Charging current selection not holding (switches to max and trips house MCB)

[TonySparks]

Hello all!
New member so please excuse any mistakes as this is all new to me.
I have a 4 week old MG4 Trophy LR (74 plate)
Ive had an intermittent problem when charging at home (Rolec wallpod dumb charger 7.4kw).
The mcb in the house sometimes trips when charging overnight. This is due to overload on the circuit (32amp mcb).
It's not leakage as this doesn't trip the built in Rcbo on the unit or the Rcd on my fuse board.
I plug the car in overnight and set the max current to 16amps but for some reason it switches to max (32a) when charging overnight and spikes at 7.5kw which trips the fuse .
It just doesn't seem to want to stay on 16amps. Some charges it goes for 4 hours and no problem as it stays on but every other charge it switches to max.
Just to add I'm an Electrician and have tested the house installation and wallpod.
Nothing back from MG yet and don't expect anything any time soon.

Thank you in advance.

 

[Alb]

The problem is almost certainly going to be down to the EVSE or the MCB feeding it. You could rule out the latter by swapping it out for another MCB. It may also be useful to put a clamp on the EVSE feed to see whether it is drawing a current in excess of 32A.

 

[Jomarkh]

Hello all!
New member so please excuse any mistakes as this is all new to me.
I have a 4 week old MG4 Trophy LR (74 plate).
Ive had an intermittent problem when charging at home (Rolec wallpod dumb charger 7.4kw).
The mcb in the house sometimes trips when charging overnight. This is due to overload on the circuit (32amp mcb).
It's not leakage as this doesn't trip the built in Rcbo on the unit or the Rcd on my fuse board.
I plug the car in overnight and set the max current to 16amps but for some reason it switches to max (32a) when charging overnight and spikes at 7.5kw which trips the fuse.
It just doesn't seem to want to stay on 16amps. Some charges it goes for 4 hours and no problem as it stays on but every other charge it switches to max.
Just to add I'm an Electrician and have tested the house installation and wallpod.
Nothing back from MG yet and don't expect anything any time soon.

Thank you in advance

A 32A breaker is a bit tight try a 40A one.
Is the Rolec new as all new installations should be with a smart EVSE and signed off part P.
Does the Rolec have Open Pen DC protection?

 

[5teep]

Hello all!
New member so please excuse any mistakes as this is all new to me.
I have a 4 week old MG4 Trophy LR (74 plate).
Ive had an intermittent problem when charging at home (Rolec wallpod dumb charger 7.4kw).
The mcb in the house sometimes trips when charging overnight. This is due to overload on the circuit (32amp mcb).
It's not leakage as this doesn't trip the built in Rcbo on the unit or the Rcd on my fuse board.
I plug the car in overnight and set the max current to 16amps but for some reason it switches to max (32a) when charging overnight and spikes at 7.5kw which trips the fuse.
It just doesn't seem to want to stay on 16amps. Some charges it goes for 4 hours and no problem as it stays on but every other charge it switches to max.
Just to add I'm an Electrician and have tested the house installation and wallpod.
Nothing back from MG yet and don't expect anything any time soon.

Thank you in advance.

Could be that the 32amp MCB is just getting old and close to burning out, it should be able to handle 7.4kw ok as long at your spike doesn't exceed that. They are not expensive to buy as you probably already know.
Alternatively...
My own dumb 7.4kw charger runs permanently at 3.5kw and this is set by physical switches inside it, maybe yours can be also?

/edit I'm assuming your Rolec is not new???

 

[TonySparks]

Thank you all for the replies.
Yes it should be on a 40amp mcb but it's wired in a 6mm twin and earth cable so stuck with a 32amp mcb because of the wiring method (insulation in ceiling/walls).
It came with the house which is a 3 year old new build and have only started using it 3 months ago as the Mrs has a Ex30.
The problem is the car pulling 32amp+.

When it's plugged in you can select charging currents .
6a/10a/16a and Ac current-32a which will pull the max it can through the charging source.
I set it to 16a and lock the car, then over night it when the schedule kicks in it sometimes changes back to
Ac current (max) and not 16a like I selected, thus overloads the mcb.
I have swapped the mcb too.
A way to solve this is:

1. Wire in a new supply (10mm swa ) and stick it on a 40amp mcb.
2. Change the charger to one where I can control charge current via app.
I feel like I shouldn't need to do either as if the car stays on 16amps there's no drama.

The wall charger doesn’t have a means to change the charge current,
But I have looked at other brands that do and you're right about the switch inside.
That said, a switch would be pain for the Mrs as her car doesn't trip the mcb so I would need to change it everytime.
I will add that the Mrs car I've set at 25amp max current, so wouldn't want hers to charge slower than it needs to.

The charger has built in PEN.
No trips from the RCBO just the upstream mcb which points to over current.


I will set it to max over the weekend with the cover off and see what it's pulling.
It usually sits up to 7.5kw which calculates to just over 32amp depending on conditions.
It's not wise to have a breaker being used on max. It's advised to have a design current with 20% spare.

Plugged it in at 6pm this evening and set it to 16amp.

It's been sitting between 3.2 and 3.4kw for the last 4 hours no problems, so only seems to be the schedule causing the car to charge at 32amps.

I did speak to MG earlier in the week and when I explained the problem the gentleman said that you can't select the current as it always sets to the max it can draw from the charging source which is nonsense as I'm proving now.
He said he would "discuss" my problem with his colleges and get back to me........

I've logged it with the dealer today and waiting for a response.

Thank you for the responses.

