Battery Cycle Life Calculator

Project battery cycle life and calendar life under a given duty cycle.

About Battery Cycle Life Calculator

Batteries fail from whichever limit arrives first. Lightly cycled home batteries are usually calendar limited, while heavily cycled commercial systems are cycle limited. A warranty quoting both a cycle count and a year count is honest about this; comparing only one number between products is misleading.

Formula

Battery Cycle Life

Life is the lesser of cycle-limited life and calendar life

calendar life: Ageing that occurs regardless of use
cycle life: Wear from charge and discharge cycles

Worked example

With the default values below, Battery Cycle Life Calculator returns Expected Life of 15.00. Change any input above and every figure here is recalculated in your browser.

Inputs used

Rated cycles to 80 per cent capacityminimum 1 cycles: 6,000 cycles
Average depth of dischargeaccepts 0–100 %: 80 %
Cycles per dayaccepts 0.01–10: 1
Calendar life limitaccepts 1–40 years: 15 years

Results

Expected Life: 15.00 years
Cycles Available at That Depth: 7,173 cycles
Life if Cycle Limited: 19.65 years
Limiting Factor: Calendar limited — it ages out before the cycles are used
Cycles per Year: 365

Step by step

1Values used
2Battery Cycle Life
3Expected Life= 15.00 years
4Cycles Available at That Depth= 7,173 cycles
5Life if Cycle Limited= 19.65 years
6Limiting Factor= Calendar limited — it ages out before the cycles are used
7Cycles per Year= 365

Assumptions and limits

The result is derived only from the 4 inputs listed above. Anything not among them is not part of the calculation.
In particular, this calculator does not take inflation, tax or compounding frequency into account.
Figures are rounded for display to 2 decimal places, so totals built from several rounded parts can differ slightly from the unrounded arithmetic.

How these calculators are built and tested is described on the Methodology page. If a figure looks wrong, please report it.

Frequently Asked Questions

How is Battery Cycle Life calculated?

Life is the lesser of cycle-limited life and calendar life Batteries fail from whichever limit arrives first. Lightly cycled home batteries are usually calendar limited, while heavily cycled commercial systems are cycle limited.

Why does Battery Cycle Life matter?

A warranty quoting both a cycle count and a year count is honest about this; comparing only one number between products is misleading.

What values do I need to enter?

This calculator takes 4 inputs: Rated cycles to 80 per cent capacity, Average depth of discharge, Cycles per day, Calendar life limit. The pre-filled defaults are a realistic starting point — replace them with figures from your own environment for a result you can act on.