Lighting knowledge
How to Estimate Rechargeable LED Light Runtime
A practical explanation of battery energy, power draw, mode selection and why real runtime differs from a simple capacity calculation.
Estimate runtime from usable battery energy divided by the light's average power draw, then apply an allowance for driver loss, battery protection, temperature and output regulation. Final runtime should be verified by a controlled test on the exact mode.
Use watt-hours, not mAh alone
Battery capacity in mAh cannot be compared correctly without voltage. Convert nominal battery energy to watt-hours, then divide by average system power. The result is only an estimate because the LED driver and protection circuit consume energy.
Why real runtime changes
Brightness regulation, temperature, battery age, charging state and low-voltage protection affect runtime. Some lights reduce output during operation, so a single runtime figure must always identify the tested mode.
- Battery voltage and usable capacity
- Average rather than rated maximum power
- Driver conversion loss
- Temperature and battery condition
- Brightness step-down behaviour
How buyers should verify a claim
Ask for the tested mode, starting charge condition, environment, cut-off definition and sample configuration. Use the approved product specification as the purchasing reference.
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