Skip to content
Northline Post.

Explained

The concepts behind the coverage: what the terms mean, how the technology works, and which numbers are worth arguing about. Each one written once and kept current.

EV & mobility

Four plugs, three markets, and where the rectifier sits

The connector on the car is a regional decision, not a technical one. What actually separates charging types is whether the conversion from alternating to direct current happens inside the car or inside the charger.

Updated 17 Sept 2026 · Explainer · 2 min

Batteries & energy

From cell to pack, and what cell-to-pack took out

A car battery is built in three layers, and each one adds mass that stores no energy. Removing the middle layer is why a pack figure and a cell figure have moved apart.

Updated 17 Sept 2026 · Explainer · 2 min

The one number the electric car investment case turns on

Battery cost per kilowatt-hour decides whether an electric car can be sold at a profit. The figure is quoted constantly and defined loosely, and cell price and pack price are not the same number.

Updated 17 Sept 2026 · Explainer · 2 min

What a 70 per cent warranty floor actually commits a maker to

Batteries lose capacity through two separate mechanisms, only one of which is driving. Here is what degrades a pack, what a state-of-health figure means, and what the standard warranty does and does not promise.

Updated 17 Sept 2026 · Explainer · 2 min

Mobile phones

The same model number is a different radio in three markets

Mobile networks run on licensed frequency bands, and those bands differ by country. A phone supports a fixed list of them, so an imported handset can be fully functional and still lose service where a local one does not.

Updated 17 Sept 2026 · Explainer · 3 min

The chip in a phone is five processors in a trench coat

A phone's chip is not a CPU. It is a system-on-chip bundling a processor, a graphics unit, a neural engine, an image signal processor and usually a modem, and the marketing name covers all of it at once.

Updated 17 Sept 2026 · Explainer · 3 min

Every term, A to Z

Band
A named slice of radio spectrum an operator is licensed to use, defined by 3GPP as a number such as n78. Two phones sold under the same model name can support different sets of them.
C-rate
Charge or discharge power divided by pack capacity. A 100 kWh pack taking 200 kW is charging at 2C, which says more about the stress on the cells than the raw kW figure does.
Calendar ageing
Capacity lost with time regardless of use, driven mainly by temperature and by how long the pack sits at a high state of charge.
CCS
Combined Charging System. An AC connector with two DC pins added below it, so one socket serves both. Combo 2 is the European variant, Combo 1 the North American.
Cell
The electrochemical unit: anode, cathode, separator and electrolyte in one container. The only part of a battery that stores energy.
CLTC
China Light-duty Vehicle Test Cycle. The Chinese procedure that replaced NEDC for new type approvals from 2021. Lower average speed than WLTP, which flatters an electric car.
Cost per kWh
The price of a battery divided by its energy capacity, the standard unit for comparing batteries across sizes. Quoted at either cell or pack level, which are materially different numbers.
Cycle ageing
Capacity lost through charging and discharging. Counted in full equivalent cycles, so two half charges count as one.
Emissive display
A panel where each pixel generates its own light, as in OLED. Black costs no light and therefore no power, which is what gives the technology its contrast ratio.
EREV
Extended-range electric vehicle. A series hybrid in which the combustion engine drives a generator only and has no mechanical path to the wheels.
Gravimetric energy density
Energy stored per unit mass, in watt-hours per kilogram. Quoted at cell or pack level, and the two differ substantially.
Kilowatt (kW)
A unit of power: the rate at which energy moves, at one instant. A motor's output and a charger's speed are both rates, so both are quoted in kW.
Kilowatt-hour (kWh)
A unit of energy: one kilowatt sustained for one hour. A battery's capacity and a car's consumption are amounts, so both are quoted in kWh.
Milliamp-hour (mAh)
A unit of electric charge: a thousandth of an amp flowing for an hour. It becomes an amount of energy only once you know the voltage it flows at, which is why it cannot be compared between batteries of different voltage.
mmWave
5G on frequencies above roughly 24 GHz. Very high capacity over very short distances, stopped by walls and by rain, which is why it is deployed in stadiums and airports rather than across a country.
Module
A group of cells in a shared housing with its own wiring and monitoring. The intermediate layer that cell-to-pack designs remove.
NEDC
New European Driving Cycle. Withdrawn in Europe in favour of WLTP and in China in favour of CLTC, but still attached to older listings and press material.
Neural processing unit (NPU)
A block built for the multiply-and-accumulate arithmetic that machine-learning models are made of. Quoted in TOPS, trillions of operations per second, which says nothing about which models actually fit.
Nit
A unit of luminance, one candela per square metre: how much light a surface sends toward the viewer. It measures the screen's output, not the light falling on it, which is why a sunlit screen needs more nits rather than fewer.
Nominal voltage
The average voltage a cell holds across a discharge, not its peak. A single lithium-ion cell is usually quoted at about 3.8 volts; two in series are quoted at roughly twice that.
Onboard charger
The rectifier inside the car that converts alternating current from the grid to the direct current the battery needs. Its rating, typically 7 to 22 kW, is the hard ceiling on AC charging speed.
Pack price
The cell price plus the module and pack hardware, wiring, thermal management, battery management system and assembly. Always higher than the cell price.
Parallel hybrid
A layout where both the engine and the motor can drive the wheels, together or separately.
Peak brightness
The luminance a panel reaches on a small fraction of its area for a short time, typically for a highlight in HDR content. It is not a level the whole screen can sustain.
Series hybrid
A layout where the engine generates electricity and the motor alone drives the wheels.
State of health (SoH)
Current usable capacity as a percentage of the pack's original capacity. A measure of ageing, and not to be confused with state of charge, which is how full the pack is right now.
Sub-6
5G on frequencies below roughly 6 GHz, which is where almost all real 5G coverage lives. It travels far and penetrates buildings reasonably well.
System-on-chip (SoC)
One piece of silicon carrying several different processors plus the memory controller and interconnect that link them. A phone has one where a desktop has a CPU, a graphics card and a chipset.
Tank-to-wheel efficiency
The share of the energy stored on board that reaches the wheels. It excludes what was spent producing the fuel or the electricity, which is the separate well-to-wheel question.
Thermal throttling
The chip reducing its own clock speed to stay inside a temperature limit. It is why a benchmark run cold and the same benchmark run for ten minutes give different answers.
Torque
The twisting force at the driveshaft. What accelerates a car, as distinct from power, which is torque multiplied by how fast it is turning.
Watt-hour (Wh)
A unit of energy: one watt drawn for one hour. mAh times nominal voltage, divided by a thousand. It is what airlines regulate, what the EU requires on a label, and the only battery figure that compares across devices.
WLTP
Worldwide Harmonised Light Vehicles Test Procedure. The laboratory cycle used for type approval in the European Union since 2017, and the figure quoted on European price lists.