# Public charging stations



## GoElectric (Nov 15, 2015)

Hi - this is close to a dumb question. How can a DIY car use public charging stations? How do they know what voltage you are running at??


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## Hollie Maea (Dec 9, 2009)

GoElectric said:


> Hi - this is close to a dumb question. How can a DIY car use public charging stations? How do they know what voltage you are running at??


I presume you mean DC quick chargers, since otherwise your voltage is irrelevant.

Your car needs to have the capability of communicating with the quick charger, following whatever protocol the charger uses. That's...not trivial for DIYers.


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## miscrms (Sep 25, 2013)

L1/L2 public chargers (EVSEs) aren't really chargers, just fancy power sockets. They just supply AC power at 120V or 240V to your on board charger. To use them you'd need a charger (or interface board) and socket that's compatible with the SAE J1772 spec that governs these charging stations (EVSEs). I believe you can get kits to add this capability to a DIY EV pretty easily. DC Fast charging is a whole other ball of wax as HM indicates, and is not impossible but a pretty tall order for DIY.


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## mizlplix (May 1, 2011)

For the L1 & L2 set up, I got the spoofer board and socket from 
http://tucsonev.com/

They work fine. I was lucky enough to get the plug and 16 ' of cable from a board Member for $50.(as they are costly)

For my home charging set up, I simply got power from my garage sub panel and made a charging relay from a small metal box and a simple Air Conditioner line voltage relay. 

It works just like the commercial stations: When you plug in, it gets a pilot signal and turns the relay on starting the charging operation. 

This type always uses your on-board charger. Mine is an Elcon. It takes 120VAC or 240Vac either and I keep a short extension cord to charge from a 120VAC socket in a pinch.

Miz


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## GoElectric (Nov 15, 2015)

Hi - wow, that is like Christmas!!!

Thanks a lot!

(not such a dumb question after all - and there was even a solution)


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## GoElectric (Nov 15, 2015)

Hi. So I went to the website last night and was going to order, but this looks like another function which could be taken care of by the PLC.... I have the right socket.

Anyway, I clearly don't know much about charging stations. I didn't know there were two kinds. And I thought OEM cars did not have chargers in them - you have to buy one and put it on the wall in your garage, don't you?? 

So, for a fast-charger the station pumps mega-current directly into the battery - somehow by-passing the on-board charger?

Can somebody clear up where the charger is for an OEM??


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## dougingraham (Jul 26, 2011)

GoElectric said:


> Hi. So I went to the website last night and was going to order, but this looks like another function which could be taken care of by the PLC.... I have the right socket.
> 
> Anyway, I clearly don't know much about charging stations. I didn't know there were two kinds. And I thought OEM cars did not have chargers in them - you have to buy one and put it on the wall in your garage, don't you??
> 
> ...


There is a charger in the OEM car that accepts AC over a fairly large range and outputs the DC appropriate for battery in that OEM vehicle. These are typically around 3.2 kilowatts. In some cars you can get an optional second charger which will almost cut the charge time in half.

Tesla Model S has standard a 10kw charger and you can add a second 10kw charger for a total of 20kw. These chargers are located under the rear seats.

The onboard charger(s) in the car are for Level 1 and Level 2 charging only. Level 3 or DC charging the charger is in the charge station. Chademo which is what the Leaf uses for its DC fast charging can charge at up to 48 kw. The Tesla Superchargers are DC fast chargers that can operate at up to 120kw. The Teslas have an adapter that will let them use Chademo.

The device you put in your garage is called an EVSE or Electric Vehicle Support Equipment. It has the plug on it that fits the charge port in the car. The ones you would buy are going to be Level 1 or Level 2. A Chademo station will run around $30000 to $50000 so not something most people would consider for their garages. The L1 and L2 EVSE have the protection circuitry in them so they handshake with the car to turn on the AC power only when properly plugged in. In a properly installed EVSE you could sit in a tub of water or stand in the rain and nothing you do to the plug will cause it to turn on and shock you. In other words, they make it safe. An L1 or L2 EVSE will cost a few hundred dollars to a couple of thousand depending on features. The EVSE that is provided with every OEM car may be enough for daily use depending on how many miles you drive. Even with a 110 vac outlet at 12 amps you can charge at least 30 miles overnight.


