MG4 Restricted speed - weird

[jon0881]

No. Given the small difference in cost I thought the LFP was more future proofing and maybe a higher resale value since the pack lasts a lot longer. I wish I’d gone for the LR but still love the mG

 

[bowfer]

No. Given the small difference in cost I thought the LFP was more future proofing and maybe a higher resale value since the pack lasts a lot longer. I wish I’d gone for the LR but still love the mG

We don’t know the LR isn’t affected, I don’t think….
Some reporting the issue have been asked and not said either way.

 

[Mars6394]

im driving an SE SR. today i was able to repeat the issue and im convinced this is due to a cold of <40% charged battery. i started the day at 50% and coming out of work i had about 33%. Work to home is about 10miles. i got home with 11% whilst it was limiting power to 20% at motorway, then 80% on normal roads. it chewed through the battery so im convinced this is a poor battery or bad software protecting the battery. I videoed it too.

I had this same issue with mine before Christmas had to have the BMS system reflashed/updated since then it hasn’t happened again.

 

[G48MG4]

That's the first time I hear about a BMS update/fix for this. Can you find out whether it was just a reflash or an actual update?

I have the LFP, too, with the same problem on the Autobahn: 7 °C and sunny, after 120 km/h the car slooowly creeps to a maximum of ~144 km/h. It took 14 % SoC to drive about 14 km (37 % to 23 %).

PS: Hello friends, new MG4 Standard driver here.

 

[bowfer]

That's the first time I hear about a BMS update/fix for this. Can you find out whether it was just a reflash or an actual update?

I have the LFP, too, with the same problem on the Autobahn: 7 °C and sunny, after 120 km/h the car slooowly creeps to a maximum of ~144 km/h. It took 14 % SoC to drive about 14 km (37 % to 23 %).

PS: Hello friends, new MG4 Standard driver here.

So restricted speed is beginning to show worldwide….

 

[Macadoodle]

So restricted speed is beginning to show worldwide….

And it's looking like LFP is featuring more ? Lower voltage and marked reluctance to flow current when cold are proving to be a bigger Achilles heel than I thought they would be.
I notice wide variations in what power my car can supply depending on SOC and how cold soaked the battery is.
Unfortunately it does affect how you can drive the car. I know I'll usually get a brisk, safe overtake if the battery is above 40% and warmed up.
Totally different taking it out the day after say with below 30% and a cold battery, much caution needed.
I do miss the predictability of my turbodiesel in this regard, it just bloody worked !

 

[bowfer]

And it's looking like LFP is featuring more ? Lower voltage and marked reluctance to flow current when cold are proving to be a bigger Achilles heel than I thought they would be.
I notice wide variations in what power my car can supply depending on SOC and how cold soaked the battery is.
Unfortunately it does affect how you can drive the car. I know I'll usually get a brisk, safe overtake if the battery is above 40% and warmed up.
Totally different taking it out the day after say with below 30% and a cold battery, much caution needed.
I do miss the predictability of my turbodiesel in this regard, it just bloody worked !

I miss the predictability of my EVs that worked.
Which has been any EV other than the 4.
Are we sure it’s just the LFP models yet?

 

[Macadoodle]

I miss the predictability of my EVs that worked.
Which has been any EV other than the 4.
Are we sure it’s just the LFP models yet?

Dunno, thought there was a LFP pattern beginning to emerge though.

True, our leaf didn't display any weird behaviour at lower SOC, maybe a little less punch, which is to be expected, only 110BHP to begin with of course.

 

[tsedge]

I miss the predictability of my EVs that worked.
Which has been any EV other than the 4.
Are we sure it’s just the LFP models yet?

I think we only have a single report from an LR car, from Stageshoot, but that was ages ago. It makes sense that this is either the design of the LFP battery or a BMS issue with it. Since other manufacturers don't have this issue with LFP (eg Tesla), either corners have been cut too far or it is just buggy.

 

[bowfer]

Dunno, thought there was a LFP pattern beginning to emerge though.

True, our leaf didn't display any weird behaviour at lower SOC, maybe a little less punch, which is to be expected, only 110BHP to begin with of course.

