Molicel P45B 21700
4500mAh / 45A
Ultra-high-power 4.5Ah 21700 lithium-ion cell engineered for demanding applications that need both high current and strong energy density.
Molicel 21700 P45B 4500mAh 45A Battery
The Molicel P45B is a low-impedance 21700 power cell built for high-drain applications where a standard energy cell would experience too much voltage sag or heat rise. It improves on the classic 21700 power-cell category by pairing a 4500mAh typical capacity with a 45A continuous discharge rating and high fast-charge capability.
The 45A continuous discharge rating is specified with an 80°C cut-off, and the 13.5A maximum charge current is specified with a 70°C cut-off. Final pack current should be validated under the actual cooling, enclosure, busbar, BMS, and load conditions.
| Brand / Model | Molicel INR-21700-P45B |
|---|---|
| Cell Series | Molicel low-impedance power cell |
| Cell Type | 21700 cylindrical lithium-ion rechargeable cell |
| Typical Capacity | 4500mAh / 16.2Wh |
| Minimum Capacity | 4300mAh / 15.5Wh |
| Nominal Voltage | 3.6V |
| Charge Voltage | 4.20V |
| Discharge Cut-Off Voltage | 2.50V |
| Standard Charge Current | 4.5A |
| Maximum Charge Current | 13.5A with 70°C cut-off Thermal control required |
| Standard Charge Time | 1.5 hours |
| Continuous Discharge Current | 45A with 80°C cut-off |
| Typical Impedance | 7mΩ AC at 30% SOC; 15mΩ DC at 50% SOC |
| Charge Temperature | 0°C to 60°C |
| Discharge Temperature | -40°C to 60°C |
| Energy Density | 643Wh/L volumetric; 242Wh/kg gravimetric |
| Dimensions | 21.55mm max diameter × 70.15mm max height |
| Weight | 70g max |
| Protection | No — unprotected flat-top cell |
Electrical operating envelope at a glance.
These quick-reference visuals summarize the P45B’s current capability, voltage window, energy translation, and C-rate interpretation.
1. Current Capability Stack
Key current reference points for standard charge, maximum charge, data-sheet discharge curves, and continuous discharge rating.
2. Voltage Operating Window
Basic per-cell voltage limits used for charger, BMS, and pack design.
3. Capacity and Energy Translation
The data sheet lists 16.2Wh typical energy; nominal-voltage math gives a close planning estimate.
4. C-Rate Conversion
For a 4500mAh cell, 1C equals approximately 4.5A.
| 0.9A | ≈0.2C low-rate reference |
|---|---|
| 4.5A | 1C standard charge and cycle reference |
| 10A | ≈2.2C cycle / discharge reference |
| 13.5A | 3C maximum charge current with thermal cut-off |
| 30A | ≈6.7C high-rate discharge curve reference |
| 45A | 10C continuous discharge rating with 80°C cut-off |
High-current output should be evaluated with voltage sag, heat rise, and pack resistance in mind.
The P45B data sheet includes discharge-rate curves at 0.2C, 1C, 10A, 20A, 30A, and 45A. The cell is rated for 45A continuous discharge, but the highest-current condition uses an 80°C thermal cut-off, so pack design must manage heat as much as current.
The simplified discharge-curve graph below visualizes voltage versus delivered capacity under light, medium, high, and maximum-current conditions. It is not a digitized manufacturer graph; it is a product-page visualization designed to explain voltage sag and cutoff-limited capacity at higher current.
Discharge-rate references
| 0.2C / 1C | Low-rate and 1C curves shown in the data sheet |
|---|---|
| 10A / 20A | Medium-load discharge curve references |
| 30A | High-load data-sheet curve reference |
| 45A | Maximum continuous discharge curve reference with thermal cut-off condition |
| Design takeaway | For high-current packs, validate voltage sag and cell temperature under the actual enclosure, BMS, weld, and busbar design. |
5. Simplified Discharge-Curve Graph
Voltage vs. capacity illustration for 4.5A, 20A, 30A, and 45A operation. Simplified for product-page visualization.
6. Estimated IR Voltage Drop
Planning reference using Molicel’s typical AC and DC impedance values. Real pack sag includes cells plus interconnects.
Charge, discharge, and thermal behavior should be treated as one system.
Molicel’s data sheet includes charge curves, discharge-rate curves, discharge-temperature curves, and cycle-characteristics curves. These visuals are condensed into customer-friendly diagrams below.
7. Charge Profile Reference
Standard charge: 4.5A to 4.2V with 50mA cut-off. The data sheet also shows 2C and 3C charge characteristics.
