One of the Highest Power Cells in Our Database: Ampace JP40 Full Review and Specs

The Ampace JP40 is a high-power 21700 lithium-ion cell designed for demanding applications like drones, e-aviation, and defence. In this blog, we use our own lab-tested electrical models to simulate JP40 performance under various loads, streamlining cell selection and benchmarking.

Introduction: Ampace JP40 Datasheet Limitations

The Ampace JP40 is a high-power 21700 lithium-ion cell designed for demanding applications like drones, e-aviation, and defence.

The cell offers a typical capacity of 4 Ah and delivers 14.4 Wh of energy at a nominal voltage of 3.7 V. It supports a maximum continuous discharge of 60 A (15.4C) with thermal cut-off at 80°C, and a rated charge of 8 A (2C). Gravimetric energy density is 215 Wh/kg and power density at 3217 W/kg, based on a standard 21700 form factor.

It’s one of the highest power cells in our database.

Even with a detailed datasheet, engineers lack visibility into how battery behaves under dynamic or edge-case conditions. Key performance factors, such as temperature rise, rate capability, and voltage polarisation, only emerge under realistic operating scenarios.

Simulation can also be used to address the most commonly seen problems in the traditional process:

1. Verification Challenges - Publicly available or supplier-provided data often lacks consistency or critical testing details. Engineers must spend time verifying claims, introducing uncertainty into performance assumptions.

2. High Initial Investment - Accurate cell testing requires specialised equipment, environmental chambers, and safety systems. For most teams, this means significant capital expenditure before meaningful insights can be generated.

3. Delayed Timelines - Cell sourcing, shipping delays, and long testing cycles all add up. Teams can lose weeks or even months confirming whether a cell is suitable for their application.

This white paper uses lab-tested electrical models to simulate JP40 performance under various loads, streamlining cell selection and benchmarking.

In the sections below, we evaluate the cell under constant current, constant power, and a representative eVTOL drive cycle to demonstrate its suitability for real-world applications.

Simulated Performance Data: Constant Current Discharge

In this constant current analysis of the Ampace JP40, simulations were run across five discharge rates: 0.5C, 1C, 3C, 5C and 10C. The voltage profiles (Figure 1.1) show voltage behaviour characteristic of NMC-Graphite chemistry across the full capacity range. As the rate increases, polarisation becomes more pronounced, especially at 10C, where voltage drops significantly earlier and the capacity delivered falls to approximately 4 Ah.

Thermal behaviour (Figure 1.2) shows a significant rise in cell temperature at 10C, reaching 63 °C, compared to just 34 °C at 3C and under 26 °C at 0.5C and 1C. Notably, at the higher C-rates the rate capability of the cell improves due to the lower internal resistance.

Constant Current Summary Table

Figure 1.1: Voltage profiles show voltage behaviour characteristic of NMC-Graphite chemistry across the full capacity range

Figure 1.2: Thermal behaviour shows a significant rise in cell temperature at 10C, reaching 63 °C, compared to just 34 °C at 3C and under 26 °C at 0.5C and 1C

Why this matters

For engineers designing aerospace-grade battery systems, this data offers a more accurate perspective of performance at high rates, crucial when deciding whether a specific cell type can safely meet mission energy targets.

The insight into capacity retention and thermal performance helps teams estimate pack sizing and cooling requirements, before investing significant resource into testing.

Without simulation, much of this would require weeks of hardware testing. Here, engineers can rapidly compare thermal response and available energy across duty cycles aligned to actual use cases.

Operating Conditions

• Initial SoC: 100%

• Initial Cell Temperature: 25 °C

• Heat Transfer Coefficient: 50 W/m²·K

These conditions reflect moderate passive cooling (e.g., air flow across cylindrical cells), which is more representative of drone or aerospace enclosures than idealised thermal chambers. This makes the data more realistic and actionable for system-level cell selection decisions.

Simulated Performance Data: Constant Power Discharge

While constant current tests provide clear rate-dependent benchmarks, real-world systems, especially in aerospace and drone propulsion, require specific power demands on cells. Constant power discharge gives engineers a better approximation of actual flight loads or satellite requirements, revealing how the cell handles changing current demands over time.

In this simulation, the JP40 was discharged at 5 W, 25 W, 50 W, 75 W, and 100 W. The voltage profile (Figure 2.1) remains flat and near-spec at lower powers (5 W–25 W), with almost full capacity delivered. At higher powers, particularly 75 W and 100 W, voltage polarisation becomes more pronounced, and the delivered capacity drops.

Current draw (Figure 2.2) increases significantly under higher loads, with the 100 W case pulling nearly 40 A.

The cell’s thermal profile (Figure 2.3) reflects this rise, with peak temperatures reaching 47 °C at 75 W and 55°C at 100 W. At 50 W and below, cell temperature remains under 40 °C.

Constant Power Summary Table

Figure 2.1: JP40 was discharged at 5 W, 25 W, 50 W, 75 W, and 100 W.

Figure 2.2: Current draw increases significantly under higher loads, 
with the 100 W case pulling nearly 40 A

Figure 2.3: Cell’s thermal profile reflects this rise, with peak temperatures reaching 47 °C at 75 W and 55°C at 100 W. At 50 W and below, cell temperature remains under 40 °C.

Why this matters

System designers working on high-power applications, like VTOL thrust modules or active communication payloads, often size battery packs based on constant power requirements.

These results allow engineers to model flight profiles, validate cooling needs, and anticipate derating behaviour at higher power bands.

The ability to see how current draw ramps in response to voltage drop gives a much more realistic understanding of electrical and thermal performance under peak conditions, enabling better insight during cell selection.

