Dumb Wall Box Units - 32 Amp 7.00 Kw Compared To 16 Amp 3.60 Kw Unit's ?.

[Lovemyev]

Second the car should only charge to 80% on max charge 7kw/22kw/50kw and then the charge slows to protect the batteries.

The basic style Rolec units ( mine is now five years old ) has only a simple task to perform, too provide 7 kw's to the car, when requested by the car.
I have proven ( and others have confirmed my findings ) that the car should demand the full 7.0 kw's at any point, as long as the SOC is BELOW 97%.
At between 97 and 98% the car will throttle back the demand down to 3.6 kw's until it reaches 100% SOC.
At this point, the MG logo has changed from a slow pulse when charging, to a constant low glow from the MG logo.
The demand from the wall box is reduced right back to around 500 watts now.
It is now in the "Balancing" cycle.
When this has completed, the wall box will stop supplying any charge and the MG logo will stop displaying any light at all.
D/C Rapid charger are charging at a much higher rate and therefore the "Throttling" will start at around the 80% mark.

 

[notdodgy]

Thank you correcting me but please read my reply again my friend.
"0 to 80% is at 7kw (max car allows) then the charge drops off"

My car charges at 7KW until it reaches 97% then drops to 3kW. At 100% it drops to 0.3kW while balancing.

The 80% is for Rapids - DC charging.

I didn't realise until I got the car the maximum AC charging rate is 7kW.
So a 22kW charger becomes a 7kW for our cars and the same as a 7kW (single phase charger).

 

[Cocijo]

Thank you correcting me but please read my reply again my friend.
"0 to 80% is at 7kw (max car allows) then the charge drops off"

I wasn’t correcting you - sorry if it came over like i was - just trying to add more clarity

 

[Cocijo]

My car charges at 7KW until it reaches 97% then drops to 3kW. At 100% it drops to 0.3kW while balancing.

The 80% is for Rapids - DC charging.

I didn't realise until I got the car the maximum AC charging rate is 7kW.
So a 22kW charger becomes a 7kW for our cars and the same as a 7kW (single phase charger).

Yes - mine is the same.

 

[Lovemyev]

Pure guess which I hope does not cloud the issue.
During this cold weather is it possible that the very cold battery will only take the lower current?
After a few minutes charging at 3.7 kW the battery will be slightly warmer but will continue charging at the lower initial rate.
Stopping and unplugging the cable resets the car ECU and when you start charging again the rate goes up to 7.2 kW as the battery is warmer than on initial charge.
Please excuse my non technical language but when your clutching at straws!!!

Thanks for your reply.
But I have proven that not to be the case really.
If I commence a charge, it requests 3.6 kw's only.
If I let it charge for either 2 minutes or 5 minutes, then unlock the car ( to stop the charge ).
Unplug the car, plug it straight back in and commence the charge again.
The car now demands 7.0 kw's in that very short time scale.
Go figure that !.
I somehow have to prove if it's the car or the wall box ( which I very much doubt ).
This behaviour has only started AFTER the latest BMS update, just over 2 weeks ago.
I have decided to take the car to my local Tesco about 5 miles away.
They have recently had two new 7 kw Pod Point posts fitted.
I will plug in the car and use the display in the car to try and judge what the car is receiving.
E.G. - When I arrive and start the charge, it will display the SOC and remaining mileage left.
Then the display will give a pretty good estimate of how long it will take to complete the charge to 100%.
So, if the SOC is showing 75% and pulling 7.0kw's - It should only take about 1 hour ( ish ) to hit the 97% mark, then the car will throttle back the charge to 3.6 kw's.
Therefore, I would expect to see a total charge time to 100% at around 1 hour - 30 mins.
Then I can compare this to my results at home.
The first time the external ( Tesco ) units demands only 3.6 kw's - I pretty much have my answer.
It's the car and nothing at the home address that is causing this strange behaviour - pure and simple !.
I am still awaiting a call back from Rolec to see what light ( if any ) they can offer that would rule out my home charger.
Just to say, that the basic dumb Rolec ( not favoured by a lot of folks I know ) is giving me no reason to think that this is the issue here.
But I just need assuring from Rolec that it could not be ANY fault of the wall box.
Conducting the brief charging checks just rules in or out, any issues with the wall box or it's charging lead.
I am using a brand new ( proven ) type 2 charging cable at the Tesco unit of course.

 

[Lovemyev]

Yes - mine is the same.

