Smart granny chargers and portable EV chargers in the UK: the 2026 picture, and when to skip them

A smart granny charger is a portable EV charging cable that plugs into a household socket and adds an app: you can start and stop the charge remotely, schedule it for cheap-rate hours and see how many kWh went into the car. In the UK it charges at about 2.3 kW from a 3-pin plug, the same speed as a basic granny cable.

It is a useful tool for a renter, a second home or a car that cannot schedule its own charge. It is not needed to get your charging repaid: HMRC asks for reasonable evidence of the car's electricity, not for a specific device. Voltaback, for example, reads each charge from the car itself.

This guide explains what these cables are, what is actually sold in the UK in 2026, how accurate their energy readings are, what the Smart Charge Points Regulations mean for them, and when a fleet should skip them.

The essentials in 30 seconds

• Same speed, more control: a smart granny charger still draws about 10 A (2.3 kW) on a 3-pin plug; the "smart" part is the app, scheduling and energy readings.
• UK market is thin: several well-known European portable chargers are not sold in the UK. What you find are UK-plug Mode 2 cables with an app, car makers' portable cables, and commando-plug portable units.
• Readings are indicative: the meter in a cable is not a certified billing meter. Fine for your own tracking, weaker as proof.
• Tax: HMRC requires no particular meter. What counts is separating the car's electricity from the household's.
• For a company car: you can be repaid in full without buying anything, as long as the charging is measured reliably.

What is a smart granny charger?

"Granny charger" is the UK nickname for the portable cable that charges an EV from a domestic socket. Technically it is a Mode 2 charger: a plug, a cable and an in-line control box that checks the earth, talks to the car and cuts the power on a fault.

A smart version adds a Wi-Fi or Bluetooth module in that control box. Typical features:

• Remote start and stop from a phone app;
• Scheduling, so the charge starts inside an off-peak window;
• Adjustable current (often 6, 8, 10 or 13 A) from the app or a button;
• Energy readings: kWh per session and cumulative totals;
• Temperature monitoring at the plug, with automatic current reduction if it heats up.

It does not charge faster. On a 13 A UK socket, the power is limited by the plug, not the electronics. Most cables default to 10 A, about 2.3 kW, which adds roughly 7 to 8 miles of range per hour. Our guide to charging from a 3-pin plug covers speed and socket safety in detail.

UK plugs: what a portable charger can draw

A portable charger's speed depends on the socket at the other end of the cable.

Most UK homes have a single-phase supply, so the 11 kW and 22 kW portable chargers sold on the Continent bring no benefit at home. The realistic upgrade from a 3-pin plug is a 16 A commando socket on a dedicated circuit, at about 3.7 kW.

What is actually sold in the UK in 2026

The portable charger market is much thinner in the UK than in Germany or the Netherlands. Several premium European portable chargers built around Continental plugs and three-phase supply, such as the Juice Booster and the go-e portable range, are not sold in the UK. Before buying any imported unit, check that it has a UK plug, UK instructions and a UK warranty.

Here is what you will realistically find.

1. Smart Mode 2 cables with a UK 3-pin plug

Several UK accessory brands sell Mode 2 cables with an app. Masterplug, for example, sells a 10 m Mode 2 cable that UK retailers describe as working with the Tuya Smart or Smart Life app, with selectable 6, 8 and 10 A, remote start and stop, off-peak scheduling and energy monitoring; it lists at around £120 to £140. The same brand's shorter and longer models are sold as non-smart, so check the exact model code.

Good for: renters, a second address, drivers whose car cannot schedule a charge. Limits: speed capped at about 2.3 kW; app quality depends on a generic smart-home platform; energy readings are indicative.

2. Car makers' portable cables

Most new EVs come with a portable cable in the boot, and some car makers sell an upgraded one with interchangeable plugs (3-pin and commando). Tesla's Mobile Connector is the best-known example.

Good for: warranty peace of mind; scheduling is done by the car's own app. Limits: usually no separate energy readings in the cable; the car's app shows what went into the battery.

3. Portable units with a commando plug

Some portable chargers come with a 16 A commando plug and a 3-pin adapter. On a dedicated commando socket they reach about 3.7 kW.

Good for: holiday homes, small workplaces, drivers who need more than 3-pin speed but cannot fit a wallbox. Limits: needs a dedicated commando socket fitted by an electrician; check that the unit is sold with UK documentation.

4. The wallbox, for comparison

A fixed 7 kW smart wallbox is not portable, but it is the alternative a portable charger competes with. Fitted, it costs £800 to £1,200 for a standard job, triples the speed and fits a week of driving into the cheap-rate window. Our guide to the cost of installing a home charger gives the line-by-line budget.

Earlier smart portable products from wallbox brands have been withdrawn, which says something about the UK market: most buyers who want "smart" end up with a wallbox, and most who want "portable" keep the car's own cable.

Comparison table

The Smart Charge Points Regulations: do they cover portable cables?

The Electric Vehicles (Smart Charge Points) Regulations 2021 apply to private chargepoints sold for home or workplace use in Great Britain since 30 June 2022. They expressly cover smart cables, defined as a cable that is a charge point and can send and receive information. Non-smart cables and rapid chargepoints are outside their scope.

A smart cable sold in GB therefore has to meet the same core requirements as a smart wallbox: smart functionality, pre-set off-peak default charging hours that the owner can change, a randomised delay, supplier interoperability, a measuring system and security requirements. Sellers must hold a statement of compliance. Source: gov.uk, Regulations: electric vehicle smart charge points.

