Battery Backup Planning
A battery backup time table helps compare many load levels at once. It turns battery ratings into practical runtime values. The table is useful for inverters, UPS systems, solar rooms, telecom racks, alarms, routers, and small emergency circuits. It also shows how efficiency and battery condition change the final answer.
Why Runtime Changes
Battery capacity is usually printed in amp hours. That rating is measured under controlled conditions. Real systems lose energy through inverter conversion, cable resistance, heat, battery age, and deep discharge limits. A small load may run for many hours. A heavy load can reduce usable capacity faster, especially on lead acid banks. This calculator includes Peukert exponent to model that effect.
Important Inputs
Start with the battery voltage and amp hour rating. Then enter series and parallel counts. Series raises voltage. Parallel raises amp hour capacity. Add the load list in watts. Use several values to create a planning table. Enter depth of discharge, efficiency, aging factor, temperature factor, rated hour base, and Peukert exponent. Keep conservative values for critical equipment.
Reading the Results
The summary shows bank voltage, bank amp hours, nominal energy, usable energy, and low voltage cutoff. Each row shows estimated current and runtime for one load. Backup minutes are useful for UPS sizing. Backup hours are easier for long outages. Compare rows and choose a battery bank that still has margin after expected losses.
Design Tips
Use larger cables when current is high. Keep batteries cool and ventilated. Avoid frequent deep discharge. Match inverter rating to surge demand, not only steady demand. Add safety margin for aging. Test the real system under normal load. The calculated table is a planning guide, not a warranty. Battery chemistry, charger behavior, and cut off settings can change actual runtime.
Common Use Cases
This table supports home backup design, workshop power, field testing, CCTV cabinets, and off grid lighting. It can compare one battery against a larger bank. It can also show when a load is too large for the chosen bank. Use the CSV file for records. Use the PDF file for quotes, reports, and client notes. Always keep measured runtime notes for future maintenance and safer replacement planning during routine yearly inspections.