EV charging stations are equipment or facility that can recharge a drained battery of electric vehicles. Not all EV charging stations are equal. Therefore, you must find one that suits your needs. This article will help you find the best EV charging stations for you.
An EV charging station is also called EV charger, electric vehicle charger or EVSE (electric vehicle supply equipment). There is slow charge and fast charge EV charging stations. Slow charge will take time to fully charge an EV battery, especially with those EVs with big battery pack. The charging time may range from 3 hours to 8 hours. This type of charger is commonly referred to as AC charger. Fast charge EV charging stations can fully charge a drained EV battery in less than an hour. Nowadays, fast charging stations are DC chargers.
EV charging stations are not the same in terms of connectivity. There are CCS1, CCS2, Type 1, Type 2, NACS, CHAdeMO, Tesla specific and others.
EV charging stations also differ in the type of authentication or payment methods. This includes card-based payments, RFID or NFC, application specific or vehicle authentication.
These are the Considerations in Looking for EV Charging Stations
1. Charging Time – How Long are You Willing to Wait?
If you are just passing by or in a hurry, you need a fast charger. A fast charge EV charging station will fully charge an EV battery in less than an hour. Superfast EV charging stations nowadays will fully charge a typical size EV battery in just 15 minutes. A fast charger is often referring to a DC charger. The bigger the charger wattage, the fastest in can fully charge your EV battery. Nowadays, you will hear about 100kW, 180kW, 360kW and so on and 500A charge current. These are the common fast charger power and current capacity.
If you are not in a hurry, such as you want to re-charge your EV while you are working or while you are in a grocery store that may take you couple of hours, then you can settle for a slow charger. A slow charger is often associated with an AC charger. Nowadays, an AC charger’s maximum power capacity is only around 22kW with a maximum current of 80A.
If you want to learn in details about EV charging stations, read How Does an EV Charger Works.
How to Estimate the Charging Time?
The energy delivered to the battery during charging is not constant. At early phase, the battery will draw huge current (may maximize the EV charging stations capacity). This will only happen in the first few minutes, for a fast charger (but it will take more time for a slow charger). Once the battery energy is replenished, the power demand will decrease until it reaches a state that the battery will not anymore draw current. However, for education purposes, we can estimate the charging time using below relation.
Charging Time = Battery Pack Size / EV Charger Power
Example 1: Battery pack size is 60kWh, charger power capacity is 180kW (fast charger)
Charging Time = 60kWh / 180kW = 0.33 hours = 20 minutes
Example 2: Battery pack size is 60kWh, charger power capacity is 22kW (slow charger)
Charging Time = 60kWh / 22kW = 2.73 hours = 164 minutes
Example 3: Battery pack size is 60kWh, charger power capacity is 360kW (fast charger)
Charging Time = 60kWh / 360kW = 0.17 hours = 10 minutes
In above examples, we did not account for the battery state of charge (SoC). SoC is the percentage of charge left in the battery by the time it is recharged. In most cases, a driver will leave around 20% of charge. It is not a good idea to empty the battery.
Nowadays, EV battery packs can range between 40kWh to 200kWh. I included here a graph with battery packs from 40kWh to 200kWh charge with different charging power. You can check the charging time using this graph.
Is it economical to charge in a fast charger with very high power in short duration than charging in a slow charger with very low power but will take longer?
You may be asking this question. If we want to get accurate data, it is best to do experiments or find out by doing actual charging to both slow and fast charger. However, for quick reasoning, the answer is, there is not much difference. If there is, it is not significant. We knew that charging profile is not linear, huge power is drawn during initial stage and gradually decreases until fully charged in a non-linear mode. But assuming a linear response (estimation), it will turn out that there is no difference at all.
2. Connector Compatibility of EV Charging Stations and Your EV
If you’re finding an EV charging station, consider the type of connector the charger has. Not all chargers offer the same charging connector or charging gun. For instance, in the US, there are CCS1, Tesla specific, NACS and few CHAdeMO. You cannot charge your Tesla EV to a charger with a CCS1 charging gun, and so on.
What to Do if the Available Charger has Different Connector?
This may be a common question from an EV owner. The short answer is to use a cord adapter. There are lot of cord adapters in the market today. You can buy CCS1 to CCS2, CCS1 to CHAdeMO, CCS1 to tesla connector and so on.
Adapters are easy to use and handy. However, there are important things to know in using a cord adapter. The mating point between the adapter and the EV inlet or charger cord may not be as fit as it has no adapter. This will result in two possible scenarios:
1) Poor Efficiency
Since the connection may be loose, there is a resistance build up. This will result in unnecessary power loss especially when charging at high current.
Power Loss = Current x Current x Resistance
When there is a power loss, the actual power delivered to the electric vehicle is less than the power that is outputted by the charger. You are paying more but receiving less.
2) Heating and Worst-case Scenario to Catch Fire
Due to the resistance built up in the mating point, there is power loss and this power loss will result in a thermal rise in the area. Imagine if high current is drawn, it is just matter of few minutes for the mating point to heat up. When this scenario is going to happen without attending, this can catch fire.
It is important to properly select your cord adapter. There are lot of options such as in ebay and amazon. But ensure to buy from a known and reputable brand. When you buy, consider checking the safety markings. Use charging cord adapter with extra care!
How to Check if the Adapter Overheat?
There are few ways to check if an adapter overheats.
1) A burning smell. You know how it smells.
2) There could be a sign of discoloration in the adapter or in its mating point.
3) Smoke may show up.
4) Fire may come out for extreme overheating.
5) If items 1-4 (obvious signs) are not showing up, try to touch the charging cord, but not directly to the adapter mating point. If there is no issue during charging, you can hold the charging cord without feeling burning your hands. If there is heating issue, you cannot put your hands longer to the cord as you can feel the heat. Take note, do not touch the adapter mating point directly as the temperature of that section could be very hot when there is overheating issue. When you try to touch the charging cord (away from the adapter mating point), do it quickly, enough to feel if it is indeed hot or not. You can figure it out…
What to Do Next if the Adapter Overheats?
In the event of overheating, always think your safety. You may follow the tips below.
1) Shutdown the charging immediately.
2) Do not touch the overheating part or section. It will burn your hands.
3) Wait for some time before attempting to remove the charging cord from the adapter or from the vehicle inlet. It may burn your hands.
4) If the adapter welded to the charging cord or to the vehicle inlet, call an expert.
5) Have your EV checked by experts to ensure there is no internal damage.
3. How to Make Payment on that EV Charging Stations
Another important aspect that an EV driver should consider in looking for an EV charging stations is the mode of payment. There are several options nowadays such as credit and debit cards, RFID and NFC and vehicle authentication methods. Cash payment is not an option.
When you travel long distances with your EV, it is a great idea to make your plan. Your plan must include:
1) The locations of EV charging stations along the way. Considering only the charging stations that suit your EV, follow items 1 to 3 above.
2) Ensure that your remaining charge when you leave home can reach the first charging station or your target place to recharge. For instance, you plan to recharge at location B that is 100 miles away, but your actual charge will only reach 90 miles, this will not work. Your dashboard will tell you the approximate charge remaining and this can guide you.
3) Checking the distance in-between charging stations if within the range of your EV. Otherwise, you are in trouble.
4) Ensuring the charging stations along the way are not offline or under maintenance.