# Public charging stations outdated?



## dougingraham (Jul 26, 2011)

If you drive less than about 25 miles per day and have a place to charge at home a 110vac 15 amp service will do fine.

If you drive less than 100 miles per day and have a place to charge at home a 240vac 30 amp service will do fine (assuming you even have 100 mile range to begin with.)

If you can charge at home the existing infrastructure will work fine. If you have to use public charging then they are not fast enough. A 30 amp Level 2 charge station can get you about 25 miles per hour of charging. Level 2 can go to as much as 70 amps however. If I had a powerful enough charger I could charge my pack at up to a 3C rate which would be 52kw and would require the ability to give me 217 amps at 240 volts. So yes I would agree that the charging stations are way behind even what could be done today. Tesla's supercharge stations are a little more than twice that power level. A typical residential service in the USA is only 48kw.


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## evmetro (Apr 9, 2012)

I understand that level 2 is good up to 80 amps, but limited to 30 by the service to the charging station. As I understand it, it is the stations that government grants pay for that are being set up this way, and that this would also be the majority of them. I think I will continue to adapt my EV builds to the main powergrid and not get left behind waiting for the government to build a new one that makes any kind of sense.


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## rwaudio (May 22, 2008)

evmetro said:


> I understand that level 2 is good up to 80 amps, but limited to 30 by the service to the charging station. As I understand it, it is the stations that government grants pay for that are being set up this way, and that this would also be the majority of them. I think I will continue to adapt my EV builds to the main powergrid and not get left behind waiting for the government to build a new one that makes any kind of sense.


Who says you can't do both?
Make the car J1772 compatible for times you can use those public stations.
Also make your own plug/connection style to be able to plug into anything.

We don't have government funded stations here, but the public ones I've seen range from 30A to 70A, I'm making my car compatible for use up to 50A. If you have a programmable or adjustable charger you could just as easily plug into 120v 15A, 240v 30A or 240v 50A+ with the same hardware, if the charger is fully J1772 compatible it will set the maximum current itself based on the power available.

I don't see how you are limiting yourself by making the car compatible. What do you plug into that is so much better?


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## evmetro (Apr 9, 2012)

I plug with a 50 amp welder plug, and at this point in time there are a lot more of these in existence than there public charging stations. I don't know that it is any better, but it is more than 30 amps. Easy to plug or unplug, and I run a welder at my shop. I am more interested in equipping my builds to actually charge faster than I am in being able to adapt to a system that limits it. It would seem that charge time is part of what gives people range anxiety, While we know that it makes sense to design an EV to our specific needs, most consumers do not. They want to plug in wherever and whenever they want, and to charge up faster than their actual need. So do I.


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## dougingraham (Jul 26, 2011)

evmetro said:


> It would seem that charge time is part of what gives people range anxiety, While we know that it makes sense to design an EV to our specific needs, most consumers do not. They want to plug in wherever and whenever they want, and to charge up faster than their actual need. So do I.


When asked "How long does it take to recharge?" I say about 10 seconds of my time. I get the dumb look and then explain that if I put in a range outlet in the garage it could be as fast as 40 miles an hour recharge but from a 110vac outlet it does 5 miles an hour recharge which has never been a problem for me. But of my time it takes about 10 seconds to plug it in and the next time I want to drive it is charged.

It will be extremely rare for me to use a public station. Unless it was free or cheaper than 11 cents a kwh there would be no point.


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## rwaudio (May 22, 2008)

evmetro said:


> I plug with a 50 amp welder plug, and at this point in time there are a lot more of these in existence than there public charging stations. I don't know that it is any better, but it is more than 30 amps. Easy to plug or unplug, and I run a welder at my shop. I am more interested in equipping my builds to actually charge faster than I am in being able to adapt to a system that limits it. It would seem that charge time is part of what gives people range anxiety, While we know that it makes sense to design an EV to our specific needs, most consumers do not. They want to plug in wherever and whenever they want, and to charge up faster than their actual need. So do I.


That's fair, and makes the most sense for your situation. and like you said it's the want to charge faster than your needs. I charge at work on a 120v 15A circuit, but I'm parked there for 8 1/2 - 9 hours a day so speed doesn't matter as much. At home I charge at 240v 20A, my detached garage is currently only wired for 120v so hooking up the 240v 20A line just for the car was an upgrade. 

