The Granny Charger is a 3-Pin EV charger that is used to charge an electric car directly from a 13 amp socket.
The best Granny Chargers are durable, portable, and capable of providing a charging solution for EV owners who do not have dedicated home chargers. While they may not boast the speed of their high-powered counterparts, granny chargers offer great convenience for a relatively inexpensive price.
In this article, we review the best granny chargers available in the UK. We investigate the pros and cons and the practical considerations of using a granny charger to plug your EV straight into your home’s 3-pin socket. We explore what product features the best granny chargers should have, look at just how safe granny chargers are and compare the best granny chargers in the UK.
The Best EV Granny Chargers 2023
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What is a granny charger?
A granny charger is a term for a portable EV charger that plugs directly into a standard 13-amp household socket. It has a slower charging speed compared to a dedicated EV charger but provides convenience, especially for occasional or emergency charging needs at home or while on the go. However, granny chargers come with a number of disadvantages: they are significantly less powerful, increase the charge time, and lose the efficiency that comes with a dedicated smart charger.
How does a granny charger work?
In order to plug your EV directly into the mains, you will need to use a 3-pin EV charger, otherwise known as a Granny charger. A Granny charger gets its name from the concept of taking the charger with you to visit family (i.e. dear old Grandmother!) and plugging your vehicle directly into their electricity supply in order to charge for the return journey.
You will likely be supplied a Granny charger by your EV manufacturer, it is a standard 13A plug attached to a cable that attaches to a control box, the box performs some of the functions that you would expect from a dedicated wall box charger – but not all.
Granny chargers offer exceptional versatility. Since they can be plugged into any conventional domestic socket, they offer EV owners the flexibility to charge their vehicles in a multitude of locations — at home, at a friend’s house, or at a holiday rental. For top-up charging, occasional charging, or for those who don’t drive very often, they can be a convenient and cost-effective solution.
A granny charger works in a simple ‘plug-and-play’ style. Here’s how it works:
- Plug and Play: One end of the granny charger features a plug designed to fit a standard 13-amp household socket. The other end connects to the EV’s charging port.
- Built-in Safety: Though it utilises a regular 3-pin socket, the charger often has in-built safety mechanisms, such as circuit protection, to prevent overloading and ensure safe charging.
- Charging Process: Once connected, electricity flows from the mains supply through the charger and into the EV’s battery. Given its design for standard sockets, the power output is typically around 2.3kW to 3kW, which means charging is slower compared to dedicated EV charge points.
- Visual Indicators: Most granny chargers come with LED indicators that show the charging status – whether it’s actively charging, complete, or if there’s a fault.
- Completion: Once the EV’s battery is full, the granny charger automatically stops the flow of electricity, ensuring the vehicle doesn’t overcharge. After charging, it’s as simple as unplugging the charger from both the socket and the vehicle.
Advantages of using a granny charger
Let’s look at the pros and cons of using a Granny charger:
One of the most significant advantages of a granny charger is its convenience. You can plug it into a standard 13 amp 3-pin electrical outlet, so it’s easy to use at home or anywhere with a power supply.
- Granny chargers are cheap
Since granny chargers often come with the purchase of an EV and don’t require any additional installation, you may already have one! If you need to buy one, you will find even the best granny chargers are inexpensive when compared to the cost of a dedicated EV charging station.
- Emergency Charging
Having a granny charger handy is a great backup charging solution. If you can’t get to your usual charging point and are concerned about running out of battery, a granny charger can ensure that you can still charge your vehicle.
Disadvantages of using a granny charger
- Slow Charging Speed
Granny chargers are SLOW. While the exact rate can vary depending on your vehicle, generally, it’s safe to say that granny chargers offer the slowest charging speed compared to dedicated chargers. This makes them less appealing for owners who frequently drive long distances.
- Electricity Load
Granny chargers use standard electrical outlets not specifically designed for EV charging. This means that extended periods of charging could put a strain on your home’s electrical system if it’s not equipped to handle the load. If you are unsure if your electrical system can handle it, you should get an electrician to inspect your electrics.
- Lack of Smart Features
Unlike smart chargers (more on that below), granny chargers typically lack features such as remote monitoring or scheduling of charging times to take advantage of the best EV off-peak electricity rates.
What KW does a granny charger operate at?
When you use a granny charger in the UK it operates at a power rate of 2.3kW, this means the charger can deliver energy to your EV’s battery at a rate of 2.3 kilowatts every hour.
So if your EV’s battery capacity is 23kWh (kilowatt-hours), it would theoretically take about 10 hours to charge from entirely empty to full using a 2.3kW granny charger,
How long does it take to charge an electric car with a granny charger plug?
