EV TECHNOLOGY
An EV battery is not a single object. It is a stack of small lithium cells, grouped into modules, assembled into a pack, and supervised by a battery management system. Understanding that stack — and the chemistry inside the cells — explains almost every range, charging-speed and longevity question new EV drivers ask.
Every EV battery starts with a cell — a sealed unit a few centimetres across that stores energy chemically. A typical Tesla Model 3 holds roughly 4,400 cylindrical 2170 cells; a BYD Atto 3 uses a smaller number of much larger prismatic Blade cells. Cells are wired in series and parallel to form modules; modules are bolted together inside an aluminium or steel pack housing under the floor of the car.
Three cell formats dominate. Cylindrical cells (used by Tesla and Lucid) are cheap to manufacture and easy to cool but waste some volume. Prismatic cells (BYD, VW Group ID.4) pack more energy into a flat space. Pouch cells (Hyundai Ioniq 5, Kia EV6, GM Ultium) are flexible in shape but need a stiff outer module to stay safe.
The total pack capacity — quoted in kilowatt-hours (kWh) — is what determines range. A 60 kWh Renault Megane E-Tech, an 82 kWh Tesla Model 3 Long Range and a 77.4 kWh Ioniq 5 all sit somewhere in the same window: roughly 350–510 km of real-world range in mixed driving.
The cathode is the positive electrode and is where most of the chemistry differences live. The three families on the road today are nickel-manganese-cobalt (NMC), nickel-cobalt-aluminium (NCA) and lithium-iron-phosphate (LFP).
NMC and NCA pack more energy into a given weight, so cars chasing maximum range — Tesla Model S, Mercedes EQS, Lucid Air — lean on them. LFP is heavier per kWh but tolerates being charged to 100% daily, lasts more cycles, costs less, and contains no cobalt. The BYD Atto 3, MG4 standard range, Tesla Model 3 RWD and many Chinese-built EVs use LFP for that reason.
See our deeper explainer on LFP vs NMC for the full trade-off, including how charging strategy should change depending on which chemistry your car runs.
The other half of the cell matters too. Today's anodes are mostly graphite, sometimes blended with a small percentage of silicon to push energy density higher. Pure silicon anodes are coming, but they swell as they charge and are hard to keep stable across 1,500 cycles.
Between cathode and anode sits a liquid electrolyte and a thin polymer separator. The electrolyte is the part you most want to replace: it is flammable and limits how high a voltage the cell can sustain. Removing it is the central promise of solid-state batteries.
A modern EV pack contains anywhere from a few hundred to a few thousand cells. The battery management system is the embedded computer that monitors voltage, current and temperature at every group of cells and decides — many times per second — how much energy the pack can safely take in or push out.
The BMS is the reason your car throttles charging when the pack is cold, why state of charge above 80% slows dramatically on a rapid charger, and why your range estimate gets more accurate as the BMS learns your driving. A failing BMS, not a failing pack, is the cause of most early EV replacement claims under warranty.
Lithium cells want to live between roughly 15°C and 35°C. Below that they accept charge slowly and can be damaged by fast DC charging. Above 50°C they age fast.
Most modern EVs run a liquid-cooled pack: a glycol loop snakes between modules and pulls heat into the same low-temperature radiator that cools the inverter. Older or cheaper EVs (early Nissan Leaf, base MG ZS EV) used passive air cooling, which is the main reason their packs degrade faster in hot climates.
Pre-conditioning — warming the pack on the way to a rapid charger — is enabled by liquid systems. On a Hyundai Ioniq 5 in 0°C ambient, pre-conditioning can cut a stop from 55 minutes down to 28.
Pack-level energy density — kWh per kg — is what limits range without making cars unmanageably heavy. A 2015 Nissan Leaf pack delivered about 90 Wh/kg. A 2025 Tesla 4680 NMC pack delivers around 240 Wh/kg. CATL's latest NMC cells used in the Mercedes EQS sit closer to 260 Wh/kg at the cell level.
LFP density has improved sharply too. BYD's Blade pack is around 150 Wh/kg, which is enough for 500 km of range without using nickel or cobalt.
| Chemistry | Typical pack Wh/kg | Range for 75 kWh pack | Cost per kWh (est.) |
|---|---|---|---|
| LFP | 140–160 | 380–460 km WLTP | $95–115 |
| NMC 622 | 180–210 | 430–520 km WLTP | $120–145 |
| NMC 811 / NCA | 210–260 | 490–600 km WLTP | $135–160 |
| Solid-state (lab) | 350–500 | 700–900 km projected | $200+ (pre-scale) |
Pack-level (not cell-level) figures including housing, BMS and thermal loop. Cost is wholesale OEM estimates from S&P Global Commodity Insights and BloombergNEF, 2026.