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## Caps18 (Jun 8, 2008)

http://www.diyelectriccar.com/forums/showpost.php?p=756402&postcount=338

Take a look at the pictures I posted yesterday. I have mounted the charger under the hood (the one with the 4 fans(, and the AVC2 sensor that detects when the plug is inserted correctly and allows the connection to be made. The charger is where the voltage gets set at, and it will deal with 110V or 220V (US type).

Anything other than level 2, J1772s are out of my comfort zone to try and hook up, if it is even possible with available parts.


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## GoElectric (Nov 15, 2015)

Doug, you are a hero! Very clear and informative.

I thought I was just going to get a darn cord, plug it into the wall, then plug the other end into my J1772. My Elcon charger needs the handshake too then? Crap, more hardware to buy.

Thanks-all.


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## Moltenmetal (Mar 20, 2014)

The handshaking is easy- an AVC2 will do it for about $50. The J1772 socket costs a few bucks. 

I basically turned my J1772 socket into a J1772 to 120VAC u ground adapter. You can unplug the 120VAC plug that the Elcon comes pre-terminated with, from that socket, and plug it into an extension cord to run the Elcon off 120VAC when you need. It was a quick and dirty solution- good enough for my DIY EV. That's actually how I charge most of the time, both at home and at work- from 120VAC. I don't have an EVSE at home- I just charge from an outdoor GFCI outlet. The vehicle chassis is grounded via the U ground pin of the 120VAC outlet during charging, so any current flowing into that ground during charging should trip the GFCI and arrest the charge. I've never had the GFCI trip.

If you do builds for others, you will have to decide whether to force them to charge using an EVSE or to give them the option of 120V direct connection- something which is very handy. They do make a little 120V level 1 EVSE which I've seen some of my co-workers using with their Volts. If you're going to give them the option to direct plug into 120V without an EVSE, you need to protect against back-feeding the 120V plug by means of the 240V EVSE. I didn't want to mess with that, so I opted for what I did. Baratong and EVMetro both have solutions they've used to make the transition more user-ignorance-tolerant if I recall correctly.

A word of warning though: 120VAC extension cords tend not to like current draws of 12A for extended periods, especially if they get at all damp. I had one go on me when I had two extension cords plugged into one another and the junction laying on a patch of damp grass. There was no ground fault, but the socket did get hot and melt. Replacing the molded socket end that an extension cord comes with, with an industrial replacement socket, seems to give adequate service life (so far!).


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## dougingraham (Jul 26, 2011)

GoElectric said:


> Doug, you are a hero! Very clear and informative.
> 
> I thought I was just going to get a darn cord, plug it into the wall, then plug the other end into my J1772. My Elcon charger needs the handshake too then? Crap, more hardware to buy.
> 
> Thanks-all.


The Elcon does not need any handshaking.

Moltenmetal mentions the AVC2. This little board goes in your car and connects to the J1772 receptacle you mount on your car. The only reason you would need this would be if you want to activate public J1772 stations. For your garage you could just wire a J1772 plug to the wall and ignore all the handshaking. This is not recommended however because you eliminate all the safety features built into the EVSE. You also can have excessive wear on the pins of the J1772 parts if you eliminate the handshake. There could be a spark when you plug the J1772 into the car if you work around using a real EVSE. This spark will cause excessive wear on the high power pins.

Get an AVC2 and wire it up and you can use public charging . The AVC2 can also be wired to your motor controller circuit so as to prevent you from driving off with the charge cable plugged in. This is a good idea as if you don't it will happen to you some day.

The downside of the AVC2 is that it cannot set the charger to a particular charge current. The EVSE as part of the handshake tells the charger in the car (in this case the AVC2) the maximum current the charger is allowed to pull from the EVSE. You will need to manually set this. Most of the time limiting the AC draw to 30 amps would be safe. But not always and if you pull too much current the EVSE could shut you down or you could pop a breaker. This can be somewhat inconvenient if it happens.

Best Wishes!


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## GoElectric (Nov 15, 2015)

Hi. More good stuff!! I don't mind if I get a big dump from an ESVE I guess, but might want to charge differently at home. So, how do you avoid sparking contacts on the home-front if there is no handshaking? 

It seems odd that the Charger can even distinguish between one and the other, as it is the AVC2 which just turns on the charging station?

Yes, MM I think 120 will have to be an option for cars I'm building - not a lot of charging stations around here, and who wants to sit there for a couple of hours anyway, when you could be plugged in and drinking beer at your friend's!

