This professional tool estimates Battery Runtime by analyzing your load characteristics and Discharge Rate (C-Rate). It accounts for inverter efficiency, Peukert effect (for Lead Acid), and system losses.

Perfect for sizing battery banks for Solar, UPS, or EV projects. Use the Live Discharge Graph to visualize voltage sag and ensure your configuration matches the power demands.

Battery Configuration

Input

Chemistry

Cell Capacity

Cell Voltage

Series (S)

Parallel (P)

Load Profile

Current Draw

Inv. Efficiency

DoD Limit

Sys. Loss

Performance Analysis

Output

Safe Runtime

Discharge Stress

C-Rate

Total Voltage

Total Capacity

Total Energy

Safety Note

Runtime based on 50% DoD limit.
Low C-Rate (< 0.5C) recommended for longevity.

Live Discharge Characteristics

Enter values above to see your load curve.

Common Battery Data Sheet

Use this reference table to find standard voltages and discharge limits for common battery types.

Chemistry	Nominal V	Charge V	Rec. DoD	Typical C-Rate
Lead Acid (Flooded)	2.0 V / 12.0 V	14.4 V	50%	0.1C – 0.2C
Lead Acid (AGM/Gel)	2.0 V / 12.0 V	14.7 V	50%	0.2C – 0.3C
Li-Ion (NMC)	3.7 V	4.2 V	80%	0.5C – 1.0C
LiFePO4 (LFP)	3.2 V	3.65 V	90%	0.5C – 1.0C
Li-Po (Polymer)	3.7 V	4.2 V	80%	10C – 50C+

Glossary

C-Rate (Discharge Rate)

A measure of discharge speed relative to capacity. A 100Ah battery discharged at 100A is 1C. At 200A, it is 2C.

Tip: Keep Lead Acid below 0.2C and Lithium below 1.0C for long life.

DoD (Depth of Discharge)

The percentage of capacity removed. 100% DoD means the battery is empty.

Tip: Never drain Lead Acid below 50% DoD to avoid permanent damage.

System Loss

Real-world inefficiencies. Inverters lose ~15% of energy as heat (DC-to-AC conversion).

Tip: Use 15% loss for Inverters, or 5% for DC loads.

Voltage Sag

Voltage drops instantly under high load, potentially triggering a low-voltage cutoff early.

Tip: If “Discharge Stress” is Red, increase your battery bank size.

Step-by-Step Guide

Follow these steps to estimate accurate battery runtime.

Configure Battery Pack

Select your Chemistry (e.g., Lead Acid, LiFePO4). Enter the specs for a single cell, then specify how many are in Series (S) and Parallel (P).

Define Load

Toggle between Amps (DC current) or Watts (AC/Power load). If using Watts, you can adjust the Inverter Efficiency (typically 85%).

Analyze Safety

Review the Safe Runtime. Check the Discharge Stress (C-Rate) indicator—if it turns Orange or Red, your load is too high for the battery size.