No reports of it on the 150bhp 40 or 208bhp 62 either.

I think we only have a single report from an LR car, from Stageshoot, but that was ages ago. It makes sense that this is either the design of the LFP battery or a BMS issue with it. Since other manufacturers don't have this issue with LFP (eg Tesla), either corners have been cut too far or it is just buggy.

So it’s not just the LFP cars then.

 

[tsedge]

So it’s not just the LFP cars then.

1 report isn't enough to make it a characteristic issue.

 

[bowfer]

1 report isn't enough to make it a characteristic issue.

Coincidence then?

 

[tsedge]

Coincidence then?

Who knows? Could be specific to one car or early software since upgraded on the LR. If there's a pattern others will report it.

 

[MoDolph]

Maybe this is why the battery heater setting was turned on when we collected the cars. Might turning it on improve things?

 

[tsedge]

Maybe this is why the battery heater setting was turned on when we collected the cars. Might turning it on improve things?

That is an interesting thought. Although with the SR, this will reduce the already limited winter range.

 

[Macadoodle]

That is an interesting thought. Although with the SR, this will reduce the already limited winter range.

I remember being stuck at 2miles kWh when using the battery heater. Not good.

 

[Deleted member 10041]

Dunno, thought there was a LFP pattern beginning to emerge though.

True, our leaf didn't display any weird behaviour at lower SOC, maybe a little less punch, which is to be expected, only 110BHP to begin with of course.

I remember reading an article back in January that thought both the UK spec MG4 and Renault Mégane were suffering more in the cold because of their very thin batteries (110mm) they reckoned that because of this they had a larger surface area that was suffering more in the cold, add LFP into the mix and maybe they might have a point, could explain the preheat being on.
Also in terms of cold Macadoodle is in the north of Scotland and Bowfer is in Aberdeen (never warm there even in the summer?)

Add in the new member who is in Germany, which having worked there years ago, can get really cold winter's and they definitely may have a point.
Has anyone in the positively tropical south of England had the issue?

 

[Deleted member 10041]

Again from the same group test in Top Gear mag, first time I've seen or heard this mentioned.

The MG also slightly trimmed its power output after a few miles of being pasted down a twisty road. That’s a hard circumstance for the battery, electronics and motor because it’s alternately pulling lots of power in both the drive and regenerate directions. Even so, thermal warnings like that seldom happen in EVs outside of hot weather track conditions.

 

[xgomes]

I remember reading an article back in January that thought both the UK spec MG4 and Renault Mégane were suffering more in the cold because of their very thin batteries (110mm) they reckoned that because of this they had a larger surface area that was suffering more in the cold, add LFP into the mix and maybe they might have a point, could explain the preheat being on.
Also in terms of cold Macadoodle is in the north of Scotland and Bowfer is in Aberdeen (never warm there even in the summer?)

Add in the new member who is in Germany, which having worked there years ago, can get really cold winter's and they definitely may have a point.
Has anyone in the positively tropical south of England had the issue?

I had it in Lisbon, Portugal.

It seams it's only with lower SOCs... and maybe cold battery pack.
I do know that there is a setting to heat the battery in the app, and the manual states we should heat it 1hr before use. But I would like to car to handle this... Should we heat the battery even in the summer when it will be 40ºC in Portugal??? Should we heat everytime or just in the morning?..

The SW of the car should do this, I don't even know what is the ºC of the pack!

 

[Macadoodle]

Again from the same group test in Top Gear mag, first time I've seen or heard this mentioned.

The MG also slightly trimmed its power output after a few miles of being pasted down a twisty road. That’s a hard circumstance for the battery, electronics and motor because it’s alternately pulling lots of power in both the drive and regenerate directions. Even so, thermal warnings like that seldom happen in EVs outside of hot weather track conditions.

Interesting, I presume it was a Trophy they were testing ? Maybe MG will loosen up the protection with sw updates once they become confident the system can take a little more 'abuse'.
Its possible that its mainly the motor / inverter they're being cautious with of course, that's the only coolant loop I've seen active on my car to date. The battery one has been dead other than when I activated battery heating out of interest.