Voltage describes electrical potential.

Battery voltage influences how electrical power is delivered, but voltage alone does not establish total stored energy.

Amp-Hours

Amp-hours describe electrical charge capacity.

Amp-hours are useful when evaluating batteries operating at comparable voltages.

However, amp-hours alone are insufficient for comparing the energy capacity of batteries with different nominal voltages.

Watt-Hours and Kilowatt-Hours

Watt-hours measure energy.

A useful approximation is:

Wh = Nominal Voltage x Ah

Kilowatt-hours represent the same energy quantity on a larger scale.

1 kWh = 1,000 Wh

Higher stored energy generally provides greater range potential under comparable operating conditions.

Actual usable energy depends on the battery and its operating limits.

Power Output

Power describes the rate at which energy is transferred or consumed.

1 kW = 1,000 W

A higher-power system can consume stored energy more quickly when that additional power is used.

However, available peak power does not automatically mean the bike consumes more energy during every ride.

Practical Comparison

Why This Matters

Two ONYX configurations can have similar stored energy while producing different range results.

The difference may come from:

• Riding speed.
• Acceleration behavior.
• Controller tuning.
• Motor efficiency.
• Rider and cargo weight.
• Terrain.
• Weather.
• Mechanical resistance.

The battery determines how much energy is available.

The complete system and riding conditions determine how quickly that energy is consumed.