18th January 2022
by Ohme


Do I need a mobile phone signal for Ohme to work?

Yes, Ohme requires a 3G/4G mobile phone signal to work as a smart charger. You will still be able to use your charger without phone signal, but you won’t be able to benefit from Ohme’s smart charging capabilities.

What networks does the Ohme charger connect to?

All of our wall chargers and cables contain a 3G/4G SIM that connects to the big four networks: Three, EE, O2 and Vodafone. The unit will connect to whichever signal is strongest in your area.

How much does it cost to charge an electric car with Ohme?

The Ohme cable and app allows users to sync their EV charging to their electricity tariff – to ensure they automatically charge when electricity is cheapest. 

Used in conjunction with a time-of-use tariff, Ohme can help drivers get their running costs as low as 2p/mile, compared to more than 10p/mile for most petrol and diesel cars. 

How long does it take to charge an electric vehicle with Ohme?

The Ohme cable can charge up to 7kW (up to 2.4kW for the 3-pin cable variant), which is about 25 miles per hour. Ohme will optimise your charge according to your personal charging preferences, finding the best time to charge within your window.  

If your plans change, the app allows you to bypass all charge schedules and simply charge as quickly as possible. The next time you plug in, Ohme will revert to your charging schedules and apply all your preferences. 

How much can I save with Ohme?

When used with a dynamic time-of-use tariff, savings of £300 per year are readily achievable.

How fast can I charge my car with an Ohme cable?

The Ohme cable has three different input connectors, each with the same smart charging capabilities: 

  • 3-pin plug: Plug this into a household socket – this can charge up to 2.4kw and allow a max of 10A 
  • Commando: Ask your electrician to install a socket – this can charge at up to 7kw and allow a max of 32A 
  • Type 2: Plug into your existing untethered chargepoint – this can charge up to 7kw and allow a max of 32A 
  • A typical time taken to charge an EV with the 3-pin variant is around 8-10 hours. With the type 2 or commando variants that time is halved, allowing a great charge time of 4-5 hours on average. Please note, this will depend on the size of your car’s battery. 

How do the Charge Schedules work?

The Charge Schedules are your default charging preferences, for instance “charge to 80% by 7am on weekdays”. When you plug in your car, Ohme will choose the schedule that will be active next and turn it into a charging profile for the current charge. For example, if you plug in your car on a Tuesday evening at 7pm, then using the above Charge Schedule Ohme will finish charging by Wednesday morning at 7am. Charge Schedules allow you to simply plug in and charge your car according to your preferences by the required end time without the need to do anything further. You can always change the settings of an active charge session without affecting your default Charge Schedules.

How does Ohme work if I do not have access to my car’s API?

Some vehicle manufacturers provide access to an API. An API is a service that allows you to get information from the vehicle, usually to a smartphone app provided by the vehicle manufacturer 

If you do not have access to the API, or your vehicle manufacturer does not provide one, then using Ohme is slightly different. Instead of using Charge Schedules to specify what state of charge you would like the battery to be in at the end of the charge session, you create a Charge Schedule that specifies how many miles you would like to add to the current range.  

For more information, please see ‘Choosing the correct type of schedule for your vehicle: Charging without API Support’. 

What happens if Ohme temporarily can’t access my car API?

If you have connected the vehicle API to Ohme, and Ohme temporarily can’t access it when you plug in your car then Ohme will assume that the battery is empty. This “worst-case” assumption is to ensure that your car has the range you need for your next journey. In this situation, it is quite common for your car to reach full charge before the end of the charge session, in which case Ohme will let you know that the car is not charging as expected.

Does Ohme still work if I have a fixed electricity tariff?

Yes, although Ohme will not be able to save you money. You will still be able to manage your charging to lower the carbon footprint of your driving and help improve battery health.

Why do all the LEDs light up when I touch the front of the charger?

This happens because Ohme has a hidden touch sensitive button that when double tapped, will enlarge the QR code on the screen, as well as display the device’s serial number.

What is ‘Max Charge’?

Max charge will temporarily disable all Charge Schedules and simply charge your car at full power until it is full. It temporarily turns your Ohme charger into a “dumb charger”. You should switch to max charge when you need a quick and uninterrupted charge, or when charging at public charge points where you wish to charge as quickly as possible.

Why is my ‘Never Charge Above’ price cap being ignored?

For a price cap to be effective, you will need to ensure you have created the price cap, enabled it, and have a charge schedule active. Otherwise Ohme will act as a dumb charger and charge your electric vehicle to full as soon as possible.

What do the Money values in the app mean?

Ohme prefers charging at the cheapest rates, so make sure you select your electricity tariff during sign-up. We also use your tariff information to calculate your charging costs as follows: 

  • Cost: The total cost estimated for the current or last charging session. 
  • Cost per mile: This value shows you the energy cost for each mile of driving. It is calculated based on your car’s rated efficiency and the cost of energy for the current charge schedule. 
  • Savings over Standard Tariff: This value is an estimate of your cost savings compared to being on a typical “Big Six” standard energy tariff.  

Don’t worry if you skipped this step, you can always change your electricity tariff in ‘settings’. 

Can I lock my charger while I’m not using it?

Yes, you can. If you have a Wall Charger, you can switch it off at the isolator switch. Alternatively, you can set a charge schedule for 0% and switch this on when you want to lock the charger (See below).

What do the lights on the charger mean?

If you own an Ohme Home:

If you own an Ohme Home Pro:

  • No light: Finished charging / unplugged.
  • Blue: Delayed charging (not currently charging, according to schedule).
  • Green: Active charging, according to schedule.
  • Flashing green: Active charging, but car not drawing power.
  • Red: Error.

