AC Type 2 chargers - Understanding different combinations

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Samstain
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AC Type 2 chargers - Understanding different combinations

Post by Samstain » Mon, 21 Oct 2019, 12:21

Hi All,

Fairly new to the EV charger world, but have been thrown in the deep end for a work project. Got a few technical questions on AC chargers, and what happens when you mix and match cars and chargers.

From what I have worked out so far, there are basically 3 common AC type 2 charger configurations:

'7.2kW' - Single Phase @30A - which covers most cars, as most have a single phase on-board chargers, and draw 30A or less.

'22kW' - 3 Phase @ 30A - which is basically the same as the above, but with a 3 phase contactor/supply rather than single - most cars will just use the red phase (so important to rotate charger supply from mains to evenly distribute load).

'11kW' - 3 Phase @15A as above, but with half the current rating.

Assuming most existing Type 2 on-board chargers are 20 - 30A single phase, if i plug one of these in to either the 7.2kW or 22kW charger, all should be ok - both chargers will supply it with power on the red phase, and will handle the 30Amps demand of the car.

What happens if I plug one of these cars into a 11kW charger, being a single phase load, does this effectively make the charger a 11/3 = 3.6kW charger, which most cars will exceed by defualt?

I understand the 1kHz comms between the charger and the car can request the car charger to slow down, but is this only after it has started charging? or will it negotiate before it starts - ie is an 11kW chargers signal not at 50% duty cycle initially, but at 25%, and work its way down from there if need be, causing the car to not start charging unless it can ensure it will not draw more than 15A?

Unless I am miss-understanding something - which is highly likely ;) - there is not much point having a public 11kW charger, at it will reduce most cars to charging at 3.6kW or less, apart from the odd 3 phase capable cars?

antiscab
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Re: AC Type 2 chargers - Understanding different combinations

Post by antiscab » Mon, 21 Oct 2019, 13:56

it usually goes like this:
car plugs in
car reads current limit from the charge station
car asks charge station to turn on
car draws current up to the current limit

if the car draws more than the current limit, charge station shuts down.

so a car with a single phase charger plugging into a 16A 11kw 3-phase charge station will only draw 16A on one phase

The charge station can change the current limit at any time during the charge cycle, but most are not setup to do so
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

antiscab
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Re: AC Type 2 chargers - Understanding different combinations

Post by antiscab » Mon, 21 Oct 2019, 14:02

Samstain wrote:
Mon, 21 Oct 2019, 12:21
Unless I am miss-understanding something - which is highly likely ;) - there is not much point having a public 11kW charger, at it will reduce most cars to charging at 3.6kW or less, apart from the odd 3 phase capable cars?
Most of the current generation cars have 3-phase chargers, capable of at least 11kw

only the renault kangoo does not (32A single phase)

if you're installing a few at the same location, some charge station models are designed to be able to current share - this is where being able to change the current limit mid charge comes in

certainly a bunch of 7kw single phase charge stations are useful than none at all

Do you have any more details on the project?

22kw charge stations cost the same as 7kw ones. the expense is all in getting a connection to the grid that's large enough
the wire is cheap compared to the labour to lay it - in general, lay enough wire to feed 22kw to every charge station, even if you don't need it now.
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

Samstain
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Re: AC Type 2 chargers - Understanding different combinations

Post by Samstain » Mon, 21 Oct 2019, 14:09

ok, thanks, so if it is a 11kW charge point, it will initially not be putting out 50% duty cycle on CP, but 25%. The car will read this, and before goes from 2k7 to 880ohm impedance (to say I'm ready, causing the charge points contactor to pull in), it will ensure it's on-board charger is configured to run at no more than 16A per phase (3.6kW single phase for most).

Do many cars have reasonably granular control of their charge current - say to 5A steps or better? I haven't been able to find any firm information in this, but was told, most are either flat out, or half current when using type 2 - though I am beginning to think this isn't the case...

antiscab
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Re: AC Type 2 chargers - Understanding different combinations

Post by antiscab » Mon, 21 Oct 2019, 14:21

the standard has 3A steps, between 6A and 32A, though I suspect most cars resolution is down to 1A or lower

a few members have at home stations that track solar use, so it's likely very granular indeed
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

Samstain
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Re: AC Type 2 chargers - Understanding different combinations

Post by Samstain » Mon, 21 Oct 2019, 14:43

Excellent thanks.

Is there a list anywhere of current cars, and the spec's of their on-board chargers - # phases and max charge current at least, controlability would be great also. The table I have seen in the past must have been misleading, it must have been telling me the max charge rate if used with a single phase supply - not what the actual on-board charger was - which is how I interpreted it.

End goal is to control current across 10's of chargers, in numerous groups, to not exceed local supply, site wide supply, and various other factors including available PV etc - via OCPP.

Specified was mostly 3P 11kW chargers, but given my belief that most cars were single phase (apparently not), this lead me to believe they would have been better off with 7.2kW 1P ones.