A friend of mine has a Solectria Force with a lithium upgrade 56x 60Ah cells and currently runs with a 600w charger, he drives the car everywhere! If he's not driving he's charging. He can't wait for the upgrade to 1500w for those day to day charings with the option to charge at up to 10kw when he comes across an appropriate location.


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## evmetro (Apr 9, 2012)

I have great respect for you guys running 110v charging. I do not use mine much, but it is the gateway to the largest charging network in the USA. While I have both 110 and the 50 amp welder plugs, I would pick the 110 really quick if I could only have 1 plug. If it came down to it, charging wherever I want would be more important than how fast. Since I do have a 110v port, I will persue faster charging methods, and I don't think I will bother with the little 30 amp public ones. Maybe 2 welder plugs and 2 charge cords? Hmm...


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## ElectriCar (Jun 15, 2008)

evmetro said:


> I understand that level 2 is good up to 80 amps, but limited to 30 by the service to the charging station. As I understand it, it is the stations that government grants pay for that are being set up this way, and that this would also be the majority of them. I think I will continue to adapt my EV builds to the main powergrid and not get left behind waiting for the government to build a new one that makes any kind of sense.


Depends on the station. Eaton makes a 3.8Kw and a 7.2Kw L2 charger. All of them I've tried are 3.8 and will kick off because my 5kw charger wants about 30A from the wall and all they want to give you is about 24.

But that's what happens when the government gets involved and has the power to take from people. They far too often spend it stupidly as they have with these things. My local Burger King has one. Who on earth is going to be there long enough to get any power??? And that one is a Chargepoint which you must pay for. If you live in my area and park in a parking garage where you work or at the county offices, you can charge all day on them which makes sense but a dang burger joint? Naw.


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## adeyo (Jun 6, 2012)

evmetro said:


> ... I have both 110 and the 50 amp welder plugs...
> 
> 
> ... Maybe 2 welder plugs and 2 charge cords? Hmm...


Wow...so how fast could a 24kw pack be recharged from a welding plug? 


And, I'm a novice when it comes to this, but are dual plugs a viable option? I mean, wood it take much to accomplish this and actually plug into two 110 outlets at once??


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## dougingraham (Jul 26, 2011)

adeyo said:


> Wow...so how fast could a 24kw pack be recharged from a welding plug?
> 
> 
> And, I'm a novice when it comes to this, but are dual plugs a viable option? I mean, wood it take much to accomplish this and actually plug into two 110 outlets at once??


Welding plugs vary too. We are probably talking about 240V at 50 amps service which could in theory deliver 12kw which would mean 2 hours. You can't actually do that, about the best would be 80% so 2 and a half hours.

If your chargers are isolated then there is no problem with paralleling the outputs. The input 110vac outlets would need to be on separate breakers or you would just pop the breaker. If the chargers are not isolated then it gets lots trickier and I would not recommend trying it. Certain configurations could work but there are possibilities where one or both chargers burn out and that is not what you are hoping for. And with two chargers it would cut the charge time almost in half. So unless you really know what you are doing it is a bad idea to parallel non-isolated chargers.


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## adeyo (Jun 6, 2012)

dougingraham said:


> Welding plugs vary too. We are probably talking about 240V at 50 amps service which could in theory deliver 12kw which would mean 2 hours. You can't actually do that, about the best would be 80% so 2 and a half hours.
> 
> If your chargers are isolated then there is no problem with paralleling the outputs. The input 110vac outlets would need to be on separate breakers or you would just pop the breaker. If the chargers are not isolated then it gets lots trickier and I would not recommend trying it. Certain configurations could work but there are possibilities where one or both chargers burn out and that is not what you are hoping for. And with two chargers it would cut the charge time almost in half. So unless you really know what you are doing it is a bad idea to parallel non-isolated chargers.


Thanks for the response. And by isolated I assume you mean a battery bank that can be split in half to charge each portion separately?


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## dougingraham (Jul 26, 2011)

adeyo said:


> And by isolated I assume you mean a battery bank that can be split in half to charge each portion separately?


No. Isolated chargers have a mechanism which electrically isolates the input from the output sides. The most common way is to use an isolation transformer. With switching supplies this is usually done as part of the switching supply because the high frequencies mean a much smaller transformer can be used. Chargers that are not isolated might have a nearly direct path from the input AC to either the positive or negative output of the charger depending on the topology. Thus if you measure the voltage of a non isolated charger from one or the other lead to ground you will see 60 cycle AC or a DC offset from ground. In this case you can't simply wire up the outputs of a pair of chargers and expect no fireworks. Isolated chargers are more expensive to manufacture and usually a tiny bit less efficient.

