Ebike Motor: Should You Choose a 48-Volt or 36-Volt System?

Energy is basically what mainly enables mankind to transform the world on a large scale, although other factors like knowledge play a decisive role too. We could label the last two centuries, from the starting of the industrial revolution onwards, as the fossil fuel age. Even though fossil fuel availability will remain paramount for the next couple of decades at least, we are progressively although slowly transitioning to the electric age. For instance, electric cars market share in China YoY (2025 over 2024) growth is +28.2%, with a penetration gain of +7.0 percentage points (40.9% → 47.9%). That makes more than 16 million EV sold in China in 2025 alone. In Norway, EV market share is 98%. In Ethiopia, internal combustion cars sales are now banned. Of course, ebikes have a good slice of the electric mobility pie. It is interesting delving into some basics of electric motors, like the relevance of their voltage.

What role does the voltage of ebike motors play?

Up to 2010, many ebike manufacturers offered 26-volt motors. Now they’ve all shifted to 36-volt motors, with a growing number of them opting for 48-volt motors. Even the voltage of electric cars motors keeps on growing, the most powerful ones sporting more than 1000-volt. Let’s analyse the stakes of electric motor voltage.

Volts and amperes, the two forces of electric motors

The power of electric motors is normally expressed in watts. One kilowatt corresponds to 1,34 electric HP. An electric car with a 100-kilowatt motor delivers the same power as an internal combustion car with 134 HP.

One can calculate the power of an electric motor, or the capacity of a battery, by multiplying its amperes for its volts. For instance, a 36-volt motor with 10 amperes delivers 360 Watts. A battery with the same specifications would have at 360 Wh capacity.

In electric motors, torque is directly proportional to current (amperes), whereas speed (RPM, rotations per minute) is directly proportional to voltage. Torque is the sheer power, it is not strictly correlated to the speed (RPM) of the motor. For instance, a tractor engine turning at 2000 RPM delivers more torque than a Ferrari engine turning at 6000 RPM.

Let me break it down.

Why current (amperes) controls torque

Inside an electric motor, torque is generated by magnetic fields pushing against each other. When you feed more current (amps) into the motor’s copper coils, it creates a stronger electromagnet. The stronger the magnetic field, the harder the motor pushes, resulting in more torque.

Why voltage controls speed

Voltage is the “electrical pressure” pushing the current through the wires. Every motor has a specific “Velocity Constant” ($K_v$), which dictates how fast it will spin per volt applied. For example, if a motor has a $K_v$ of 10 RPM per volt, applying 36V will make it spin at 360 RPM, and applying 48V will make it spin at 480 RPM.

• Torque is set by current; voltage mainly sets achievable speed and power headroom.
• For the same Wh battery, range is similar; 48 V can do better under high current demands.

Short answer: voltage mostly sets speed/power headroom; current sets torque.

How this applies to ebikes

In the European Union, since legal power limit for ebikes is 250 W, manufacturers increased the power of motors in two ways: enabling them to deliver both more torque, and to deliver up to 1500 W of peak power. In order to respect legal limits, the electric assistance is always limited to 25 km/h, so the basic power of a 36 V, 250W / European Ebike always results from 36V multiplied by 6.95 amperes, or 48V multiplied by 5.25 amperes.

The difference is in the peak power, which is delivered only when the conditions demand it, for instance, when you are pushing on the pedals on a steep climb, or carrying a heavy load.

 

Ebike motors comparison: 36-volt versus 48-volt

Depending on each e bike features and usage, more or less voltage could be preferable.

Compared to a 36-volt electric motor, a 48-volt electric motor offers several distinct advantages and a few disadvantages, primarily related to power delivery, efficiency, and system cost.

Breakdown of how 36-volt and 48-volt compare

Key differences (assuming similar motor design and same overall power/energy goals):

Advantages of 48 V

• Lower current for the same power, so thinner wires/connectors, less I²R loss, less heat.
• Better efficiency under heavy load; less voltage sag, typically a bit more range at high loads.
• Higher potential top speed (with suitable windings/controller).
• Allows higher power within the same controller current limit.
• Cooler running for controller and cabling; improved reliability.

Disadvantages of 48 V

• Requires 48 V-specific battery, charger, and controller (less interchangeability with 36 V systems).
• Slightly higher cost/complexity (more cells in series, higher-voltage BMS/charger).
• Increased arcing risk on connectors and stricter component voltage ratings.
• Marginally higher shock risk versus 36 V.
• If power/speed must be limited (legal/usage), benefits may be minimal over 36 V.

36 V pros

• Usually cheaper, more common on entry-level bikes.
• Lower voltage simplifies component ratings; slightly safer to handle.