Likely 22kW 3P ones will get installed - as long as we can control charge rates from the get go - and not have them start at up to 32A and then request they slow down from there. So if one car is in the carpark, it will have the full 22kW available to them, but once car 3 or 4 rolls in, it might be down to 10kW each or so, if they started at full current, we would have to have 32A up our sleeves ready for another car to start, not knowing how hard it would start.

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Re: AC Type 2 chargers - Understanding different combinations

Post by Samstain » Mon, 21 Oct 2019, 14:59

hang on - from the AEVA fact sheets:

Ioniq/ Kona AC charging:
>Although fitted with the 3 phase type 2 AC socket as
>part of the CCS2 system, the Ioniq electric charges using
>single phase AC only at a maximum of 7kW (30A).


Leaf:
>Although fitted with the 3 phase type 2 AC socket, the
>ZE1 Leaf charges using single phase AC only at a
>maximum of 7kW (32A).

Kangaroo


>The Kangoo ZE is fitted with a Mennekes type 2 socket.
>It can charge at a maximum of 32A on a single phase AC
>EVSEs (Electric Vehicle Supply Equipment).


So all 3 of these are better off on a 7.2kW charger than a 11kW - where they would charge at a max of 3.6kW?


>The Model 3 can charge at a maximum rate of 7.4 kW
>using single phase AC, or 11kW using 3 phase AC

So some benefit going 11kW.

>Small BMW i3 - single phase only
>Bigger two look to be 3 phase 3.7kW per phase, but can run on one if that is all that is available.

Won't hit the current limit of a 11kW charger, so is better with that than 7.2kW.

Is this correct? or do the fact sheets need updating?

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Re: AC Type 2 chargers - Understanding different combinations

Post by Bryce » Mon, 21 Oct 2019, 15:14

Hi there-fact sheets are as correct as I can get them given the difficulty of getting some of the data 'officially'! All are currently right though. (I monitor for vehicle updates). BTW: As far as I understand it-all Type 1 and 2 plug cars can step up and down in a fairly granular manner.
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Re: AC Type 2 chargers - Understanding different combinations

Post by coulomb » Mon, 21 Oct 2019, 17:29

Edit: oops, already covered.
antiscab wrote:
Mon, 21 Oct 2019, 14:02
Most of the current generation cars have 3-phase chargers, capable of at least 11kw
Just checking the EV fact sheets, the Kona and Leaf 2.0 both have single phase chargers (7 kW). The model 3 is 11 kW on 3-phase, but somehow 7.4 kW (at least the UK models) on single phase. I guess they parallel two chargers when single phase is detected, but don't parallel all three chargers because then the line current would exceed 32 A.

Any modern charger (on-board or not) can adjust its output current (edit: and therefore, its input current) to very fine values, that's not a problem. I believe that the type 2 signalling (essentially identical to J1772 signalling) is essentially analogue, i.e. it doesn't have a particular resolution like 3 A or 1 A.

Edit: so you could ask for 7.3 A say, and maybe get 7.28 A or 7.41 A due to tolerances in the components, measurement inaccuracies, and so on.
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Re: AC Type 2 chargers - Understanding different combinations

Post by antiscab » Mon, 21 Oct 2019, 18:25

oops, quite right, there are a few cars that have higher single phase current limts
coulomb wrote:
Mon, 21 Oct 2019, 17:29
so you could ask for 7.3 A say, and maybe get 7.28 A or 7.41 A due to tolerances in the components, measurement inaccuracies, and so on.
I saw this on my zoe the other day when I was doing the charge testing.
phase current was slightly either side of the pilot signal for most measurements
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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Re: AC Type 2 chargers - Understanding different combinations

Post by Samstain » Mon, 21 Oct 2019, 19:53

Cool, 2 or 3 amp accuracy is more than enough for our needs.

Was just worried it was a case of the car having say 2x16A chargers on board on the same phase, and they were either on or off, to run at 3.6 or 7.2kW - if they were plugged in to a 11kW 3-phase charger, then running 2 was out of the question (only 16A available) , so that left our demand management with the choice of either 'on' or 'off' for one of the chargers only - clearly this is not the case.

I'll do a bit of a table tomorrow, but looks like rather than just having 11kW AC chargers, they would be far better off having a mix of 7.2kW and 11kW AC chargers (clearly labelled as to which best suits which car), most in demand would be the single phase 7.2kW.

Or preferably spend a couple bucks extra (it would likely be less than 1or2% in the scheme of the whole project) and upgrade them all to 22kW, and let us keep the current under control in software, then any car can go to any charger and charge to the on-board chargers limits, as long as the local supply is up to the task. Could even get smart with an app or something and know what chargers and phases are currently in use, and suggest which bay you should pull up in given the car are driving - to ensure single phase cars are evenly spread.

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Re: AC Type 2 chargers - Understanding different combinations

Post by antiscab » Tue, 22 Oct 2019, 09:17

so this arrived in my inbox this morning:
https://e-station.com.au/dynamic_load_balancing/

so that's at least one commercial plug and play solution for having way more charging station capacity than you have power supply capacity
Matt
2017 Renault zoe - 25'000km
2007 vectrix - 156'000km
1998 prius - needs Batt
1999 Prius - needs batt
2000 prius - has 200 x headway 38120 cells

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