roger1818
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Re: How many amps for new 240V install?

Wed Jan 29, 2020 1:12 pm

goldbrick wrote:
Wed Jan 29, 2020 12:48 pm
How do the Power Sharing EVSE's communicate with each other? Is this a dual plug EVSE that has only 1 connection to the power source and then divides the power between them? Is one of these units cheaper than 2 separate EVSE's? or just more convenient?
There is no industry standard. Here are the ones I know of. There may be others.
  • The Flo X5 uses HomePlug powerline communication.
  • It looks like the ClipperCreak Share2 charging stations use 3 low voltage wires .
  • The Tesla Wall Connector has a pair of low voltage wires that connect them in a daisy chain. One is set as a master, with the total currant available and the others are set as slave.
AFAIK, they are hard wired and don't come with a plug, so you would need to connect them together. The ClipperCreek are sold as a pair or as one dual station, but the others are sold individually. The cost savings comes from only needing one breaker and power cable from the panel.
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Oilpan4
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Re: How many amps for new 240V install?

Wed Jan 29, 2020 1:34 pm

Sounds like a gimic. How much does it cost?
Bet it would be cheaper to run 2 evse circuits with 2 regular no thrills evse units.
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roger1818
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Re: How many amps for new 240V install?

Wed Jan 29, 2020 1:46 pm

Oilpan4 wrote:
Wed Jan 29, 2020 1:34 pm
Sounds like a gimic. How much does it cost?
Bet it would be cheaper to run 2 evse circuits with 2 regular no thrills evse units.
For Flow and Tesla, you just buy a second EVSE at the same price as it is a standard feature on the Flow X5 and all Tesla Wall adapters.

ClipperCreek seems to sell them in bundles that appear to cost more than two individual ones, which seems strange. I don't really know much about their product line though.

EDIT: It looks like all Juice Boxes come with Load Sharing and they use WiFi to communicate with each other, so similar to Tesla and Flo, all you need to do is buy a second EVSE..
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Oilpan4
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Re: How many amps for new 240V install?

Wed Jan 29, 2020 2:01 pm

The new 120/240v nissan leaf evse that will charge at full 6.6kw are going for about $250 on ebay. It's new, it says nissan on it, comes with 2018 and up leaf. Can't get much better than that.

I'm going to say the fancy line sharing protocol is a gimic if you're installing less than 3 or 4 level 2 chargers.
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roger1818
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Re: How many amps for new 240V install?

Wed Jan 29, 2020 2:23 pm

Oilpan4 wrote:
Wed Jan 29, 2020 2:01 pm
The new 120/240v nissan leaf evse that will charge at full 6.6kw are going for about $250 on ebay. It's new, it says nissan on it, comes with 2018 and up leaf. Can't get much better than that.

I'm going to say the fancy line sharing protocol is a gimic if you're installing less than 3 or 4 level 2 chargers.
If you are confident that it is genuine, then great! It could be a cheap knock off though. You have to careful with cheap EVSEs sold on eBay and Amazon, as many aren't safety certified. Hardly a bargain if it burns your house down. :shock:

Durability is another factor. Cheaply made EVSEs often won't last as long as a good quality one. Those savings go out the window if you have to replace it regularly.

Cheap EVSEs usually don't have smart features. Not only can you set up timers and control the charging rate, but you may be able to subscribe to a demand management program with your utility and save money by letting them control how quickly your car charges to match the demand on the grid. Who cares how quickly your car charges overnight as long as it is fully charged when you leave in the morning. Those savings can add up over the life of your EVSE.

The other factor in all of this is the size of your electrical service. If you have a 200A service, then is is very likely that you can add two additional 40A circuits (what would be needed for the Nissan portable EVSA). If you only have a 100A service, you can probably only get 1 additional 40A circuit. Upgrading your service can cost thousands of dollars.
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goldbrick
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Re: How many amps for new 240V install?

Wed Jan 29, 2020 4:27 pm

A 35A circuit is sufficient for a Nissan portable EVSE. 2 of those would draw 55A if both are running at full output. I think many or most 200A services could handle that extra load, although I would strongly recommend that anyone contemplating this have a professional electrician do a load analysis to be sure.

Unless the shared EVSE's have some sort of feed-through power connections this will require making Y-connections in the wiring to the multiple EVSE's. That isn't a trivial matter when working with large gauge wires. It also means the communications between the EVSE's is somewhat safety critical so they don't over-load the circuit if they both turn on full by mistake. Of course the breaker should handle that situation but using wifi or something to limit the current on a circuit is a bit dicey IMHO.

