Molicel P42A 21700 Cell 4200mAh 45A Li-ion INR for E-Bikes & E-Motorcycles

The Molicel P42A is a high-drain 21700 lithium-ion cell built for e-bike, e-scooter and e-motorcycle battery packs. It delivers a typical capacity of 4200 mAh at a nominal voltage of 3,6 V. Discharge current reaches 45 A, which suits controllers that pull heavy loads.

This cell uses Li-ion INR chemistry with a flat top contact. It ships unprotected, so there is no PCB on the cell itself. Every pack built from these cells requires a BMS (battery management system) for safe operation.

A single cell is not a finished battery. Instead, cells are joined in series and parallel to reach the voltage and capacity your project needs. Therefore the P42A is intended for pack building rather than direct use in a device without control electronics. Pack builders, power modders and technical enthusiasts choose it when energy density and current output matter equally.

Key Benefits

• 4200 mAh typical capacity – a per-cell figure that lets you assemble a high-energy pack with fewer cells.
• Discharge current up to 45 A – headroom for power modifications and strong controllers.
• Continuous discharge around 30-35 A – real limits depend on your BMS, cooling and manufacturer guidance.
• Li-ion INR chemistry – a balanced mix of energy density, safety and cycle life.
• 21700 format – higher energy density than 18650 cells in a comparable build.
• Nominal voltage 3,6 V – the standard value for calculating series strings with a BMS.
• Flat top contact – suited to spot welding with nickel or copper strips.
• Made by Molicel – cells are produced by E-One Moli Energy, a lithium-ion cell manufacturer.

Who Is This Cell For?

The Molicel P42A 21700 cell is aimed at electric bicycles (e-bikes), electric scooters (e-scooters) and electric motorcycles (e-motorcycles). It also fits other projects that run on a 3,6 V nominal cell voltage and use a BMS.

Battery pack manufacturers rely on it for builds where the controller draws large currents. Technical enthusiasts pick it for the same reason. In addition, it works with a single-cell charging and management module, provided that module includes the required protections.

Typical scenarios include assembling a new pack, refreshing an aging pack, or increasing available power. Because the 21700 format packs more energy into the same volume, builders often select it in place of 18650 cells.

Technical Specifications

Handling Notes

• A BMS with overvoltage, low-voltage, current and short-circuit protection is mandatory.
• Spot welding with nickel or copper strips is the recommended joining method.
• Avoid overheating during soldering, since heat damages the internal structure of the cell.
• Never use damaged cells.
• Charge only with Li-ion chargers that match the stated specification.

Why Choose the Molicel P42A?

The core difference is 4200 mAh paired with a high current rating. Many large-capacity cells give up current output to reach that capacity. The P42A datasheet figure, however, reaches 45 A, so the cell serves both energy-focused and power-focused builds.

The 21700 format also improves energy density compared with 18650. As a result, a given pack needs fewer cells and fewer interconnections. That shortens assembly time and reduces the number of weld points across the build.

INR chemistry holds a stable cycle count under high current draw. Furthermore, the 3,6 V nominal figure matches common e-mobility pack configurations, which keeps series-string calculations straightforward.

Frequently Asked Questions

Does the Molicel P42A have integrated protection (PCB)?

• No. This is an unprotected 21700 cell without an integrated protection board.
• It is used inside packs that include a BMS.
• The cell offers no short-circuit or over-discharge protection on its own.

Is the P42A suitable for e-bike and e-scooter battery packs?

• Yes. It is intended for e-bike, e-scooter and e-motorcycle packs.
• Cells are joined in series and parallel to reach the target voltage and capacity.
• A BMS is required in every such pack.

Can I use it in an e-motorcycle build?

• Yes. E-motorcycle packs are among its listed applications.
• The 45 A rating supports controllers with high current draw.
• Plan cooling and BMS limits around the ~30-35 A continuous figure.

What is the real continuous discharge current?

• Around 30-35 A in practice.
• Actual limits depend on your BMS, cooling and manufacturer guidance.
• The 45 A value applies to short-duration draw.

How should these cells be connected?

• Spot welding with nickel or copper strips is recommended.
• Soldering risks overheating and internal damage.
• Series and parallel arrangement depends on your target voltage and capacity.

What are the charging limits?

• Maximum charging voltage is 4,20 V.
• Discharge cut-off voltage is 2,50 V.
• Use only Li-ion chargers that match this specification.

How does the 21700 compare with 18650 cells?

• The 21700 format offers higher energy density in the same volume.
• Fewer cells and fewer connections are needed per pack.
• Physical size here is 21,00 mm diameter by 70,00 mm height.

The Molicel P42A combines 4200 mAh of usable capacity with a 45 A rating in a flat top 21700 body. For e-bike, e-scooter and e-motorcycle packs assembled around a BMS, that pairing keeps cell counts low and current headroom generous.