Volusiano
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Re: Do It Yourself: 240v from two 120v sources

Tue Jun 14, 2011 11:21 pm

johnr wrote:So this would be something to bring when going on a long trip. But in a location where there are two out of phase 120V outlets, there is likely to be a 240V outlet as well, right? For that matter, in most places where there is 120V, there's likely to be 240V. So, what would be the advantage?
You just can't count on most homes to have 240V outlet by default, especially if they already have gas for their dryer. Also, many homes now, especially newer homes, may locate their washer/dryer upstairs near their bedrooms and the 240V source may not be that easily accessible. This is where the usefulness of such a device will shine.

Also, if you're not at a home but at a commercial property and need to do opportunity charging. Having a 120V source is good, but if you can find two 120V sources out of phase, that's even better.

It's all about having all the options at your disposal. Without it, you don't have extra options to choose from.

You may not be able to use it all the times. But the few times you are in a bind and having it to bail you out, it'll be worth its cost and you'll be glad you have it. It's like buying insurance to have peace of mind but you hope you never have to use it.
johnr wrote:But to have two long cords strewn across the place to get at two outlets might be too much of an imposition to one's guest. I'm just not sure...
If you already plan to go far enough out of range such that you'd need to charge at a host's house so you can make the return trip, you should have already asked your host ahead of time and make sure it's OK with them so that there'd be no imposition. And usually these kinds of visits are to close friends or relatives who are not just mere acquaintances, and since you've made such a long trip to visit them, I'm sure they wouldn't mind accommodating you a little bit in return for your long drive to see them.

I would never bother asking to opportunity charge at people's house if I still have enough juice to return home.

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Re: Do It Yourself: 240v from two 120v sources

Wed Jun 15, 2011 12:21 am

Very cool Phil, thanks for sharing. Not sure yet if I'll build or buy from quick220. Depends on the cost, so I'll take the parts list to my local electrical supplier and price the components before I decide. I do like wiring projects though.

I've actually done a lot of 120 volt wiring work but never had to mess with 240 other than connecting new breakers to a 240 service panel. 240 in the US is considered an instant end of the word for the average DIY-er (nothing to fear but fear itself and not properly following critically important directions). I've always wondered why the rest of the world doesn't live in fear of 220/240 volt outlets considering how we fear it here.

Either were crazy with caution in this country or the rest of the world is careless and nuts. I learned the hard way to always wear eye protection and non conductive gloves when messing with voltage. Testing equipment is also advisable.

Caution is always healthy for the DIY-er and when in serious doubt, don't do it.
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johnr
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Re: Do It Yourself: 240v from two 120v sources

Wed Jun 15, 2011 1:12 am

GeekEV wrote:
johnr wrote:But in a location where there are two out of phase 120V outlets, there is likely to be a 240V outlet as well, right?
At someone's house (particularly if its a recent construction) - yes. In retail locations, not likely. Or, if they do, they're either in use or not in a location accessible to you. From what I'm given to understand, many outdoor 120v outlets tend to be on dedicated circuits.
Volusiano wrote:You just can't count on most homes to have 240V outlet by default, especially if they already have gas for their dryer. Also, many homes now, especially newer homes, may locate their washer/dryer upstairs near their bedrooms and the 240V source may not be that easily accessible. This is where the usefulness of such a device will shine.

Also, if you're not at a home but at a commercial property and need to do opportunity charging. Having a 120V source is good, but if you can find two 120V sources out of phase, that's even better.
Thanks guys for the helpful replies! So, I like this idea, I have some electronics experience and it's fairly simple so I intend to make one - but I haven't even ordered the EVSE upgrade yet. It sounds like maybe I shouldn't get the 16 amp rev2 upgrade, because in the event I find two out-of-phase 120V outlets to use a device like this, they might not be capable of supporting 16 amps. So maybe it would be best to go with the 12 amp rev1 EVSE upgrade. Then include a 240V adapter like this, and NEMA 10 and NEMA 14 pigtails, and I'd be ready for anything! :P
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garygid
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Re: Do It Yourself: 240v from two 120v sources

Wed Jun 15, 2011 7:35 am

1. Instead of two 8' cords, I would suggest one 2' to 4' length and one 16' length. Or, as I made mine, two short lengths, and a standard extension cord.

2. The 240v plugs and sockets typically used in other countries are often designed for "safety", where one cannot touch energized plug pins/contacts. Stupidly, in the USA we continue to require the use of non-safe plugs. The NEC should allow the installation of the safer sockets, and the use of adapters to use the new sockets. Otherwise, we are stuck with un-safe plugs and sockets.

3. Has anybody tried switching abruptly from 240v 16A charging to 120v while charging is in progress? Does the car's charger gracefully drop to 12A, or will it continue at 16A?

Or, if charging at 120v 12A, will a sudden switch to 240v increase the current draw to 16A (with the Rev2 L1 EVSE, of course).
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Ingineer
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Re: Do It Yourself: 240v from two 120v sources

Wed Jun 15, 2011 8:13 am

I find the "Easy240" the most-used 240v charge solution when I'm visiting friends or relatives. Dryer outlets are often hard to access compared to locating the two 120v outlets.

I find the two 8' cords (16' span) work for 90% of the scenarios with no extra extension cords needed (other than the L6-20). Sorry Gary, I like the symmetry of two 8 foot cords, and it stores easily! =)

Image

I also carry a 25' and a 50' L6-20 extension cord that almost always is enough for any situation I encounter.

Kitchens and Laundry rooms are the best locations to "attack". In most houses you can find 2 outlets in the kitchen within a few feet of each other on the required different circuits.

