EV Charging - Frequently Asked Questions
Core EV Questions
A: There is a quick and easy calculation you can do to answer this question. Take the size of your car battery and divide it by the Kw per hour that your charger and cable provide. For example, a Tesla with a 74kW battery will take 10hrs to fully charger from a 7.4kW charger using a 7,4kW EV charging cable. The same Tesla would take 24.6hrs to charge using a 3kW plug in charger.
A: You can now check your EV charging type using our new vehicle checker on our home page. However, there is a quick and easy way to check as well. If you look at the charging socket on your electric car, it will either have 5 or 7 pins. A Type 1 socket will have 5 pins and a Type 2 socket will have 7 pins. If you still have any doubts, please feel free to contact us or read our guide on the difference between a Type 2 and Type 1 Connector.
A: You can calculate the cost of fully charging your EV whether you are at home or using a public EV charger. Simply check your pence per kW with your electricity supplier and times this by the size of your car battery. For example, if you are paying £0.33 per kW with your energy supplier and you have a 74kW car battery, the total cost for a full charger will be 74 x £0.33 = £24.42.
A: A “granny” charger is a portable unit that plugs into a standard 3‑pin UK socket, typically delivering up to 2.3–2.6kW and best suited to slow or occasional top‑ups. A dedicated home or workplace charger is hard‑wired to your electrical supply, can offer higher power (for example 7kW), and is designed for regular, over night or daily use.
A: In most cases, home charging on a good electricity tariff works out cheaper per kWh than rapid public charging. Public rapid chargers are convenient and fast, but you pay a premium for the service and speed.
- 7.4kW (Single Phase): The standard for UK homes. It adds about 25–30 miles of range per hour.
- 22kW (Three Phase): Found in businesses and some modern "smart" homes. It can charge up to 3x faster, but only if your car's onboard charger supports it.
A: Yes. Our chargers work with all major EV brands, including Tesla, BMW, Mercedes, Kia, Hyundai, Nissan, VW, Audi, and more. If your vehicle uses a Type 2 or Type 1 connector, we have a compatible solution. Check out the new vehicle compatibility checker on our homepage, to find the best chargers suited to your car.
A: A portable EV charger is a compact charging cable that allows you to charge your electric vehicle from a standard electrical outlet. Unlike permanently installed wall chargers, portable EV chargers can be used anywhere with access to a compatible socket. They are ideal for home charging, travel, or as a backup charging solution when public charging points are unavailable.Use our guide to explore more about the best charging set up.
Safety & Setup
A: Absolutely. Our chargers are rated IP65 (control box) and IP54 (connectors), meaning they are built for the British weather. The system only "energises" once a secure, sealed connection is made with your car. Find out more about safe charging in the UK weather.
Pro Tip: Try to keep the control "brick" off the ground to prevent it from sitting in standing water during heavy downpours.
A: No. We strictly advise against using standard household extension leads. They are not rated for the high, continuous current an EV draws and can overheat or melt. If you need more reach, we sell specialised 10m and 15m portable chargers designed specifically for that distance. This guide will help you find the right length charger to suit your needs.
A: Every unit we sell is UKCA/CE certified and includes:
- RCD Protection: Trips the power if a leak is detected.
- Over-temperature sensors: Automatically slows or stops charging if the plug gets too hot.
- PEN Fault Protection: Essential for UK safety standards to prevent electric shocks if the grid's "Earth" fails.
A: Yes. A qualified electrician should install any 16A or 32A Commando socket intended for EV charging to ensure safety and compliance.
A: Slow charging can be caused by:
- Low amperage settings
- A cold battery
- Vehicle‑limited charging speeds
- Using a 3‑pin socket
- Electrical load balancing in your home
Our chargers allow you to adjust amperage to suit your power supply, see our safe setup guide.
A: Yes, charging from a 3-pin socket is safe when using all Third Rock Energy’s high-quality portable EV chargers. All of our reliable chargers include features such as over-current protection, temperature monitoring, and RCD protection to ensure safe operation during charging.
