MG4 Restricted speed - weird

[stevegus]

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.

Either you have a bad battery or a confused controller.

The chemistry in the SR holds the voltage high at a stable level for pretty much the entire charge and collapses in voltage in the final 10% or so. As a result it cant use cell voltage as a way of determining charge remaining. The software has to make a calculation- no idea how - so that it can predict range prior to the point it actually sees voltage fall in the last 10% of range.

Perhaps your controller software has got it wrong and your battery is not as discharged as it thinks it is

 

[bowfer]

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.

Cold battery, possible as I’ve only got a short commute and ask for full power for a few seconds up a motorway slip road.
Some cry ‘overheating’, but that’s impossible.
State of charge definitely has some part to play as if I have 100% charge it doesn’t do it.
The problem seems to get incrementally worse as charge reduces, but not in a linear/measurable/predictable way.

 

[jon0881]

Cold battery, possible as I’ve only got a short commute and ask for full power for a few seconds up a motorway slip road.
Some cry ‘overheating’, but that’s impossible.
State of charge definitely has some part to play as if I have 100% charge it doesn’t do it.
The problem seems to get incrementally worse as charge reduces, but not in a linear/measurable/predictable way.

Exactly the same! if i give it a good full charge with a balance then we are good. If its been a couple of weeks of top ups and drains it seems to have less and less of a clue of the state of the pack. Battery seems to drain quicker, limited power trips (no dash warning).

Id say this is dangerous, if you enter the motorway and put your foot down to make a lane change and nothing happens the car is not responding to your input. Ill be mentioning it to the dealer when it goes back for round 2

 

[bowfer]

Exactly the same! if i give it a good full charge with a balance then we are good. If its been a couple of weeks of top ups and drains it seems to have less and less of a clue of the state of the pack. Battery seems to drain quicker, limited power trips (no dash warning).

Id say this is dangerous, if you enter the motorway and put your foot down to make a lane change and nothing happens the car is not responding to your input. Ill be mentioning it to the dealer when it goes back for round 2

My dealer seemed hamstrung by MG, clueless as to what was causing it and finally allegedly attempting a traction motor change.
Seven continuous weeks with them.
Didn’t work.
So be prepared for a long wait for this to be resolved.

 

[Nikkwarn55]

My dealer seemed hamstrung by MG, clueless as to what was causing it and finally allegedly attempting a traction motor change.
Seven continuous weeks with them.
Didn’t work.
So be prepared for a long wait for this to be resolved.

Well all I say, is luckily it wasn't 40mph limited

 

[jon0881]

My dealer seemed hamstrung by MG, clueless as to what was causing it and finally allegedly attempting a traction motor change.
Seven continuous weeks with them.
Didn’t work.
So be prepared for a long wait for this to be resolved.

Thankfully its not happening frequently enough for it to be a big problem for me it just sits at the back of my mind that something is either not right with the battery or the software managing it. Adding that ive yet to see charge speeds above 55kw i 100% feel i bought the wrong model now. I still love the car, its drives really nice. If they can fix the anoying wind noise on the drivers side its super pleasant to drive, just a bit beta

 

[NickHeynes]

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 have occasionally suffered this but as I drive on very congested roads it's been very hard to tell as I'm not able to attempt a test.
It seems that it happens when the SOC is below 30% and/or it's below about 2 degrees .
My range is good and the battery doesn't discharge quickly so I'm tempted to think that it's some sort of protection.
Also I don't have a home wall charger yet so it maybe because I only balance charge every couple of weeks.
I'm going to drop it into my dealer in a couple of weeks so will se3e what they say.

 

[jon0881]

I have occasionally suffered this but as I drive on very congested roads it's been very hard to tell as I'm not able to attempt a test.
It seems that it happens when the SOC is below 30% and/or it's below about 2 degrees .
My range is good and the battery doesn't discharge quickly so I'm tempted to think that it's some sort of protection.
Also I don't have a home wall charger yet so it maybe because I only balance charge every couple of weeks.
I'm going to drop it into my dealer in a couple of weeks so will se3e what they say.

Correct, and i also faced this more when i was trickle granny charging or public charging before the home charger. Id be happy if it was protecting but it should give a warning as such and maybe not be so agressive at protecting. If the issue was cold temps then i would want it to lift the restriction as the pack gets warmer but it seems you are stuck until reset

 

[NickHeynes]

Correct, and i also faced this more when i was trickle granny charging or public charging before the home charger. Id be happy if it was protecting but it should give a warning as such and maybe not be so agressive at protecting. If the issue was cold temps then i would want it to lift the restriction as the pack gets warmer but it seems you are stuck until reset

Also .I have had my battery SOC display turn orange a couple of times but haven't seen anything to explain why this is .It has always turned green again shortly afterwards. eg when I've left the car for a short-time then returned.
Another baffling idiosyncrasy

 

[siteguru]

I had the orange thing for the first time the other day.