8. Thermal Operating Envelope
Published charge and discharge temperature ranges.
9. Discharge Rate Characterization
Customer-friendly summary of the data-sheet discharge-rate curve families.
10. Discharge Temperature Characterization
The data sheet charts 4.5A discharge behavior from -40°C through 60°C.
11. Cycle-Life Visualization
Data-sheet cycle characteristics are shown for 4.5A, 10A, and 100W discharge at 23°C.
12. Energy Density Summary
Data-sheet energy density values for design comparison.
| Typical Energy | 16.2Wh |
|---|---|
| Minimum Energy | 15.5Wh |
| Volumetric Energy Density | 643Wh/L |
| Gravimetric Energy Density | 242Wh/kg |
| Design implication | Strong energy for a high-power 21700, with low impedance and fast-charge support. |
21700 dimensional envelope for holders, sleds, weld fixtures, and pack CAD.
13. Cell Dimension Diagram
Mechanical envelope based on Molicel maximum dimensions.
14. Pack Scaling Formulas
Quick math for series/parallel planning. Validate current limits thermally and electrically.
Pack Voltage ≈ Series Count × 3.6V
Pack Capacity ≈ Parallel Count × 4.5Ah
Pack Energy ≈ S × P × 16.2Wh
Cell-Level Current Capability ≈ Parallel Count × 45A
15. Example Parallel Scaling
Approximate scaling using cell-level continuous discharge rating, not a finished-pack guarantee.
| 1P | 4.5Ah, 16.2Wh, 45A cell-level current reference |
|---|---|
| 2P | 9.0Ah, 32.4Wh, 90A cell-level current reference |
| 3P | 13.5Ah, 48.6Wh, 135A cell-level current reference |
| 4P | 18.0Ah, 64.8Wh, 180A cell-level current reference |
| 5P | 22.5Ah, 81.0Wh, 225A cell-level current reference |
16. Common Series Voltage Examples
Nominal voltage examples only. Full-charge and cut-off pack voltages scale separately.
| 1S | 3.6V nominal / 4.2V full / 2.5V cut-off |
|---|---|
| 3S | 10.8V nominal / 12.6V full / 7.5V cut-off |
| 4S | 14.4V nominal / 16.8V full / 10.0V cut-off |
| 5S | 18.0V nominal / 21.0V full / 12.5V cut-off |
| 10S | 36.0V nominal / 42.0V full / 25.0V cut-off |
| 13S | 46.8V nominal / 54.6V full / 32.5V cut-off |
Use the P45B inside a controlled electrical and thermal system.
This is an unprotected high-power cell. Safe implementation requires a charger, BMS, fuse strategy, interconnect design, and thermal-management plan that respect the cell’s limits.
17. Suggested Control Threshold Map
System-level control guidance derived from the live listing and Molicel data-sheet values.
| Charge upper limit | 4.20V per cell |
|---|---|
| Discharge floor | 2.50V per cell |
| Charge temperature gate | 0°C to 60°C |
| Discharge temperature gate | -40°C to 60°C |
| Standard charge | 4.5A CC-CV to 4.2V, 50mA termination |
| Maximum charge | 13.5A with 70°C cut-off; validate thermally before use |
| Continuous current | 45A with 80°C cut-off, subject to system-level thermal and interconnect validation |
18. Risk-Control Checklist
Recommended pack-building and use practices.
- Use only in devices or packs designed for lithium-ion 21700 cylindrical cells.
- Use a BMS or controller that monitors voltage, current, and temperature.
- Do not charge above 4.20V or discharge below 2.50V per cell.
- Validate high-current operation under the actual enclosure, cooling, and load profile.
- Never carry loose cells with conductive objects such as keys, coins, tools, or metal cases.
- Spot weld for pack assembly; do not solder directly to the cell body.
- Inspect wraps and top insulator rings before use.
- Size busbars, nickel, fuses, wiring, and BMS MOSFETs for both electrical resistance and heat rise.
Best suited for high-drain systems that need both power and usable capacity.
Power Tools
- Strong option for tool packs requiring high current per cell.
- Low impedance helps reduce voltage sag under heavy tool loads.
EV / Micro-Mobility
- Suitable for performance mobility packs with the correct BMS, fusing, and cooling.
- Parallel count should be based on measured current, voltage sag, and heat rise.
Drones / eVTOL
- Useful for high-power airborne systems where current density matters.
- Thermal validation is essential under peak discharge profiles.
