A Tesla Model 3 owner in Minnesota plugged in at 100% before a January cold snap. Three weeks later, the battery showed 97%. A Chevy Bolt driver in Phoenix fast-charged twice daily for two years. At 80,000 miles, capacity dropped to 88%. Both are real. Both are normal. Understanding why requires looking at what happens inside the cells every time you press the accelerator or plug in.

EV batteries lose capacity because the chemistry that moves energy gradually wears itself out. The pace is slow—around 2.3% per year in modern fleets—but the mechanisms are predictable. Lithium ions shuttle between graphite and metal oxide through liquid electrolyte. Every round trip leaves microscopic residue. Temperature accelerates the process. Charging habits either protect the cells or stress them. The difference between 88% capacity and 81% at 100,000 miles often comes down to three behaviors most drivers already control.

How Lithium Moves—Until It Doesn't

Inside each cell, lithium ions travel from a graphite anode to a metal-oxide cathode during discharge, then reverse during charging. Every cycle deposits a thin layer called the solid electrolyte interphase, or SEI. Think of it like rust on a hinge. The hinge still moves, but it takes more effort.

The SEI consumes active lithium. Fewer ions remain available to store energy. Over 1,000 cycles, a 75 kWh pack might lose 5–7 kWh of usable capacity just from SEI growth, according to Argonne National Laboratory testing published in 2024.

The cathode also cracks under repeated expansion and contraction. Nickel-manganese-cobalt (NMC) chemistries used in most EVs expand roughly 2% during charging. After 200,000 charge cycles in lab conditions, University of Michigan researchers documented 12–15% capacity loss tied directly to cathode fracturing. Real-world driving rarely stresses cells that hard, but the principle holds: mechanical wear compounds chemical wear.

Heat Speeds Aging, Cold Masks Capacity

A battery operated continuously at 95°F degrades 40% faster than one kept at 68°F over 100,000 miles. Idaho National Laboratory fleet data tracked 12,500 EVs from 2020–2025. Phoenix and Las Vegas Model 3 owners reported an average 11% capacity loss after 100,000 miles. Seattle and Portland owners showed 6% loss at the same mileage. The difference: sustained cabin and battery temperatures above 90°F during summer months.

Tesla's thermal management runs coolant through the pack, but it can't overcome physics when ambient temperature stays high for months.

Cold weather—below 20°F—temporarily reduces available capacity by slowing lithium-ion movement through thickened electrolyte. A Rivian R1T rated for 314 miles EPA combined delivered 220 miles on a single charge at 5°F during MotorTrend's February 2025 Montana test. Warming the battery to 50°F restored the missing 94 miles. No permanent damage occurred, but the temporary loss is real and predictable.

Fast Charging's Trade-Off

DC fast charging above 150 kW generates heat and forces lithium ions through the electrolyte faster than the chemistry prefers, accelerating SEI formation. Car and Driver tracked two identical 2023 Hyundai Ioniq 5s over 50,000 miles. One charged exclusively on a 7.2 kW home Level 2 unit. The other fast-charged three times per week at Electrify America 350 kW stations.

After 50,000 miles, the Level 2 car retained 96% capacity. The fast-charge car retained 91%. Both figures remain within Hyundai's warranty threshold of 70% at 8 years/100,000 miles, but the 5-point gap represents roughly 15 miles of lost range in daily driving.

The stress isn't evenly distributed. Charging from 10% to 50% at 350 kW generates less heat than pushing from 70% to 90% at the same rate, because the battery management system tapers current as cells fill. TFLcar's instrumented Rivian R1S logged peak cell temperatures of 102°F during a 10–80% session versus 118°F during an 80–95% top-off, both at the same 350 kW Electrify America station in Colorado.

Occasional road-trip fast charging—once or twice a month—produces negligible long-term impact. Daily fast charging to 90% or higher shifts the degradation curve noticeably faster.

What Each Charge Cycle Does to the Cells

Modern EV batteries are rated for 1,500–3,000 full charge cycles before dropping below 80% capacity, which translates to 300,000–600,000 miles depending on pack size and driving efficiency. A full cycle means 0% to 100%. Charging from 40% to 70% counts as 0.3 cycles. Most drivers never complete a true full cycle.

Fuelly.com user data from 4,200 Tesla Model Y owners shows an average plug-in state of charge of 32% and an average unplug at 78%. That's 0.46 cycles per charge session. At 250 miles per session, reaching 1,500 cycles requires 815,000 miles—well beyond the lifespan of most vehicles.