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Re: How many amps for new 240V install?

Thu Jan 30, 2020 12:44 am

I have a cheap $160, 16 amp 240v duosida evse that I have had for a year and a half.

If the panel is full add a sub.

No need to do a load analysis on residential. That's what the main breaker is for. If anything switch breakers around to ballance both legs of 120v current flow.
Panels are designed to be safe as long as codes are followed. That's why they are a certain physical size, have a max main breaker rating and only allow a certain numbers of circuits to be installed.
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roger1818
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Re: How many amps for new 240V install?

Sat Feb 01, 2020 10:41 am

goldbrick wrote:
Wed Jan 29, 2020 4:27 pm
A 35A circuit is sufficient for a Nissan portable EVSE. 2 of those would draw 55A if both are running at full output.
Does the Nissan EVSA limit the current to 28A (current limiting is in 1A steps in the J1772 protocol) or is its limit higher and the charger inside the Leaf is the one limiting the current to 27.5A. Plugging a load that is capable of drawing more than 80% of the circuit's maximum would be a code violation. Ignoring that, wiring 35A breakers to a NEMA 14-50 outlet is asking for a wold of pain in the future. At some point someone will plug a 32A (or maybe even a 40A) EVSA into the outlet (with a car capable of drawing that much current) and that would result in the breaker tripping.
I think many or most 200A services could handle that extra load, although I would strongly recommend that anyone contemplating this have a professional electrician do a load analysis to be sure.
For those lucky enough to have a 200A service, sure (I even said that in my previous post), but if you only have a 100A service, it would be a stretch.
Unless the shared EVSE's have some sort of feed-through power connections this will require making Y-connections in the wiring to the multiple EVSE's. That isn't a trivial matter when working with large gauge wires. It also means the communications between the EVSE's is somewhat safety critical so they don't over-load the circuit if they both turn on full by mistake. Of course the breaker should handle that situation but using wifi or something to limit the current on a circuit is a bit dicey IMHO.
I believe that when configured in shared mode, if it loses communication with the other station, it would fall back to 50% to keep things safe, but that would need to be verified. They are UL certified, so there must be some sort of safety mechanism beyond letting the breaker trip.
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roger1818
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Re: How many amps for new 240V install?

Sat Feb 01, 2020 11:00 am

Oilpan4 wrote:
Thu Jan 30, 2020 12:44 am
I have a cheap $160, 16 amp 240v duosida evse that I have had for a year and a half.
From what I have heard, that is about the average life expectancy for cheap EVSAs. Maybe you will be lucky and get 3-4 years out of it. A good one should last over 10 years.
If the panel is full add a sub.
I said if the service is full, not if the panel is full. Adding a sub panel allows you to add more breakers, but it won't increase the capacity of the service (in Amps). Increasing the service size likely means dragging in a new wire from the transformer (unless the one you have happens to be oversized) which is going to be very expensive (especially if you have underground wiring).
No need to do a load analysis on residential. That's what the main breaker is for. If anything switch breakers around to ballance both legs of 120v current flow.
The main breaker is designed to protect you from exceptional circumstances, not to protect you from blindly adding additional circuits until you are over capacity. Having any circuit breaker blow is a warning that something isn't right, but having the main breaker blow is a sign that something is very seriously wrong. It should not be relied upon as a test that everything is okay.
Panels are designed to be safe as long as codes are followed. That's why they are a certain physical size, have a max main breaker rating and only allow a certain numbers of circuits to be installed.
That is the key. Part of the code requirement is that you not put more load on the panel than the service was intended for.
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Re: How many amps for new 240V install?

Sat Feb 01, 2020 12:04 pm

goldbrick wrote:
Wed Jan 29, 2020 11:33 am
I would rather run dedicated lines to each EVSE rather than splicing the wires to multiple EVSE's. There are probably ways to do the splice that is up to code but IMHO, it would be much simpler to run a separate circuit to each EVSE. And in that case, having a sub-panel nearby makes the job much easier.

I'm planning to put a sub-panel in my garage due to some factors that are unique to my situation. I don't plan to install more than one EVSE but if I ever did, the sub-panel should handle it easily. In the mean time, I have some other circuits that need to be updated and that will be much easier with a sub-panel in the garage.
It's actually easiest to use a subpanel to "split" the power when doing the power sharing thing. You run your 50a feeder (or whatever size) circuit into the subpanel, then two more 50a circuits from the subpanel to each EVSE. The EVSEs manage the load so you don't overdraw the feeder circuit.
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