Battery Life Calculator for Electric Vehicles

Units

Battery capacity, kWh

Annual mileage, mi/yr

Consumption, kWh/100 mi

Depth of discharge, %

Cycles to end of life

Start SOH, %

Critical SOH, %

Annual degradation, %/yr

This calculator provides a concise projection of EV battery life and health. It returns an estimated service life in years, the expected mileage until replacement and a year by year State of Health trajectory. Use it to compare degradation scenarios and to plan replacement timing. Keyword: EV battery life.

Table of Contents

Input parameters

Battery capacity — total pack energy in kWh.
Annual mileage — average kilometers driven per year.
Energy consumption — kWh per 100 kilometers, actual vehicle consumption.
Depth of discharge DoD expressed as percent of full capacity used per typical cycle, for example 70 percent.
Full equivalent cycles to end of life — approximate number of full cycles before the pack reaches end of rated cycle life.
Starting SOH — current State of Health in percent, usually near 100.
Critical SOH — threshold percent at which replacement is planned, for example 72 percent.
Annual calendar degradation — average percent loss of SOH per year when idle or under normal use.

What the calculator computes

Annual energy demand in kWh per year based on mileage and consumption.
Equivalent full cycles per year derived from energy throughput and DoD.
Years limited by cycle life using the declared cycles to end of life.
Years limited by calendar degradation derived from annual SOH loss.
Estimated service life equal to the smaller of the two limits, cycles and degradation.
Projected kilometers to replacement, expected replacement year and SOH at replacement.
A simple year by year SOH profile and a horizontal indicator showing resource decline over time for quick visualization.

Key formulas

Annual energy

$$
E_{year} = Mileage_{year}\cdot \frac{Consumption}{100}
$$

Energy per full equivalent cycle

$$
E_{cycle} = Capacity\cdot DoD
$$

Full cycles per year

$$
Cycles_{year} = \frac{E_{year}}{E_{cycle}}
$$

Years limited by cycles

$$
Years_{cycles} = \frac{Cycles_{total}}{Cycles_{year}}
$$

Years limited by degradation

$$
Years_{deg} = \frac{SOH_{start}-SOH_{crit}}{Deg_{year}}
$$

Expected service life

$$
Years_{expect} = \min(Years_{cycles}, Years_{deg})
$$

Kilometers until replacement

$$
Mil_{replace} = Years_{expect}\cdot Mileage_{year}
$$

Worked example with new numbers

Example inputs

Capacity 75 kWh
Annual mileage 12 000 km
Consumption 16 kWh per 100 km
DoD 65 percent
Full cycles to end of life 1 800
Starting SOH 99 percent, critical SOH 73 percent
Annual degradation 1.8 percent per year

Step one, annual energy

$$
E_{year} = 12\,000\cdot \frac{16}{100} = 1\,920\ \text{kWh}
$$

Step two, energy per full cycle

$$
E_{cycle} = 75\cdot 0.65 = 48.75\ \text{kWh}
$$

Step three, cycles per year

$$
Cycles_{year} = \frac{1\,920}{48.75} \approx 39.4\
$$

Step four, years by cycles

$$
Years_{cycles} = \frac{1\,800}{39.4} \approx 45.7\ \text{years}
$$

Step five, years by degradation

$$
Years_{deg} = \frac{99-73}{1.8} \approx 14.4\ \text{years}
$$

Step six, expected life is the minimum

$$
Years_{expect} = \min(45.7,14.4) = 14.4\ \text{years}
$$

Step seven, kilometers until replacement

$$
Mil_{replace} = 14.4\cdot 12\,000 \approx 172\,800\ \text{km}
$$

Summary of the example

Annual energy about 1 920 kWh
Full cycles per year roughly 39
Service life limited by calendar degradation about 14.4 years
Expected distance until replacement about 172 800 km
Estimated used cycles at replacement about 568 cycles which is well below declared cycle limit

Additional practical guidance and calibration tips

Battery chemistry matters. LFP packs usually tolerate deep cycles and show slower calendar fade, NMC and NCA packs offer higher energy density but may age faster under fast charging stress.
Both calendar and cycle ageing contribute. High average state of charge and repeated fast charging amplify calendar fade and bring forward replacement.
Adjust DoD and annual degradation in the model if you have logged telematics. Real data makes projections far more reliable than generic defaults.
Cell balancing and a robust battery management system reduce capacity spread between modules and extend useful life. Monitor cell voltage drift and internal resistance when diagnosing packs.
For fast charging heavy users, increase annual degradation estimate by 0.5 to 1.5 percent per year depending on charge power and thermal management quality.
Consider secondary uses before disposal. Even after reaching critical SOH a pack may retain value for stationary energy storage or less demanding applications.

Parameter	LFP (LiFePO₄)	NMC (Li-Ni-Mn-Co)	NCA (Li-Ni-Co-Al)	Notes
Typical energy density, Wh/kg	90–160	150–220	200–260	Higher density usually trades off with cycle life and thermal sensitivity.
Cycles to ~70% SOH	2,000–5,000	1,000–3,000	800–2,000	Range depends on DoD, C-rate and temperature history.
Calendar degradation, % / year	0.5–1.5	1.0–3.0	1.5–3.5	Higher average SOC and temperature accelerate calendar fade.
Recommended daily DoD (practical)	20–90%	20–80%	20–80%	LFP tolerates deeper cycles better; limiting DoD extends cycle life.
Fast-charge tolerance	Good	Moderate	Lower	Fast charging increases stress; thermal management mitigates impact.
Temperature sensitivity	Low	Moderate	High	High temperatures amplify both calendar and cycle aging.
Typical usable capacity fraction per full cycle (DoD)	0.6–1.0	0.5–0.8	0.5–0.8	Defines energy per full equivalent cycle used in lifetime models.
Common end-of-life threshold	70–80% SOH	70–80% SOH	70–80% SOH	Industry commonly uses 70% as economic replacement point.

Practical notes and cautions

Use both cycle limited life and calendar degradation to produce conservative plans. Take the smaller result as the planning horizon.
Do not rely solely on age or odometer reading to judge pack health. Capacity tests and internal resistance measurements are more informative.
When possible, obtain BMS logs to measure actual equivalent cycles, charge power distribution and temperature history for an accurate prognosis.
Apply sensitivity checks. Recalculate with slightly higher degradation and slightly higher DoD to understand worst case service life.
Factor in software updates. Firmware changes can influence charging curves, thermal management and therefore long term degradation.

Battery Life Calc for Electric Vehicles summary

📉 All estimates are approximate. For investment decisions and replacement budgeting validate projections with manufacturer guidance and actual battery diagnostics.