EV Charging Glossary: Every Term Explained

EV charging has its own vocabulary, and most of it comes down to a few simple ideas: the plug shape, how fast the power flows, and who or what is controlling the speed. This glossary explains the terms you are most likely to meet in plain English, so you can read a product listing, a charger spec, or a help article without second-guessing yourself. If you want the wider picture first, start with our EV charging guides, then come back here whenever a term trips you up.

Where a word deserves a fuller explanation, we have linked to a dedicated guide. Everything here is written for UK drivers, so you will see references to RCDs, 13A sockets, wallboxes and the usual British kit.

Connectors and cables

This is where most confusion starts. The connector is the shape of the plug, and the cable is the lead that carries the power. Getting these right matters more than almost anything else when you are buying.

Tethered

A charger with the cable permanently attached, like a fuel pump. Convenient because the lead is always there, but you are tied to its length and connector type.

Untethered

A charge point with just a socket, so you bring your own cable. More flexible, and the reason a good EV charging cable matters. Our cable length guide helps you pick the right reach.

Charging lead vs supply cable

The charging lead is the cable between the car and the charge point, defined by its length, its connector (Type 1 or Type 2) and its current rating in amps. A supply cable usually refers to the fixed wiring that feeds the charger itself, which is an electrician's job, not something you plug in.

Charging speeds and power

Speed is where the biggest myths live. The headline number is often decided by your car, not your cable or charger. A bigger cable never beats the car's own limit.

AC vs DC charging

AC is alternating current, the type that comes from your home supply and most public destination points. The car's onboard charger converts it to DC to fill the battery. DC charging feeds direct current straight into the battery at much higher power, which is why rapid and ultra-rapid points are DC.

kW vs kWh

kW (kilowatts) is the rate of power, how fast energy flows. kWh (kilowatt-hours) is the amount of energy, roughly how much is in the battery. A 7kW charger adding energy for an hour delivers about 7kWh, battery conditions allowing.

Charging speed tiers (3.6, 7, 11, 22, 50kW)

Rough bands you will see quoted. 3.6kW and 7kW are common single-phase home speeds. 11kW and 22kW are three-phase AC speeds, and your car's onboard charger has to support them to benefit. 50kW and above are DC rapids. See 7kW vs 22kW for which makes sense at home.

Single-phase

The standard UK domestic supply, which typically supports home charging up to around 7.4kW. Most homes are single-phase.

Three-phase

A heavier-duty supply that can deliver 11kW or 22kW AC, more common in commercial settings than UK homes. Our guide on single-phase vs three-phase explains whether it is worth chasing.

Onboard charger

The component inside the car that converts AC to DC and sets the maximum AC speed the car can accept, commonly 7.4kW or 11kW. If your onboard charger caps at 7.4kW, a 22kW charger or cable will not make AC charging any faster.

Charging curve and taper

On DC rapids the rate is not constant. The car usually charges fastest when the battery is low and warm, then tapers as it fills, often slowing noticeably past around 80 percent. This is the car protecting the battery, not a fault.

Home and grid

These terms crop up when you have a charger installed or look into how the house supply copes.

Wallbox

The wall-mounted home charge point, typically delivering up to 7kW on a single-phase supply. It can be tethered or untethered. For what fitting one involves, see home charger installation.

Granny charger (portable charger)

A portable lead with a control box that plugs into a normal 3-pin socket. Slow by design, around 2.3kW, and best seen as a backup rather than a daily charger. We stock these as portable EV chargers, and our granny charger vs wallbox guide weighs them up.

ICCB (in-cable control box)

The box partway along a portable charger that handles safety and communication with the car. It usually has status lights and sometimes a reset button, and it needs a sound, dedicated socket to work reliably.

DNO

Distribution Network Operator, the company that runs the local electricity network. Installing higher-power charging may need you or your installer to notify or get approval from the DNO.

Load management (CT clamp)

A system that stops your charger overloading the house supply. A CT clamp (a sensor on the incoming supply) measures how much the home is drawing and tells the charger to back off when demand is high, then ramp up again later.

Smart charging and tariffs

Modern charging is often scheduled rather than constant. Knowing these terms helps you work out why charging sometimes starts, pauses or stops on its own.

State of charge (SoC)

How full the battery is, shown as a percentage. Many drivers set a daily limit such as 80 percent to look after the battery, and charging stops when that figure is reached.

