[Dave Davies]

I went to Buckinghamshire from Reigate last weekend and the route required en-route or destination charging to get home again. Before leaving I checked and found Nissan HQ RC offline so we parked in the multi story in the destination town of Amersham and plugged into a 2x13A charge master post @ 13A
As always on public charging I measured the charge rate and it was 5.5Amps, this seems to be a common thing as all of the dual port units I have seen deliver half the rate of the maximum including dual type2 posts.
It wasn't an isolated item as every charge master unit I have tried delivers half the advertised rate.
Now whilst this meant we had to hang around longer to be able to get home it brings up an interesting quirk of being charged for time at a rate that is much lower than implied.

Looking at the standard £20 PAYG Chargemaster tariff it uses the term: socket chargers.
The implication being the socket type is the only factor in charging

• £1.00 per hour for 13 amp socket chargers (minimum charge one hour and then pro rata)
• £1.50 per hour for Type 2 socket chargers (minimum charge one hour and then pro rata)

Not to mention that the post software referred to both 13A sockets differently with the lower port described as fast. I tried both and they both supplied the same pilot signal and ran at 5.5A.
All type2 units I have tried sit between 9A and 16A, whilst I fully understand site supply is the primary factor I would like to hope its not widespread.

Has anyone any other data ?

 

[PTM101]

Wow, that's an interesting discovery, and is particularly pertinent considering you are paying for an advertised service.

I have no data on CM posts or direct measurements but having looked at my CYC data from the GMEV network, I average 28.4Amps on Type 2 posts. That's worked out by dividing total kWh supplied by time connected. Then dividing the result by 230V & multiply by 1000 to get Amperage. Obviously removing sessions where SOC has reached >95%. On the one occasion another Leaf was plugged into the same post, and power was shared I got 15.9Amps.

I hope you can get more CM data, because it's quite a revalation.

 

[fenlander]

How do you get a pilot signal out of a 13A socket? The pilot would come from the EVSE brick, which IIRC should be 10A for a standard Leaf EVSE.

How are you taking these measurements? Do you get a full 32A at home? Which T2 cable do you use? The Nissan one?

 

[Dave Davies]

Yes thats written without things I know to be obvious in my own head!

In the case of the 13A socket of course the pilot is set by the external EVSE, at Amersham I used both the Nissan EVSE and I tried my own OpenEVSE unit with a pilot set 12A. In both cases LeafDD displayed 5.5A

I have a hydra unit which measures the incoming EVSE pilot to determine the rate at which you can do both cars
This I have tried on type2 posts and in both cases the rate was limited by the supplying post to approximately half.
In all cases I have a LeafDD display showing the charge rate.

 

[Dave Davies]

On the one occasion another Leaf was plugged into the same post, and power was shared I got 15.9Amps.
.

Which makes total sense and I would be happy with that assuming the pilot was ramped as the soc changed.
I hope we get to see more CYC posts in the South East they do seem to be the best.

 

[fenlander]

Yes thats written without things I know to be obvious in my own head!

In the case of the 13A socket of course the pilot is set by the external EVSE, at Amersham I used both the Nissan EVSE and I tried my own OpenEVSE unit with a pilot set 12A. In both cases LeafDD displayed 5.5A

So the fault must be with your equipment, the car or LeafDD, not the 13A socket.

I have a hydra unit which measures the incoming EVSE pilot to determine the rate at which you can do both cars
This I have tried on type2 posts and in both cases the rate was limited by the supplying post to approximately half.
In all cases I have a LeafDD display showing the charge rate.

I'd be suspicious of the hydra - is this really the rate that you see the car charge at with a 32A cable?

 

[PaulMorris]

Yes thats written without things I know to be obvious in my own head!

In the case of the 13A socket of course the pilot is set by the external EVSE, at Amersham I used both the Nissan EVSE and I tried my own OpenEVSE unit with a pilot set 12A. In both cases LeafDD displayed 5.5A

I have a hydra unit which measures the incoming EVSE pilot to determine the rate at which you can do both cars
This I have tried on type2 posts and in both cases the rate was limited by the supplying post to approximately half.
In all cases I have a LeafDD display showing the charge rate.

Ignoring all the technology and measurements for a second...

How could this have anything to do with the 13A socket?

Scenario a) the EVSE knows somehow - can't see how
Scenario b) the post tells the EVSE - as above, can't see how any protocol exists to do this
Scenario c) the post does something yucky like triac switching of the 240V to a PWM signal - surely this would play havoc with an intelligent load like an EVSE and charge controller.

Do you have control measurements from a 13A socket at home?

 

[Dave Davies]

So the fault must be with your equipment, the car or LeafDD, not the 13A socket. I'd be suspicious of the hydra - is this really the rate that you see the car charge at with a 32A cable?

Im not sure how you can conclude that it is my end? As for the hydra it simply detects the incoming pilot signal and allows the car to pull at that rate, it adjusts the outgoing pilot if two cars are connected, and yes I get the full rate on a known 32A capable commando outlet. The car also pulls at 7kw if connected to a rolec evse.
My SoC is too high to test it right now at work as my 4 mile commute means I am over 90%

 

[fenlander]

Im not sure how you can conclude that it is my end? As for the hydra it simply detects the incoming pilot signal and allows the car to pull at that rate, it adjusts the outgoing pilot if two cars are connected, and yes I get the full rate on a known 32A capable commando outlet. The car also pulls at 7kw if connected to a rolec evse.
My SoC is too high to test it right now at work as my 4 mile commute means I am over 90%

As @PaulMorris says, there is no physical way for it to be the fault of the 13A socket.

