Battery State of Health Calculator

Because SOH is defined purely as Current Capacity divided by Original Capacity -- it is a snapshot measurement of how much capacity remains right now, not a prediction based on usage history. Total Cycles and Battery Age are used separately to estimate a rate of degradation and project Remaining Cycles to end of life, but they play no role in the SOH percentage itself.

An 80% capacity retention threshold is a widely used convention across the battery industry, particularly for electric vehicles and grid storage, marking the point where a pack's usable range or runtime has degraded enough that most manufacturers and warranty programs treat it as functionally worn out, even though the battery can often keep working well past that point at reduced capacity.

Treat it as a rough projection, not a guarantee -- it assumes the capacity loss per cycle observed so far continues at exactly the same linear rate all the way to the 80% threshold. Real battery chemistries frequently degrade non-linearly, often fading slowly at first and then accelerating in later life, so a linear extrapolation from early or mid-life data can understate how soon a battery actually reaches end-of-life.

No -- Nominal Voltage only converts the amp-hour capacity figures into kilowatt-hours for the Current Energy and Original Energy outputs. State of Health, Capacity Lost, Remaining Cycles, and Annual Degradation are all computed entirely from the capacity and cycle/age figures and do not use voltage anywhere in their formulas.

Because this calculator divides total Capacity Lost by Total Cycles to get an average per-cycle fade rate, which attributes the entire measured capacity loss to charge-discharge cycling. In reality, batteries also lose capacity from calendar aging (simple time passing, even in storage), so this per-cycle figure can overstate cycling's true contribution for a battery that has also spent a lot of time sitting idle.