Robotics / RC
- Supports high motor current and compact pack geometry.
- Useful where power response and moderate energy density are both important.
High-Output Lighting
- Good fit for demanding LED systems that pull high current from each cell.
- Use only in devices designed for unprotected 21700 flat-top cells.
Custom Battery Packs
- Designed for experienced builders and integrators who can manage current sharing and heat.
- Requires matched cells, correct welding, insulation, protection electronics, and pack-level testing.
19. Selection Bias: Power vs. Runtime
Product-page positioning for shoppers comparing high-power and high-energy cells.
20. Application Suitability Matrix
Simple product-page fit guidance.
| Power tools | Strong fit |
|---|---|
| Drones / eVTOL / RC | Strong fit |
| Performance mobility packs | Strong fit with validation |
| Runtime-focused electronics | Good, but may be more power than needed |
| Maximum runtime per cell | Consider higher-capacity energy cells |
| Unmanaged consumer devices | Not recommended |
Safety, Handling & Compatibility Notice
This product is an unprotected lithium-ion cell. It should only be used by customers who understand lithium-ion cell safety and who are using the battery in compatible hardware, managed packs, or professionally designed assemblies. Improper use can lead to overheating, venting, fire, or explosion.
- Charge only with lithium-ion chargers or managed battery systems designed for the correct chemistry and cell count.
- Never short circuit, crush, puncture, incinerate, or expose the cell to water.
- Do not use cells with damaged wraps, dented cans, or missing top insulator rings.
- Do not mix with cells of different age, capacity, model, or state of charge in the same pack.
- For assembly, use spot welding rather than direct soldering to reduce heat damage risk.
- Store and transport in non-conductive cases; never carry loose cells in pockets or bags.
- Keep away from children and from applications for which the product is not specified.
- Not for e-cigarette, vape, or similar use.
Common technical questions about the Molicel P45B.
What is the capacity of the Molicel P45B?
The P45B has a typical capacity of 4500mAh and a minimum capacity of 4300mAh. The data sheet lists typical energy as 16.2Wh and minimum energy as 15.5Wh.
What is the discharge rating?
The P45B is specified for 45A continuous discharge with an 80°C cut-off condition. Finished pack current should still be limited by thermal design, busbar/weld resistance, BMS ratings, fusing, and device requirements.
Is this a protected battery?
No. This is an unprotected flat-top 21700 cell and should be used only in equipment or packs with appropriate electrical and thermal protection.
What charger should be used?
Use a lithium-ion charger or battery-management system that uses a CC-CV profile to 4.20V per cell. The standard charge current listed by Molicel is 4.5A.
Can the P45B fast charge?
Yes. The data sheet lists 13.5A maximum charge current with a 70°C cut-off condition. Applications using high charge current should include temperature sensing, derating, and validation for cycle life and safety.
What is the correct discharge cut-off voltage?
The data sheet states a 2.50V discharge cut-off voltage per cell. Many pack designers choose a higher system cut-off to reduce stress and improve service life.
Can the P45B be used in battery packs?
Yes. It is a strong candidate for high-power custom battery packs when cell matching, spot welding, BMS sizing, fusing, insulation, and thermal validation are properly engineered.
Can I solder wires directly to this cell?
Direct soldering is not recommended. Spot welding is the preferred pack-assembly method because it reduces the risk of heat damage to the cell.
What are the cell dimensions?
Molicel lists the maximum cell envelope as 21.55mm diameter and 70.15mm height, with a maximum weight of 70g. Always confirm physical fit in the actual device or holder.
What temperature range is allowed?
The P45B data sheet lists 0°C to 60°C for charging and -40°C to 60°C for discharging. High-current use should include temperature monitoring and derating.
Is the P45B better for power or runtime?
It is a power cell with strong energy density. Choose it when the design needs high current and useful runtime in a 21700 format. If maximum runtime per cell is the only priority, compare it with higher-capacity energy-focused cells.
What does 7mΩ AC impedance mean?
It indicates very low cell impedance, which helps support higher current delivery and reduced voltage sag. Real pack resistance also includes welds, nickel, busbars, wiring, holders, fuses, and BMS components.
How many cycles should I expect?
The product listing uses a general 300+ cycle-life description, while the data sheet shows cycle-characteristics curves at 4.5A, 10A, and 100W discharge. Actual cycle life depends on temperature, charge current, discharge current, depth of discharge, and pack design.
Can I carry this battery loose?
No. Loose transport is unsafe because conductive objects can short the terminals. Always use a non-conductive battery case.