Charging below 1.4kW / 6A?

NeilJonesOnline · Jun 02, 2021#12021-06-02T08:03+00:00

I always thought the minimum charge level of 6A was prescribed by an EV charging standard, but when I mentioned this recently on a Polestar 2 forum I was corrected by several other UK members (with different chargers) whose cars quite happily charged below 1.4kW.

So what's the story, is 6A just a minimum requirement of a standard, i.e. cars have to be able to charge at 6A but anything below this is fine too? Or is the Polestar 2 'non-compliant'?

Which brings me on the the crux of my question - can the zappi 2 be set to allow charging below 6A surplus? Due to the orientation of my house and the layout of my solar panels, I get several hours on summer evening when my PV surplus is constantly about 1kW, but could never reach 1.4kW. By this time of day, my PowerWall is normally full, so all my surplus just gets flushed back to the grid - it would be great if it was going into my car instead.

G6EJD · Jun 02, 2021#22021-06-02T09:14+00:00

1.4KW is the lowest charge rate set by the standard, yes it could be usefully reviewed.

The dilemma and irony is there will be some EV’s that won’t start charging until that amount of power is made available and may stop charging below that value, so an EVSE designer and supplier can’t win!

It would be commercially disastrous to design or modify a product that did not comply with the standard as EV suppliers would not then recommend a product for use with their EV or the product would be sidelined as being non-compliant.

It might be worth reviewing the charging process (1-phase examples):

Fast mode charging- the Zappi signals to the EV it can deliver 7kW, the EV accepts that and starts charging.

ECO mode charging - the Zappi waits for 1.4kW of surplus power then signals to the EV the available charge rate and charging starts. If the solar energy drops and available power is eg 1kW the Zappi drops it’s power delivery signal to the EV, but because of the standard the minimum it can signal is 1.4kW even though only 1kW is available, and stops its output, now it’s down to the EV to decide what’s it’s going to do, either wait for power to return or stop altogether. Some EV’s do the latter.

None of this is under the control of the Zappi it’s the EV that decides.

I suspect all EV’s charge below the minimum power set, because the final part of a battery charge called cell balancing, might only need a small amount of power to complete that stage necessitating a breach of the standard if indeed it is that rigid.

The answer is to the use the ECO mode with a minimum green level set to a value that is acceptable, then a minimum 1.4kW is always delivered.

Jun 02, 2021#32021-06-02T09:25+00:00

Addendum: a conventional charger won’t have variable power delivery and the EV will charge below the minimum until the EV signals a stop.

The Zappi has been designed to only use surplus generated power, and so it stops by design when is there is insufficient availability of power.

NeilJonesOnline · Jun 02, 2021#42021-06-02T09:26+00:00

Thanks. I agree that EVSE manufacturers have to make devices that are going to be compliant with standards out-of-the-box, but we already have compatibility settings on the zappi, so why not have an option to reduce the minimum charging level for those cars that would support it? As mentioned, I was surprised that there seems to be several basic chargers out there which are already doing this by default if the responses I got on the Polestar forum were correct (but just seen your addendum).

G6EJD · Jun 02, 2021#52021-06-02T09:36+00:00

Yes and it could be in time the Zappi has a selectable EV type in compatibility modes to accommodate any differences in charging tolerance.

prawlin · Jun 02, 2021#62021-06-02T10:39+00:00

NeilJonesOnline wrote: ↑
Jun 02, 2021
I always thought the minimum charge level of 6A was prescribed by an EV charging standard, but when I mentioned this recently on a Polestar 2 forum I was corrected by several other UK members (with different chargers) whose cars quite happily charged below 1.4kW.

So what's the story, is 6A just a minimum requirement of a standard, i.e. cars have to be able to charge at 6A but anything below this is fine too? Or is the Polestar 2 'non-compliant'?

Which brings me on the the crux of my question - can the zappi 2 be set to allow charging below 6A surplus? Due to the orientation of my house and the layout of my solar panels, I get several hours on summer evening when my PV surplus is constantly about 1kW, but could never reach 1.4kW. By this time of day, my PowerWall is normally full, so all my surplus just gets flushed back to the grid - it would be great if it was going into my car instead.

On my Kia Eniro UK model 4 (single phase 7.2kW OBC) there is an incredibly useful screen menu that enables easy modification to the standard full charging rates. There is High(default) medium and low settings for AC charging. This appears to effectively scale down the PWM commands from the EVSE. The result is that when it’s on High, everything is as expected with 1.4kW being the minimum and 7.2kW the maximum charge rate.

However, when I set the car rate to low, it gives ~600W minimum (instead of 1.4kW) and ~4.2kW maximum (instead of 7.2kW). This is perfect to support my PV charging as it can continue right down to 600W surplus without using any grid power. Then if I reduce the MGL to 10%, my charging can continue uninterrupted right down to approximately 200W of PV, but with just a little support from the grid. The result is nice continuous charging dawn till dusk with a tiny amount of grid power support.

