Sep 08, 2015
The public charging units from many companies help us all drive cleaner and farther. We need to know how they work and thank the owners who add this ability where we shop and work. If we understand how they work we can make it even better.
PUBLIC CHARGING 9/8/2015 by Jim Stack, Phoenix EAA
Public charging sites make it possible to drive your Electric vehicle much further that we could in the past. Some areas like the greater Phoenix area have a lot of charging sites (approx. 500) while other areas only have a few. The power from each unit called an EVSE can vary a lot even between locations and units at the site. There are Level 1 (120 vac), Level 2 (240 vac)and Fast Charger sites (400 vDC) for the average vehicle. The Tesla Super Chargers are in a class by themselves. In this article I just want to write about the J-1772 Level 2 sites that are usable by just about every Plugin vehicle. This includes Electric Motorcycles and conversions that have been equipped with a J-1772 interface.
I’ll try to refer to the power to your car as charging and the cost to you as billing. Since the word charging could be used for both. Tthis should help keep it clear when I mention the word charging.
Your charging power is a factor determined by your vehicles on board charger, the site power and software in the site and your car. You don’t have to know all the details to be able to drive and charge but you can be sure to get the best value by knowing about all the factors. You can also report problem that you notice before others have a problem.
The equipment at each site is called EVSE, Electric Vehicle Supply Equipment. Most are level 2 which is at a nominal 208 volts. The amperage is the part that can vary by location and equipment. Power in kW, Killowatts is the voltage times the amperage. You may be aware that the Blink Network started with their EVSE set at 32 amps (208 Volts x 32 amps = 6.6 kW) but later reduced them to half power 16 amps ( 208 x 16= 3.3kW ) because of some overheating J-1772 cables. Early in 2015 they restored them to a higher 26 amps (5.4 kW) but some got missed. I note and report these to get them powered higher. Charge Point equipment in our area seems to be the highest power of any public units but I have seen them from 5 kW all the way to 8 kW. Each area can vary. In some areas the public EVSE site may bill you $ by the time you are plugged in or it may charge by the kWh Killowatt hour. In fact the ones billing by time may bill you for an hour even if you only plugged in for 5 minutes. They also bill you even when your car is done charging but is still plugged in. Make sure you know how they bill you.
Each Plugin vehicle has on board charging equipment that also varies by model and brand of vehicle. One example is the LEAF which so far has outsold all over vehicles. The 2011-2012 models all have a 3.3 kW on board charger. The 2013-2015 models have a 6.6 kW charger in the SV and SL models but a 3.3 kW in the base S model unless it was ordered with a 6.6 kW unit in a base S model. I have not seen any upgrade offer from Nissan to change a 3.3 to 6.6 kW on board charger.
So if you have an early LEAF or model S with the standard 3.3 kW charger you won’t get more than that even at a Public EVSE that have full 6.6 kW available because your car limits the power it can take. If it’s a site billing you by time you are paying twice as much as a LEAF that can charge at the faster rate.
Just to add another factor to the issue is the fact that many Electric Vehicles have a software timer you can set to only charge at certain times and to a certain level. Let’s say your LEAF is set to only charge to 80% instead of 100%. Your car will stop charging at home or at public charging sites unless you override the menu option. You many have the vehicle set to only charge Off Peak from 11 PM to 6 AM or similar hours to save money and the GRID. When you plug in the EVSE will not charge unless you override the menu option. If it’s a time based public site it may bill you even though the vehicle is not charging.
The EVSE also communicates with your car when it is charging. Many start low and them ramp up as the car and EVSE send messages to determine how fast to charge. I’ve seen a LEAF model S only get to 2.5 kW even when the car has a 3.3 kW charger and the EVSE can handle 6.6 kW. On the other hand I’ve heard of Tesla Roadsters trying to use 9.6 Kw from a EVSE only able to provide 6.6 kW and it trips the circuit breaker off at the site. Most Public sites don’t give you access to reset the circuit breaker so you may be stuck.
So in summary be aware of the options on your vehicle from the charger to the software menu option. Also be aware of the EVSE equipment you are using and what it can or can’t do. Finally monitor your vehicle when it starts charging to be sure you are getting what you are paying for and unplug and move as soon as you can so others can charge. If there is a problem be sure to report it to the charging network so others don’t have the same problem. I use PlugShare.com and also add notes in there about problems. I also note if it a great location with things to do or high power from a good price. This gives all users an idea what to expect. Always try to consider your fellow drivers.
Together we can make all public charging better and keep it working so it’s there if and when we need it. Also report any vandalism. Don’t drop the J-1772 cords or connector since they may break. Don’t hit the screen if the unit doesn’t work since they also get damaged. We all need to work together to help create a great public network.
In a future article we can talk about Fast Charging, Super Charging and all the variables they cover. Wireless charging and plain outlets for charging will also be included. We do have standards but there are a lot of them and at times they can change. CHARGE ON =D--------------------
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