A: In many UK locations you are responsible for preventing trip hazards and keeping public areas safe. If a cable must cross a path, it should be covered with a suitable cable protector and must not create a danger to pedestrians; always follow your local council’s guidance.
A: All reputable UK suppliers should openly display the following UK safety requirements on their website and product data sheets. Discover a comprehensive list of all UK Safety Requirements.
Maintenance & Product Care
A: Usually, no. However, if you notice debris or green "oxidation" on the silver pins, wipe them with a dry, lint-free cloth. Never spray water or cleaning fluids directly into the charging head.
A:Yes — our chargers are weather‑resistant and built for outdoor use, provided they are not submerged in water. Explore safe outdoor charging practises.
- Keep the cable clean and free from debris
- Avoid leaving the charger in direct sunlight for long periods
- Inspect connectors regularly for wear
- Store the charger properly when not in use
A: It is normal for charging cables to become slightly warm while in use because electricity is flowing through them. However, they should never become excessively hot. If you notice unusual heat or damage, stop using the charger and contact support.
A: Unplug both ends, coil the cable loosely without tight bends and store it in a cool, dry place, ideally in the Third Rock Energy cable bag. Avoid leaving it on the ground where it can be driven over, soaked in water or damaged by sharp edges.
A: Tightly coiling a cable while it is carrying current can contribute to localised heat buildup and puts stress on the insulation. It is better to lay out the length you need with gentle curves and only loosely loop any excess.
Energy Tariffs & SMART Charging
A: All energy suppliers will now offer EV tariffs and will offer you some useful calculation tools. Rates change all the time so making a recommendation is difficult. However from our experience, here are some of the competitive and easy to use sites.
Octopus Energy: The UK's most awarded energy supplier
A: By switching to a "Time-of-Use" tariff (like Octopus Go or British Gas Electric Driver), you can charge for as little as 7p – 10p per kWh overnight. Many of our portable chargers feature a "Delay Timer,"allowing you to plug in at 6 PM but tell the charger to start at midnight when prices drop.
A: Yes! If you have a solar array, you can use our adjustable-amperage chargers to "match" your solar output. By dropping the charger to 6A or 8A during a sunny day, you can essentially charge your car for free using 100% renewable energy.
A: Most off‑peak EV tariffs require a smart meter so your energy provider can track usage during specific time windows.
A: There are several ways to reduce charging costs, including:
- Charging overnight on off-peak tariffs
- Charging regularly rather than letting the battery fully drain
- Using efficient home charging equipment
- Monitoring electricity usage with smart meters
A: The price you pay per kWh on your tariff directly affects how much it costs to charge your car. Off‑peak or EV‑specific tariffs typically offer much cheaper rates at certain times of day, which can significantly reduce your cost per mile compared with standard flat‑rate tariffs.
A: As long as you set your desired departure time and target charge level, smart charging will aim to complete charging before that time. If you ever need to override the schedule, you can usually start charging immediately via the charger, app or your vehicle settings.
Delivery, Warranty & Returns
A: We offer Free UK Delivery on all orders. Most customers receive their chargers within 2–3 working days. You’ll receive a tracking link as soon as your order leaves our warehouse.
A: We stand by our gear. All Third Rock Energy chargers come with a full 2-year warranty. If your unit develops a technical fault, we will repair or replace it at no cost to you.
A: Yes. We offer a 30-day "No-Hassle" return policy. As long as the charger is in its original condition and packaging, you can return it for a full refund.
A: If you believe your product is faulty, contact our support team with your order number, a description of the issue and, if possible, photos or video. We’ll help troubleshoot and, if the item is covered, arrange repair, replace mentor another appropriate solution in line with the warranty terms.
A: Please contact us via the details on our Contact page with your order number and the item you’d like to return. We’ll confirm eligibility, provide packing and shipping instructions and explain any costs or next steps.