Battery Lifespan Calculator
Estimate battery bank lifespan in years from cycle depth, cycles per year, chemistry and operating temperature.
Results
Cycles, not years
Batteries are rated in cycles, and the shallower each cycle, the more of them you get. A bank cycled to 30 % every day will outlast an identical bank cycled to 80 % by a factor of two or more.
Heat is the quiet killer
As a rule of thumb, every 10 °C above 25 °C halves the calendar life of a lead-acid bank. A battery box in an unventilated garage or against a sunlit wall can lose years of service without a single fault ever showing up in the logs.
Common mistakes
Judging a bank by its warranty rather than by how it is used. Two identical banks can differ by years depending on cycle depth, charging discipline and where they are installed.
Questions people ask
Does a battery age when not used? Yes. Calendar ageing continues regardless, and lead-acid left partly discharged sulphates whether or not it is cycling.
Is cold better than heat? For ageing, yes; for capacity, no. A cold bank delivers noticeably less than its rating while it is cold, but it lasts longer overall.
What actually kills a bank
Rarely a single event. Usually it is a pattern: routinely deep cycles, charging that never quite completes, a battery box that sits at 35 °C all summer, or months spent at a partial state of charge. Each of those shortens life on its own, and they compound.
Chronic undercharging
In solar systems this is the most common failure mode by a distance. If the array cannot finish the absorption phase on a short winter day, lead-acid cells sulphate a little more each cycle, and capacity falls quietly for months before anyone notices. Oversizing the array relative to the bank is what prevents it.