Battery Backup Calculator

Calculate backup time and required battery capacity

Battery Backup Calculator

Calculate backup time and required battery capacity

Calculation Mode

Find Backup Time

Calculate how long your battery will last with a known load

Find Required Capacity

Calculate the battery capacity needed for desired backup time

Load Devices

Device Name

Power Type

Power (W)

= 100.00 W

Total Load: 100.00 W

Battery Configuration

Battery Voltage (V)

Capacity per Battery (Ah)

Number of Batteries

Depth of Discharge (%)

Inverter Efficiency (%)

Backup Time Result

1 × 100.00Ah @ 12V

5h 24m

Backup Time

100.00W

Total Load

540.00Wh

Usable Energy

50.00%

Depth of Discharge

Calculation Formula

Where: t = Backup Time (hours), V = Voltage, C = Capacity (Ah), N = Number of batteries, DoD = Depth of Discharge, η = Efficiency, P = Load Power (W)

Energy Analysis

Battery Energy

Total Stored: 1,200.00 Wh

Usable (50.00%): 600.00 Wh

Effective: 540.00 Wh

System Configuration

Batteries: 1×100.00Ah

Voltage: 12V

Efficiency: 90.00%

Load Analysis

Devices: 1

Total Power: 100.00 W

Runtime: 5h 24m

About Battery Backup

Calculate backup time from known battery specifications or determine required battery capacity for desired backup duration.

Perfect for UPS systems, off-grid power solutions, and emergency backup planning with comprehensive energy analysis.

Configuration Tips

Depth of Discharge:

Lead-acid: 50% | Lithium: 80-90%

Inverter Efficiency:

Modern inverters: 85-95%

Power Factor:

Resistive loads: 1.0 | Electronic: 0.6-0.8

Safety Notes

• Never discharge lead-acid batteries below 50%

• Allow safety margin for temperature variations

• Consider battery aging (20% capacity loss over time)

• Use proper ventilation and safety equipment

Calculation Mode

Find Backup Time

Calculate how long your battery will last

Find Required Capacity

Calculate needed battery capacity

Load Devices

= 100.00 W

Total Load: 100.00 W

Battery Configuration

Voltage (V)

Capacity (Ah)

Batteries

DoD (%)

Efficiency (%)

Backup Time Result

1 × 100.00Ah @ 12V

5h 24m

Backup Time

100.00W

Total Load

540.00Wh

Usable Energy

50.00%

DoD

Formula

Backup Time = (Voltage × Capacity × Batteries × DoD × Efficiency) ÷ Load

Energy Breakdown

Battery Energy

Total Stored: 1,200.00 Wh

Usable: 600.00 Wh

Effective: 540.00 Wh

Battery Backup Calculator

Calculate backup time or required capacity for UPS systems, off-grid power, and emergency backup solutions.

Quick Tips

• Lead-acid: 50% DoD max

• Lithium: 80-90% DoD safe

• Allow 20% safety margin

• Consider temperature effects