Conventional Charging Concept
Later, we will discuss more about EV charging basic things and information but let us take a glimpse of the conventional charging like on our smart phones, tablets and other gadgets. Charging is a process of restoring energy to a cell or battery by forcing electric current to flow into it. Not all batteries or cells can be recharged. Only those secondary type can be recharged. The term secondary types batteries are less familiar to ordinary people but take into memory that if talking about a rechargeable battery/cell, it is always referring to a secondary type.
In order to make charging happen, there must be a
(1) power source
(3) connection wires/cords and (4) device to be charged.
Power source is usually the available power from the wall outlet that is coming from the power grid. It could be 90Vac-240Vac depending on the country.
Charger is the device responsible in doing the charging activity. It will accept the power source and process it such that safe to the device to be recharged. In most cases, chargers have constant current and constant voltage feature. A constant current means the current cannot exceed to a level set by the charger no matter how big the battery will demand. For instance, the constant current setting of a charger is only 2A, this is the only maximum current that can be drawn by the device under charged. Constant voltage on the other hand is a feature in which the output voltage of the charger is set constant like 3.3V (for Lithium ion-based batteries) or 13V (for lead acid batteries).
Connection wires or cords are simply the accessories that will connect the charger to the device under charged. In most cases, they are already built-in to the chargers in electronics gadgets we have used today.
The device to be charged is any electronic gadgets like cell phones and tablets, appliances like speakers, radio and so on or batteries.
Safe versus Unsafe Method
There are both safe and unsafe way of charging. We can called them as non-smart charging and smart charging techniques.
Non-smart charging is not a safe charging method. The maximum current is not limited and only rely into the resistance of the connection wires or chords that connects the charger to the device under charged. There is no battery auto termination feature and generally there is no safety features. This method is can be simply done using a fixed voltage power supply like an off the shelf 12V DC power supply and connect the device under charged to it directly. The device under charged will demand an amount of current depending to the state of charge available or remain on it. Simply saying, the lower the remaining charge, the higher the current it will demand.
There are two possible scenarios that might happened;
(1) the fixed 12V DC power source may not able to provide the current demand and trip off (in case a low power voltage source has been used) and
(2) the device under charged will get damage or may even explode at extreme cases if the power source can provide the current demand.
Not all the times though that will end up to these scenarios. Several cases also this charging method will work for some applications. But now you know, take note of the possible drawbacks
Another charging technique is the so-called smart charging. Smart simply means and intelligent or an engineering method of charging. This is complex. Chargers are designed specific to each device or battery configurations or types. There is a constant current or over current protection. There is an over voltage protection, automatic charge termination and over temperature protection to name few safety features. There is no danger of over using the charger capacity or damaging the device under charged when it is heavily drained as there a safe constant current set in place. Smart charging is the method adopted to many commercial charging systems nowadays.
I guess it is worth to tackle this up a bit for better understanding and differentiation to the EV charging basic later. For general charging methods like gadgets and consumer electronics, the battery is rated in terms of ampere-hour (Ah) or milliampere-hour (mAh). Ampere is the amount of current drained from the battery while hour is simply the total number of hours that current is flowing to the battery. In engineering, the Ah is the unit of charge. Charge is simply current (in Amperes or milliamperes) times time (time in in hour).
Supposing a battery has a rating of 2500mAh, how long it will last when a device that consumes 0.5A connected to it? See below calculations.
EV Charging Basic Things You Need to Know
Nowadays electric vehicles are gaining popularity in the US, Canada, Europe and in few countries in Asia. There are several EV charger makers also nowadays who support the EV industries like BTC Power, ABB and Tesla to name few who are recently on the spotlight of being few of the biggest EV charger maker in the world. This article is perfect if you are looking forward to learning about EV charging basic things. We are going to tackle here about EVSE, the EV itself, how the EV and EVSE talk to each other, the protocols, connectors and so on. By knowing this EV charging basic thing, we will be prepared to the EV future!
EV Charging Basic Concept
There is no big difference as the conventional charging concept we discussed earlier. In Electric vehicle charging (EV charging), there are
(a) Power source
(c) Connection wires/cable assembly and
(d) Electric Vehicle.
Power source is simply the grid and it can be 90-240Vac single phase or 208Vac/400Vac/480Vac/600Vac three phase depending to the country. A single-phase power source is only involving two power wires; the live and neutral and maybe an addition of a ground wire. For three phase set-ups, there maybe three power cables and a ground wire for a delta connection or a four-power cable and a ground wire for a wye connection. In most cases, the connection is delta.