Thanks for the pic of your set-up Caps18. If the AVC2 is the bottom bit, what is on the top?


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## Moltenmetal (Mar 20, 2014)

The J1772 pins are undersized for disconnection under load.

Irrespective of whether you use a J1772 plug or the 120V plug that the Elcon comes with, you should NOT unplug the charger while it is charging, or otherwise disconnect the AC power from it while it is charging. It's also hard on the plug and socket of course. If you look at the Elcon repair thread, there is enough evidence of failures that can likely be attributed to that kind of disconnection to make it not an advisable thing to do on a routine basis. Of course if you get a breaker trip or a power outage you're going to lose your input 120VAC, but you shouldn't do it deliberately.

Instead, I use a pushbutton switch wired in series with my BMS cell loop, placed right next to my J1772 charger port. Pressing that switch trips the BMS interlock on the charger, which allows the charger to shut down normally. A few seconds after pressing that switch, when the charge current has dropped to zero, you can unplug the charger's input side at will.

So again: you can either force your clients to buy a 120V level 1 EVSE- little black box with an extension cord attached to it- to use when they want to charge from 120V, or you can come up with a 2-socket solution with some means of preventing back-feeding of the 120V plug with 240V when you plug into the J1772. Given that it's a PLUG, i.e. male ends, that's pretty important if you don't want dead clients! If I were building cars for others, I'd sell them a 120V EVSE with the build.

https://www.clippercreek.com/store/product/pcs-15-portable-level-1-evse/

Link is just the 1st thing I found when Googling "120V EVSE"


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## dougingraham (Jul 26, 2011)

GoElectric said:


> So, how do you avoid sparking contacts on the home-front if there is no handshaking?


The sparks depend on the way the charger is designed. If you plug it in now and you see a spark this will still be there at the relay or contactor contacts when the contacts close in the EVSE. This will cause additional wear on the contactor contact surfaces. If you don't have an EVSE and it does spark when connected you can plug in the J1772 plug to the car and then plug the other end of the cable into the wall receptacle. This would move the spark to the plug and receptacle which are considerably less expensive to replace. If there is no connection spark then you don't need to be concerned about this. There is probably some sort of inrush current limiting already built into the charger.


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## Caps18 (Jun 8, 2008)

GoElectric said:


> Thanks for the pic of your set-up Caps18. If the AVC2 is the bottom bit, what is on the top?


The box I bought at Lowe's is for an outdoor Air conditioner/hot tub type of enclosure. The top is where the J1772 plug wires get screwed into a terminal along with the Elcon charger wires. This makes a secure connection, and could be disabled by flipping the top metal contact that bridges them. But, you would not need this feature in this application.


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## PStechPaul (May 1, 2012)

I have just done a lot of research on the J1772 interface as part of my project for the EMW charger (which seems to have an incorrect circuit). My discussion is actually on Tony Bogs's thread on his modular charger, but the last few posts have addressed this handshaking protocol.

http://www.diyelectriccar.com/forum...dular-charger-design-162082.html?goto=newpost

I think I have figured out and explained clearly how this works, and several ways to implement it so the proximity and pilot circuits do their job and deal safely with various charging scenarios. 

Please let me know if you try any of these ideas or have further experience with public charging stations. Thanks.


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## electric85 (Apr 10, 2008)

Hey! Lots of great info in this thread! I do have another question though. I would love to be able to charge at public level 2 stations. I see that I can as long as I buy a device that will work with EVSE, Awesome. And then if I also wanted to charge off of a regular household plug, I need to get a level 1 EVSE...Awesome. But What if I wanted to use a dryer plug when I am at home or a welder plug. I found this picture on the internet before and thought it would be pretty awesome to have these adapters and charge off anything whenever I need to. But as public charging stations are growing in numbers, I thought it would be great to do it all. Is that a pipe dream?


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## PStechPaul (May 1, 2012)

I think all the level 1 and level 2 charger plugs and sockets are the same, so you can add your own industry standard plugs for the other end, to connect to 120 or 240 VAC receptacles.

http://www.ebay.com/itm/J1772-Plug-...sla-UMC-Voltec-or-any-EVSE-Cord-/181959667188



















These J1772 connectors are not cheap, in the order of $100 each. But the rest of the system can be done on the cheap using a DIY circuit and inexpensive components. You can get what you need from:

https://store.openevse.com/


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