On my way home this afternoon (with <40% SoC) I put it into Sport mode and gave it a bit of welly ... I got to and maintained 100% power for a period (before I had to lift off) with no signs of throttling. I haven't had an opportunity to give it welly for a longer period as yet.

FWIW I always home charge (except on long journeys) and charge to 100% (and let the car decide when it's had enough), so I'm regularly letting the car balance if it feels the need to.

 

[bowfer]

Also .I have had my battery SOC display turn orange a couple of times but haven't seen anything to explain why this is .It has always turned green again shortly afterwards. eg when I've left the car for a short-time then returned.
Another baffling idiosyncrasy

Yup, I’ve also had this and actually have it right now.
There’s another thread about this where I give MG’s tweeted reply.
They don’t have a clue what it means.
“A glitch in the system” was their exact words.

 

[NickHeynes]

Yup, I’ve also had this and actually have it right now.
There’s another thread about this where I give MG’s tweeted reply.
They don’t have a clue what it means.
“A glitch in the system” was their exact words.

Well that's helpful! Lol

 

[bowfer]

Well that's helpful! Lol

Self diagnosing where MG have failed, I’ve been away for a few days and my car has been under about a foot of snow.
The fact the yellow battery light came on as I soon as I started it today suggests it’s the battery saying it’s exceptionally cold.
But you’d think MG would know this, right…?

 

[Ian Key]

Self diagnosing where MG have failed, I’ve been away for a few days and my car has been under about a foot of snow.
The fact the yellow battery light came on as I soon as I started it today suggests it’s the battery saying it’s exceptionally cold.
But you’d think MG would know this, right…?

Taking in to account your previous posts I guess that's a rhetorical question

 

[bowfer]

UPDATE
Had a heated call with MG finance this afternoon where they stated that as this was the first time they had got involved, the dealer/MG had one opportunity to fix.
That set me off like a cheap firework, I told them in the 7 weeks it was with the dealer they didn’t have a clue what to do to fix it, I have emails where the dealer service manager actually says this.
MG finance changed tack and said they would call the dealer and get back to me this afternoon.
No surprise, no call back….
If they tell me I have to give MG another chance to fix what they’ve failed to fix in 7 weeks, I’m going legal.

 

[Eber]

Self diagnosing where MG have failed, I’ve been away for a few days and my car has been under about a foot of snow.
The fact the yellow battery light came on as I soon as I started it today suggests it’s the battery saying it’s exceptionally cold.
But you’d think MG would know this, right…?

Never had this, even when parked outside at below -10°C. The SE's battery really seems to be a different animal.

 

[Macadoodle]

Never had this, even when parked outside at below -10°C. The SE's battery really seems to be a different animal.

That's the impression I'm getting from living with LFP cells. Low SOC, low temps and trying to pull too much current really makes the system mad.
My one does seem to be ok once everything is warmed up however. 2 degrees today and the way it launched down the dual carriageway when I floored it trying to shake off a tailgater had me smiling, was shocked to see 90 on the speedo within seconds. I swear it's getting faster as it loosens up.
love humiliating aggressive SUV drivers while emitting no greenhouse gasses

 

[Diggsy]

It’s loosening up for you because of how much attention you’re giving the reduction gearbox

 

[TheHypnoToad]

That's the impression I'm getting from living with LFP cells. Low SOC, low temps and trying to pull too much current really makes the system mad.
My one does seem to be ok once everything is warmed up however. 2 degrees today and the way it launched down the dual carriageway when I floored it trying to shake off a tailgater had me smiling, was shocked to see 90 on the speedo within seconds. I swear it's getting faster as it loosens up.
love humiliating aggressive SUV drivers while emitting no greenhouse gasses

I think that LFP cells can give the needed current if the circumstances are good.

Even the cheaper Teslas are now on LFP, but while some have reported slightly different throttle response, I've not heard of issues with limiting speed / power like the MG4.

I imagine Tesla's may heat the batteries a lot more in colder temps possibly to allow for full power.

 

[Macadoodle]

I think that LFP cells can give the needed current if the circumstances are good.

Even the cheaper Teslas are now on LFP, but while some have reported slightly different throttle response, I've not heard of issues with limiting speed / power like the MG4.

I imagine Tesla's may heat the batteries a lot more in colder temps possibly to allow for full power.

Yes, its all in the software I guess, the cells can give a current burst at any temp and voltage but it's what damage may be caused in doing so.
LFP is probably better suited to warmer climates, don't think I would consider it if I lived in Canada or Norway etc .