January 2017 Jeff Miller Charging Infrastructure Presentation

[jeffrey.miller]

I filed the permit application with the city for the two big charging stations.  I expect no issues with that from them. 


"Permit application addendum May 22nd 2018

As you likely recall from my recent work I have four disconnects that can support four 80 amp charging stations, along with two 50 amp outlets to support two 40 amp charging stations. 

I don’t yet have a method ready to deploy that automatically manages the power split between these potential six stations, however if I only install two 80 amp charging stations, one per sub panel, I cannot exceed the total 120 amps continuous available.  This will allow me to fully utilize my Tesla and not create any risk of exceeding the circuit capacity. 

Once I have a system in place to manage the total current draw across the full complement of stations then I will return and put a permit in place to do the last two and discuss with you the details of that system.  That functionality requires some serious time and thought to make it a robust solution that both fits my needs and a less technical future owner.  I have some good concepts on this, just need to build and validate them.  In the mean time I can deploy two at full rate and have no concern of overloading anything.  "

[jeffrey.miller]

I did have to jump through a couple of hoops, especially provide an updated drawing, but I got the permit today to install the first two big charging stations.  This along with the two 50 amp outlets will bring me up to four stations. 

I had a good discussion with the city electric plan guy and explained some of the bigger picture things I am doing and he said he would be looking at some of these concepts as people submit paperwork in the future.  Also he really likes my ASCI art diagrams! 

I imagine in a week or so I will have the easy one installed.  The hard one, which will be recessed into the wall, will be a bit longer as I sort out the mounting for it. 

[jeffrey.miller]

First station is installed.  It is surface mounted, so fairly easy compared to the other one which will be recessed into the wall.  A bit of metal working went into the backer plate to make the contactor fit in the enclosure. 

When I run it at 80 amps it seems to drop the line voltage to the car by by about 5 volts, compared to when charging at only 10 amps.  In theory that is 400 watts turning into heat to get energy to the car.  Voltage drop at those sorts of current levels isn't surprising, but I suppose I will be checking to make sure it is not all happening in one spot.  400 watts of loss on all of the lines and connections between the transformer and my car isn't concerning, but if most of that is concentrated in a single connection then that would be concerning.  400 watts assumes that the transformer and it's upstream feed is completely stable when I add my 19kw load which is likely not to be the case.  I was testing this when the outside temp was above 90 degrees, so good chance the upstream lines, transformer, and grid weren't all that happy.  I will do some measurements tomorrow and confirm that none of my connections are going to get hot due to excessive voltage drop. 

Fuses and breakers both create heat and since I have three breakers, and a set of fuses in the path, those could account for most of the heat being generated when I charge at 80 amps.     

[jeff.green]

80 amps is HUUUUUUUUGE compared to myy 13

[simon.gibson]

You can measure the voltage wrt to ground or neutral at various points along the way when its drawing 80 amps. where the biggest drop occurs is where the culprit lies! Depends how sensitive your meter is, how many decimal places! But, you are right, a large voltage drop in one spot would indicate a bad connection...
Simon

[jeffrey.miller]

A brief check this morning and I saw the same voltage on both panels, and since the only common point for those two panels is the meter box and the comed stuff, I am no longer worried.  That voltage was fairly close to what the car was showing  (it is a cheap meter).   

[jeffrey.miller]

I gave a short update on my charging system at the last meeting.  The performance of this set up is impressive to me (the car and the kit I have installed working together).

One of the big things is to make sure you use wire ferrules, or some other crimp on connector, on the flexible cables going from the charging station to the car.  If you just try to shove fine stranded wire into a screw terminal you could have serious problems.  
http://www2.schneider-electric.com/resources/sites/SCHNEIDER_ELECTRIC/content/live/FAQS/126000/FA126881/en_US/Fine%20Stranded%20Wire%200515DB0301.pdf
The OpenEVSE Advanced kit comes with pre crimped ring terminals that fit the included contactor, so this isn't an issue with that kit as much.  The standard kit comes with ferrules.  Since I am designing my own to a large degree I had to provide my own ferrules.  


https://www.amazon.com/gp/product/B01I9E0X0A
https://www.amazon.com/gp/product/B01I7X480E   (I cut the red pieces off as I was using them on earth ground)
https://www.amazon.com/gp/product/B01I9DUNM4 (these weren't in stock when I was buying the 8ga ones)
https://www.amazon.com/gp/product/B01I93KA90
If anyone is tackling a project like this, let me know, I have quite a few extras.

I didn't speak specifically about the cable gland, but it is a nice metal unit, it costs a bit more than the plastic ones, but not THAT much more.  
https://www.amazon.com/gp/product/B071VT8PW8

I also showed the metal channels that will get mounted to the studs with some means of mounting the charging station to it.  This will allow the two charging stations to be recessed into the wall a few inches.  This makes it easier to walk through the garage and also not as likely to hit them with the cars.
I had those metal plates bent out of galvanized 1/16th inch steel (16 gauge) and each cost me $32.  I could have left it not galvanized, or thinner gauge, but for the cost of $32 each (about half labor half materials) I was happy to buy the heavy material.  The shop that did this was
https://adamssteelservice.com/
I dropped off the design of what I needed one afternoon and it was done the next day.  