I very much doubt ME would want to send a PWM for lower than the 1.4kW as defined in the standard. But if your car has a similar scale down charge setting, then that is a great solution, and Zappi doesn’t seem to mind at all if the charging power drawn by the car goes lower than the PWM value it sent.

The MGL Zappi setting via the app does allow charging to occur with lower than 6A solar surplus.....
100% needs 1.4kW
50% needs 0.7kW
10% needs 140W

Peter

nigel.ledeux · Jun 02, 2021#72021-06-02T11:37+00:00

prawlin wrote: ↑
Jun 02, 2021
NeilJonesOnline wrote: ↑
Jun 02, 2021
I always thought the minimum charge level of 6A was prescribed by an EV charging standard, but when I mentioned this recently on a Polestar 2 forum I was corrected by several other UK members (with different chargers) whose cars quite happily charged below 1.4kW.

So what's the story, is 6A just a minimum requirement of a standard, i.e. cars have to be able to charge at 6A but anything below this is fine too? Or is the Polestar 2 'non-compliant'?

Which brings me on the the crux of my question - can the zappi 2 be set to allow charging below 6A surplus? Due to the orientation of my house and the layout of my solar panels, I get several hours on summer evening when my PV surplus is constantly about 1kW, but could never reach 1.4kW. By this time of day, my PowerWall is normally full, so all my surplus just gets flushed back to the grid - it would be great if it was going into my car instead.
On my Kia Eniro UK model 4 (single phase 7.2kW OBC) there is an incredibly useful screen menu that enables easy modification to the standard full charging rates. There is High(default) medium and low settings for AC charging. This appears to effectively scale down the PWM commands from the EVSE. The result is that when it’s on High, everything is as expected with 1.4kW being the minimum and 7.2kW the maximum charge rate.

However, when I set the car rate to low, it gives ~600W minimum (instead of 1.4kW) and ~4.2kW maximum (instead of 7.2kW). This is perfect to support my PV charging as it can continue right down to 600W surplus without using any grid power. Then if I reduce the MGL to 10%, my charging can continue uninterrupted right down to approximately 200W of PV, but with just a little support from the grid. The result is nice continuous charging dawn till dusk with a tiny amount of grid power support.

I very much doubt ME would want to send a PWM for lower than the 1.4kW as defined in the standard. But if your car has a similar scale down charge setting, then that is a great solution, and Zappi doesn’t seem to mind at all if the charging power drawn by the car goes lower than the PWM value it sent.

The MGL Zappi setting via the app does allow charging to occur with lower than 6A solar surplus.....
100% needs 1.4kW
50% needs 0.7kW
10% needs 140W

Peter

I find that MGL set at 40% works really well for me in tandem with my Powerwall 2.
Nigel

planetf1 · Aug 05, 2021#82021-08-05T17:34+00:00

I'm extremely borderline for any useful PV -- I expected this. Moved into a house with only 1.45kW nominal panels, so currently set to only charge when 70% from renewable (since on octopus my night rate is about 1/3 day rate). I rarely get much charge.

No regrets getting the harvi though - I expected this was the case, and capturing the data will help me think about solar (tricky, small roof) or battery storage in future.

I have a Tesla model 3. The lowest charge supported by their plugin-in 240V/13A charger is 5A, this is selectable within the car. Would also love the zappi to try a little lower, but at the same time we have to reflect on specs, and the difficulty of accommodating every possible variation that is out of spec.!

Mausy5043 · Aug 07, 2021#92021-08-07T14:09+00:00

prawlin wrote: ↑
Jun 02, 2021
On my Kia Eniro UK model 4 (single phase 7.2kW OBC) there is an incredibly useful screen menu that enables easy modification to the standard full charging rates. There is High(default) medium and low settings for AC charging. This appears to effectively scale down the PWM commands from the EVSE. The result is that when it’s on High, everything is as expected with 1.4kW being the minimum and 7.2kW the maximum charge rate.

Peter, that is interesting. I have not found that screen yet. Can you share the path?

prawlin · Aug 07, 2021#102021-08-07T15:08+00:00

Mausy5043 wrote: ↑
Aug 07, 2021
prawlin wrote: ↑
Jun 02, 2021
On my Kia Eniro UK model 4 (single phase 7.2kW OBC) there is an incredibly useful screen menu that enables easy modification to the standard full charging rates. There is High(default) medium and low settings for AC charging. This appears to effectively scale down the PWM commands from the EVSE. The result is that when it’s on High, everything is as expected with 1.4kW being the minimum and 7.2kW the maximum charge rate.
Peter, that is interesting. I have not found that screen yet. Can you share the path?

Yes it was a complete revelation. It makes this ENiro car a superb system partner with Zappi and solar PV. I leave mine set to low always. As I type this now it is outside charging at around 700W with today’s cloudy skies.
Select EV Button screen/Charge Management/Charging Current/AC Station/HIGH-MED-LOW.....
Peter.

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