Hero image: AI-generated illustration of battery-pack concepts. Appearance does not establish chemistry, capacity or endurance.
Sources reviewed 10 October 2026. This article uses manufacturer documentation and illustrative calculations; it does not report THL battery or flight testing.
A drone battery must do two jobs: store enough energy for the mission and supply enough power for its most demanding moments. A pack that looks attractive for steady cruise may reach a voltage or temperature limit during takeoff, climb or a gust response. A larger pack can also increase the aircraft’s power demand by adding mass.
That makes “LiPo or Li-ion?” a useful starting question, but an incomplete purchasing or design decision. Compare the exact finished packs, their operating limits and the aircraft carrying them. Endurance comes from usable energy divided by representative power, with a suitable reserve.
What the names actually mean
In drone and radio-control discussions, “LiPo” usually describes a lithium-ion battery supplied in a flexible pouch format, often designed for high current. “Li-ion” commonly means a pack assembled from cylindrical cells. These labels are useful shorthand, but they are not two mutually exclusive electrochemical families. NASA’s pouch-cell research explicitly notes that lithium-ion pouch cells are not necessarily true polymer cells. NASA: Characterization of Commercial Li-ion Cells in Pouch Format.
The electrode chemistry, cell design and pack construction matter more than the nickname. A pouch can save packaging mass and fit a flat space; cylindrical cells can suit a different mechanical arrangement. Neither shape guarantees higher energy, safer operation or longer life. Even the nominal-voltage label does not establish the permitted full-charge voltage or discharge cutoff.
Compare the complete pack
| Question | What to compare | Why it matters |
|---|---|---|
| How much energy? | Nominal watt-hours and delivered energy under relevant conditions | Capacity in mAh alone does not compare packs at different voltages. |
| How much current? | Continuous and pulse limits, their conditions and pulse duration | Cruise capability does not establish takeoff or climb capability. |
| How much mass? | Complete installed pack, including leads, casing and protection | Cell-only Wh/kg can overstate the installed pack’s specific energy. |
| Which voltage range? | Full-charge voltage, loaded voltage and permitted cutoff | The battery, charger and aircraft power system must agree. |
| How much life? | Retention and retirement criteria under stated operating conditions | A cycle count without test conditions is an incomplete comparison. |
| Which protections? | Cell monitoring, balancing, temperature and current protection behavior | Protection can constrain delivery even while stored energy remains. |
Do not assume cylindrical cells are restricted to moderate current. For example, Molicel’s P45B datasheet specifies 45 A continuous discharge with an 80°C cutoff. That is a conditional cell specification, not approval to operate an assembled aircraft pack at that current. Interconnects, cooling and protection still require assessment. Molicel P45B datasheet, version 1.4.
Nominal energy is not all available for flight
For a first estimate, nominal energy in watt-hours is nominal voltage multiplied by capacity in amp-hours. Delivered energy instead follows the terminal voltage and current throughout discharge: add up voltage × current × time until the applicable limit is reached. The result depends on load, temperature, age and the system’s cutoff. TI’s battery-management guidance explains how usable capacity changes with impedance, temperature and load. TI: Impedance Track Configuration Considerations.
Keep availability and reserve separate. An available-energy allowance represents energy expected to be accessible under the operating conditions. An operational reserve is energy deliberately held back for landing and contingencies. Applying the same allowance twice under different names can produce a misleading estimate; omitting one can be equally misleading.
Read C-ratings with their conditions
A C-rating converts to current by multiplying the stated rate by capacity in amp-hours. A hypothetical 5 Ah pack labelled 10C therefore corresponds to 50 A. This arithmetic does not prove that every component can sustain 50 A, or that a pulse rating is suitable throughout a flight. Read the manufacturer’s continuous-current conditions, temperature limits, cooling assumptions, cutoff and pulse duration.
The power path matters too. Horizon’s battery guidance warns that a battery may be capable of more current than its installed connector can carry. Treat the pack, leads, connector, protection and aircraft wiring as one system. Horizon/Spektrum lithium battery safety guidance.
Voltage sag can decide the result
Under load, terminal voltage falls below the resting voltage. A simple approximation is voltage drop ≈ current × effective resistance, including the battery and its connections. Resistance changes with temperature, state of charge and age. A high-current event can reach the aircraft’s minimum operating voltage before all nominal energy is delivered. TI’s pulsed-load training discusses voltage limits and available power under these conditions. TI: Battery Management for Pulsed Load Applications.
Check the most demanding flight phases, including those near the intended landing reserve. Lower cruise current does not remove a late-flight climb or wind-response requirement. Where telemetry is available, review loaded voltage and current together, alongside temperature and cell balance, rather than judging pack condition from resting voltage alone.
A worked estimate, with explicit assumptions
Consider a hypothetical 6S pack labelled 22.2 V nominal and 5,000 mAh. Convert capacity to 5 Ah: 22.2 × 5 = 111 Wh nominal. Assume 80% is available under the mission conditions, then hold back 20% of that available energy. Mission energy becomes 111 × 0.80 × 0.80 = 71.04 Wh.
If representative average battery current is 12 A, the nominal-voltage approximation gives 266.4 W. Add a separately accounted 33.6 W auxiliary load to obtain 300 W total. The estimate is 71.04 ÷ 300 × 60 = 14.2 minutes. These inputs are invented for explanation, not measured performance or a recommended reserve. If the measured battery current already includes auxiliary equipment, do not add its power again.
Use the existing Electric UAS Flight Endurance Estimator to explore these assumptions. It uses nominal voltage and representative current; it does not reproduce a discharge curve, phase-specific loads or thermal limits.
The aircraft carries the energy
A comparison using unchanged power after adding battery mass is incomplete. In ideal hover at fixed rotor disk area and air density, induced power scales with thrust to the 3/2 power. Real electrical power also includes rotor, motor, controller and other losses. NASA’s rotor-performance report gives the underlying relationship. NASA technical memorandum on proprotor performance.
For each candidate, reassess installed mass, centre of gravity, takeoff limits and representative power. Fixed-wing cruise has different aerodynamic tradeoffs; hover scaling cannot predict it. Higher stored energy improves endurance only when the usable-energy gain outweighs the change in required power.
The existing Battery Pack Builder helps compare configurations and entered current ratings. Its mass calculation totals cells only; add casing, wiring, connectors and protection separately. Its nominal-voltage presets do not determine charger settings or certify compatibility.
Handle both battery families with care
Follow the exact pack and charger instructions for chemistry/profile, cell count, voltage, current and temperature. Inspect before use, protect exposed terminals, monitor charging and use the prescribed storage settings. Remove damaged or swollen packs from service and follow the manufacturer’s handling and disposal instructions. Horizon’s guidance covers these precautions; its values should not be transferred automatically to another manufacturer’s battery. Horizon/Spektrum battery handling and charging guidance.
Choose a pack by the mission it can support within its limits: enough usable energy, adequate power throughout the flight and acceptable installed mass. The label identifies a starting point. The complete battery and aircraft system determine the endurance.