A pair of isolated chargers could be configured to charge the pack in halves as you mention, they could also be paralleled over the whole pack. BTW, charging packs in halves is not a stellar idea with lithium types if you are running bottom balance.


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## evmetro (Apr 9, 2012)

How about 1 big ass charger with paralleled charge cords? If you only have access to a single plug, just use one, but at my shop where I have two welding circuits on different breakers use two cords? Or would I need to use a single 100 amp breaker with two welder outlets on it?


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## Siwastaja (Aug 1, 2012)

evmetro said:


> How about 1 big ass charger with paralleled charge cords? If you only have access to a single plug, just use one, but at my shop where I have two welding circuits on different breakers use two cords? Or would I need to use a single 100 amp breaker with two welder outlets on it?


Won't work and is very dangerous. Don't do it.


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## evmetro (Apr 9, 2012)

What are the dangers and what stops it from working? Your response sounds sincere, but I am curious and like to learn new things. I am not aware of any higher amp plugs, and am assuming that two of these in parallel would double the contact area of the pins, and double the 6 gauge wire area as well. Can you fill me in?


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## dougingraham (Jul 26, 2011)

evmetro said:


> How about 1 big ass charger with paralleled charge cords? If you only have access to a single plug, just use one, but at my shop where I have two welding circuits on different breakers use two cords? Or would I need to use a single 100 amp breaker with two welder outlets on it?


Because of the possibility of the wiring being different (cross connecting phases in the charger) it would be a bad idea to just parallel the cables at the input to the charger. The charger would need to have separate precharge or inrush limiting for each cable and their own separate diode bridge. And of course you would need the "big ass charger" which is one of those things that isn't currently a product you can buy. And if you do find such a charger it would most likely be designed for a particular high voltage/current plug (not a pair of welding type sockets).

In your case you could probably make it work once you got the wiring sorted out and verified the phases were wired correctly but it would not be a good idea to take such a thing to a place with unknown wiring.

Without a careful design you won't find such a thing surviving in the marketplace because miss wired sockets are more common than you would imagine. Wiring the correct outlet to a breaker panel with the correct breaker is really the best way. The other side of this is probably nobody will make such a charger because there isn't a need for it. People who do not drive EV's have range anxiety and part of that is charge time anxiety. If you drive more than average your car is still parked 22 hours out of the day. And 22 hours from a 15 amp 110VAC outlet gives a recharge of between 25 miles and 110 miles depending on how efficient your car is. If everyone who can charge slowly from a 110vac outlet does so then the infrastructure won't need upgrading in any way for a very very long time. If everyone puts in a 72 amp EVSE and plugs in at 5:30 pm when they get home from work, just so they can recharge completely their less than 40 mile commute in less than an hour then the infrastructure is going to need upgrades a lot sooner.


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## evmetro (Apr 9, 2012)

I see, and miswired plugs alone kills the idea. Those are indeed pretty common! Thanks


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## njloof (Nov 21, 2011)

Well, there are commercial devices like this:

http://www.quick220.com/220_catalog/voltage-converters.html


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## adeyo (Jun 6, 2012)

njloof said:


> Well, there are commercial devices like this:
> 
> http://www.quick220.com/220_catalog/voltage-converters.html


Would this be something that would help charge an ev much quicker, from any 110v outlet at my parents home, friends or public outlet? Without causing damage or tripping breakers?


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## njloof (Nov 21, 2011)

It requires some care to set up, because it will do you no good unless you can find two 110V circuits on opposite sides of the home's electrical feed. (Most homes get 220V power with a center tap; 110v circuits at the breaker panel are placed on one side or the other of that circuit.) How the circuits are wired can be pretty random, but these boxes will at least tell you when you have or have not found both circuits without setting anything on fire  So whether you can use this at each of those locations is a matter of trial and error, unless you know the wiring well.

That said, if you would normally charge at 110V/12A on a circuit, you could in theory charge at 220V/12A with this adapter, which is twice the power. Not shabby but not as much as charging off a 220V/30A welding plug.

As has been pointed out, you could do the same with two 110V chargers and plugs, and (if isolated) that would only require that you have separate circuits for each 110V feed, not that they be fed from separate sides of the panel. Does that make sense?


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