My suspicions of the hydra would be around the resistance of the PP-PE loop which would limit the charging rate (in addition to the CP pulse width). Maybe someone with access to the spec can elaborate on that.

Is your 32A Rolec EVSE un-tethered using the same cable/hydra as you use to test the Chargemaster one?

 

[Dave Davies]

Ignoring all the technology and measurements for a second...
How could this have anything to do with the 13A socket?
Scenario a) the EVSE knows somehow - can't see how
Scenario b) the post tells the EVSE - as above, can't see how any protocol exists to do this
Scenario c) the post does something yucky like triac switching of the 240V to a PWM signal - surely this would play havoc with an intelligent load like an EVSE and charge controller.
Do you have control measurements from a 13A socket at home?

It is a very interesting point.
A:It doesn't unless it has some form of green phy kit built into it, which is highly unlikely.
B:Agreed
C:Very plausible, and not a problem, I have a triac controlling a dump load via solar and its rated for driving a 3kW load, all the time the power exists the load is on with no issues, and all the time the power is high enough it runs any device happily its only when the power is too low and its on/off flickering is an issue, in the case of a known supply source (unlike solar) it would be very easy to set the rate supplied to the socket.

Personally I feel it is C

 

[Kevin Sharpe]

@Dave Davies as other people have said the 13A Charging Station has no controlled way of limiting the charge current to the car.

Your EVSE will tell the car how much current it can consume with a minimum limit of 6A set by the EVSE protocol. If you are reading 5.5A something is wrong with your measuring equipment IMO.

What happened to the AC voltage during your charge cycle?

 

[Dave Davies]

As @PaulMorris says, there is no physical way for it to be the fault of the 13A socket.
My suspicions of the hydra would be around the resistance of the PP-PE loop which would limit the charging rate (in addition to the CP pulse width). Maybe someone with access to the spec can elaborate on that.
Is your 32A Rolec EVSE un-tethered using the same cable/hydra as you use to test the Chargemaster one?

Im not suggesting it is a fault, I am suggesting its by design and set in software.

For the purpose of explanation and discussion only:
A: If we assume the EVSE is in good order and capable of 32A
B: We ignore the safety aspects of the BS1363 plug and being unsuitable to draw 32A

We then have
The 32A Commando Plug plugged into a 32A commando socket we get a full charge rate.

If we then use a 32A Socket to 16A Plug to 16A Socket to BS1363 Plug (because I have one)

We then plug into a CM post fitted with BS1363 Sockets we get 6 amps

As for hydra have you seen one?

 

[Kevin Sharpe]

We then plug into a CM post fitted with BS1363 Sockets we get 6 amps

As stated I believe this is your measuring equipment at fault.

One other (remote) possibility is that your car is defaulting to a Mode 1 charge with a 6A limit. Maybe the voltage drop or impedance through your connectors is enough for the car to enter a safe charge mode.

This is not the 13A socket!

 

[fenlander]

Im not suggesting it is a fault, I am suggesting its by design and set in software.

I just don't see how that is physically possible

As for hydra have you seen one?

Not in person, but I have a good idea how it works. My concern is how it handles the PP-PE signal that means a lot more to Type-2 than it does to J1772 where it is just a connected/not connected signal. By my understanding this is the signal used to detect the cable capacity. Maybe Kevin can put my mind at rest here

 

[Dave Davies]

I agree this is not the socket.
The LeafDD potentially is wrong, although it reports ok when on DC rapids, in as much as the rate on the DD matches the display on the RC.

We don't have many CM posts where I live to test on but in all cases I haven't seen more than 16A.

I agree, I can see I am going to have to build a jig and take a clamp meter, certainly the standard nissan evse sucks up 10A at home reported by openenergy monitor.

 

[Dave Davies]

I just don't see how that is physically possible

Using An SCR or triac, its possible to do.

Going back to my original post, I wonder if anyone else has a DD they can compare whilst i build something!

 

[PaulMorris]

Using An SCR or triac, its possible to do.

Going back to my original post, I wonder if anyone else has a DD they can compare whilst i build something!

Yes, but I'm concerned the choppy wave would cause havoc with an electronic load like an EVSE and a smart charge controller. This is why you only see these solar load dump devices designed for immersion heaters, or storage heaters. Dumb resistive loads that know no different.

Would love to be proved wrong, as it makes my solar aware EVSE design much simpler.

 

[Dave Davies]

Its pointing to LeafDD , I will measure when I get home as certainly the LeafDD rate is half the AC.

 

[Kevin Sharpe]

Using An SCR or triac, its possible to do.

Correct but completely pointless.... nobody needs to restrict a 13A Charging Station to 6A (which interestingly is the minimum supported by the EVSE protocol and is the clue to whats going on IMO).

In the early days I tested a lot of CM 13A posts and they worked as expected with the Roadster which can draw 13A from a 13A socket.

 

[Edd Beesley]

My LeafDD shows charging amps, into the battery. The battery is usually in the 350-390V range while charging. When charging on my 16A EVSE at home I see about 8.5amps going into the battery shown on LeafDD.... On the 10A brick EVSE I see about 5.5amps going into the battery.