Covering the Basics – Electric Vehicle (EV) Charging

It really is quite simple. First, you need to know your EV’s “Battery Pack Rating”. Then you need to know your vehicle’s “Acceptance Rate” and the EV charging station’s “Output Rate”. To find the time needed to fully charge your car from empty to full charge, divide your car’s “Battery Pack Rating” by its “Acceptance Rate”, OR the EV charging station’s “Output Rate”, whichever number is lower.

Eqn

For example, the 2017 Nissan Leaf battery has a rating of 30kWh and can draw 6.6kW from a charging station. If the charging station output is 6.6kW, then the time to charge a Nissan Leaf battery pack from empty to full is

Eqn2

See here for a list of charging times for electric cars currently on the market.

4.5 hours may seem a long time, but considering our daily commute falls in the range of 40-50 miles per day, we seldom need the full 4.5 hours to charge a Leaf. A Nissan Leaf can travel approximately 107 miles on a full charge. A commute of say 50 miles from a fully charged battery will mean only half of the battery drained at the end of the day. That leaves you to charge the battery to full for less than half of the time needed.

A car’s range is useful information for a potential EV buyer. It tells the buyer how often he will have to charge his car. Obviously, the greater the range, the better it is.  The Nissan Leaf’s range is 107 miles on a 30kWh battery pack. Compare that to the Tesla 3’s model which offers either the 50kWh or the 75kWh battery options with ranges of 220 miles and 330 miles respectively. I will leave you to do the Math.

See here for a list of driving ranges for electric cars currently on the market.

Charging a car is often limited by the charger. This is where we need to understand the three different types of EV chargers that are currently available.

Level 1 Chargers

ClipperCreek Level 1 Charger

ClipperCreek Level 1 Charger

Level 1 chargers are basically the type of chargers that you can set up at home in your garage simply by plugging it into a 120V wall socket. Level 1 chargers are slow compared to their counterparts because of their low output rate, typically around 2kW.  However, it is easy to use, does not require rewiring for high amperage and the set itself is cheap enough for home use. Therefore, it is still a choice for many electric car owners provided they have an accessible wall socket.

The problem is, I was able to find only a few available for sale on Amazon. Just to give us an idea what it costs, an Orion Motor Tech, 110V 16A portable Level 1 charger costs $239.99 on Amazon. Another company that manufactures Level 1 chargers is ClipperCreek. You can find their listings for Level 1 chargers here.

 

Level 2 Chargers

Siemens Level 2 Charger

Siemens Level 2 Charger

Level 2 chargers unlike Level 1 chargers require a 208-240V AC source. They provide a wide range of output, ranging from 3.3kW to 10kW or some even more. Ultimately, the speed for charging your vehicle is dependent on how high an output your vehicle can accept. The 2017 Nissan Leaf can accept an output of 6.6kW. It thus benefits from the higher output from a Level 2 charger.

There is a lot more choices for Level 2 chargers on the market if you wish to install one for your home. Bosch, ChargePoint and ClipperCreek are three of the companies that manufacture Level 2 chargers. Many of the public chargers are Level 2 chargers by the way.  Just to give us an idea how much they cost, a Siemens 30A Level 2 charger is sold on Amazon for $429. This is about the cheapest one that I can find. The rest of the Level 2 chargers are sold for between $500 – $600.

The problem with Level 2 chargers for home use is, owners must ensure that their wires and plugs can withstand high amperage before plugging in, the kind typically used by ovens and dryers. I have read of some Level 2 chargers that are designed to use the electricity supply for your home laundry dryer. But then again, your laundry room may not be close to where you park your car.

 

DC Fast Charging

DC Fast Chargers are the heavy weights in EV chargers. They provide a DC supply at a much higher output, ranging from 50 – 120kW. Current Tesla Superchargers can however go up to 150kW. Elon Musk in Dec 2016 tweeted about 350kW (or maybe even higher) off-grid superchargers being developed.

Only cars that are fitted with DC Quick Charge (DCQC) technology can be charged with a DC charger.

DCQC technology comes in 3 standards,

  1. CHAdeMO
  2. Combined Charging System (CCS)
  3. Superchargers by Tesla

CHAdeMO standard has charge speeds of between 40 – 60 kW but can potentially go up to 100kW in the near future. CCS on the other hand can theoretically go as high as 350kW. The Tesla Supercharger is already pushing boundaries by testing at 350kW.

Which standard to use depends on the car manufacturer but both CHAdeMO and CCS charging are usually provided at the same charging station. Superchargers on the other hand are proprietary to Tesla.

DC Fast Chargers are perhaps never installed for home use. The high voltage source it needs, the very high amperage wires needed for the charger and the cost of a DC charger makes it simply unreachable for the average EV owner. However, when you buy an EV like Nissan or Tesla, it usually comes with a membership for fast charging in its nationwide DC Charger network.

What Is Next?

I guess pushing boundaries for charging speed is what most electric car manufacturers are focused on and for good reasons. Faster charging, a bigger and denser charging network, and cars with greater ranges will certainly convince car lovers to make the switch. The market is accelerating faster than ever before and it certainly looks promising. In the years to come, it will be interesting to see technology evolving to make owning an EV possible for everyone.

Written August 30, 2017


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