Future-Proofing

[bpodbielski]

So I just recently leased a 2014 Nissan Leaf S w/ QC and I am looking at installing a level 2 charger in my garage. Because Leafs are becoming more and more popular here (South of ATL), the electric company I work for is looking at using me as a guinea pig for a pilot program. They will be installing a second meter that jumps off the primary service and will be charged a special time of use rate just for charging the car. Because of this, I will need to install breaker box in my garage and then run my 240 outlet off of that. I know an electrician who is going to help me out with the permits and connections. So what I'm trying to figure out is, what can I do to future-proof this installation; so that no matter what changes in the future, I won't have to redo the entire project (or at least minimize my future expenses). For example, which ESVE should I go with, what size breaker should I use, what size wire should I run, etc?

 

[Nubo]

Although the ultimate DC fast-charge standard is still up in the air, the J1772 standard is fairly well-settled. Any J1772-compliant EVSE will likely charge any EV for the foreseeable future. Even the Tesla will charge from it with a small adapter.

You'll get different opinions on how many amps to provide. I tend to think that anything over 30 amps is overkill for a home station. Truthfully, I'm happy enough with 16 amps, which was the most a 2012 LEAF could charge at and the largest circuit we could install due to load considerations. If I get a 2015 LEAF (likely), I will still use the 16A EVSE.

People tend to think in terms of charge-time from 0% to 100%. And they worry that a larger pack will "take too long to charge". In my view the situation is somewhat reversed. As pack size increases, the average percent-range of your charging will tend to decrease. For example, adding 70 miles of range in LEAF may require a full charge. Adding 70 miles to a Tesla may only require charging 25% of the pack.

A better way to interpret your charging needs is miles of range per hour of charging. A 30A charge adds about 25 miles of range per hour to LEAF. Somewhat less for a larger heavier car like a Tesla. That's 100 miles in 4 hours, 200 miles in 8 hours, etc...

Another consideration to me is the "good neighbor" aspect. A high-amperage charger puts a heavy load on the local infrastructure such as the local transformer you may be sharing with your neighbors. Even 30 amps at 240 volts is as much as some households use in their entirety at peak load. As EVs become more prevalent, higher charge rates may prove to be too high if you have multiple neighbors on the same transformer all trying to charge at high rates at the same time. Depending on where you live, this may not happen for some time. But since we're talking "future-proofing" here...

Keep in mind that household load calculations should be done to determine how much amperage can be allocated to the new circuit without exceeding the capacity of the panel or even the electrical service line itself.

 

[smkettner]

As long as J1772 standard is common you are future proof.

A 30 amp evse will provide charging for most anyone's commute and daily needs. 40a circuit, #8 wire.
Leviton 40a on 50a circuit with #6 wire would be about max anyone could need at home.
Tesla with dual chargers needs a 100 amp circuit but is overkill for ordinary people. (Tesla evse required)
Unless you have two or more EVs.... cross that bridge when you get there.

 

[bpodbielski]

I hadn't thought about it like the miles of range per charging hour, that's a good point!

As far as the "good neighbor" aspect, that's really not an issue. I had a discussion with the engineer and after looking at the transformers in the neighborhood, junction box near the house, and service wire to the house, the panel off the second meter can support up to 180 amps without needing to run additional service lines or make any other changes to the grid. (It's sometimes helpful to work 50 feet from the guy in charge of the electric grid!) And actually, if I wanted to pay for it, there is 3 phase wire about 50 feet from my house and they could run that into my garage for a quick charger (not that I could afford a QC station though).

 

[asimba2]

240V 30 amps - 4.2 hours from turtle to 100%
240V 25 amps - 4.7 hours
240V 20 amps - 5.9 hours
240V 16 amps - 7.4 hours

I charge daily on 25 amps and it takes just under 2 hours to go from ~25% to 80%. It seems like an hour of the 4.7 hours you see above (at 25 amps) is cell balancing as it will charge from ~25% to 99% in 3.5 hours. Hope that provides some frame of reference.

I future-proofed with 6/3 wire on a 50 amp NEMA 14-50 outlet, with a 30-amp breaker, but reality is I doubt I will ever want more than the 24 amps provided by the openevse, even with a battery twice the size. My house (any many other new ones) only have a 125 amp panel to start with, so 80-100 amp service may require other expensive upgrades.

 

[johnrhansen]

If you are burying conduit, use a larger size than you need, this way if you want to increase the capacity later, at least you won't need to dig everything up again.

 

[hpver]

If you have the capacity (and it sounds like you do), you might consider installing the Clipper Creek HCS-60, which is reasonably priced, (J1772) and puts out 48 amps, requiring a 60 amp circuit. I agree with others about J1772 being the way to go as it's become the standard. But it is also designed to take higher rates of charge (up to 70 amps, I think) than most EVSE manufacturers are running through it now. So, it might not hurt to get an EVSE that makes use of a little more of that capacity. Even though your current Leaf can't use it, future cars might be able to (and Teslas and the RAV4 already can).

 

[r1234567]

With the Leaf, it charges in the front of the car and with the Tesla it's towards the back of the car. If you don't have a long cord, make sure to place the unit in the middle of the garage since you won't know where the port will be located on future EVs.