Yep !.
Totally normal practice.
This is way it is supposed to work ( unless you are me of course ).

 

[Iain]

Thanks for your reply.
But I have proven that not to be the case really.
If I commence a charge, it requests 3.6 kw's only.
If I let it charge for either 2 minutes or 5 minutes, then unlock the car ( to stop the charge ).
Unplug the car, plug it straight back in and commence the charge again.
The car now demands 7.0 kw's in that very short time scale.
Go figure that !.
I somehow have to prove if it's the car or the wall box ( which I very much doubt ).
This behaviour has only started AFTER the latest BMS update, just over 2 weeks ago.
I have decided to take the car to my local Tesco about 5 miles away.
They have recently had two new 7 kw Pod Point posts fitted.
I will plug in the car and use the display in the car to try and judge what the car is receiving.
E.G. - When I arrive and start the charge, it will display the SOC and remaining mileage left.
Then the display will give a pretty good estimate of how long it will take to complete the charge to 100%.
So, if the SOC is showing 75% and pulling 7.0kw's - It should only take about 1 hour ( ish ) to hit the 97% mark, then the car will throttle back the charge to 3.6 kw's.
Therefore, I would expect to see a total charge time to 100% at around 1 hour - 30 mins.
Then I can compare this to my results at home.
The first time the external ( Tesco ) units demands only 3.6 kw's - I pretty much have my answer.
It's the car and nothing at the home address that is causing this strange behaviour - pure and simple !.
I am still awaiting a call back from Rolec to see what light ( if any ) they can offer that would rule out my home charger.
Just to say, that the basic dumb Rolec ( not favoured by a lot of folks I know ) is giving me no reason to think that this is the issue here.
But I just need assuring from Rolec that it could not be ANY fault of the wall box.
Conducting the brief charging checks just rules in or out, any issues with the wall box or it's charging lead.
I am using a brand new ( proven ) type 2 charging cable at the Tesco unit of course.

I am inclined to agree with you.
The problem must be with the car as it has the ability to limit the charge.
As far as I am aware the (dumb) Rolec has no ECU to control output and only reacts to the signal from the car.
I am married and know how the poor Rolec feels.
Anyway good luck and keep us posted.

 

[Lovemyev]

Quick update as requested.
I have spoken to the Tech Team at Rolec at some length this morning.
Adam was extremely helpfully and listened to my predicament.
The concussion is that there is nothing inside my basic wall box or cable that could cause the problems I am seeing.
He said there was nothing wrong with me trying to prove my point, by using a different external source to charge my car.
However, he said that it will be the car that is the problem and NOT any of the 7.0 kw units that I am using.
He went on to say, that the basic dumb Rolec units are just a massive switch in affect, in it’s very simplest terms.
He even offered to speak to the dealership if they try to convince you that it is equipment that is at fault here.
It looks like my worse fears and suspicious are pretty much confirmed then.
Something has changed in the last visit to the dealership, that has caused this problem.
I am still continuing to log / record my findings, but I am really unsure why I should bother to be totally honest.
All this has been the result of a simple visit to the agents for some simple tasks plus it’s first service !.
Getting it sorted in lock down situation is going to be a problem now.
What a pain the bum !.

 

[Davloc]

Quick update as requested.
I have spoken to the Tech Team at Rolec at some length this morning.
Adam was extremely helpfully and listened to my predicament.
The concussion is that there is nothing inside my basic wall box or cable that could cause the problems I am seeing.
He said there was nothing wrong with me trying to prove my point, by using a different external source to charge my car.
However, he said that it will be the car that is the problem and NOT any of the 7.0 kw units that I am using.
He went on to say, that the basic dumb Rolec units are just a massive switch in affect, in it’s very simplest terms.
He even offered to speak to the dealership if they try to convince you that it is equipment that is at fault here.
It looks like my worse fears and suspicious are pretty much confirmed then.
Something has changed in the last visit to the dealership, that has caused this problem.
I am still continuing to log / record my findings, but I am really unsure why I should bother to be totally honest.
All this has been the result of a simple visit to the agents for some simple tasks plus it’s first service !.
Getting it sorted in lock down situation is going to be a problem now.
What a pain the bum !.

Don't know if anyone has mentioned it or not, but is there any evidence of damage/debris in the plug or charging port?

Plugging, unplugging then re connecting could be enough to clean a poor connection enough for the car to charge at 7kW over the 3kW

 

[Lovemyev]

Don't know if anyone has mentioned it or not, but is there any evidence of damage/debris in the plug or charging port?

