The dilemma is to understand the charging cost and to choose which method is convenient for you to limit the cost as well as the time when the charging cost will be less than you expected.
The important terms in EV are Voltage, (V), Electric (A), Power (KW), and Energy (KWh).
Mostly, the measurement terms Voltage (V) and Electric (A) are not for you to worry about while charging your EV or to calculate how much it will cost you? The technical terms will be used as data in the electric batteries or charging stations.
Now, we come to KW and KHW, the most complicated terms to understand be used in your EV, and the daily need to understand how your EV is more efficient enough than the internal combustion engine.
The charging speed of an electric vehicle or the vehicle power output is measured in KW. So, coming from the background of internal combustion engine cars, you can see sports cars with high horsepower.
The next is the measurement of the battery capacity or how much the battery energy capacity is in KWh. And here the differences can be seen with different EV models. The more battery capacity of an EV model means higher energy capacity and with less battery capacity, it provides less energy capacity.
Now, in the case of a charging station, you need to check the KW power charger used to charge your car. How much energy a charging station is putting into your battery (kWh) during the charging session? So, some the charging station, use the billing method based on how much energy the battery consumed with the charger in that particular session.
Well, there are charging stations using the time taken by you to charge the EV car. You can also see the voltage and current measurements in the charging station. (Well if you want to cross-check the power value, you can simply multiply the voltage and the current value and convert it into KW by diving it by 1000).
Calculating the cost
So, suppose you got a battery capacity of 50 kWh and a power charger of 10KW, then to get the full battery charge it will take you 5 hours.
But, let’s say you are using a rapid charger 60 kW, (gives 1 kWh of energy in 1 minute), then you will get 50 kWh of energy in 50 minutes.
Charging at home
Now, let’s say you got a Tesla Model with a 50 kWh battery, and a 10 kW power charger in your home garage. My battery is 50% charge, 25 kWh battery capacity, if I charge my battery for 1 hour, I will get, 35 kWh battery capacity. In 2 hours I will get 45 kWh battery capacity. (The numbers are theoretical, but used for understanding the concept)
If your home tariff is 10 paise/ kWh. So for 1 hour charging an EV with a 10 kW power charger will cost you Rs 1. Now the full charge of a 50 kWh battery will cost you Rs. 5. (So, now if you know the time at which you got the lowest tariff, you will end up saving a lot of money)
So if you are using one of the rapid chargers with 50 KW power, then in 30 minutes, you will get 25 kWh.
So, if the rapid charge tariff is 10paise/ kWh, then for 30 minutes it will cost you, 25 kWh * 10 paise /kWh is Rs. 2.50, 1 hour of charging 50 kWh will cost you Rs. 5.
Usually, the rapid tariff cost is more than the home tariff. So, if you are in an emergency, and don’t have the time to wait at a charging station for 1 hour. You need to have enough cash for a rapid charger.
And also, check out which is cheaper, based on the time needed to charge your vehicle or the tariff on the final energy, kWh, put inside your battery. If you do get the option to choose any one of them.