Battery Life Calculator
Estimate how long a battery will last under a specific load.
Ah
A
η
Default is 0.85 (85%) for lead-acid batteries. Li-ion is usually higher (0.95).
How to Calculate Battery Life
To estimate battery life, divide the battery capacity in Amp-hours (Ah) by the load current in Amps (A). It is also important to consider the efficiency of the battery and the discharge depth.
Formula
Time(h) = (Capacity(Ah) × Efficiency) / Load(A)
Calculation Example
Question: A 100 Ah battery is powering a device that draws 5 Amps. The battery efficiency is 85%. How long will it last?
Answer:
Time = (100 Ah × 0.85) / 5 A = 17 Hours
Factors Affecting Battery Life
- Discharge Rate: Drawing current faster reduces the effective capacity (Peukert's Law).
- Temperature: Extreme cold or heat can reduce performance.
- Age: Older batteries hold less charge.
- Type: Lead-acid batteries should not be discharged below 50%, while Lithium-ion can go deeper.