36 V cons

• Higher current for same power: thicker wiring, more heat, more sag under load.
• Lower top speed/power ceiling with typical controllers.

Torque is set by current; voltage mainly sets achievable speed and power headroom.

For the same Wh battery, range is similar; 48 V can do better under high current demands.

Summary If you prioritize range, light weight, affordability, and a smooth, casual ride, a 36V system is often perfectly sufficient. However, if you need higher speeds, better hill-climbing capabilities, or are moving heavier loads, the 48V system is the clear winner due to its superior power and thermal efficiency.

A practical, meaningful example

To better understand the role played by volts and amperes, let’s compare 2 popular German motors, both 36 Volt:

• The Bosch Performance Line SX à 60Nm  600 W peak power
• The Performance Line CX GEN 4 à 85Nm, 600 W peak power

Now, why the the Bosch Performance Line CX GEN 4 offers 85Nm of torque, whereas the Bosch Performance Line SX offers only 60Nm? That is because the former is conceived to reach its 600 Watt peak power through increased amperes, what boosts its torque, while the latter reaches this same peak power increasing its voltage, what let torque unchanged. Indeed, you will not find a cargo ebike equipped with the SX, which is more indicated for lighter ebikes.

Here are popular ebikes that commonly use 48 V systems, with example models:

In Europe, because of the 25 kilometres per hour speed limit, 36-volt motors are much more common, with the following exceptions, all with high peak power and torque:

• Giant SyncDrive Pro 3, 90 Nm
• BAFANG GTV Technology 2-Speed Automatic, 80Nm
• ZF Centrix 90, 105 NM
• Brose  Drive 3 Peak, 100 Nm
• Yamaha PW-X4, 100 Nm

In the USA, where ebikes are allowed to ride at at least 20 mph, 48 Volt is more common:

• Rad Power Bikes: RadRover 6 Plus, RadCity 5 Plus, RadRunner 2/3, RadExpand 5, RadWagon 4
• Aventon: Aventure.2, Level.2, Pace 500.3, Soltera.2
• Lectric: XP 3.0 (step-over/step-thru), XPedition, XPeak, XP Trike
• Ride1Up: Core-5, 700 Series, LMT’D, Turris, Cafe Cruiser, Rift (Prodigy mid-drive is 36 V)
• Himiway: Cruiser, Zebra, Escape, Big Dog, Cobra
• Super73: S2, ZX, Z Miami (48 V nominal packs)
• Pedego: Interceptor, City Commuter, Element (many Pedego models are 48 V)
• Magnum: Metro, Pathfinder, Peak series (varies by year)
• Surface 604: Rook, Colt, Shred, Twist, Boar
• Velotric: Discover 2, Nomad 1
• QuietKat: Ranger, Warrior (many models use 48 V)
• Biktrix: Stunner LT, Hub Duo variants (others may be 52 V—check specs)
• Many bikes using Bafang M600/M620 (Ultra) mid-drives are 48 V (e.g., Frey, Watt Wagons, some Biktrix builds).

Torque of electric motors depend more on current/amperes than on voltage, yet…

48V e-bikes often feel like they have more torque. If torque depends on amps, you might wonder why upgrading from a 36V to a 48V system usually results in better hill-climbing and acceleration. It comes down to Total Power (Watts) and how motor controllers work.

Power = volts × amps: An e-bike’s motor controller limits the maximum number of amps the system can use to prevent overheating. Let’s say both a 36V bike and a 48V bike have controllers limited to 20 Amps.

• • 36V System: 36-volt × 20 Amps = 720 Watts of peak power.
  • 48V System: 48-volt × 20 Amps = 960 Watts of peak power.

Even though the maximum current (and therefore the absolute peak torque off the starting line) might be similar if the controllers have the same amperes limit, the 48V system has vastly more total power.

More importantly, as an electric motor spins faster, it generates “Back EMF” (a force that resists the incoming voltage). A 36V system will lose its ability to push high amperes into the motor at a much lower speed than a 48V system. The 48V system has enough “pressure” (voltage) to keep pushing those high amps into the motor even as the bike speeds up, meaning it can maintain its torque at higher speeds, making it much better at climbing hills without bogging down.

In the end, what should we choose?

The above indications can be useful, although what makes the most difference is the way a motor is engineered, i.e. the quality and balance of its hardware and software. For instance, according to what we wrote above, one with the expect the most powerful ebike motor (legal in the EU) to be 48-volt. Instead, the Avinox M2S delivers 1,500W peak power and 150 Nm with only 36-volt.

Images: Giant NV, Brose GmbH, ZF GmbH