EVSE stands for electric vehicle supply equipment. This is being referred by many as the electric vehicle charger or EV charger. But technically, not all EVSE is can be called a charger. We will discuss this later. EVSE is an infrastructure that will connect the power source to the battery in order to re-store charge. It delivers electrical energy to the EV to charge the battery. Let us adopt the belief of many; this the so-called “charging station”.
Connection wire or cable assembly is an appropriately rated and compatible cable with connector that use to connect the EV and the EVSE. In most cases, this connector or cable assembly is attached to the EVSE itself so nothing to worry about. This cable assembly has protocol to follow and will be discuss later.
Electric vehicle is the equipment or device under charged. EVs are also has few variations like battery EV (BEV), plug-in hybrid EV (PHEV) or Hybrid EV (HEV). In my research, only BEV is can be charged to a level 3 EVSE. We will discuss the level of EVSE later.
Not All EVSE a Charger…
In many people, they often called any EVSE stations a charging station. Basically, this is correct and acceptable terminology as we go to EVSE stations to recharge our EV. But, does all EVSE or the so-called charging stations perform the charging of the battery itself? One of the important EV charging basic knowledge you need to know is that not all charging stations perform charging activities.
An EVSE is can be an AC or a DC type. If the EVSE an AC type, the charging will be facilitated by the on-board charger on the EV. The EVSE’s role is only to connect to the power source and perform safety precautions as well as energy related monitoring and recording. This best describes in below illustration.
Left side of the above illustration is an AC type EVSE or let us use the term charging station. As you can see, the EVSE cable is passing through the on-board charger and the on-board charger is the one charging the car battery.
The right side is a DC type EVSE or charging station. It will no longer pass through the on-board charger and go directly to the car battery as the charging actions and controls are already performed by the EVSE itself. DC type EVSE or chargers are more powerful than the AC type. To many, AC EVSE is referred as slow charger while DC EVSE is referred as fast charger as it can fill a car battery from 20% state of charge to 80% by less than 30 minutes.
EV Charging Basic Configurations and Ratings
Note: All definitions below are referred from SAE International ver. 31611.
AC Level 1
An AC level 1 charging will have 120Vac single phase, 1.4kW of power at 12A and up to 1.9kW of power at 16A. Since this is AC, the EV should have the on-board charger. Basically, this charging mode is can be done at home using a wall outlet that can at least carry 16A. When buying an EV, most of the times accessories for this charging method is being provided. If not, I think this can be bought after market. The estimated charge time (again according to SAE International) is:
(a) PHEV – 7 hours from 0%-full state of charge
(b) BEV – 17 hours from 20% – full state of charge
PHEV is short for plugin hybrid electric vehicle. This type of EV uses both petrol/gas and a battery. Its battery is not as big as the pure battery electric vehicle or BEV wherein all car power demand is derived from the battery alone.
DC Level 1
A DC level 1 charger will have an output voltage range from 200-450Vdc. It can go as high as 36kW at 80A. Since this is a DC, the EVSE itself will do the charging and no need the on-board charger. Based on a 20kW EVSE/charger, the estimated charging time is:
(a) PHEV – 22 minutes from 0% – 80% state of charge
(b) BEV – 1.2 hours from 20% – 100% state of charge
AC Level 2
The electric vehicle must have an on-board charger. This configuration has 240Vac and up to 19.2kW (80A) of power.
Using a 3.3kW on-board charger, the estimated charging time is:
(a) PEV – 3 hours from 0% – 100% state of charge
(b) BEV – 7 hours from 20% – 100% state of charge
Using a 7kW on-board charger, the estimated charging time will be:
(a) PEV – 1.5 hours from 0% – 100% state of charge
(b) BEV – 3.5 hours from 20% – 100% state of charge
Using a 20kW on-board charger, the estimated charging time will be:
(a) PEV – 22 minutes from 0% – 100% state of charge
(b) BEV – 1.2 hours from 20% – 100% state of charge
DC Level 2
A DC level 2 charger will have an output voltage range from 200-450Vdc. It can go as high as 90kW at 200A. Since this is a DC, the EVSE itself will do the charging and no need the on-board charger. Based on a 45kW EVSE/charger, the estimated charging time is:
(a) PHEV – 10 minutes from 0% – 80% state of charge
(b) BEV – 20 minutes from 20% – 80% state of charge
AC Level 3
This is still TBD on the SAE International ver. 031611. But it indicates power of greater than 20kW and with single phase or three phase AC input.
DC Level 3
Same with the AC level 3, this is still TBD. But few information has been provided like an output voltage of 200-600Vdc (proposed) and up to 240kW (400A) of power.
