Calculation Mode
Choose what you are designing
Battery Chemistry
Select your battery type
Lead-Acid
12V / 6V cells
DoD: 50% | η: 80%
~300–500 cycles
DoD: 50% | η: 80%
~300–500 cycles
Lithium-Ion
3.2V–3.7V cells
DoD: 80% | η: 95%
~2000–5000 cycles
DoD: 80% | η: 95%
~2000–5000 cycles
Gel / AGM
12V cells (sealed)
DoD: 60% | η: 82%
~500–800 cycles
DoD: 60% | η: 82%
~500–800 cycles
LiFePO₄
3.2V cells
DoD: 90% | η: 97%
~3000–6000 cycles
DoD: 90% | η: 97%
~3000–6000 cycles
System Parameters
Enter your load and system requirements
Load Parameters
W
Total connected load in watts
p.f.
0.8–1.0 (1.0 = pure resistive)
▾
Actual vs rated load (%)
Backup & Duration
hrs
Required autonomy time
▾
Battery Configuration
Higher DoD = more usable capacity
Inverter + cable + battery losses
V
Nominal voltage per cell/unit
Oversize for aging / temperature
Ah
Capacity of a single battery unit
Sizing Results
Battery Bank Design
Total Battery Capacity Required
—
Ah · — kWh
—
Batteries in Series
—
units (for system V)
Strings in Parallel
—
strings
Total Battery Units
—
batteries
Actual Capacity
—
Ah installed
Discharge Current
—
Amperes (DC)
Backup Autonomy
—
hours
Configuration Diagram
Calculation Trace
Valid Design
DoD Applied: —
Battery Type Reference
Typical specifications
Lead-Acid DoD40–50%
Gel / AGM DoD60%
Lithium-Ion DoD80%
LiFePO₄ DoD80–90%
Lead-Acid η80%
Li-Ion η95%
LiFePO₄ η97%
Inverter η (typical)92–96%
C-Rate Guide
Discharge rate selection
C/20 (20 hr)Gentle · max capacity
C/10 (10 hr)Standard UPS / solar
C/5 (5 hr)Moderate discharge
C/2 (2 hr)High demand
C/1 (1 hr)Peak · reduce capacity ~80%
⚡ Higher C-rates reduce effective battery capacity. Lead-acid is especially sensitive — size generously.
Design Tips
Best practices
- Always derate for temperature — battery capacity drops ~1% per °C below 25°C for lead-acid.
- Add 20–25% safety margin for aging over the battery lifespan.
- Keep series strings ≤ 4 for lead-acid to maintain cell balance.
- Use a BMS for lithium banks to prevent over-charge and deep discharge.
- Size cables for maximum discharge current, not average.
- Ventilate lead-acid banks — hydrogen gas is released during charging.
Glossary
DoD — Depth of Discharge
% of battery capacity that can be used before recharging. Exceeding damages the battery.
Ah — Ampere-Hour
A measure of battery capacity. 100Ah = 100A for 1hr, or 10A for 10hrs.
C-Rate
Discharge speed relative to capacity. C/10 means full discharge in 10 hours.
η — Efficiency
Ratio of output to input energy, accounting for losses in battery, inverter, and cables.
BMS
Battery Management System — monitors and protects lithium cells from unsafe conditions.