Plugging, unplugging then re connecting could be enough to clean a poor connection enough for the car to charge at 7kW over the 3kW

Thanks for the response, but there does appear to be any evidence of damage etc.
I have just been outside to attempt a charge.
Plug in, charge commences, car pulling 3.7 kw’s.
Stop the charge after about 1 minute.
Unplug the charging lead and reinsert straight away.
The charge recommences and I am receiving 7.0 kw’s within less than 2 minutes !.
This is the same behaviour the car is displaying on a 70 - 30 basis.
Yesterday it pulled 7.00 kw’s at the local Tesco’s and again when I returned home.
The car has not moved since yesterday and straight away it only demands 3.7 kw’s on the first attempt, then 7 kw’s on the second attempt !.
Pre judging a period of time to have the car charge for on “Off - Peak” is pretty much impossible to predict accurately now.
Charging in the day is a no go given the price of the tariff !.

 

[TomLane]

Pure guess which I hope does not cloud the issue.
During this cold weather is it possible that the very cold battery will only take the lower current?
After a few minutes charging at 3.7 kW the battery will be slightly warmer but will continue charging at the lower initial rate.
Stopping and unplugging the cable resets the car ECU and when you start charging again the rate goes up to 7.2 kW as the battery is warmer than on initial charge.
Please excuse my non technical language but when your clutching at stra

Podpoint home 7kw chargers have limited functionality from the app - they’ve been promising to improve this for a long time! The reason a 22kw ac charger takes 6.5hrs is that the MG dc transformer accepts a max rate of just under 7kw - anything over that doesn’t charge any quicker.

Thank you correcting me but please read my reply again my friend.
"0 to 80% is at 7kw (max car allows) then the charge drops off"

 

[Cocijo]

The MG on AC charging does not drop off at 80%.

 

[Lovemyev]

The MG on AC charging does not drop off at 80%.

At between 97 - 98% the charger in the car, will throttle back the demand from 7.0 to 3.6 kw's.
Plugging in the car with a SOC of less than 97% should give you the full 7.0kw's.
When the battery is 100% SOC and the balancing process then commences, he demand from the on board charger should drop to around 500 Watts.

 

[AndyNWuk]

The charging current as Mike and DP said is controlled with a resistor built into the lead that in turn controls the Pulse Modulation.

Also, another common fault on the older ROLEC box is RCCD failure.

Check for "browning" on the side of the RCCD switch unit, this could mean the contacts are arcing and this can start to vary the output of the unit, worth a look.



This video might help to explain the pulse width modulation process, the guy replaces the resistor in the cable with a variable resistor to demonstrate the Pulse width modulation process.



By the way, I am personally using a ROLEC dumb charger unit with my MG and it works absolutely fine. I installed the Shelly 1 Relay to upgrade the unit into a timed system instead of the Sonoff as shown in this video.

Hope this helps.

Andy (Blackpool)

 

[Lovemyev]

The charging current as Mike and DP said is controlled with a resistor built into the lead that in turn controls the Pulse Modulation.

Also, another common fault on the older ROLEC box is RCCD failure.

Check for "browning" on the side of the RCCD switch unit, this could mean the contacts are arcing and this can start to vary the output of the unit, worth a look.



This video might help to explain the pulse width modulation process, the guy replaces the resistor in the cable with a variable resistor to demonstrate the Pulse width modulation process.



By the way, I am personally using a ROLEC dumb charger unit with my MG and it works absolutely fine. I installed the Shelly 1 Relay to upgrade the unit into a timed system instead of the Sonoff as shown in this video.

Hope this helps.

Andy (Blackpool)

Hi Andy - I have a dumb Rolec unit, it is about five years old now but works absolutely fine ( until the latest update of course ).
In the time I have had the Rolec, it has managed to eat through 3 of their recommended RCBO's.
The old "Blue" breakers always failed on the "Negative" side of the breaker by over heating.
The newer Rolec "Green" RCBO's are now failing on the "Line" ( Live ) side of the breaker.
This can be clearly seen from the video made by Jordan from Artisan Electrics.
I have a long conversation with the Tech Team at Rolec only last week.
They have told me that there is nothing inside the wall box or in the tethered cable that can cause the fluctuation in the rate of charge, that I am witnessing.
In short, the car controls the level of current being drawn from the wall box.
He said :- Put in it's simplest terms, the wall box is a giant light switch !.
I am trying to replicate the same problem when using my local Tesco Pod Point fast post.
But under C19 restrictions, this is proving difficult.
If I can get the car to draw 3.6 kw's from a different source, then I have 100% confirmation of the car is the problem in some way.
The guy at Rolec told me that I am wasting my time because it's the car and not the post's.
But feel free to continue with my quest !.
I was kind of hoping it WAS the wall box or cable somehow, but according to Rolec, no chance !.

