MG4 Low Charging speed compared to friends EV

[bbstr]

Hi all,

I got an MG4 in October and have been enjoying it (despite a few touch and go situations when charging apps aren’t playing ball).

I have recently started a new job which has a free charging point however for some reason my MG4 is capped at 3.2-3.3kW and can never go higher when plugged, while my friend's Polestar can get as high as 10kW.

I’ve tried two three-phase cables (returned my first as I thought it was an issue with it, the new one still had a capped charge rate at this point, but still reaches 6-7kW at other public chargers via Electroverse etc), messed with the scheduled charging setting in the app, tinkered with the in car charging settings, resetting the AC charging option etc. and had a google around and not saw too much regarding a similar issue.

Could this just be a handoff/connection issue between the free point and the car since there’s no app to handshake or something like that? As I said this is my first EV so still trying to wrap my head around things.

Any advice greatly appreciated. Thanks all.

 

[ReintjeWA]

The MG4 has an on board inverter that works at 7 kW single phase. It sounds like the Polestar has 11kW three phase. If you plug into a three phase charge point, you can only use 1 of those phases, which results in the kW figure you see.

It is unlikely down to your cable, but the way the charge point is set up.

 

[MickeySw]

I have recently started a new job which has a free charging point however for some reason my MG4 is capped at 3.2-3.3kW and can never go higher when plugged when my friends Polestar can get as high as 10kW.

The charging point delivers 16A/phase on 3 phases.

According to below, MG4s only support single phase AC charging?

MG MG4 EV Long Range

All details and specs of the MG MG4 EV Long Range (2022). Compare price, lease, real-world range and consumption of every electric vehicle.

ev-database.org

 

[siteguru]

The early LR cars supported (up to) 11kW 3-phase charging, but now it is only the ER that supports that ... all other models are (up to) 6.6kW single phase.

 

[Kithmo]

To put it simply, it sounds like it's a 11kW, 3 phase charger, the MG4 can only use one phase, 11/3 = 3.7kW

 

[Anon70]

Do you see the charge rate change when you change the AC charge setting, as it does in the video below (time stamp 9:30 onwards)

 

[bbstr]

Do you see the charge rate change when you change the AC charge setting, as it does in the video below (time stamp 9:30 onwards)

Yes, everything shown here appears on mine.

Sounds like it’s just the way the charger is set up then. A bit disappointing as it is as slow as molasses and there’s only two chargers so I’m a bit of a hog trying to recoup the 30% it takes for a round trip

Even more so by the sounds like an older LR would have gave me at least 7kW.

Oh well, thanks all!

 

[Macadoodle]

Makes me wonder why manufacturers don't do away with on board chargers and just have a simple DC port.
It would save a decent amount of weight, space and cost . Home chargers would be more expensive with the step up transformer and rectifier it would need but I can't see it being prohibitive, electronic components have never been cheaper.
Having a cable with 400V DC running through it at someone's home might be the reason they shy away from it I guess

 

[OriginalBigAl]

If your new bosses were amiable ,would they consider installing some 7kW EVSEs at single phase as that is more the norm in the UK, especially as more and more people are turning to EVs. Grants and subsidies may be available?

 

[brilig]

My 2023 MG4 trophy is hooked up in my garage to a Heidelberg Wallbox, maximum 11kW and I charge every time at 9.4 kW.

 

[Bam Bam]

My 2023 MG4 trophy is hooked up in my garage to a Heidelberg Wallbox, maximum 11Kw and I charge every time at 9.4 Kw

European Spec may be different.

In the UK the vast majority of homes are single phase.

 

[Coulomb]

hooked up in my garage to a Heidelberg Wallbox, maximum 11kW and I charge every time at 9.4 kW.

The car reports power into the battery after losses and 12 V loads. The on-board charger is rated at something less than 16.0 A per phase AC-in, so depending on your mains voltage, you may only be drawing 10.0-10.5 kW from the wall.

The Wallbox and the car are both trying to be careful not to exceed the 16 A current limit, so they will be erring on the low power side.

There will be some 700 W losses in the on-board charger, another 100 W in house wiring, and roughly 300 W used by the 12 V system for charging the 12 V battery, DC-DC losses, pumps, fans, computers, and so on. So that's over a kilowatt difference between the distribution box power and the HV battery power.

So this is not unexpected.

 

[craigupnorth]

Just my understanding … Mg4 does 1 phase only. 1 phase at 32 amp is 6kW, but 16 amp would be half that. A lot of electricians dont realise (or cheap out?) and install home chargers with 16 amp fuses. You've got to insist on a 32amp fuse.
Edit: and the charger needs to support 32 amps.

 

[Coulomb]

Just my understanding … Mg4 does 1 phase only.

Some do 3 phase, like the extended range models, my own included. If it's showing 9.4kW, then it must have an 11kW on-board charger.

More European models have the 3-phase charger as well.

 

[Coulomb]

A lot of electricians dont realise (or cheap out?) and install home chargers with 16 amp fuses. You've got to insist on a 32amp fuse

And of course you need the cable rated for that current too, and that's the expensive part (more copper). 11kW is 230V x 16A x 3 phase, so for an 11kW EVSE and car, you need 20A cable and breakers, because you have to derate to 80% of rated current when the load is continuous and long term, as EV charging is.

For single phase, the cable needs to be rated for 40A (6 mm²), and of course breakers also 40A.

 

[Corindikev]

Yep, I installed 6mm² cable (12 metres from the supply) a 40 Amp RCCB and my ZJ Benny EVSE delivers the maximum 6.6kW to the battery through the cars inverter drawing a maximum of 32 Amps at 230 volts AC (7.36 kW). Often the voltage is higher especially on sunny days when my solar panels are delivering over 6kW and the grid is being flooded with energy from rooftop solar. I have seen voltage up to 250 volts but the EVSE will adjust the current back to 29-30 Amps or so to ensure constant power delivery.

 

[Coulomb]

I have seen voltage up to 250 volts but the EVSE will adjust the current back to 29-30 Amps or so to ensure constant power delivery.

I think it's the on board charger doing that power limiting. As long as the EVSE and cable insulation don't break down, they doesn't care about the voltage, only the I²R heating from the current. So I would expect a 32A EVSE to set the control pilot signal to signal a 32A limit regardless of the mains voltage.

The OBC has to worry about the temperature of its components, and also the current rating of the path to the high voltage battery. The final AC to DC rectifiers for example could exceed their ratings, both temperature and current, if the total charge power snd hence output current gets too high.

 

[Corindikev]

I can set the maximum current on the EVSE from 6 amps to 32 amps. When set to 32 amps and the voltage is higher than 230 volts the current is reduced automatically on the EVSE app. It may be the on board charger/inverter that is doing the limiting refusing to accept more than 7kW or thereabouts.