Charging Compatibility Between EVSE and EV
Currently (at least as of this writing), there are three commonly used connector and protocol between EVSE and EV. They are CHAdeMO, CCS and Tesla. CHAdeMO is commonly used in Japanese cars like Nissan and Mitsubishi. CCS is used by US automakers and some others. On the other hand, Tesla is used by Tesla cars. These three has different connector shapes, orientation, size and wiring. A car with a CHAdeMO inlet must use an EVSE with a CHAdeMO nozzle. In same manner, a car with a CCS inlet should use an EVSE that has CCS nozzle. Same with the Tesla. However, there are already available adapters so charging from EVSE not compatible to the car inlet is no longer a problem.
CHAdeMO is developed by Japanese automakers. This is widely used by Japanese cars. In fairness, this standard is very rugged and very mature. The drawback is that this is only available for DC charging. This means, there is another inlet for the AC charging. So, each vehicle will have 2 charging inlets for the DC and AC. CHAdeMO has gaining popularity in the past and even as of this writing it is still widely patronize. However, it seems the trend will go to CCS type.
CCS stands for combo charging system. It is very popular in the US and Europe. In the US, it is called combo type 1 while combo type 2 in the Europe. It is a combo of the AC and DC charging configurations. Meaning, each car has only one inlet that is valid for both AC and DC charging. This saves space and less complicated as compared with the CHAdeMO. This is why CCS is gaining now popularity.
US Combo connector. Taken from SAE International ver. 031611.
Tesla has its own proprietary inlet; that is can be used for tesla cars only. However, Tesla car owners has now many options as Tesla is continue expanding their infrastructure.
EV Charger Battery Ratings
Electric vehicle battery is commonly derived from a lithium-ion. EV batteries are rated in terms of kilowatt-hour (kWh). Pure EV (or BEV; battery electric vehicle) nowadays are equipped with huge battery packs. Just like the Nissan Leaf 2019, its battery is 40kWh rated and that is around 150 miles of range. Moreover, the Leaf plus has a battery rating of 62kWh that can reach to 226 miles.
A 40kWh when charged by a 50kW charger from 20% to full load may take only less than 40 minutes. When charged to a 100kW charger will only take less than 20 minutes.
What Option Available for Your Garage – Things Needed
Only the AC level 1 and level are practically OK to install in your garage. The level 1 AC is just a matter of plugging in the provided cord to your wall outlet that can handle the specified current. AC level 1 can only give you a shorter range as it is limited to a small charging current. You can also consider buying an AC level 2 if you have the budget and if you need badly that higher range from charging from home. With an AC level 2, you can fully charge your EV for the whole night. However, you need to ensure that your house is ready for that. You need to have a dedicated power line with right wire size and safety features for the EVSE.
Is it necessary for you to buy an AC level 2 charger? The answer is depending on you. If you have the extra budget, then it is good idea. Just few things; assess if your car will be battery drained when you get home, so you need the AC level 2 to make the battery charge to full by morning and ready to go again. If your car battery is only fraction of it being consumed when you are going home, then you can make use of the AC level 1 or the plug-in charging provided when you bought the car. I believe you can see a fast charging station in your place and from time to time make use of it for fast recharge of your battery.
How Much Really the Savings in Using EV Compared to a Petrol or Gas Vehicle?
I read from EnergySage (https://www.energysage.com/electric-vehicles/advantages-of-evs/do-electric-cars-save-money/), the average cost to operate an electric vehicle in the United States is $485 per year, while the average for a gasoline-powered vehicle is $1,117. Gas is costing more than double the EV electricity cost. The price of electricity is more stable than the price of petrol/gas in general so it can be projected a constant cost year per year. In addition to the savings, EVs has lower maintenance cost compared to the petrol or gas engine.
If you are not in the US, you can estimate the EV cost versus petrol or gas engine. Supposing you are using the 2019 Nissan leaf which battery is 40kWH rated and can reach to 150 miles. Always maintain 20% charge left (this is a safe minimum limit I guess), so only 80% of the battery has been discharged and to recharge. This is equivalent to 120 miles (193km). The battery rating is 40kWH but only 80% is been consumed that is 32kWH. Assuming the electricity cost is 0.22$/kWH, the total cost in each charging is 7.04$. Usual petrol/gas vehicle will average a fuel consumption of 1 liter is to 10 km. So, 193 km is equivalent to 19.3 liters. Assuming the cost of gasoline is 1.2$/liter, thus 19.3 liters will cost 23.16$. The cost of the EV is only around 35% of the petrol/gas engine in this example.