YouTube comment about MG4 battery management, LFP vs NMC

[gdog]

Since the SoH reported by OBD2 went below 97 on my SE SR, the GoM shows 217 miles instead of the original 218 when fully reset. So I lost 1 mile in around 1 year since manufacturing (8 months ownership).

Do you know the SOH of your battery when new? I have a new SE SR and the OBD indicates SOH as 96.5%

I assumed it was suboptimal manufacturer or delivery abuse. Maybe it's standard enough. Who knows

 

[fnegroni]

Do you know the SOH of your battery when new? I have a new SE SR and the OBD indicates SOH as 96.5%

I assumed it was suboptimal manufacturer or delivery abuse. Maybe it's standard enough. Who knows

From empirical evidence, the SOH on the LFP battery pack degrades by 0.0104 % each day.
It’s believed this is a built in value for calendar ageing in the first year of life. I don’t have the number from when my battery pack was new, but others on this forum (I think in the mg zs sub-forum) did.

 

[Tig170]

From empirical evidence, the SOH on the LFP battery pack degrades by 0.0104 % each day.
It’s believed this is a built in value for calendar ageing in the first year of life. I don’t have the number from when my battery pack was new, but others on this forum (I think in the mg zs sub-forum) did.

Mine is doing this:

 

[fnegroni]

My SoH is currently 96.5

That was on 16th April.
Today 11th May it's 96.93 ??‍

 

[siteguru]

I suspect the reading is temperature-dependant.

 

[fnegroni]

I suspect the reading is temperature-dependant.

Might very well be, I’ll have to have another go when it’s cooler

 

[PJWey]

Not meaning to be harsh, but that sounds like something I would expect of MG. BMS configuration is a software thing so I wouldn't be surprised if they managed to mess it up too. The fact that my car is regenerating mildly even below -20° celsius when it certainly should not corroborates that. It is either a bug or a BMS misconfiguration.

The consensus is that LFP lasts longer than NMC but in my opinion, given that LFP has a much lower fire risk, manufacturers are now able to squeeze out every last bit of the battery pack at the expense of its health and therefore LFP will probably wear out quicker, especially in colder environments. Data will show in the years to come. People don't like to wait for the battery to warm up when they have a long journey to make. Maybe that -0.01% is there to compensate for excessive lithium plating, just to be on the safe side, if there is any truth to the claim?

As long as the battery's health is above 70% after seven years all is well for MG.

There are sound chemical structure reasons why LFP lasts longer, the iron lace is much more stable and resistant to degradation at high and low charge as well as temperature. On the flip side the battery is more sensitive to low temperature for charging. Personally I have not had any issues after a few minutes driving the battery warms up even on cold days here in the UK

 

[siteguru]

To be fair ... it doesn't exactly get really cold in Dorset, eh?

 

[Ian Key]

Some would say it doesn't really get anything in Dorset ?

 

[EVentropy]

The trend that I'm finding with the LFP version is that it reduces down to 95%, and then fluctuates for example 3rd April (19700miles) it was at 95.43%, and today SoH was 95.72% (20600miles) - done with carscanner (yes I have checked the values - as take a screen shot)

Did you plot this or is it a screen in carscanner?
Have you uploaded any PID's to CS?
Cheers

 

[fnegroni]

Did you plot this or is it a screen in carscanner?
Have you uploaded any PID's to CS?
Cheers

This is already available in car scanner you just need to enable the experimental support for the mg4

 

[EVentropy]

Ok, cheers. When I can prise my missus butt out of the car I’ll look for charting page . Do you have to have the 0BD plugged in full time to get to chart SOH vs km or do you just get a reading whenever you do it, save and it plots?

 

[Kithmo]

I'm pretty sure I don't. ??

I'm pretty sure I don't need (or care) to understand it to get what I want out of my car. ?

 

[EVentropy]

Yep, ignorance is bliss.
Not so much if you’re 500Nmi offshore. I have vested interest in knowing as much about LFP characteristics as possible.
And my shame coefficient is above normal, as in I need to make it home under my own steam with no singed parts.

 

[Tig170]

Updated plot (LFP 51kWh battery): Read with car scanner, and plotted in excel, I suspect that the car has now done approx 300 equivalent full charge cycles (I installed a home battery system at the same time as getting the car ~ 2 years ago, and thats what my oldest pylontech batteries are telling me.)