Battery Life Calculator
Calculate battery life in hours. Enter capacity (Ah/Wh), load power, voltage, depth of discharge, and efficiency to find runtime.
battery discharge calculator
To estimate battery life, one needs to first convert battery capacity to usable energy. Multiplication of ampere-hours (Ah) by voltage (V) and depth of discharge (DoD), and efficiency is used. Divide by the load power in watts, then. The output provides approximated hours of run-time.
Formula & Table Summary:
Usable Energy (Wh): E = Ah × V × DoD × η
Battery Life (h): t = (Ah × V × DoD × η) ÷ P_load
Reverse (Required Ah): Ah_req = (P_load × t) ÷ (V × DoD × η)
battery usage time calculator
The calculation of the time period that a battery can support a load before needing a recharge is done using a battery life calculator. Run time in hours will be calculated by entering some battery capacity (Ah or Wh), system voltage, load power, depth of discharge (DoD), and efficiency. The tool can be applied to the backup systems, solar systems, electronics, UPS, and EVs. The formula is based on the available energy = Battery Capacity Voltage DoD Efficiency. This energy, divided by the load power, will achieve the expected run time. Divide system losses, inverter efficiency, and DoD restrictions to avoid excessive discharge and lengthen battery time.
battery runtime calculator
| Battery | Load (W) | Voltage (V) | DoD | Efficiency | Life (h) |
|---|---|---|---|---|---|
| 12V 100Ah | 100 | 12 | 0.8 | 0.9 | 8.6 |
| 24V 150Ah | 300 | 24 | 0.85 | 0.92 | 10.4 |
| 48V 200Ah | 500 | 48 | 0.9 | 0.95 | 16.4 |
| 400V 62Ah | 2000 | 400 | 0.9 | 0.9 | 12.5 |
Frequently Asked Questions - Battery Life Calculator:
How do I calculate battery life?
Multiply Ah × V × DoD × efficiency ÷ load (W).
What is depth of discharge?
DoD is the usable portion of capacity without damaging the battery.
Why include efficiency in battery life?
System and inverter losses reduce usable runtime.
How many hours will a 100Ah battery last?
At 12V, 100W load, DoD 80%, η 90%, runtime ≈ 8.6 h.
How to extend battery life?
Use lower DoD, efficient loads, and proper charging.
Can I calculate runtime in Wh instead of Ah?
Yes, Wh ÷ Load (W) = hours.
Does battery type affect DoD?
Yes, lead-acid ≈50%, lithium ≈80–90% recommended.
How do I size a battery for runtime?
Use Ah_req = (W×t) ÷ (V×DoD×η).
Does temperature affect runtime?
Yes, cold reduces available capacity.
What if load varies?
Use average load power or simulate in steps.
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