/  Petrus Holm

Smart charging of electric vehicles: all you need to know


Smart charging of electric vehicles is more common than ever. However, common doesn’t mean that everyone understands how smart charging services work in detail. In Synergi’s instance, we have been approached by customers who are genuinely curious about how it all works: how are their savings generated, who controls their vehicle, and most importantly, what does this all require from each of them?

In this blog post, we engineers at Synergi want to give you the scoop on how we built our smart charging service and approached the user experience. We also share some of the math essentials behind smart charging.

If you simply want to scroll down a specific section of this blog just click below:

What is EV smart charging?

Smart charging is about charging your vehicle when the electricity is relatively cheap, usually at night. The system uses the exchange electricity prices (market prices), published 24 hours in advance, and the electric vehicle owner’s usage habits to optimize charging. With this information, apps like Synergi’s can calculate the cheapest daily charging intervals based on when an EV driver wants their car to be fully charged – fully automatically. 

Some EV manufacturers might offer the possibility of controlling car charging on a scheduled basis on their apps; quite a good amount of savings can be achieved by simply setting the charging to happen between 1 AM and 7 AM (assuming that’s when electricity is cheapest for any given day). But it’s too much hassle for most drivers to do this every day! 

For this reason, it is so popular for EV drivers to use dedicated Smart Charging apps to control the charging automatically. You set it up once and enjoy the benefits. All these services need to know is when you will leave in the morning to control the vehicle’s charging or the so-called “smart charging deadline.” We use this input at Synergi to allocate the charging between when you plug your car in and when you leave in the morning.

After coming home from work, just decide by when your EV should be fully charged – Synergi handles the rest!

What are the benefits of EV smart charging?

Smart charging comes with several benefits for you as an EV driver. The most significant ones are the following:

  • Cheaper charging costs: With a spot-priced electricity contract, you can save up to 50% on EV charging.
  • Efficient use of electricity: Intelligent charging optimizes charging so that you waste less energy during charging. 
  • Reduced CO2 footprint: Electricity is generally cheaper when produced from renewable energy sources; on average, you would charge 15% cleaner.

However, smart charging benefits individual users and national electricity production. For example, many EV drivers typically charge their vehicles after work, coinciding with peak electricity usage. As the number of EVs increases, this can strain national electricity grids because they suddenly have to deliver more electricity. 

To mitigate this, energy companies suggest scheduling high-energy-consuming activities like EV charging during off-peak hours, usually in the evening. Thankfully, Smart charging addresses this issue by automatically adjusting charging times to periods of lower electricity demand. 

The graph below shows how this works in practice. Even though most of our drivers plug in their chargers between 18:30 and 20:30, “smart charging” begins only four hours later, aligning with lower prices and increased electricity availability. 

Synergi’s latest “Finland EV Smart charging & Optimization Report 2024” shows that the average time users (in Finland) plug in their chargers using the Synergi app is between 18:30 and 20:30. Smart charging then initiates four hours later, helping users bank on lower prices and greater electricity availability.

How much time will it take to smart charge my EV?

After determining the available time and upcoming prices, we have almost completed the smart charging puzzle. The final step is determining how fast the vehicle can charge to the wanted level, say 80%. To do this accurately, the charging must be “tried out”: the vehicle is programmed to charge for a few minutes while monitoring the charging power and battery metrics. With this information, we can simplify the equation into four variables:

  1. The amount of energy needed (kW)
  2. The time available (h)
  3. The electricity prices (€/kWh)
  4. The charging speed, affected by both the vehicle and the charger (kW/h)

As the logic here is relatively simple, most smart charging services can reach a similar efficiency level. Reliability matters from the user’s viewpoint: in the end, you want your vehicle topped up in the morning.

Where should I smart charge my EV?

To avoid unwanted behavior and large invoices, smart charging should not be used in public chargers, which often charge at a minute rate.
Some providers have removed this hassle by developing geolocation-based smart charging, which automatically turns the control on and off based on your vehicle’s latest location.

With Synergi, you can add locations based on your vehicle’s current location, so there is no need to learn the coordinate system. Some providers also allow you to enter a location manually, either by exact location or street address. Both are sufficient.

What car brands does Synergi smart charging support?

All EVs can be smart-charged. Certain car brands have limitations that will hopefully be removed in the coming years.

At Synergi, we currently support most EV brands out there. If you want to check the full time head over to our supported EV brands page

We are constantly adding EV brands, so if your brand needs to be listed and you want to see it there, please let us know.

What personal information does EV smart charging gather?

All smart charging services collect and store customer data. It’s super important for you to read the fine print in every smart charging service privacy policy. At Synergi, we have a privacy policy that details what data we collect from each user and how we use it to deliver an excellent service. In principle:

  • We do not collect data on individual use unless necessary
  • We encrypt all personal data collected
  • We never save or store vehicle login information

We have an in-depth blog post about data privacy in smart charging services, which you can read to get a clearer view of what you should pay attention to. It would be best to familiarize yourself with Synergi’s terms of use

Smart charging at home is the easiest way to save on your electricity bills

Smart charging is a simple way to reduce emissions , save on charging fully automatically, amongst many other benefits. Using a robust provider lets you leave the calculations to the algorithm.

See our smart charging calculator to find out how much you could save with Smart charging.

Get the Synergi app and start saving on your electricity bill! Here’s how:

  1. Get the app and connect your devices: Download the Synergi app and connect your devices. You don’t need any extra equipment.
  2. Change settings and preferences: Set up and use the smart features you want! Set preferences for smart charging, set limits for home heating & cooling systems, and more coming to the app soon!
  3. Enjoy the savings: Sit back and save money as Synergi adjusts your electricity use to cheaper times.

Download the app in Apple App Store or Google Play Store

Petrus Holm