This revision replaces a nominal amp-hour-times-voltage runtime claim with a declared usable-energy ledger. It keeps emitter efficacy, driver efficiency and driver loss explicit, and separates ideal constant-state arithmetic from standardized flashlight runtime and beam testing.
Pocket-Light Declared Energy Explorer
Enter declared usable battery energy, luminous flux, emitter efficacy and driver efficiency. The worksheet reports LED electrical power, battery input power, driver loss and ideal constant-state runtime.
Equation Used
- Usable battery energy is entered directly in watt-hours for the declared operating case.
- Luminous flux and emitter efficacy are declared constant-state values at a compatible operating point.
- Declared emitter efficacy converts LED electrical power to source luminous flux; it is not complete-flashlight optical efficacy.
- Declared driver efficiency is constant at the stated operating point and includes no separately modeled standby or switch loss.
- Ideal runtime ends when the declared usable energy is exhausted at constant input power.
- Battery voltage and current, discharge curve, protection, cell chemistry, temperature, driver quiescent power, LED junction temperature, thermal step-down, optics, beam distribution, illuminance, beam distance, FL 1 test behavior, ingress protection, impact resistance, charging and safety are excluded.
Replaces nominal Ah-times-voltage realistic-runtime claims with a declared usable-energy ledger and a connected electrical/optical topology.
The switch closes one connected battery-to-lamp circuit
US 1,119,663 describes a pocket lamp with a battery casing, conductors, switch contacts, lamp, reflector and lens. A modern LED light adds a current-regulating driver between the battery and emitter. The animation keeps those components connected and uses moving markers only to trace the declared energy path.
The reflector and rays are qualitative. They do not predict candela, beam shape, illuminance or distance.
Portable-light performance is product- and operating-point-specific
Texas Instruments' TPS92201 is one example of a constant-current battery-powered flashlight LED driver. Its published efficiency depends on operating conditions. Cree likewise documents that LED flux changes with drive current and junction temperature. Real output and runtime therefore require the actual cell, driver, emitter, optics and thermal system data.
Keep source efficacy and driver efficiency separate
The U.S. Department of Energy defines luminous efficacy as luminous flux in lumens divided by electrical power in watts and distinguishes LED-package performance from complete-product performance. The difference can include driver, thermal and optical losses.
This worksheet uses declared emitter efficacy to recover LED electrical power, then declared driver efficiency to recover battery input power. Driver loss is their difference.
A transparent declared-state example
At 800 lm and 120 lm/W declared emitter efficacy, LED electrical power is 6.67 W. At 90% declared driver efficiency, battery input is 7.41 W and driver loss is 0.74 W. Dividing 12.0 Wh declared usable energy by 7.41 W gives 1.62 h ideal constant-state runtime.
Ideal energy division is not standardized flashlight runtime
Streamlight's explanation of ANSI/PLATO FL 1 defines runtime from the 30-second initial light output until output falls to 10% of that initial value. A constant-state energy quotient does not reproduce that discharge-and-output test.
Nominal amp-hours multiplied by nominal voltage is also not automatically usable energy at the intended load. Actual performance depends on discharge curve, cutoff, temperature, cell aging, driver behavior, LED temperature and thermal step-down. The former realistic-runtime wording, generic optical-conversion percentages, universal thermal limits, PWM thresholds, cell recommendations, brand claims and fabricated field examples are removed.
Pocket-light energy questions
Is ideal constant-state runtime an FL 1 rating?
No.
Does emitter efficacy include the reflector and lens?
No.
Can nominal amp-hours and voltage replace usable watt-hours?
Not without a discharge model and operating conditions.
Does this predict beam distance?
No. Beam distance requires measured illuminance and a defined criterion.
Pocket-light energy and performance references
- U.S. Department of Energy, LED Basics: source versus complete-system efficacy and the role of optics.
- U.S. Department of Energy, Energy Efficiency of LEDs: lumens-per-watt definition and package, driver, thermal and optical distinctions.
- Texas Instruments TPS92201 Datasheet: regulated constant-current flashlight driver and operating-point-dependent efficiency.
- Cree LED, XLamp Testing and Characterization: flux dependence on current and junction temperature.
- Streamlight ANSI/PLATO FL 1 Information: runtime, light-output and beam-distance definitions.
- US 1,119,663, Electric Pocket-Lamp: battery, contacts, switch, lamp, reflector and lens topology.
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