An EV's headline DC peak — 150 kW, 250 kW, 350 kW — is a brief peak that lives at low state of charge on a warm pack. The full session is a curve: power rises, holds briefly, then tapers. A Tesla Model 3 Long Range hits 250 kW at 15% SoC, holds it for a few minutes, then falls steadily; by 70% the car is pulling closer to 100 kW.
This is why 10→80% is the right window to compare cars and chargers, and why 80→100% on a rapid charger almost always wastes time. See rapid charging explained for full charge curves and stall-picking advice.
Lithium packs lose capacity in two ways. Calendar ageing is loss over time, accelerated by storing the pack at very high or very low state of charge and by heat. Cycle ageing is loss per full equivalent charge cycle, accelerated by DC fast charging and by charging in extreme cold.
Real-world fleet data from Geotab, Recurrent and Tesla's own 2024 impact report puts average loss at about 1.8% per year for the first five years, then tapering. A 2018 Tesla Model 3 with 200,000 km on the clock typically still has 88–92% of its original usable capacity.
Three big shifts are visible in 2026. Solid-state batteries (Toyota, QuantumScape, Samsung SDI) promise 2× energy density and faster charging by replacing the liquid electrolyte with a ceramic one. Sodium-ion (CATL, BYD's Seagull and Yuyou) trades range for cost and cold-weather performance using sodium instead of lithium. Structural packs (Tesla 4680, BYD CTB) bond cells directly into the chassis to save weight and free up space.
Read more on solid-state batteries and 800V platforms for how these technologies change real-world charging.
Take a 2021 Hyundai Ioniq 5 with the 77.4 kWh NMC pack. Owner telemetry from the EV Database fleet sample shows an average of 3% capacity loss in the first 12 months, then around 1.2–1.5% per year afterwards. A car that left the factory with 73 kWh usable typically sits at 67–69 kWh usable after five years and 90,000 km.
In day-to-day terms that is a real-world range drop from roughly 380 km to 350 km in mixed UK driving — small enough that most owners only notice it on long motorway trips. The pack is still well inside Hyundai's 8-year / 160,000 km warranty floor of 70% capacity, which would not trigger until usable capacity fell below 51 kWh.
The same arithmetic applied to a 60 kWh LFP MG4 looks slightly better on cycle life but slightly worse on cold-weather usable range, because LFP loses more apparent capacity below 5°C. Both cars will comfortably outlast a typical 7-year UK ownership cycle.
Lithium cells are happiest between roughly 15°C and 35°C. Outside that window the BMS limits charge and discharge power to protect the chemistry. That is why a Model 3 in Edinburgh in January takes longer to rapid-charge than the same car in Marseille in May, and why a Kia EV6 in Brisbane summer can sustain its peak 240 kW rate for longer than the same car in Milan winter.
Active liquid thermal management — standard on Tesla, Hyundai-Kia, BMW, Mercedes, Audi and most Chinese premium EVs — pre-conditions the pack on the way to a rapid charger when you set the destination in the nav. Air-cooled packs (early Nissan Leafs, base trims of some budget EVs) have no such defence and visibly slow when hot or cold.
In practical UK, French and Italian driving the difference shows up as 15–30% longer winter charging sessions on a 150 kW rapid. In Australia, the bigger risk is sustained 40°C ambient temperatures gradually accelerating calendar ageing if the car sits at 100% in direct sun.
The most persistent myth is that EV batteries 'wear out like phone batteries'. They do not. A phone is charged from 0–100% almost every day on a cheap cell with no thermal management; a car uses 20–80% of a much larger pack on a liquid-cooled chemistry tuned for cycle life. The two systems share a name and almost nothing else.
A second myth is that rapid-charging destroys batteries. Long-term Tesla and Hyundai-Kia fleet data show that cars rapid-charged most of the time degrade only 1–2 percentage points faster than cars charged exclusively at home — a real but small effect well inside the warranty envelope.
A third is that battery replacement is inevitable and ruinous. Out-of-warranty whole-pack replacement is genuinely expensive (£8,000–£15,000 for a mid-size EV), but module-level repair — replacing only the failed group of cells — is increasingly available and typically costs a fraction of that. The repair ecosystem is still maturing and varies a lot by country.
