MG5 long range 71 plate SOH After 62000 miles. Do you have any figures?

[5teep]

My soh has been doing an odd thing. At 9k it was 99.2
Then it suddenly dropped to 97.2 and a thousand miles later its 96.7 at 15500 miles

Is this likely to be a read error on the obd (I use a Carly adaptor with car scanner) or do the batteries degrade like this?

I am not overly worried as long as it stabilises if it keeps dropping like this it could be an issue. I mostly ac charge with a dc charge about twice a month. I do about 2000 miles a month.

I keep the cells balanced monthly the voltage differences between max and min are .01 or less

The voltage at 100 charge is about 405v

Anything I should look out for? Or is the soh generally a bit pointless to worry about?

The OBDII is probably not giving you an accurate reading of your soh.

 

[Pebblefeline]

Yeah my understanding is it’s a bit of a guess. My six is around 242 which makes it feel close. Be interesting to see what they say at service

 

[MickeySw]

Yeah my understanding is it’s a bit of a guess. My six is around 242 which makes it feel close. Be interesting to see what they say at service

The service department reads out the same PID on the CAN bus, would be very surprised, if it’s different.

What many owners don’t realise is that internally SoH starts a couple of points above 100% when new (a trick most EV manufacturers use to mask initial, rapid degradation).

When you see SoH of 99.2% you think it dropped 0.8%; in reality the battery lost around 5% of its initial capacity.

The good news that degradation isn’t linear and will slow down after the initial dive.
Therefore very few, (if any) will go below the guaranteed 70% SoH during battery warranty.

 

[Gomev]

My soh has been doing an odd thing. At 9k it was 99.2
Then it suddenly dropped to 97.2 and a thousand miles later its 96.7 at 15500 miles

Is this likely to be a read error on the obd (I use a Carly adaptor with car scanner) or do the batteries degrade like this?

I am not overly worried as long as it stabilises if it keeps dropping like this it could be an issue. I mostly ac charge with a dc charge about twice a month. I do about 2000 miles a month.

I keep the cells balanced monthly the voltage differences between max and min are .01 or less

The voltage at 100 charge is about 405v

Anything I should look out for? Or is the soh generally a bit pointless to worry about?

See post #54 in this very thread for an alternative means of checking SOH.

MG5 long range 71 plate SOH After 62000 miles. Do you have any figures?

It’s all a bit random I am at 79 percent charged overnight and it says 244 which is patently unachievable But I did a reset 150 miles ago Last week the same charge was about 199 pre reset. I think the software can be a little misleading. This just might eliminate another possible gremlin.

www.mgevs.com

 

[MickeySw]

See post #54 in this very thread for an alternative means of checking SOH.

The above method gives you a good indication of SoH without using diagnostic equipment, but there shouldn’t much in the difference as the alternative is also based on the SoH value.

The only way to update/correct it is to run a calibration charge (discharge SoC <10% then fully AC top up to 100% and leave it plugged in to do the balancing)

 

[kla456]

My MG5 LR 2022 (pre-facelift) with 38k miles went into a limp mode last week while driving (with the family) on the motorway. Battery still showed 25%. Managed to eke out a couple of miles crawling towards an exit ramp before it finally packed in. Stressful and even a bit dangerous.
Rescue service to the MG service and taxi home for us.
MG service say there is a defective cell(s) in the main battery.
MG service are currently waiting advice from MG how to proceed. They say they expect to be told to replace the battery. I'm not sure how I feel. I think I'd like to sell it, maybe trade it in for a 2024 MG5.

 

[MickeySw]

MG service say there is a defective cell(s) in the main battery.
MG service are currently waiting advice from MG how to proceed. They say they expect to be told to replace the battery. I'm not sure how I feel. I think I'd like to sell it, maybe trade it in for a 2024 MG5.

While it’s unusual to have a cell failure it’s not unheard of, the easiest solution is to replace the complete pack.

If that’s the plan, I would not get rid of the car in a hurry…

 

[Caramaddy]

Please keep the forum informed on how you get on with the warranty.

 

[kla456]

Sure, I'll report back to the forum how I get on with the battery warranty, but first to say something about Macklin Motors Kia Edinburgh (owned by Bristol Street Motors who are part of Virtue Motor Group) because I don't have roadside recovery on my insurance. I called Macklin and they arranged for the recovery (including the family in the recovery truck cab) back to Macklin. They then drove us home (60 miles) in the company bus. There has been no talk (yet) about recovery cost or taxi cost, but they did say that recovery is free within 12 months of the car's last service (I'm serviced with Macklin but a bit outside the 12 months this year). All in all I'm gob-smacked by their service so far.

 

[Pebblefeline]

On the issue of SoH, looking at the ZS forums they seem to have a standard algorithmic degradation built in at about 0.01 percent per day as lfp batteries are so difficult to read. I wonder if the 5 has something similar?

 

[MickeySw]

On the issue of soh, looking at the zs forums they seem to have a standard algorithmic degradation built in at about 0.01 percent per day as lfp batteries are so difficult to read. I wonder if the 5 has something similar?