Smart charging

Charging controlled by software, usually through the car, the charger app, or your energy tariff, so it runs at the cheapest or greenest times rather than the moment you plug in.

Off-peak tariff

An electricity plan with cheaper overnight rates, designed for EV owners. Brands such as Octopus and OVO offer EV tariffs, and the charger or car can be told to charge only in that window.

Preconditioning

Warming the battery (and sometimes the cabin) before charging or driving. A warm battery accepts charge faster, especially on DC rapids, so many cars precondition automatically when a rapid stop is set in the sat nav.

V2L (vehicle to load)

Using the car's battery to power external devices, like a tool or a kettle, through an adaptor or built-in socket. The energy flows out of the car rather than in.

V2G and V2H (vehicle to grid, vehicle to home)

Two-way charging where the car can feed energy back to the grid (V2G) or into the home (V2H). Still relatively uncommon in the UK and needs compatible hardware, but increasingly talked about.

OZEV and chargepoint grants

OZEV is the Office for Zero Emission Vehicles, the government body behind various EV grant schemes. Eligibility and what is available change over time, so check the current rules before counting on any support.

ISO 15118 and plug and charge

A communication standard that lets the car and charge point talk to each other automatically. Plug and charge means you simply connect and the session starts and bills itself, with no app or card needed, where both ends support it.

Destination charging

Slower AC charging at places you stay a while, like hotels, car parks and supermarkets. The idea is to top up while you do something else, rather than wait at the point.

Rapid vs ultra-rapid

Loose labels for DC public charging. Rapid generally means around 50kW, while ultra-rapid refers to much higher-power points. Your actual speed still depends on the car, its state of charge and the battery temperature.

Safety and electrical

These terms are about protection. You do not need to be an electrician to understand them, but anything involving the fixed wiring or repeated faults is a job for a qualified professional.

Mode 2

Charging through a portable lead with an in-cable control box, typically from a domestic socket. This is what a granny charger uses, and it is the slower, backup method.

Mode 3

Charging through a dedicated AC charge point such as a wallbox or public post, with proper communication between car and charger. This is standard home and public AC charging.

RCD (residual current device)

A safety device that cuts the power quickly if it detects current leaking to earth, protecting against electric shock. If an RCD keeps tripping when you charge, stop and get the setup checked rather than resetting it repeatedly.

RDC-DD and 6mA DC detection

EV charge points must guard against DC fault current. This is done either with a Type B RCD, or a Type A RCD plus 6mA DC fault detection, or a charger with that protection (RDC-DD) built in. Your installer handles this, and it is not something to bypass.

Cable current rating (amps)

The maximum current a charging lead is built to carry, often 16A or 32A, which maps to roughly 3.6kW or 7kW on single-phase. An under-rated lead caps your speed, so match the cable to your charger. Our cable sizing guide covers this in detail.

When a cable gets warm or hot

A lead running mildly warm under load is normal. Hot to the touch, discoloured, smelling of burning or showing any melting is not. Stop charging, unplug at the source, stop using that cable or socket, and get it checked. Do not try to repair a damaged lead: replace it.

Handy tools: put the jargon to use with our free cable length, charging time and charging cost calculators.

Frequently asked questions

What is the difference between Type 1 and Type 2?

Type 1 is an older five-pin AC connector with no lock and single-phase only, while Type 2 is the UK and European standard with seven pins, a locking latch and support for single and three-phase. Most UK charging uses Type 2. Our Type 1 vs Type 2 guide covers it in full.

What does kW mean versus kWh?

kW is the rate of power, how fast energy flows, and kWh is the amount of energy delivered or stored. Roughly, a 7kW charger running for an hour adds about 7kWh, depending on battery conditions.

What is a granny charger?

A granny charger is a portable lead with an in-cable control box that plugs into a standard 3-pin socket. It charges slowly, around 2.3kW, and is best kept as a backup rather than your main way of charging.

What is CCS?

CCS stands for Combined Charging System. It is a Type 2 socket with two extra large pins below it for high-power DC rapid charging, and it is the standard DC inlet on most new EVs sold in the UK.

Why does charging slow down as the battery fills?

This is the charging curve, and it is normal. On DC rapids especially, the car charges fastest when the battery is low and warm, then tapers as it fills, often slowing noticeably past around 80 percent to protect the battery.

What is smart charging?

Smart charging is when software, through the car, a charger app or an energy tariff, controls when charging happens so it runs at cheaper or greener times. It is why charging can start, pause or stop by itself overnight.