Free Destination Charging: 50x L2 80A Stations @ Caltech, Pasadena, CA

MITE46 · Nov 26, 2015

We've been trying to increase EV adoption and transportation sustainability @ Caltech in Pasadena, CA. It took a couple months to get the design in place and things approved, but we have finally started construction. The system is designed to satisfy the needs of a substantial number of EVs, not just a couple of stations here and there.

The goal is to provide free 50x L2 80A stations in a single parking structure for the campus and visitors. Parking Spots are not time enforced, so there is no rush to come back to move your car when it is done.

We're doing 2x 150kva transformers(32inx27inx44in), these made the most sense for the wiring size, distance, expected demand, and parking geometry.

They are quite heavy...800lbs, so floor mounting was the easiest method...We also needed 3ft clearance in front of the unit, so the easiest thing was to point them at each other.

Stuck my hand in there...

We also started mounting the actual stations...it's going to be 30x on one side and 20x on the other...should not have a problem finding an open station.

We will have to relocate some of the existing 480v breakers to make space for larger breakers feeding new transformers...We had to take readings to prove we have excess capacity...lots of it.

Anyway, the stations will go live in January, 2016. I'll more progress soon...

bredi · Nov 26, 2015

All this work to accommodate your EV stable?

This is such great work and I hope other parking structures do EXACTLY this! Well done! PR the heck out of it please!

Cosmacelf · Nov 26, 2015

What kind of EVSE are you using?

MITE46 · Nov 26, 2015

@bredi: Yes..hoping there will be lots of EVs taking advantage of this. We do plan to replicate the this same setup in other garages on and off campus.

@Cosmacelf: OpenEVSE v4 + our own adaptive software and scheduling algorithms

Cosmacelf · Nov 26, 2015

Ah, so building them yourself?

swaltner · Nov 27, 2015

Cool on deploying this with OpenEVSE installs that are tied together. Something like that would be required since you're putting equipment that could draw 416 kVA (25 units, 208 Volts, 80 Amps each) sustained on a 150 kVA transformer. Coordination between all the EVSEs would be required. As long as you're below the total power budget, feed an 80 Amp pilot signal to every car, but reserve the ability to ratchet the power available to each car down in the case of a peak demand situation.

Keep us updated, very slick.

Cottonwood · Nov 27, 2015

swaltner said:
Cool on deploying this with OpenEVSE installs that are tied together. Something like that would be required since you're putting equipment that could draw 416 kVA (25 units, 208 Volts, 80 Amps each) sustained on a 150 kVA transformer. Coordination between all the EVSEs would be required. As long as you're below the total power budget, feed an 80 Amp pilot signal to every car, but reserve the ability to ratchet the power available to each car down in the case of a peak demand situation.

I had the same concern. Glad that you worked out a great solution.

Great work, on an interesting scale.

For your next garage, consider using 3 each of 480V to 240V single phase transformers. Although not as common as the 3-phase, 480V to 208V transformers, they are available and would provide 15% more charging power to each car.

TTT · Nov 27, 2015

Mite46, this is great news, I've been traveling to Pasadena since Sept for a project and have been renting an ICE. Starting next week I'll be driving my MS, but was disappointed when I checked out the two chargers that Plugshare showed in the South Wilson parking structure and found Leafs plugged into both. Will the new stable of chargers be in the same structure? Would appreciate a heads up if they will be available before January

KJD · Nov 27, 2015

MITE46 said:
@bredi: Yes..hoping there will be lots of EVs taking advantage of this. We do plan to replicate the this same setup in other garages on and off campus.
@Cosmacelf: OpenEVSE v4 + our own adaptive software and scheduling algorithms

What a great project please keep us posted as it progresses. Would love to hear more details on your adaptive software and scheduling.

Cosmacelf · Nov 27, 2015

Adaptive pilot signals make a lot of sense! How are you handling the EVSE to EVSE communication?

MITE46 · Nov 27, 2015

@Cosmacelf: was able to lure unsuspecting family members during thanksgiving to assemble...got about 20 units done yesterday.

Big contactors...

@swaltner: Correct, adjustable pilot depending on available capacity and other variables. Have been testing the initial prototype for months now, originally in this thread: http://www.teslamotorsclub.com/showthread.php/45448-HPWC-Hacking/page2

Here's a sample of some of the aggregation charts: http://ev.caltech.edu/stations.html

@Cottonwood: had the same thought about 240V vs 208V, raised some concerns about phase imbalance, will take a closer look on the next garage.

@TTT: S Wilson garage will be looked at in the next phase...These stations will be a 5 minute walk away...will keep you updated on the completion date, we will probably have a soft opening in late December.

Vger · Nov 27, 2015

Finally someone addressing EVentual charging needs in a strategic fashion. I hope you write this up when done and publish widely.

Lots of other institutions and businesses need to start thinking this way to break the persistent public (and media-hyped) perception that charging infrastructure is (and by implication always will be) insufficient.

Cottonwood · Nov 27, 2015

MITE46 said:
@Cottonwood: had the same thought about 240V vs 208V, raised some concerns about phase imbalance, will take a closer look on the next garage.

Because the EVSE's in the U.S. are all single phase, as long as you distribute the EVSE's around all three phases and do your monitoring, pilot adjustment on each phase as its own resource/pool, you should not have any problems. In fact, 3, 100 kVA single phase transformers versus 2, 150 kVA 3-phase transformers would give you 3 100 kVA pools for allocation of power instead of 6 50 kVA pools.

Have you had any thoughts about demand charges and how that should factor into your allocation of power (current) to each unit?

Keep up the great work!

David99 · Nov 27, 2015

This is what we need! Not just one or two stations, but a large enough number so that you don't have to worry about finding a spot.

FlatSix911 · Nov 27, 2015

Congratulations on this project ... well done!

Chris1howell · Nov 27, 2015

Looks great...! I am very much looking forward to heading over the hill and seeing your work in action. I am thrilled OpenEVSE is a key piece in your solution.

This is the kind of solution that needs to be deployed on a much wider scale.

Cosmacelf · Nov 27, 2015

The contractors are a key component. What kind did you use?

abasile · Nov 27, 2015

Very impressive project! Having 50 EVSEs in one location will, for some time to come, provide EV drivers with the assurance that there *will* be a place for them to charge, without contention issues.

My personal question is regarding acceptable use. Occasionally we spend the night in Pasadena, visiting at a residence that lacks a good place to charge our LEAF. While it's easiest to "just drive the Prius", we've in the past used our LEAF and hunted down charging locations. We could conceivably leave our 2011 LEAF (with its measly 3.3 kW onboard charger) parked overnight at Caltech and walk from there. Would that be frowned upon? We'd be willing to pay a reasonable fee, though it seems best to avoid charging a whole lot more than the cost of an equivalent amount of gasoline, and a full charge in the LEAF (in terms of drivable miles) is worth only a couple of gallons of gasoline or so.

Buying a Tesla should reduce our need to charge while in Pasadena, though even with a long range EV it's helpful to have destination charging. I also understand that many Caltech affiliates may not have access to residential charging. I hope that many other organizations choose to follow your lead.

Rush · Nov 27, 2015

Mite46 - If you're looking for some J1772 Plugs and Cords either 30A or 40A let me know. I can give you a discount. Rush - TucsonEV

Chris1howell · Nov 27, 2015

Cosmacelf said:
The contractors are a key component. What kind did you use?

Contactors are Packard C390C, they are massive and can handle 120A resistive or 90A inductive.

Free Destination Charging: 50x L2 80A Stations @ Caltech, Pasadena, CA

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