Electric cars, the guide on how to recharge at home or at columns

Since when electric cars have begun to spread, part of the specialized press has consciously or unconsciously passed on the idea that to use a battery-powered vehicle you need to be an expert. On the one hand we can certainly say that knowing the technical terms is not a bad thing at all, and for this reason in this new episode of the “driving electric cars” We’ll talk about it. On the other hand, however, we need to dispel the myth and tell it like it is: recharging an electric car is as easy as recharging your mobile phone… it just takes a little more time because the battery is bigger…

An important premise

Reviews, datasheets and advertisements have accustomed us to being targeted by numbers. “This electric car recharges in 30 minutes thanks to the direct current fast charge that reaches up to 150 kW. This other one, on the other hand, takes two hours in alternating current three-phase columns”… and so on. But do we really need to know all these terms? What does direct current mean? And what are kW? We have partly talked about it here, in our electric car glossaryfor the rest you will find useful definitions and explanations at the bottom of the page.

The answer to the above question, however, is that we don’t need to know any of this. When I bought my first electric car I didn’t even have to install one wallbox or a socket: to get started, the very common Italian three-prong socket that had already been installed in my garage was enough since the house was only about ten years old.

Charging an electric car

Some might object that recharging from the classic household socket takes longer, and it is true, but it does not mean that you need to “fill up” quickly: it all depends on your consumption and daily distances. If your electric car has a range of 300 kilometers and you drive an average of 30 kilometers a day, it is easy to calculate that you will have to recharge once every ten days. And here is the first mistake: the previous statement is valid only for those who do not have a trick in the box.

If, on the other hand, you can top up in your garage (or in the driveway of your villa for the lucky ones), you have to get into the “topping up” perspective. Do you arrive home after shopping? Put the car in charge. Do you go out in the evening for a pizza? On your return you will put the car on charge, and so on…

This way you will never need to do that long, slow 5, 10 or more hour charge because you will always be recharging. By analogy, imagine that instead of filling up with 40 liters of petrol every week, there was someone who, without you having to get your hands dirty, goes every evening to top up the liters you have consumed during the day: it is not enormously more comfortable going to the gas station on purpose and maybe standing in line at the always crowded one that has the best prices in the area?

How to calculate charging times

The formula for calculating the charging times of your electric car is very simple, but you need to know some data:

– Battery capacity, its unit of measurement is kWh (e.g. 50 kWh)

– Maximum recharging power of the alternating current charger (AC or AC in English) with which your vehicle is equipped. It is usually 7.4 kW on older or cheaper electrics, or 11 kW. Some cars also have a 22 kW option.

– How do you recharge the car: the domestic charger (the one that connects to the Italian three-prong plug) usually reaches 1.8 kW, maximum 2.3 kW. If, on the other hand, you have installed a wallbox, the maximum power is that used by the meter. Recharging in alternating current is what we commonly do at home or in public columns equipped with a Type 2 connector:

Type 2 cable

The latter usually have an output of 11 kW or 22 kW. Direct current charging is only available in public stations, which are larger than alternating current columns (they are similar in size to lockers). It is distinguished by this connector, the CCS Combo 2:

Nc2 combo

Summarizing: is there the CCS Combo 2 connector from the first picture? You are recharging in direct current. Is there the Type 2 connector of the second photo? It means you are recharging in alternating current.

Let’s take two examples. We are charging a Nissan Leaf with a 40kWh battery, 7.4kW max AC charging, and 46kW max DC charging.

We installed a wallbox in the garage and our meter manages a maximum power of 4 kW. Well, the formula is as follows:

charging time (h) = battery capacity (kWh) / charging power (kW)

For our Leaf: 40 kWh / 4 kW = 10 hours (ten hours) to recharge it to 100%. Two things must be specified: the first is that it won’t be exactly 10 hours, it will take a little longer because there are leaks when recharging the car, just like there are leaks when recharging the PC or smartphone. The second is that it will be very difficult that we will need to recharge it from completely discharged: we will probably recharge starting from a residual capacity of 10%, or 25% and so on.