 

[Gomev]

The Rolec at 3 years old should be a smart one, using the ev.energy app. My 4 year old Rolec is smart.

 

[siteguru]

How old is your Trophy LR? i.e. does it have a rear wiper? If it does then the max. charging current fed into the car's batteries should be 6.6kW as that is the rating of the onboard charger. That equates to about 7.2kW or so drawn from the supply including losses, so no higher than 32A.

Is your grid voltage on the lower side at your property? (Nominal is 230Vac but it can go down as low as 216.2Vac and still be within grid tolerance ... at that level 7.2kW would equate to 33.3A).

 

[5teep]

Thank you all for the replies.
Yes it should be on a 40amp mcb but it's wired in a 6mm twin and earth cable so stuck with a 32amp mcb because of the wiring method (insulation in ceiling/walls).
It came with the house which is a 3 year old new build and have only started using it 3 months ago as the Mrs has a Ex30.
The problem is the car pulling 32amp+.

When it's plugged in you can select charging currents.
6a/10a/16a and Ac current-32a which will pull the max it can through the charging source.
I set it to 16a and lock the car, then overnight it when the schedule kicks in it sometimes changes back to
Ac current (max) and not 16a like I selected, thus overloads the mcb.
I have swapped the mcb too.
A way to solve this is:

1. Wire in a new supply (10mm swa ) and stick it on a 40amp mcb.
2. Change the charger to one where I can control charge current via app.
I feel like I shouldn't need to do either as if the car stays on 16amps there's no drama.

The wall charger doesnt have a means to change the charge current,
But I have looked at other brands that do and you're right about the switch inside.
That said, a switch would be pain for the Mrs as her car doesn't trip the mcb so I would need to change it everytime.
I will add that the Mrs car I've set at 25amp max current, so wouldn't want hers to charge slower than it needs to.

The charger has built in PEN.
No trips from the RCBO just the upstream mcb which points to over current.


I will set it to max over the weekend with the cover off and see what it's pulling.
It usually sits up to 7.5kw which calculates to just over 32amp depending on conditions.
It's not wise to have a breaker being used on max.its advised to have a design current with 20% spare.

Plugged it in at 6pm this evening and set it to 16amp.

it's been sat between 3.2 and 3.4kw for the last 4 hours no problems,
So only seems to be the schedule causing the car to charge at 32amps.

I did speak to MG earlier in the week and when I explained the problem the gentleman said that you can't select the current as it always sets to the max it can draw from the charing source which is nonsense as I'm proving now.
He said he would "discuss" my problem with his colleges and get back to me........

I've logged it with the dealer today and waiting for a response.

Thank you for the responses .

Found this on lowering the output of an older tethered rolec by adding a resistor. Post #3 says it needs to go between PX and PE in the charger, post #10 tells you what resistor to choose for your desired output. Of course you need to be competent to do this yourself.

Does not apply to untethered ones.

How to limit a Rolec charger from 32A to 16A

www.speakev.com

 

[TonySparks]

How old is your Trophy LR? i.e. does it have a rear wiper? If it does then the max. charging current fed into the car's batteries should be 6.6kW as that is the rating of the onboard charger. That equates to about 7.2kW or so drawn from the supply including losses, so no higher than 32A.

Is your grid voltage on the lower side at your property? (Nominal is 230Vac but it can go down as low as 216.2Vac and still be within grid tolerance ... at that level 7.2kW would equate to 33.3A).

Hi there. The car is new (4 weeks old 74 plate), yes the rear wiper one, and it's the Trophy LR.
Nominal voltage is 230 volts.
The app and in car screen sometimes shows it pulling 7.4kw. So not sure if this is showing what the car is actually getting to the battery or if its capped at 6.6kw as you've said.
The problem I have is that when I set it at 16amp charge rate and start the charge it holds at that (about 3.2kw to 3.5kw)

If I do the same but set the schedule to come on it automatically sets it to mx (32a) then from that it sometimes tips over 32 amps and trips the broker.
My problem is solved if it will just stay on 16amps charge current.

Found this on lowering the output of an older tethered rolec by adding a resistor. Post #3 says it needs to go between PX and PE in the charger, post #10 tells you what resistor to choose for your desired output. Of course you need to be competent to do this yourself.

Does not apply to untethered ones.

How to limit a Rolec charger from 32A to 16A

www.speakev.com

Thank you for response.
Unfortunately it's not the tethered one.
I also don't want to lower the EVSE charge current as the Mrs charges her car and hers doesn't trip the breaker. If I did that then she charges at a lower current for no reason.
I just want the charge current to stay at the rate I select which is 16a.
The schedule doesn't like that and changes to max over night and trips the breaker.

The main problem is the car pulls more than it should and overloads the mcb in the house.
The 2nd problem is it doesn't stay on the selected current when schedule charging.
Only stays on if I select it and begin charging.
I need the schedule so I can charge overnight cheaper (Octopus Energy).

 

[TonySparks]

UPDATE: (Solved?)
Hi all just to give an update so far.
I've charged the car 5 times since my last post from under 30% to 80% and no trips.

I've changed the mcb (type B 32amp)
To a type C.
This allows for a higher amp rate briefly at start up.
I've also got rid of the app completely as I've noticed when schedule charging kicks in the contactor in the EV charger comes on and off 4 times during start up.
I believe this is down to the app and car talking to each other.(maybe different times )
I find the app note very useful in my opinion.
Handy to warm the car up or cool it and that's about it.

if anything changes over the next couple of months I'll update .
Also nothing back from MG yet.

Thank you all.