 

[AndyNWuk]

Hi Andy - I have a dumb Rolec unit, it is about five years old now but works absolutely fine ( until the latest update of course ).
In the time I have had the Rolec, it has managed to eat through 3 of their recommended RCBO's.
The old "Blue" breakers always failed on the "Negative" side of the breaker by over heating.
The newer Rolec "Green" RCBO's are now failing on the "Line" ( Live ) side of the breaker.
This can be clearly seen from the video made by Jordan from Artisan Electrics.
I have a long conversation with the Tech Team at Rolec only last week.
They have told me that there is nothing inside the wall box or in the tethered cable that can cause the fluctuation in the rate of charge, that I am witnessing.
In short, the car controls the level of current being drawn from the wall box.
He said :- Put in it's simplest terms, the wall box is a giant light switch !.
I am trying to replicate the same problem when using my local Tesco Pod Point fast post.
But under C19 restrictions, this is proving difficult.
If I can get the car to draw 3.6 kw's from a different source, then I have 100% confirmation of the car is the problem in some way.
The guy at Rolec told me that I am wasting my time because it's the car and not the post's.
But feel free to continue with my quest !.
I was kind of hoping it WAS the wall box or cable somehow, but according to Rolec, no chance !.

So is your box the ROLEC 32amp 7Kw Tethered type? or Non-Tethered?

In normal Type 2 cables (non tethered type) there is a resistor in the charging cable lead across PP and earth only at the charger end. The charge controller can sense the resistor value and therefore the current limit of the cable i.e. 20A or 32A.

Could be a possible bad connection in the lead or with the resistor itself but as you say if this has only happened since the latest update then it could well be the Car or the way the update has been applied.

I am having my ZS EV updated on Wednesday to the latest software, so will keep you updated once I get back to see how it performs with my ROLEC Dumb Box.

Andy (Blackpool)

 

[Lovemyev]

So is your box the ROLEC 32amp 7Kw Tethered type? or Non-Tethered?

In normal Type 2 cables (non tethered type) there is a resistor in the charging cable lead across PP and earth only at the charger end. The charge controller can sense the resistor value and therefore the current limit of the cable i.e. 20A or 32A.

Could be a possible bad connection in the lead or with the resistor itself but as you say if this has only happened since the latest update then it could well be the Car or the way the update has been applied.

I am having my ZS EV updated on Wednesday to the latest software, so will keep you updated once I get back to see how it performs with my ROLEC Dumb Box.

Andy (Blackpool)

Hi Andy - Yep, I have a 32 Amp 7kw tethered wall box.
When I had it installed, I had a VW Golf GTE that only requested 3.6 kw's by the car's charger.
But my friendly EV installer ( a EV owner himself ) recommend that I installed the higher output 32 Amp unit to offer some future proofing should I go full BEV !.
Brilliant piece of advice on his part !.
I believe the resistors that you refer too, is in all type 2 cables tethered or untethered.
My EV installer fitted a Sonoff relay inside the wall box to allow delayed charging on cheaper "Off Peak" electric from my supplier.
This has worked great until the car went into the dealer for some work.
Now it has a complete mind of it's own.
Sometimes it will pull 3.6 kw's when I place on charge, then if I stop and unplug and commence the charge again, it will then pull 7.0kw's ????.
I have NO IDEA !!!!.

 

[TomLane]

My car charges at 7KW until it reaches 97% then drops to 3kW. At 100% it drops to 0.3kW while balancing.

The 80% is for Rapids - DC charging.

I didn't realise until I got the car the maximum AC charging rate is 7kW.
So a 22kW charger becomes a 7kW for our cars and the same as a 7kW (single phase charger).

Correct.

 

[Pokerpiazza]

Have you tried looking at the WiFi relay connections to ensure there is no additional intermittent resistance. I assume the relay is in line with the cars output as this is how it controls the actual on and off of the charger without being on the high load side. If the resistance is crating a varying signal it could do enough to change the output. Worth a look?

 

[WilsonPranoto]

@Lovemyev, Is there any update? Did you resolve it? My car is also only drawing about 3kW on a 7kW wall box.