By far, I use the Easy240 way more often when opportunity charging compared to all other 240v plug adapters.

FYI: for the light you can order a simple Neon 240v pilot light and save yourself the complexity of the LED implementation. Here's a cheap one from Newark:
Image

-Phil
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Re: Do It Yourself: 240v from two 120v sources

Wed Jun 15, 2011 8:40 am

garygid wrote:Has anybody tried switching abruptly from 240v 16A charging to 120v while charging is in progress? Does the car's charger gracefully drop to 12A, or will it continue at 16A?
Or, if charging at 120v 12A, will a sudden switch to 240v increase the current draw to 16A (with the Rev2 L1 EVSE, of course).
Yes, I would like to know about that too.


Also, what would happen if you managed to plug into two different outlets on different transformers?
For instance, some public parking garages have 120V outlets available for EV use. Lets say you plugged one side in there, and the other side into a 120V at a neighboring building... Is there any way you could end up with 480V or some other non 120/240?


I was once working at a bank in Manhattan where the building was in two halves that were opened up when the two neighboring banks merged. It turned out that the two halves were served by two different power companies. Someone tried running an ethernet cable between the two sides and it caused sparking and buzzing in the equipment. Someone said something about different ground potential between the electrical systems in the two halves of the building, so they ended up running non-conductive fiber optic cables between the two halves.

Volusiano
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Re: Do It Yourself: 240v from two 120v sources

Wed Jun 15, 2011 9:44 am

Ingineer wrote:I also carry a 25' and a 50' L6-20 extension cord that almost always is enough for any situation I encounter.
Have you ever had an occasion where you need to connect both the 25' and 50' together to reach somewhere? I read somewhere that the recommendation is to keep the length to 50' or less. But if 50' is not enough, is there any risk in using a length of 75' or even 100' at 12 gauge size other than maybe causing enough voltage drop that may render the device not working? I notice most 20A rated wiring at 75' or 100' are at least 10 gauge size.

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TonyWilliams
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Re: Do It Yourself: 240v from two 120v sources

Wed Jun 15, 2011 11:14 am

Volusiano wrote:
Ingineer wrote:I also carry a 25' and a 50' L6-20 extension cord that almost always is enough for any situation I encounter.
Have you ever had an occasion where you need to connect both the 25' and 50' together to reach somewhere? I read somewhere that the recommendation is to keep the length to 50' or less. But if 50' is not enough, is there any risk in using a length of 75' or even 100' at 12 gauge size other than maybe causing enough voltage drop that may render the device not working? I notice most 20A rated wiring at 75' or 100' are at least 10 gauge size.

So, make your 25 footer a 10/3, and your 50 footer a 12/3. When you need 75 feet, connect the the 25' to the power source, and the 50' to the EVSE.

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Ingineer
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Re: Do It Yourself: 240v from two 120v sources

Wed Jun 15, 2011 12:07 pm

TEG wrote:
garygid wrote:Has anybody tried switching abruptly from 240v 16A charging to 120v while charging is in progress? Does the car's charger gracefully drop to 12A, or will it continue at 16A?
Or, if charging at 120v 12A, will a sudden switch to 240v increase the current draw to 16A (with the Rev2 L1 EVSE, of course).
Yes, I would like to know about that too.
If you switch from 240v to 120v, the LEAF stops charging just as if power was interrupted, but will resume unless a charge timer prevents it. From 120v to 240v, it's instant, and the charging does not stop. On a rev2, it goes from 12A to 16A almost instantly.
TEG wrote:Also, what would happen if you managed to plug into two different outlets on different transformers?
For instance, some public parking garages have 120V outlets available for EV use. Lets say you plugged one side in there, and the other side into a 120V at a neighboring building... Is there any way you could end up with 480V or some other non 120/240?
No problem, there is no way you can get higher than 240v. You might get lower though.
TEG wrote:I was once working at a bank in Manhattan where the building was in two halves that were opened up when the two neighboring banks merged. It turned out that the two halves were served by two different power companies. Someone tried running an ethernet cable between the two sides and it caused sparking and buzzing in the equipment. Someone said something about different ground potential between the electrical systems in the two halves of the building, so they ended up running non-conductive fiber optic cables between the two halves.
I don't believe this. Any twisted-pair Ethernet (10Base-T and up) have galvanically isolated transceivers at each end in the PHY. However, Some of the really old co-ax ethernet may not have been. However, you should never run copper ethernet between buildings, as it's not meant for that. Fiber is the proper choice.

-Phil
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Volusiano
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Re: Do It Yourself: 240v from two 120v sources

Wed Jun 15, 2011 1:16 pm

TonyWilliams wrote:
Volusiano wrote:
Ingineer wrote:I also carry a 25' and a 50' L6-20 extension cord that almost always is enough for any situation I encounter.
Have you ever had an occasion where you need to connect both the 25' and 50' together to reach somewhere? I read somewhere that the recommendation is to keep the length to 50' or less. But if 50' is not enough, is there any risk in using a length of 75' or even 100' at 12 gauge size other than maybe causing enough voltage drop that may render the device not working? I notice most 20A rated wiring at 75' or 100' are at least 10 gauge size.

So, make your 25 footer a 10/3, and your 50 footer a 12/3. When you need 75 feet, connect the the 25' to the power source, and the 50' to the EVSE.
Wouldn't you want to use the 10/3 size on the 50' length and 12/3 on the 25? To offset the higher resistance due to the longer length?

Also, I don't understand why it'd make any difference if you use one length cord over the other length cord near the source or the EVSE. The combined voltage drop across both cords is not going to change either way.

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