The rate of charge using a 3-pin plug in a regular UK power outlet is 2.3 kWh. In terms of how long this will take to charge an EV, if you are planning to completely charge a battery from empty at 2.3kWh then it could take up to 2 days depending on the type of vehicle and size of the battery.
In order to calculate exactly how long it will take to charge your car from a regular 3-pin plug, you need to know the capacity of your vehicle’s battery.
For example, if your EV has a 40kWh battery and is completely empty, it would take approximately 17 hours to fully charge it with a granny charger (40kWh ÷ 2.3kW = roughly 17.4 hours).
This is obviously very slow and at first glance not very practical, however, if you consider the fact that most of the time you may just be topping up a partially charged battery, and not need to use a granny charger to fully charge your battery, it may not be as inconvenient as it appears.
Are EV granny chargers waterproof?
The question ‘Are Granny Chargers Waterproof’ is an important one given that many EV owners might find themselves charging their vehicles outdoors, exposed to various weather conditions.
Granny chargers are designed for outdoor use and are built to handle everyday environmental factors. Most of them come equipped with an Ingress Protection (IP) rating, which basically gives you a rating of how waterproof it is.
A granny charger with an IP rating of IP65 would be dust-tight and protected against water projected from a nozzle. Those with higher ratings, such as IP67, can even withstand being submerged in water up to a meter deep for around 30 minutes.
The majority of granny chargers are water-resistant, they are likely not fully waterproof. This means you can use them to charge your electric car in the rain but they may not fare well if totally submerged in water!
If you use a granny charger outdoors:
- Check the IP Rating: Before purchasing, look at the charger’s IP rating to understand its level of water resistance.
- Position Thoughtfully: Avoid placing the charger in areas that get puddles or flooding.
- Regular Inspection: Periodically check for any wear and tear, especially if the charger is frequently used outdoors.
Always read the manufacturer’s guidelines to work out the waterproofing IP number and safety instructions.
Is it safe to use granny chargers for a long time?
Are Granny Chargers safe? Well, they are safe but it’s not recommended that you use a granny charger for prolonged periods. If do have to use it for a long time, make sure you monitor it and look for any signs of overheating.
Make sure the electrical socket used for charging is in good condition and able to handle the load of continuous charging, older or damaged sockets could pose a risk.
Don’t cover the charger if you are using it for a long time (or even a short time!) as it will overheat.
How to compare Granny Chargers
The are a lot of Granny Chargers to choose from in the UK, so which one should you opt for? Let’s review the must-have features of the best granny chargers in the UK:
- Available in various lengths: Everyone’s parking situation is different, so having the option to choose between a 5m, 10m or even 15m cable length is crucial. Whether you’re parked close to the house or a bit further away, you want a cable that fits without falling short.
- 100% dust and waterproof: The wonderful UK weather means your granny charger needs to be able to withstand the elements. A charger that’s both dust and waterproof does this come rain or shine.
- Extended warranty: A long warranty speaks volumes about the manufacturer’s confidence in their product.
- Safety features: Electrical equipment needs a high safety standard, the best granny chargers should come with electrical current protection and short-circuit protection.
- User-friendly design: A good granny charger should have an intuitive design. This includes clear LED indicators for charging status and a durable build.
Can I use an extension lead when plugging an EV into the mains?
Yes, it is OK to use an extension cable to charge your EV, but try not to use an extension lead for prolonged periods when using a granny charger.
EV manufacturers do actually advise against using an extension lead to charge an EV directly from the mains. This official advice is based on the fact that extension leads are much narrower than Granny chargers and therefore less suited to handling the current required to charge an electric car.
The flex of the cable is generally lighter and less durable and therefore not suited to sustained outdoor use.
It’s much safer to plug your granny cable directly into a mains outlet. If your charging cable isn’t long enough to reach your vehicle, you can buy a longer granny cable rather than an extension.
If using an extension lead is unavoidable, make sure that it’s specifically designed for outdoor use and the high electrical load.
The Best Extension Leads for EV Granny Chargers
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IP66 WATERPROOOF RATING
IP66 WATERPROOOF RATING
IP66 WATERPROOOF RATING
EASY STORAGE DESIGN
What Makes the Safest EV Extension Lead?
Safety is paramount when dealing with electric vehicle charging. Generally speaking, EVs are safe during the carging process but what about with extension leads? Given the very high currents, ensuring that you’re using the safest possible extension lead is crucial.