The problem with LFP is to accurately determine SoC based on cell voltage as the charge/discharge curve is very flat.

Most (all?) PFL MG5s use NMC cells and some owners have reported near 100% SoH after years of heavy use, which would suggest there either isn’t an age based degradation element or it’s much lower than 0.01% per day.

 

[Pebblefeline]

The pfl long ranges 61kWh use LFP.
That’s really why I wondered because as you say the voltage curve is very flat until high soc.
After reading the hs forum this method of measuring degradation seems to very closely match my degradation curve, like scary close.

 

[Verdigris]

The 61kWh pfl is NMC.,

 

[MickeySw]

The pfl long ranges 61kwh use lfp
That’s really why I wondered because as you say the voltage curve is very flat until high soc.

LFP has a lower energy density than NMC, therefore you need more battery volume to achieve the same capacity hence its only used in SR models.

After reading the hs forum this method of measuring degradation seems to very closely match my degradation curve, like scary close

Your SoH didn’t start at 100%, it’s always a couple of points higher to mask initial rapid degradation of a new pack, not sure if you took that into account?

 

[Pebblefeline]

The 61kWh pfl is NMC.,

Oh didn’t know that. Thanks there is a lot of conflicting info.

LFP has a lower energy density than NMC, therefore you need more battery volume to achieve the same capacity hence its only used in SR models.

Your SoH didn’t start at 100%, it’s always a couple of points higher to mask initial rapid degradation of a new pack, not sure if you took that into account?

Yes took that into account. I assumed a 106percent which at just under three years old at 0.01 per day is 10 percent which perfectly matched my degradation curve.

 

[MickeySw]

Yes took that into account. I assumed a 106percent which at just under three years old at 0.01 per day is 10 percent which perfectly matched my degradation curve.

Pure fluke imho, lithium battery degradation isn’t linear and 106% seems quite high to start with.

Curious, how many data points have you over the past 3 years? How may times did you run a calibration charge to check/update SoH?

Ours is just over a year old and SoH is around 99%, which isn’t what the formula predicts?

 

[Pebblefeline]

Was really just out of interest as I thought the LR had an LFP pack.

Car is nearly 3 years old, My ownership has only been three months and it has been calibrated and balanced.

Started at 99 soh in May and has dropped to 96 in aug, just seemed to tally.

The 106 percent was because the pack is 61kWh and the usable is 57 which is a difference of about 6 percent though I guess some of that would be at the bottom end.

Was just wondering and the drop seems steep suddenly.
Not overly worried though. ……. Yet.

 

[MickeySw]

The 106 percent was because the pack is 61kWh and the usable is 57 which is a difference of about 6 percent though I guess some of that would be at the bottom end.

The BMS is programmed to keep the cells in the usable range at all times. It’s not possible to access this top/bottom ‘buffer’. SoH calculations are therefore always based on usable capacity.

Was just wondering and the drop seems steep suddenly.
Not overly worried though. ……. Yet.

I wouldn’t be either, the initial, rapid SoH reduction rate will slow down rather sooner than later..

 

[kla456]

Sure, I'll report back to the forum how I get on with the battery warranty, but first to say something about Macklin Motors Kia Edinburgh (owned by Bristol Street Motors who are part of Virtue Motor Group) because I don't have roadside recovery on my insurance. I called Macklin and they arranged for the recovery (including the family in the recovery truck cab) back to Macklin. They then drove us home (60 miles) in the company bus. There has been no talk (yet) about recovery cost or taxi cost, but they did say that recovery is free within 12 months of the car's last service (I'm serviced with Macklin but a bit outside the 12 months this year). All in all I'm gob-smacked by their service so far.

Just an interim report for now. Macklin are'nt (yet) technically certified by MG for main battery issues. They initially asked me to remove the stricken car but then relented and located an MG certified service in Glasgow. They are making arrangements to move the car there (at their effort and cost, which is good). They said that warranty work is slow and could take up to three months (assuming a new main battery). I am without the car until the Glasgow service confirms a warranty repair. At that point I will ask MG for a temporary car.
I asked Macklin for the approximate trade in value of my 2022 MG5 (pre-facelift) assuming a full repair and was quoted £9.2k (it cost £26.5k), which probably rules out trading in.

 

[kla456]

Just an interim report for now. Macklin are'nt (yet) technically certified by MG for main battery issues. They initially asked me to remove the stricken car but then relented and located an MG certified service in Glasgow. They are making arrangements to move the car there (at their effort and cost, which is good). They said that warranty work is slow and could take up to three months (assuming a new main battery). I am without the car until the Glasgow service confirms a warranty repair. At that point I will ask MG for a temporary car.
I asked Macklin for the approximate trade in value of my 2022 MG5 (pre-facelift) assuming a full repair and was quoted £9.2k (it cost £26.5k), which probably rules out trading in.

Update this morning 2nd September: Macklin secured a workshop appointment for 21st October at Arnold Clarke's battery-certfied workshop in Glasgow. Assuming they assess a replacement main barrery under warranty, I should be able to ask MG for a temporary car, which will be 2.5 months after the breakdown. I am told it might take a further 2 months for the repair.