The same formula applies to DC charging, only the charging power is higher. By recharging our Leaf at a 40 kW rapid column, for example, it will take 1 hour to recharge.

Unfortunately, however, in direct current the above calculation is not the most correct because the batteries do not constantly absorb the maximum power of the column. For example, a direct current recharge can start at 50 kW, but as the battery recharges, the maximum power supplied will decrease, to then drop significantly to around 80%.

For this reason, when making long journeys, it is advisable to recharge up to about 80% or, if your car provides for it, not to make calculations and rely on the advice of the on-board computer which will tell us how long to recharge to minimize the total time of the trip.

Homework: we did the example with the Leaf, try to calculate the charging times for a Tesla Model 3 in the comments, below are the data of the problem:

– Tesla Model 3 battery: 75 kWh

– Model 3 AC charger: 11 kW

– where do I top up? at an 11 kW public column and at home with a 6 kW wallbox and meter.

Write the answer to the two questions in the comments: how long does it take to charge the battery from 0 to 100% in the public column? And at home with the 6 kW wallbox?


How to recharge your electric car at home

The ideal situation is to have a garage connected to your electricity meter (or with a separate meter), or an outlet close to where you park your car, such as the garden, a driveway of a house or an external outlet accessible.

When you buy the car, you will usually receive two cables. The first is the Type 2 cable, which is essential for connecting to public columns. The second is a cable with the Type 2 connector (which is inserted in the car) and which on the other end ends with an Italian three-pole socket or with a Shuko socket. With a small expense we can change the Italian socket of our house with a Schuko socket (if you don’t already have one) and have greater safety. At that point we connect our slow charger and recharge at maximum 2.3 kW.

The ideal, however, is to purchase a wallbox which is often offered free of charge or for a fee by the dealers themselves. Have it installed and you will have maximum safety, because the wallboxes already include all the protections and the cable is larger, so there is no risk of the socket overheating, even if the most modern chargers with Schuko or Italian sockets already have a temperature sensor: if things get hot, they stop drawing current at maximum intensity and try to lower it. If even this is not enough, they are deactivated avoiding any security risk.

The wallbox will be fixed and will have the cable with the Type 2 connector: at that point follow the previous rule: plug in the charging car when it is not in use and forget about calculations and strategies, as long as your movements are compatible with the vehicle autonomy.

Electric recharge

How to recharge the electric car at public columns

By now, almost all manufacturers will offer you, when you buy an electric car, a card and a subscription account (free for a certain number of years) which allows you to recharge at any public column, both in alternating current and in continues. This is the simplest solution because, while travelling, you just need to follow the car’s navigator, which usually indicates where and how long to top up, stop, use the card to top up. During small daily trips, on the other hand, if you see a charging station nearby or if you look for it via the app, you can take advantage of the recharge while you’re shopping or while you’re at the gym, at work, at the doctor’s office and so on.

Alternatively, there are service providers such as Enel X (the app is called Juice Pass) and BeCharge which offer you a top-up subscription exactly like the one provided by car manufacturers. You register, download the app, ask for the card if necessary (it is not mandatory) and top up the car, receiving, from time to time, invoices for automatic payment to your account or credit card. In general it is advisable to make a subscription to spend less, but we will talk about this in a later episode. Some cities and some shops (restaurants, hotels, supermarkets) then offer free top-ups for a specific time.

When does the electric car become a burden?

The electric car can become a boring chore if you don’t have a socket in the garage, although I personally know more than one person who cannot recharge at home and yet has lived with a battery-powered car for some time, because they have a public charging station near the apartment. In any case, the only annoyance is to remember to recharge the electric car once or twice a week from the nearest column, then returning to unplug it and park it elsewhere. Over the years, Italy has grown a lot in terms of the availability of charging points, and it is expected that in the not too distant future, every commercial establishment or car park will integrate a good number of columns, as electric cars spread. Already today there are many columns, even if it is true that there are “hyper” served areas and areas where instead it is difficult to find a recharging point; Also consider this before buying an electric car if you don’t have the possibility to charge it at home.

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Electric cars, the guide on how to recharge at home or at columns

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