So how do decide on the safest expansion lead option? Here are the features of a safe extension lead:
Certifications and Standards
Ensure the extension lead conforms to UK safety standards. Look for marks of certification from recognized testing bodies, assuring that the product has undergone rigorous testing and meets the required safety criteria.
The best extension leads use top-tier materials that can withstand wear and tear. This includes robust insulation materials that resist degradation and high-quality metals.
Adequate Cable Thickness
The thickness, often denoted by its cross-sectional area in mm², should be appropriate for the current it’s meant to handle. A thicker cable can typically carry higher currents without overheating.
For outdoor use, it’s essential for the extension lead to be waterproof.
Secure and Robust Connectors
The connectors should fit snugly, ensuring a stable connection. Loose connections can lead to arcing and potential fire risks.
A safe extension lead will have clear markings, indicating its maximum current capacity, voltage, manufacturer details, and other essential specifications.
Built-in Safety Mechanisms
Features like circuit breakers or fuses add an extra layer of protection, preventing electrical overloads
Does preheating my EV affect my rate of charge from a granny charger?
EV manufacturers recommend you preheat your car before you set out whilst you are connected to your charge point. This allows you to preheat your car without taking energy directly from the battery and effectively reducing the range of the vehicle.
If you are charging your car from the mains supply and not using a dedicated charger, in some circumstances the rate of charge may not cover the basic features of the vehicle such as the heater or the air conditioning.
Therefore if you are seated in your vehicle on a cold day whilst charging from a normal 240-volt UK power socket, the rate of charge is so slow the battery could start to decrease instead of increasing!
Is it safe to leave EV plugs in granny charger sockets?
Generally, yes it is safe to leave an EV charger plugged into a socket when it’s not in use. Modern EV chargers are designed with safety features that prevent power from flowing unless they are connected to a vehicle, meaning that leaving one plugged in should not pose a safety hazard.
What are the benefits of using a dedicated EV charging unit instead of a granny charger?
Installing a home charger to charge your vehicle is the most time-efficient and energy-efficient approach.
In terms of speed, you can expect a 7kWh charger to take an average of 4.5 hours to charge your vehicle (this will vary depending on model & battery size). It can take between 20-40 hours to charge using a 3-ping plug and a standard UK electricity outlet.
The energy efficiency of using a dedicated charger is another advantage over a 3-pin plug. With a dedicated charger, you have the ability to schedule your charging time. This is a neat feature of dedicated chargers that you will not get from plugging your car directly into the main electricity supply. If you set your EV to charge at off-peak hours (typically during the night) then you should benefit from a cheaper energy price.
There are many other features offered by a dedicated EV smart charger
that you cannot get by plugging your electric car directly into a regular outlet. Some EV charging models offer voice-activated features so you can just yell at the charge station when it’s time to start or stop charging. Safety features in your dedicated home charger protect your vehicle and the device from damage, for example, if there is an electrical fault the dedicated charger is able to detect this and cease its flow accordingly.
The final word on the best granny chargers in the UK
There are plenty of benefits to using a dedicated EV granny charger instead of charging your EV direct from a regular outlet:
- Safety features are better in dedicated chargers and UK houses tend to have dated electricity systems that are not designed for a long period of sustained charge
- The battery charge time is far slower if you plug your EV into a standard power outlet
- Using a schedule on a dedicated charger will save you money by allowing you to charge at times when the electricity price is lower
Despite the benefits of a dedicated charger, personal circumstances will ultimately dictate if it’s practical to use a standard wall socket to charge your EV. If your commute is a short distance and you do not drive a huge amount of miles outside of work, using a granny cable connected to a standard outlet is a solid option.
Premium chargers have features such as overheating protection, ground fault circuit interruption, and waterproofing.
Most of the time granny chargers will be used outdoors, so they need to be heavy-duty. The length and flexibility of the 3-pin charging cables play a pivotal role. Lpting for a longer cable offers varied parking options relative to the power outlet.
Granny chargers are simple to use for a plug-and-play approach. Some granny chargers come with smart charging intelligent features such as scheduled charging, remote monitoring, or even compatibility with home energy systems.
There may be other options available to supplement your car’s charging without the need for a dedicated home wall box charger. Does your workplace have a charger you can use to top up? Or are you located near a supermarket with free EV charging? If so it may not be necessary to purchase a dedicated unit, charging via a standard outlet may be sufficient if you are able to supplement the charge elsewhere.
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John is the Editor and Spokesperson for Electric Car Guide.
With over 20 years of writing experience, he has written for titles such as City AM, FE News and NerdWallet.com, covering various automotive and personal finance topics.
John’s market commentary has been covered by the likes of The Express, The Independent, Yahoo Finance and The Evening Standard.