In practice: a basic granny cable is outside the rules, a UK-market smart cable should comply, and an imported cable with an app bought from an overseas marketplace may not. That is one more reason to buy from a UK retailer.

How accurate is the energy reading of a smart cable?

A smart cable measures the current and voltage passing through it and adds them up into kWh. That gives a useful number, but not a billing-grade one.

• It is not a certified meter. Electricity meters used for billing in the UK are approved to the Measuring Instruments Directive (MID) standards. The meter in a portable cable is not designed or certified for that.
• It measures the cable, not the car. It cannot tell which vehicle was plugged in. If two cars share a cable, or a private car uses the company driver's cable, the reading does not show it.
• It can lose data. A session started while the cable is offline, or a reset of the app, can leave gaps.

For a private driver, that is fine: the reading tells you roughly what each charge costs. For an employer repaying a company car driver, it is a weaker proof than it looks, because the link between the reading and a specific vehicle relies on trust.

Voltaback relies on the home's MID-certified meter, not on a standalone cable meter. The car's own data identifies which vehicle took the energy, and the driver's tariff values it.

Does HMRC require a specific meter?

No. HMRC's guidance on electricity for company cars says that an employer can reimburse the electricity a driver uses to charge a company car at home without a tax charge, under s.239 ITEPA 2003, but that the employer must make sure the payment covers only the company car. Source: HMRC, EIM23900.

There is no rule on a certified meter, an accuracy threshold or a specific device. The burden is reasonable evidence: what was the car's consumption, separate from the household's, and at what price. A cable reading is one form of evidence. A per-vehicle record of each charge, valued at the driver's real tariff, is a stronger one.

An employer that prefers not to collect energy data can instead pay the HMRC Advisory Electricity Rate per business mile: 7p per mile for home charging and 15p for public charging since 1 September 2026. That route needs business miles and the place of charging, not kWh. Source: gov.uk, advisory fuel rates. For the practical side of charging at home, see our guide to charging an electric car at home.

Buying checklist: seven points to check

1. UK plug and UK documentation. A BS 1363 plug moulded on, not an adapter, and instructions written for the UK market.
2. Statement of compliance with the Smart Charge Points Regulations if the cable has an app. A UK seller should be able to provide it.
3. Car-side connector. Type 2 for almost all current models; Type 1 only for some older cars.
4. Selectable current, with 10 A or lower as the default.
5. Temperature sensor in the plug, which reduces the current if the socket heats up.
6. App that works without a cloud account, or at least keeps local control if the Wi-Fi drops. A cable that stops charging when the internet fails is a poor choice.
7. Warranty and support in the UK, so a fault does not mean posting the unit abroad.

If any of these is missing, the car's own cable plus the car's scheduling is usually the safer combination.

When a smart granny charger is worth buying

• You rent and cannot fit a wallbox, and your car cannot schedule its own charge.
• You charge at a second address: a holiday cottage, a partner's home, a family visit.
• You want to track your own costs on a tariff where the car's app does not show kWh.
• You use a small workplace or garage with a commando socket and want a schedule and readings.

When to skip it

• Your car already schedules charging in its app. The basic cable does the same job.
• You drive a lot. Speed is the bottleneck, not intelligence. A wallbox fits more miles into the cheap window.
• Your employer repays your charging. Buying a cable for evidence is unnecessary if the employer measures charging another way.
• The cable comes from an unknown seller. A cheap import without UK compliance is a risk at 10 A for 10 hours.

Why a fleet should not equip every driver with a cable

Some fleet managers consider giving each driver a smart cable to measure home charging. It looks cheap per unit, but the logistics add up:

• Purchase and distribution: one cable per driver, plus replacements when cables are lost, damaged or left behind.
• Adoption: the driver must use that cable, not the one supplied with the car, every time.
• Data collection: each cable has its own app and account; consolidating readings across a fleet becomes a manual job.
• Vehicle identification: the cable does not know which car it charged.
• Speed: the cable keeps drivers on 2.3 kW, which pushes high-mileage drivers to public rapid chargers.

A wallbox for every driver solves speed but costs £800 to £1,200 each and stays at the driver's address. For most fleets, the cheaper path is to measure charging without hardware.

Being repaid without a smart cable

Voltaback is 100 % software. It connects to the car (more than 48 brands), records each charge, identifies where it happened, and values the energy at the driver's own tariff: Intelligent Octopus Go, Agile half-hourly prices, Economy 7, a fixed deal or the price cap.

• No hardware to buy or distribute, whatever socket the driver uses at home.
• Car versus household separated automatically, which is exactly what HMRC asks for.
• Two reimbursement modes: real cost from the driver's tariff, or the HMRC Advisory Electricity Rate per business mile with the charging location measured.
• Privacy built in: UK GDPR compliant, ISO 27001 certified, and the company never receives drivers' geolocation.
• A monthly export ready to import into your payroll software.

See how home charging reimbursement works for company cars, compare options for connected chargepoints in a fleet, and read what to do when the home has no smart meter. If you still want a cable, our charging cable page explains what to check.

Measure the charge, not the cable

A smart granny charger is a good gadget for a driver who needs one. For a fleet, the question is not which cable to buy but how to measure each car's charging reliably and repay it at the right price.

Talk to Voltaback to see how your drivers' home charging can be measured and reimbursed without distributing any hardware.