Type 2 to 3 Pin Charging Cable, Granny Charger

The cable for when there is no charge point

Most people call this a granny charger, and the name tells you the job: you are at someone else's house, or a cottage, or a unit with no wall box, and there is a socket. This plugs into it and charges the car slowly overnight.

It is a proper piece of equipment rather than an adapter. The control box between the plug and the car handles the residual current protection and the handshake with the vehicle, and the current can be turned down where the circuit is old or shared.

What to expect from a socket

A household socket gives you roughly 2.3 kW, which is about eight miles of range an hour on a typical car. Left plugged in from six in the evening to seven in the morning, that is in the region of a hundred miles put back.

Times below are computed from the pack size and the power drawn with 13 per cent allowed for charging losses. The range column is deliberately cautious, at 3.5 miles per kWh.

Set the current lower than maximum if the socket is on an old circuit, an extension reel or a shared supply, and give the plug a check by hand after the first half hour. Warm is normal, hot is not.

Which length, and where it plugs in

Pick the length by where the socket is rather than where the car is. A garage socket with the car on the drive outside usually wants ten metres. A socket in a utility room reaching a car on a shared forecourt wants fifteen. Five metres is for a socket within a car length of the inlet.

Run it straight out, not coiled on a reel, and keep the plug indoors or in a weatherproof outdoor socket. The cable is IP67, which is the highest rating we put on anything, but a household socket is not.

How it is built

The three pin version is an IEC 62752 unit, CE marked and IP67 sealed, specified -30C to +60C. The adjustable current, the RCD protection and the display all sit in the moulded control box. Warranty is two years from the manufacturer, delivery free next working day, returns accepted for 30 days.

See also: 3 pin charging cables, Type 2 to Type 2 cable, 5m charging cable and 10m charging cable.

Granny charger questions

What is a granny charger?

A portable EV charger that plugs into an ordinary 13A socket instead of a dedicated wall box. It has a control box built in for protection and current setting, and gives roughly 2.3 kW, so it is a slow overnight charge rather than a fast one.

Is it safe to charge an EV from a three pin socket?

With a purpose built cable like this one, yes, and that is what the control box and its residual current protection are there for. What matters is the socket and the circuit behind it: use a single socket rather than an extension reel, turn the current down on older wiring, and check the plug is not getting hot.

How long does a granny charger take?

Around 2.3 kW means about eight miles of range an hour. A 60 kWh car from empty is more than a day, which is why this is the second cable rather than the first. Overnight it puts back roughly a hundred miles, which covers most daily driving.

Which length should I buy?

Measure from the socket, not from the car. Ten metres is the usual answer when the socket is in a garage and the car is on the drive. Fifteen suits a socket indoors and a car parked away from the house. Five metres only works if the socket is close.

Can I leave it out in the rain?

The cable and the control box are IP67 sealed and rated to +60C, so the cable end of the job is covered. The plug and the socket are not: keep those indoors or in a proper weatherproof outdoor socket.