Enclosure
https://www.budind.com/pdf/hb10449.pdf
NBD-10469 with the clear cover, and it's matching plate
I bought them from Mouser
https://www.mouser.com/ProductDetail/Bud-Industries/NBD-10469/?qs=CzuyTOUYZuSyeuu2mwym%2FQ%3D%3D
https://www.mouser.com/ProductDetail/Bud-Industries/NBX-10996?qs=sGAEpiMZZMvJyyQy4slOTqesa7FilqJ1HkYnPTuw%252bZo%3d

The rest of the parts came from OpenEVSE, but I believe I have linked them all before.  
I did buy the J1772 cables from quick charge power.  

Fuses came from https://www.pacificcoastbreaker.com/a2k100r-100a-250v-class-rk1-fast-acting.html

Additionally I will report that I can hear the hum from the current flowing through the electrical system in many parts of my house, including my master bathroom, when the car is charging.  My master bathroom is directly above the conduit running to my car charging station.  It is quieter in the basement as that is a larger breaker, but the box in the garage hums somewhat louder as there are 80 amps flowing through a 100 amp breaker there.  It isn't excessively loud like something is broken, just the soft hum of power flowing.    


There were questions we have to defer to another day around charging costs specifically related to the Comed Residential Real time Pricing, and also the centralized control of all potential charging stations to keep them from over loading the 120 amps continuous per sub panel I have available.  Those are two complete topics to dive into very deeply at some future point.  

[jeffrey.miller]

I forgot a detail

I also used:
"MOV V275LA20AP (red disk Metal Oxide Varistor) to reduce chatter noise created by the bouncing contactor coil."
(quote courtesy of OpenEVSE build guide)
purchased at Mouser

I also used a torque wrench to tighten the large connections on the contactor to the proper spec.  I have used my torque wrenches extensively in this project.  

[jeffrey.miller]

Finally, some CHEAP electricity!
Last night my car charged for 40 minutes and took in 12.8kwh.
During that period of time the price of electricity was -2.4 cents, before delivery charges of course.  I paid about 46 cents to "fill up" my Tesla early this morning.  I have only seen negative prices a few times since I have had my Tesla.  It was very common last summer but it seems Exelon is getting better at not giving away money. 

[jeffrey.miller]

The city approved those two charging stations   
On to the next two. 

[jeffrey.miller]

My last "presentation" wasn't exactly a presentation but instead a live demo of the capabilities combined with a build session.  We did do the tour of the supporting infrastructure once everything had wrapped up with the builds but I think the cold weather discouraged some people from staying that long.  Between the last build I did, and the current one OpenEVSE has updated the design in a few small but fantastic ways.  I won't go into the full details at this point, but my assembly time to go from a pile of parts to a wired backer plate ready for the garage dropped by at least half.  On top of that it was easier to understand and all the instructions were better consolidated especially in regards to the WIFI module.  I also didn't have to use or provide any additional wire in my build (DC coil contactors might still require a piece of wire) so it was much easier to just crimp ends on than dealing with the long list of tiny terminal blocks.  I find it interesting that it took them this long to get this far into a design improvement as OpenEVSE builds and sells these stations to end users also, the labor had to be killing them. 

Updated product page
https://store.openevse.com/products/openevse-plus-v4-universal-charging-station-controller

Direct link to excellent connection diagram. 
https://github.com/OpenEVSE/OpenEVSE_PLUS/blob/master/OpenEVSE_PLUS_v5/OpenEVSE_v5.pdf
Those of you that have built these will probably notice how much easier this makes it to figure out what is what. 

We had 2x Rav4, 2x Volt, and the S10 all simultaneously charging.  I know Chris was pulling between 24 and 30 amps most of the night, the Rav's were pulling 40 each and the Volts are good for 15 so that equals at least 134 amps at some point there.  Early in the evening before the fifth station came online we would have been drawing about 120.  Not enough to cause Comed to show up at our event, but a good evening of charging and enough to get everyone back home from sticks of Crystal Lake.  The sixth station did work, I saw a few amps of current flow before we killed it due to the noise the coil in the contactor was making.  Ever so briefly we were charging six cars. 

I sent Tony Williams of Quick Charge Power a nice thank you note for overnighting the cables to my door so we could do those builds that evening and get those online. 

In related news, I no longer know of any current production Full EV that charges at less than 6KW, and with the Volt finally switching over to the higher rate charger 32 amps just like the Bolt even the new versions of those will charge much faster.  Regrettably the 2019 Outlander PHEV in the US retains the slow charger.

As someone pointed out, Friday night was the evidence to prove my theory that a house could reasonably require 4 charging stations, and potentially more in the case of guests coming over from long distances.  Some day I might be the holiday destination of choice for my family, not just because the food is good, but because it is easy to charge and get back home afterwards.   

My journey of building charging stuff at my house is almost over (they physical part anyway), others are picking up the torch though.  I know Simon is putting in substantial pieces of kit right now, and Mike W keeps saying he needs to do it.  Other members are starting to get serious and seeing my build has provided some ideas.  I am excited to see what comes next in the home charging space in the FVEAA. 

[jeffrey.miller]

I learned something new today.

https://www.tesla.com/support/home-charging-installation/onboard-charger

The Model 3 Long Range has a 48 amp charger (not 40 as originally reported), and the Mid Range and Short Range have a 32 amp charger (not 30 as originally reported). 
I am happy to hear this, more charging rate is a good thing in these cars.  48 amps is enough to receive 10kw on 208 volt service, which is a nice option for destination chargers. 


I have also heard that the 2019 Volt will finally have a 7.2kw (32 amp guesstimate) in it. 

[jeffrey.miller]

20% off Juice box charging stations, today only! 

https://evcharging.enelx.com/store/residential