MG 4 Trophy Charging Problems: Battery Percentage Not Increasing

[NiroMG]

Vehicle Details:

• Manufacturer: MG
• Model: 4 Trophy
• Model Detail: 203 Electric 64Kwh Auto Long Range

MG 4 Trophy Charging Issues: Rapid Drop in Charge Percentage at Supercharger

Last week, when charging my MG 4 Trophy at a Tesla Supercharger, I arrived with 15% battery and charged up to 35%. However, as soon as I unplugged, the charge percentage rapidly dropped in front of my eyes and, within less than a minute, was down to 16%. A few minutes up the motorway, I used a 50 kilowatt DC charger with better results, although the charging was slow. Since then, I have had no issues with AC charging (normally eleven kilowatts) and even had one successful DC charge last night.

Today, I charged at a DC charger again. Although the charger showed it was delivering 11 kilowatts and the car was receiving 11 kilowatts, with a total of 7 kilowatt hours delivered to the car, the battery percentage and range remained the same. I waited to see someone else use the charger after me, and everything worked fine for them. I tried calling the dealership, but I was put through to voicemail three times. On the fourth call, I was told someone would call me back But I'm not too hopeful.


Has anyone else experienced similar issues with their MG 4 Trophy or have any suggestions on what might be causing these charging problems?

 

[Martinonline]

Have you balanced-charged at all? Or done a 10% to 100% charge?

 

[siteguru]

And PS - your profile shows you as having an SE SR. Can you update it please to prevent any confusion for others in case they skim or mis-read your post?

 

[Deleted member 9909]

What supplier's DC charger only delivers 11kW or am I confused? I thought the minimum Rapid charging station was 50kW nowadays? If it only delivered 11kW I would question the cars DC signalling system. Did the person after you charge at the stations advertised rate do you know?

 

[Coulomb]

What supplier's DC charger only delivers 11kW

It's possible, though unlikely, that a particular charger might be limited to 11kW, because of severe power sharing arrangements, or the charger is temporarily set to a low limit because of a faulty breaker, etc. It's even possible that the owner of the site throttles the chargers at peak tariff times.

But I agree that 11kW is very low for any DC charger. @NiroMG, you mentioned that your usual AC charge is 11kW. Is it possible that you used a rapid charger that has an AC cable (typically rated at 43kW for those very few cars that can use that power from AC), either because the CCS cable was in use, or simply by mistake? That would explain the 11kW charge rate.

Edit: On re-reading, if the dash's SoC reading decreased rapidly when not driving, that sounds bad. If it happened when driving, then the BMS seems confused, or the battery may need balancing. If the former, then a 10% to 100% slow charge should help. If the latter, just doing an AC charge to 100% and leaving it plugged in for an hour after it reaches 100% (a balance charge) should help. A few balance charges may be needed if the battery is badly out of balance.

 

[tsedge]

I would follow the advice above, eg:

1. AC charge to 100% and leave connected for several hours to ensure the battery is balanced.
2. Drive down to 10% and then charge to 100% on AC to calibrate.
3. Try other varieties of DC charger to see if it happens elsewhere.
4. If there's still a problem, go to your dealer with documented evidence of the tests you've done and the behaviour of the car when charging.

You could have a DC charging fault or a problem with your battery, it does happen, but you need to do more tests to be sure.

The more investigation you have done before you go to the dealer the faster they will be able to diagnose any problem and the less likely they'll think it is user error.