Battery and health terms
State of Health (SoH)
A percentage showing how much capacity a battery has left compared to when it was new. A pack at 90% SoH holds 90% of its original energy. This is the single most important figure on any used EV.
State of Charge (SoC)
How full the battery is right now, like a fuel gauge. Not to be confused with SoH.
Degradation
The gradual, permanent loss of battery capacity over time. Normal and expected on every EV, typically running at around 2% to 3% a year.
kWh (kilowatt hour)
The unit of battery capacity, equivalent to the size of a fuel tank. A 60kWh battery holds roughly twice the energy of a 30kWh one.
kW (kilowatt)
A unit of power, not capacity. Used for charging speed (a 50kW charger) and motor output. Easy to mix up with kWh.
Usable vs total capacity
Manufacturers hold back a portion of the battery as a buffer to protect it. Total capacity is the full pack, usable capacity is what you can actually access. Usable is the more honest number.
BMS (Battery Management System)
The computer that monitors and protects the battery, balancing cells and controlling charging. Tampering with it typically voids your warranty.
Thermal management
How the battery is kept at a sensible temperature. Liquid cooled packs generally cope better with heat and fast charging than passively air cooled ones, such as the Nissan Leaf's.
LFP (Lithium Iron Phosphate)
A battery chemistry known for long life and tolerance of being charged to 100% regularly, at the cost of slightly lower energy density. Common on standard-range models.
NMC (Nickel Manganese Cobalt)
A battery chemistry offering higher energy density and therefore more range, but generally happier being kept below 100% for daily use.
Cell, module, pack
Cells are the smallest units. Cells are grouped into modules, and modules make up the pack. Faults are often confined to a single module, which is why repair is sometimes possible without replacing everything.
Range terms
WLTP
The official lab test used to quote a car's range. Real-world range is usually lower, often by around 15% to 25%, and more in winter.
Real-world range
What the car will actually do in normal UK driving. This is the figure that matters.
Range anxiety
The worry about running out of charge before reaching a charger. Tends to fade quickly with ownership.
Efficiency (miles per kWh)
How far the car travels per unit of energy, the EV equivalent of miles per gallon. Around 4 mi/kWh is good for a mainstream EV.
Preconditioning
Warming or cooling the cabin and battery while still plugged in, so you don't spend range doing it on the move. One of the most effective winter range tricks.
Charging terms
Type 2
The standard connector for slower AC charging in the UK and Europe, used for home wallboxes and most public destination chargers.
CCS (Combined Charging System)
The standard connector for DC rapid charging, a Type 2 plug with two extra pins below. Fitted to nearly all modern EVs.
CHAdeMO
An older rapid charging standard, now largely obsolete but still found on the Nissan Leaf. Worth checking, as CHAdeMO chargers are becoming scarcer.
AC vs DC charging
AC is slower charging, typically at home or work, and is gentler on the battery. DC is rapid public charging, much faster but harder on the pack over the long term.
Rapid, ultra-rapid
Loose terms for DC charging speeds. Rapid usually means around 50kW, ultra-rapid means 100kW and above.
10 to 80% charging time
The industry's standard measure of rapid charging speed. Charging slows dramatically above 80% to protect the battery, which is why nobody quotes 0 to 100%.
Charging curve
How charging speed changes as the battery fills. All EVs slow down as they approach full.
Wallbox
A dedicated home charging unit, typically 7kW, much faster than a three-pin plug.
Granny cable
The three-pin domestic plug lead supplied with most EVs. Very slow, fine as a backup, not a long-term solution.
Technology terms
Regenerative braking (regen)
The motor slowing the car and recovering energy back into the battery. Saves brake pads dramatically, which is why EV brakes last so long.
One-pedal driving
Strong regen that lets you slow to a stop without touching the brake pedal.
V2L (Vehicle to Load)
The ability to power ordinary appliances from the car's battery, handy for camping or power tools.
V2H (Vehicle to Home)
The ability to power your house from the car.
V2G (Vehicle to Grid)
The ability to export energy back to the electricity grid, potentially earning money.
OTA (Over the Air) updates
Software updates delivered remotely, which can change range, performance and features without a garage visit.
Heat pump
An efficient cabin heating system that uses far less energy than a resistive heater. A significant advantage for winter range, and worth checking whether a used car has one.
Buying and ownership terms
BEV (Battery Electric Vehicle)
A fully electric car with no engine. What most people mean by "EV".
PHEV (Plug-in Hybrid Electric Vehicle)
A hybrid with a plug and a small battery. Note that warranty terms often differ from full EVs, and sometimes don't transfer to later owners.
Capacity warranty
The manufacturer's guarantee that the battery will retain a minimum share of its capacity, usually 70%, within a set time and mileage.
OCN (Original Cost New)
The car's list price when new, used to express residual values as a percentage.
Residual value
What a car is worth after a period of ownership, the flip side of depreciation.
Battery lease
An arrangement where the battery is rented separately from the car, used on some early Renault Zoes and a small number of Nissan Leafs. Affects both running costs and resale.
Cat S / Cat N
Insurance write-off categories. Cat S means structural damage, Cat N means non-structural. Both matter more on an EV, because a write-off marker can invalidate the battery warranty.
Range and battery-health figures are estimates modelled from real-world data and are shown for the specific vehicle in the Used EV Check. Range data is powered by ClearWatt. A battery-health grade is shown where a manufacturer test record exists, it is a comparative grade, not a measured state-of-health percentage.
Now you know the terms, see what they say about a specific car
Enter a registration to see a used EV's battery health, real-world range now vs when new and remaining battery warranty, an instant report for £9.99.
Frequently asked questions
What does SoH mean on an electric car?+
What’s the difference between kW and kWh?+
Is CCS or Type 2 better?+
Related guides
Owning & Running an EV
Electric car running costs
What an EV actually costs to run in the UK: charging, servicing, insurance, tax and tyres, with honest figures and the costs most guides leave out.
Battery & Range
How to check EV battery health
How to check an electric car's battery health before you buy, what a battery health grade means, how to read real-world range now vs when new, and how to check it from just the registration.
Battery & Range
EV battery degradation
How much do EV batteries really degrade? What a normal degradation rate looks like by age and mileage, the warning signs of a tired pack, and how to estimate a used EV's degradation before you buy.