Monday, July 13, 2015

Living the life electric - part 4.

(This post follows from last week's - best read that first if you missed it).
For our Nissan LEAF, we initially we decided the supplied 120v trickle-charger would be fine, but that meant the cable would never be in the car - problematic if we ever needed some juice whilst out somewhere. Realising that the LEAF has a standard J1772 charging port, I also realised I didn't need to pay Nissan $1500 for their charging station. Bosch do one for less than $500 which does the exact same thing.
At this point I also discovered 'electric car people' are very particular about the terminology. The thing you put on the wall in your garage is NOT a charger. It's an EVSE - electric vehicle supply equipment. It's designed to provide power at a known voltage and current to the car, and the charging functions are all built in to the car itself. This means I can plug in 120V at 1.3kW, 240V at 3.3kW or 240V at 6kW and the car will adapt accordingly.
The only difference in the charging methods is time-to-charge. The cost of power doesn't vary where we live, so there's no benefit to attempting to charge overnight.
For the LEAF, from an almost-dead battery to fully-charged takes 20 hours on the trickle-charger, about 8 hours on a 3kW supply and about 4 hours on a 6kW supply.
There are three decision to make when looking at an EVSE. The first is this: do you own a Tesla? In which case you can't buy an off-the-shelf EVSE because Tesla use a proprietary charging port connection. Assuming you don't own a Tesla, the second question is AC or DC charging? AC is the most common. DC is massively powerful and for most electric cars will give you a 40 minute charge time from dead. The disadvantage is a huge cost for the EVSE, upgraded electrical system in your house or garage, and a charging cable the size of Duane Johnson's biceps. Assuming then that you go with the far more common AC charging, the final question is 'will this burn my garage down?'.
The power rating of your electrical supply is very important. In our case we have a 50amp feeded to the garage, so adding a new 30amp EVSE to that circuit would not leave a lot of 'wiggle room' in the electrical system. For that reason I chose to put in a 16amp version. Shorter charge times than the trickle charger, longer than a 6kW supply. With the 3kW supply I used, for our daily driving, it literally takes 20 minutes in the evening to top off the charge. I did all the electrical work myself as it's pretty damn simple, and I didn't pay Nissan another $1500.


Paul said...

As a matter of interest, is the voltage for the Tesla EVSE something weird or is it just the connection? Will there be an adapter in the future so Tesla owners can use something other than the proprietary Tesla charging stations?

Chris said...

The Tesla has a standard J1772 connector which is good up to 6kW / 240v. But their supercharger uses a proprietary DC connector that can deliver 120kWH at 480v, hence the much MUCH shorter charge time. Current is way up there at 250Amps on these chargers.
It also makes you itch when it's plugged in and small birds fall out of the sky dead ... :)