Shallow cycling extends battery life. A Nissan Leaf study by Plug In America tracked 350 first-generation Leafs from 2011–2023. Owners who kept charge between 30–70% retained 83% capacity after 10 years. Owners who regularly charged to 100% and drove to near-empty retained 71% capacity over the same period.

Lithium-iron-phosphate (LFP) chemistries in the 2024 Tesla Model 3 RWD and Ford Mustang Mach-E Select tolerate deeper cycling and higher temperatures without the cathode cracking seen in NMC cells. Chinese taxi fleets running LFP BYD e6 models logged 500,000+ miles with 85% capacity retention—5–7 percentage points better than NMC equivalents at similar mileage.

Why Battery Management Systems Matter More Than Chemistry Alone

Thermal management, charge-curve programming, and cell balancing determine how well a battery ages independent of raw chemistry. Tesla's liquid thermal system circulates coolant through ribbed plates sandwiched between cell modules. Nissan's first-generation Leaf used passive air cooling. Both used similar lithium-ion chemistries, but Tesla owners report 8–10% capacity loss at 100,000 miles versus 20–25% for early Leaf owners in hot climates.

General Motors' Ultium platform in the 2024 Silverado EV limits fast-charging current to 80% of maximum cell capacity and pre-conditions the battery before arriving at a charger. Rivian's software stops charging at 70% by default for daily use unless the driver manually selects a higher limit. Both strategies reduce stress on cells during the most vulnerable charge phases.

Cell balancing—ensuring all cells in a pack charge and discharge evenly—prevents individual weak cells from dragging down the entire pack. Ford's Mach-E balances cells during every charge session above 50%. Early software versions skipped balancing below 50%. This led to a 2–3% capacity variance across the pack after 30,000 miles. A January 2024 over-the-air update corrected the behavior, and subsequent capacity loss slowed by 30%, according to Mach-E Forum member tracking data from 1,100 vehicles.

The Numbers: 2.3% Per Year, 92% After Five Years

Geotab's study of 22,700+ EVs found average battery degradation of 2.3% per year. Vehicles using frequent DC fast charging degraded faster—up to approximately 3.0% per year—and hot climates added approximately 0.4% per year to degradation rates.

Recurrent Auto's research tracking 30,000+ EVs as of November 2025 shows that only 1.5% of tracked vehicles required non-recall battery replacements. The company emphasizes that 92% of vehicles retain more than 80% capacity after 5 years.

High-mileage outliers exist in both directions. A 2018 Tesla Model 3 Long Range in California logged 430,000 miles by December 2025 and retained 82% capacity. A 2020 Audi e-tron in Texas showed 79% capacity at just 62,000 miles after repeated 100% charges in 106°F heat.

Warranty thresholds reflect manufacturer confidence. Hyundai and Kia guarantee 70% at 10 years/100,000 miles. Tesla guarantees 70% at 8 years/120,000 miles for Long Range models. Rivian guarantees 70% at 8 years/175,000 miles. Claims remain rare: fewer than 4% of EVs dip below warranty thresholds before coverage expires outside of recalls, according to Recurrent's dataset.

Four Habits That Extend Battery Life

Three behaviors consistently correlate with slower degradation across all EV models: charging to 80% for daily use, avoiding prolonged storage at 0% or 100%, and minimizing exposure to sustained high temperatures. None require extreme discipline. Most drivers already operate within those parameters naturally.

Parking in shade or a garage during summer reduces pack temperature by 14–20°F on average. Setting charge limits to 70–80% through the vehicle's app takes 30 seconds. Plugging in overnight at home on Level 2 instead of stopping for DC fast charging during errands costs time but preserves capacity.

The effect compounds slowly. A driver who follows those three habits might retain 88% capacity after 100,000 miles. A driver who ignores them might retain 81%. Both numbers leave the vehicle fully functional. The difference: the first driver plans one fewer charging stop on a 400-mile road trip.

A fourth habit matters for long-term storage. Leaving a battery at 100% or 0% for weeks accelerates degradation. The sweet spot for storage is 50–60% charge. Owners who park an EV for a month-long vacation should unplug at 60%, not 90%.

Capacity loss is inevitable, but catastrophic failure is not. An EV with 75% of its original range still delivers 200+ miles in most cases—more than enough for daily driving and many road trips. Whether that threshold arrives at 150,000 miles or 300,000 depends more on thermal management and charging habits than luck.