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FAQs

How much does it cost to charge an electric car with Ohme?
How long does it take to charge an electric vehicle with Ohme?
How much can I save with Ohme?
How do I connect my Ohme cable?
How do the Charge Schedules work?
How does Ohme work if I do not have access to my car’s API?
What happens if Ohme temporarily can’t access my car API?
Does Ohme still work if I have a fixed electricity tariff?
What is Max Charge?
Why is there a “+” in front of my mileage?
What do the Money values in the app mean?
How do I improve my cost per charge?
What do the CO2 values in the app mean?
How can I improve my Green Score?
What do the Battery values in the app mean?
Does Ohme support home solar installations?
What version of iOS or Android is needed for the app to work?
How much does it cost to charge an electric car with Ohme?

The Ohme cable and app allows consumers 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 at 7kW 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 do I connect my Ohme cable?

There are three types of Ohme cable:

  • 3-pin plug: Plug into a household socket
  • Commando: Ask your electrician to install a socket
  • Type 2: Plug into your existing untethered chargepoint
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 instance, if you plug in your car on a Tuesday evening at 7pm, then Ohme will finish charging 12 hours later on Wednesday morning at 7am. Charge Schedules allow you to just plug in the car and have it charged to your liking the next morning without needing to do anything else. You can always change the settings of a currently 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, which is a service that allows you to get information from the vehicle, usually to a smartphone app provided by the vehicle manufacturer, for example NissanConnect EV. Providing your login credentials in the Ohme app allows Ohme to access the vehicle’s current state of charge. This is used to work out how much charge you need.

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 specify how many miles you would like to add to the range. So if your weekday commute is 50 miles, then you could create a Charge Schedule which says “add 50 miles range by 7am on weekdays”.

When using Ohme without an API, it is quite common for the car to become “full” halfway through a charge session, and Ohme may send an alert to tell you that the car is not charging as expected.

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

When you have connected the vehicle API to Ohme, if we temporarily can’t access the API when you plug in your car, we will assume that the battery is empty. This “worst-case” assumption is to make sure 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 part way through the charge session, and Ohme to alert you 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.

What is Max Charge?

Max charge will temporarily disable all Charge Schedules and will simply charge your car at full power until it is full. It basically turns your Ohme charger into a “dumb charger”. Use it when you need a quick and uninterrupted charge or when charging at public charge points where you pay per time.

Why is there a “+” in front of my mileage?

If you use Ohme without connecting a vehicle API, you use Ohme in a different way. As Ohme doesn’t know the state of charge of your car when you plug in, rather than specifying the final range or the battery state of charge that you require, the Charge Schedules allow you to specify how many miles or battery % you want to ADD. So, if your daily commute uses 50% of the battery, a suitable Charge Schedule could be “Add 50% by 7am”. If you were to plug in with 25% battery remaining, the car would end up with 75%.

What do the Money values in the app mean?

If you selected an electricity tariff during sign up, we will optimize your charge to save money unless you specifically disabled this option in the settings. We will also use the tariff pricing information to calculate your charging costs:

  • 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.
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 by default).
  • Give Ohme as much time as you can. The more time Ohme has to charge your car, the more likely we can 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. On a windy or sunny day, a larger part of the country’s energy generation is from renewables, lowering the carbon emissions per KWh in the grid. Ohme will pick 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 we can 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 bad Green Score for that charge session.
What do the Battery values in the app mean?

EV batteries degrade with usage and time. Certain usage patterns can accelerate this degradation. A battery has a limited number of charging cycles before the range of the vehicle will reduce, usually a few thousand. Most charging sessions with non-smart chargers will charge the car to 100%. However, most of the degradation of the battery happens when charging is above 75%. You can extend your battery life by charging more frequently (grazing) and trying to keep your battery between 40% and 75% for most of the time.

  • Battery Score: 5 lightning bolts indicate this charge is good for battery life. It is calculated as a function of the cycle percentage, i.e. short charges between the optimal range lead to a better score.
  • Energy Charged: This is the amount of energy that was drawn from your outlet. Note that this is more than was actually added to your battery, as there are energy losses from the EV charging systems.
  • Cycle use: this is an indication of the health of your charging compared to a 0-100% full charge (a low score is better). You will see that this can be a low single digit number if the car isn’t fully charged, which is better for battery health.
Does Ohme support home solar installations?

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 11.0 or later.

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