Operating Conditions

• Initial SoC: 100%

• Initial Cell Temperature: 25 °C

• Heat Transfer Coefficient: 50 W/m²·K

The moderate thermal environment simulated here reflects a passively cooled drone enclosure or lightweight aviation module. Results are more representative than idealised lab testing, and more directly applicable to real integration scenarios.

Simulated Performance Data: Real-World Drive Cycle

To capture how a cell behaves in real operation, simulation under a dynamic load profile is essential. In this case, we applied an aviation-specific eVTOL power cycle, reflecting real thrust demands, idle periods, and power spikes, scaled by a factor of 1.5 to stress the cell. These scenarios can’t be accurately assessed with constant current or power testing alone. Dynamic tests surface how cells manage rapid load transitions, recovery, and accumulated heating, all of which are critical in short, intense mission profiles.

The JP40 was tested with an initial SoC of 95% and cell temperature of 40 °C to simulate a post-charge, warm flight condition with modest heat dissipation (60 W/m²·K). Voltage (Figure 3.1) shows a generally stable decline, but with visible drops during high-power bursts at 0–100 s and again at ~750 s. The cell cuts off sharply just after 900 seconds, hitting the voltage cut-off, demonstrating this cell does not meet the profile requirements. Power demand (Figure 3.2) steps from peaks of ~140 W to peaks exceeding 50W, showing changes during take-off and flight. Thermal performance (Figure 3.3) reveals that temperature rises quickly to 49 °C in the first minute and then gradually increases to a peak of ~59 °C at shutdown.

These patterns highlight that even under non-constant loads, the JP40 maintains acceptable thermal performance, even if the cell did not meet the mission requirements.

The overall discharge duration of ~15 minutes under this aggressive eVTOL profile reflects a mission-aligned cycle with realistic constraints on operating conditions and cooling.

Figure 3.1: Voltage shows a generally stable decline, but with visible drops 
during high-power bursts at 0–100 s and again at ~750 s.

Figure 3.2: Power demand steps from peaks of ~140 W to peaks exceeding 50W, showing changes during take-off and flight.

Figure 3.3: Thermal performance reveals that temperature rises quickly to 49 °C in the first minute and then gradually increases to a peak of ~59 °C at shutdown.

Why this matters

Dynamic profiles like this one provide the closest match to real system operation.

For engineers working on drones or eVTOL systems, these simulations show not just whether the cell meets power targets, but how it responds in terms of heat, voltage, and cut-off conditions.

This allows better decisions on cell selection to enhance safety and longevity. These insights are especially critical when every gram and minute counts in airborne systems, so the adopting the best and latest technology is key. With simulations, you can tune your mission envelope before a single prototype leaves the bench.

Operating Conditions

• Initial SoC: 100%

• Initial Cell Temperature: 25 °C

• Heat Transfer Coefficient: 50 W/m²·K

The moderate thermal environment simulated here reflects a passively cooled drone enclosure or lightweight aviation module. Results are more representative than idealised lab testing, and more directly applicable to real integration scenarios.

Summary of Simulated Findings Across All Test Cases

Across the three simulations, constant current, constant power, and dynamic eVTOL cycle, the Ampace JP40 demonstrated consistent high-rate performance and thermal behaviour.

Under constant current, the cell retained >95% capacity at 10C, showing its suitability for systems for high power applications. Constant power tests revealed a clear relationship between increasing load and reduced capacity, with 100 W discharges peaking at 55 °C.

The eVTOL drive cycle introduced rapid transients and power peaks above 140 W. The cell handled these variations with stable voltage and gradual thermal build-up, reaching a maximum of 59 °C, indicating it can support short, high-intensity missions without immediate thermal runaway risk. To meet this power requirement the pack could be made larger in a real application.

These results highlight the value of simulation: enabling engineers to evaluate performance under realistic load conditions without waiting for full physical tests. It accelerates cell selection decisions, as well as informing design requirements for power- and weight-sensitive systems like drones and e-aviation platforms.

Conclusion

Based on the results from constant current, constant power, and real-world drive cycle simulations, the Ampace JP40 demonstrates consistent, reliable performance under varying load demands.

The cell shows stable electrical behaviour and thermal response under both steady-state and dynamic conditions, making it a strong candidate for high-power, weight-sensitive systems such as drones and aerospace platforms.

For engineering teams, this kind of early simulation unlocks key insights, how the cell performs under your actual use case, before committing to testing infrastructure or hardware integration. With our validated models, built from high-fidelity lab data, you can evaluate electrical and thermal behaviour in hours, not weeks. We also provide access to additional performance metrics to support early design diagrams, cooling strategy, and pack configuration.

This isn’t just a shortcut, it’s a smarter way to bring advanced cells into your programme this quarter, while reducing risk and accelerating development.

What next?

Want to run your own Ampace JP40 simulations or test it against another high-power cell? Simulate is our virtual battery cycler tool made for faster cell selection, hosted on our platform called the Voltt.

You can simulate voltage and temperature response of a cell under any given duty cycle – in seconds.

Learn more about Simulate here: aboutenergy.io/simulate

At About:Energy, we specialise in cell degradation testing, and simulation. Our data and models allow accurate forecasting of capacity fade and resistance growth during operation - allowing customers to design Battery Management Systems, size thermal systems, and ensure their performance requirements are met across the lifetime of their products.

If you’re interested in learning more about how our models can help you, book a demo here.

Further reading:

• Debating between the Molicel P45B and P50B?

  • Read Molicel P50B vs P45B: Key Differences & Specifications

• Read: State-of-Health Assessment of the Molicel P45B: How Long Will My eVTOL Battery Last?

• Reduced development time by 70%: McMurtry Case Study

  • Read our Forbes Feature