Granny Charger vs Home Wallbox

This is a mileage question, not a speed question.

Work out two numbers: how many miles you drive on a normal day, and how many hours the car sits at home. If a granny charger replaces the first within the second, it is sufficient — and a faster unit buys you capability you sleep through.

For most people driving ordinary daily distances, an overnight granny charge covers it. The wallbox earns its cost when it does not.

A note on this comparison: this rests on how each supply delivers power and on manufacturers' published guidance, not on units installed and measured here. The socket and circuit behind a granny charger are an electrician's assessment and nothing here substitutes for one. See how we test.

What actually separates them

Rows one and two are the decision. Everything else is a refinement of it.

The case for the granny charger

It is very often enough, and it is already in the boot

An ordinary daily commute is a small fraction of a modern battery. Replacing that fraction over eight or ten parked hours is well within what a domestic supply does.

If that describes your driving, the wallbox buys speed you are asleep for.

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It works away from home

A relative's house, a holiday cottage, a workplace with an outdoor socket and permission. The wallbox cannot do any of that, and it is the one clear advantage the cable retains at any mileage.

For a plug-in hybrid it is usually the whole answer

Small battery, overnight charge, done. This is the strongest case on the page for not installing anything.

The case for the wallbox

It changes what a bad day costs

The real argument is not the daily commute — it is arriving home nearly empty and needing the car in the morning. A granny charger may not recover that overnight. A wallbox usually does.

If your driving is irregular rather than merely long, that is the case for installing one.

It is designed for the duty

Weatherproof, fixed, on its own protected circuit, intended to run at its rated load for hours every night. A domestic socket doing the same job is doing something it was not primarily designed around, which is why the socket assessment matters.

Check your car's onboard limit first

The most common disappointment in this category. The car's onboard AC charger sets the ceiling, and a more capable box does not raise it. Look up your own car's AC rate before paying for headroom it cannot use.

Where the cheaper option is genuinely enough

Measuring your mileage for a month first. Most people's estimate of their own daily distance is wrong, usually in the direction that changes this decision. It costs nothing and it is the only input that matters.

Charging where the car already sits. If it is parked for hours at a workplace or near a public post as part of your normal week, home charging may be solving a problem you do not have.

Fixing the socket rather than replacing the system. If a granny charger suits your mileage and the only objection is that the arrangement is untidy or exposed, that is a small job rather than an installation.

Who should pick which

Granny charger if you drive ordinary daily distances, the car sits at home overnight, and an electrician has looked at the socket. This is most people and it is under-said.

A wallbox if your daily mileage is high, your driving is irregular enough that you sometimes arrive nearly empty, or the car has a large battery you regularly use most of.

A wallbox anyway if the granny charger arrangement means a cable through a window or across a walkway. That is not a speed problem, it is a safety one, and it is a legitimate reason on its own.

Neither if you have no off-street parking. Running a cable across a public pavement is a hazard and is restricted in many places; the answer is a public charging routine.

The part that is not a shopping decision

The socket and the circuit. A granny charger draws a substantial current continuously for hours — a materially different duty from the kettle-and-vacuum pattern most domestic sockets live with. Aged wiring, a worn socket, a long spur or a circuit already carrying other things all matter, and none of them is visible from the outside.

Have it assessed before making a habit of it, and follow the manufacturer's instruction about extension leads, which is generally not to use one. If the cable does not reach, that is an argument for a properly installed outdoor point rather than for a longer lead.

Where the cable itself should live once you have chosen, and what actually damages it, is in where the charging cable lives.