How do I improve my cost per charge?

There are a number of ways that you can lower the energy cost of running your EV: 

  • Consider selecting a tariff that offers cheaper night-time rates. The Ohme charger works brilliantly with Octopus Agile and Go tariffs. 
  • Make sure you have “save money” activated in the settings (it is enabled by default). 
  • Give Ohme as much time as you can. The more time Ohme has to charge your car, the more likely it will be able to choose an optimal time. 
  • It is often cheaper to charge your car a little every day (as Ohme can put all the charging into the cheapest period) rather than, for example, a weekly big charge. 

What do the CO2 values in the app mean?

If you have the “Favour Green Energy” setting activated in the Ohme app, we use forecasts of the energy generation mix in the UK to lower your carbon footprint.  Ohme will select the forecast lowest carbon periods and charge your car at those times. We also use this information to calculate the CO¬2 related statistics: 

  • Green Score: up to 5 “leaves”, indicating how green your current charge was. This is calculated from your average gCO2/KWh compared to the best possible gCO2/KWh in the last 24 hours. 
  • CO2 / mile. We calculate the total CO2 (in grams) of the charge divided by the rated miles we added to your battery. Note that this is based on the vehicle ratings, not your actual energy consumption which may vary with driving style and climate. 
  • Reduced vs petrol car: We compare your CO2 emissions with those of a comparable petrol or Diesel car. 

How can I improve my Green Score?

There are a number of ways that you can lower the carbon footprint of the electric miles that you drive: 

  • Ensure you have “Favour Green Energy” activated in your settings (it is active by default). 
  • Give Ohme as much time as possible to charge your car. The longer the charge session, the more likely Ohme will be able to find a green time to charge at. 
  • Please note that it if you only have “Save Money” activated in the app then we will charge during the cheapest times, not necessarily the greenest times. For instance, if your tariff is cheaper at night and there is little wind that night, you may see a low Green Score for that charge session. 

Does Ohme support home solar integrations?

Unfortunately, we do not yet support solar integrations, but we are working on it.

What version of iOS or Android is needed for the app to work?

Android customers will need version 6.0 or later and iOS customers will need version 12.0 or later.

What is the idle power consumption?

The idle power consumption of both the wall charger and cable variants is between 2-3W. Over the course of a 24 hour period this would mean the total energy consumed is around 75Wh. This works out to be about a penny a day.

What do the icons on the screen mean?

How long is the charging cable?

To ensure the product adheres to regulations, the length of the cable from the box to the input socket can be no longer than 300mm. This is to ensure the box, which houses the safety equipment inside, can never be accidentally run over or crushed whilst in operation. The output cable is 5m long.

Is the Ohme charger waterproof?

Yes, the Ohme is waterproof and is rated IP55, meaning it is resistant to all weather types. However, it should not be submerged in water.

What is the delivery time after purchase?

Our cables are shipped via ParcelForce for next day delivery. This does not include weekends.

What is load balancing?

Your incoming fuse will have a maximum load (typically 60A, 80A, 100A). Load balancing is more of a concern for households on the lower end, perhaps with a 60A fuse. The load balancing clamp (CT clamp) connects to your live meter tail and monitors the energy being consumed by your property. The Ohme charger can charge at a maximum of 32A. If the consumption creeps up to the limit that you have set when enabling the load balancing feature (maybe the power shower is running at the same time as the charger), the Ohme charger will decrease the rate that is being delivered to the car to prevent an overload.

What is PEN fault detection?

PEN (Protective Earth and Neutral) fault detection functions to disconnect the vehicle from the live, earth, and neutral conductors if the voltage is above or below the prescribed levels (in the UK, that's above 253V or below 207V).

How do I re-boot my Ohme Home Pro?

Holding down all three buttons at the same time will reboot your charger. You can also powercycle the charger by turning it off/on at the mains (or isolator switch).

What do the buttons mean on the Home Pro?

These are contextual and depend on the screen that is currently displayed.

Can I turn the screen/LEDs off?

It isn't possible to turn the screen off completely, but you'll notice that the screen dims when not being used. Tap the screen or buttons and the screen will light up again.

How do I check if the Home Pro is online?

Top left - disconnected/connected. Will have error messages on display in future. Will show on the screen if max charging so can tell if the charger is offline and not following schedule. Will switch to blue once connection restored

How do I pair my Home Pro to my app?

The base of your charger has a sticker with a QR code which is also displayed on your charger screen. Scan this to pair your charger to your app. If you don't have the Ohme app installed, scanning the QR code will take you to the App Store/PlayStore to download this.

Do I need an earth rod/alt earthing solution?

No, the Ohme Home Pro has in-built earthing so you don't need an additional earthing solution.

How do I charge instantly from the Home Pro?

Once the car is plugged in, you'll see the option to 'max charge' on the charger screen. This will override any schedule or price can you have enabled and start charging right away.

How can I edit the current session from the Home Pro?

Once the car is plugged in, you'll see the option to 'edit target' on the charger screen. Here, you'll have the option to edit the current session from the charger itself.

Is the Home Pro waterproof?

Yes, it is resistant to all weather types and IP55 rated

What is the max charge rate of the Home Pro?


How is the Home Pro attached to my wall?

The wall mount plate is screwed to the wall and charger slots into this.

Charger has just been installed but is showing as 'Offline' in the Ohme app

The Ohme app will show as online and connected once you have plugged it into your car. If you are waiting for your car to be delivered the Ohme app may show the charger as offline until you first plug in.