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- Sep 3, 2022
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- Strathaven (SE SR MY22)
- Driving
- MG4
It's the difference between SR and LR ... LFP vs NMC chemistries. Topic has been done to death in other threads. 

As @siteguru says, it is the difference between SR and LR battery types, nothing to do with SE vs Trophy spec.Why the difference between SR and Trophy?
What are SC47 and SCUK001?I have just had my annual service, including the updates R46, SC47, SCUK001, which I believe are standard for the Trophy. The result seems pretty good to me - I particularly like the new LKA, which is very restrained, and is now a positive safety feature (so far...)
I also like the new HVAC screen - it is less cluttered, with larger icons, which makes it usable while driving. I think I came across someone complaining about this screen - if so, I disagree. However, I do run the main screen permanently in dark mode, which increases contrast - I agree it is less good in light mode.
Almost certainly.It's interesting to see the UK in SCUK001 - maybe this is different in other countries?
Speaking of other countries... I have my software "updated" yesterday, on my request to get some issue sorted, and to get OPD enabled. Also I asked the team to check my under tray, and I noticed the drive shaft end, and nut is kind of rusty, so I wanted some advice.Almost certainly.
I would rather avoid Gary in the future... it is a bad sign if you have to educate someone who should give you advice... It's probably just me.Perhaps you could refer him to the video of a scientist explaining that NMC batteries
This is contrary to everything I've learned about modern NMC batteries. I do think he is completely confused.Here is Gary’s (at MG) reply… he really has put doubts in my head as to what is the best practice… I think I’ll keep charging to 80% twice a week as don’t need huge range, and give it a100% monthly..
DC charging leads to acceleration of lithium plating of the graphite anode in the battery, and at >80% this increases exponentially.This is contrary to everything I've learned about modern NMC batteries. I do think he is completely confused.
All NMC batteries have a finite lifespan, but it is very long. If thermally controlled, like on the MG4, typically they'll give 85-90% or even more of their original capacity after many years and after "going around the clock". Battery lifespan should not be a worry for the average user - there are many MG EV taxis out there reporting huge mileages are possible.
You can shorten the life of the battery, although it is debatable how big the effect of any of these is:
- Leaving it at a high state of charge (e.g. >80%) for long periods of time.
- Rapid charging constantly, due to the effects of very high input current (ie the ultra fast part of the charge curve).
- Failing to balance the battery for extended periods.
- Constantly topping up a little bit rather than waiting.
- Never draining the battery to a low SoC around 10%, apparently it likes it twice a year or so.
But this is not like some high-maintenance ICE car where you need to be tinkering with the valves and the timing every weekend - plenty of people will not know about the above or not do them and hire cars will be constantly abused - the evidence seems to be that it makes less difference than people think.
I have never heard of 80% being a DC only thing. Has anyone else?
My understanding is this is exactly why the car limits the charge rate at higher SOC: to manage this effect, also taking into account the battery temperature. Rates at high SOCs (>80%) typically always drop down to AC charging levels, protecting the battery.DC charging leads to acceleration of lithium plating of the graphite anode in the battery, and at >80% this increases exponentially.
Understood. These higher temperatures are typically associated with the peak charge rate rather than just the SOC though, are they not? This would mean, for example, that Rapid charging on a hot summer's day after a long drive would do the most damage. Is that what you are saying?During use of the battery after charging, some plating will breakdown and become reusable lithium, some will become inert "dead" lithium that is no longer useable, some will remain on the anode and lead to increased battery resistance, the plating caused by DC charging is harder to breakdown as it is formed at higher temperatures than by AC lithium plating.
But this says nothing of leaving the battery for extended periods at a high SOC - it is my understanding this is worse for the battery than rapid charging per se.Leading to acceleration of battery degredation, some cells will degrade easier and faster than others like anything that is mass produced some perform worse than others, but the fundamental science is the same.
Maybe the behaviour has changed slightly but it's always done this. The faster you drive the shorter the interval gets. It also does an additional wipe when you pass certain speed thresholds - I've noticed it when you start moving from a standstill, then at about 10 mph, then again at 30 mph.Intermittent wipe update? I drove home from Greenwich tonight in light drizzle using intermittent wipe, and it seemed to be different. Crossing Blackheath at 24mph the wipe interval was typically 9 seconds, but occasionally it was much shorter - one or two seconds. I don't think it was doing this before my software update.
Anybody else noticed this, or is it my imagination?
The anode and battery have already been heated due to high current by this point, as such the DC charging has already caused higher levels of lithium plating than AC charging as temperature is an accelerator of the process.My understanding is this is exactly why the car limits the charge rate at higher SOC: to manage this effect, also taking into account the battery temperature. Rates at high SOCs (>80%) typically always drop down to AC charging levels, protecting the battery.
The MG4 charging curves which I can't post here as the forum doesn't permit SVG images, drops to 3ph AC levels (circa 22kW) around 90% and it's been found to be around 30-40kW is the point where higher levels of heat are produced in a battery while charging. This is ignoring any cooling system available on a battery however and even then two identical cars won't perform the same here due to deterioration of coolant with age.Understood. These higher temperatures are typically associated with the peak charge rate rather than just the SOC though, are they not? This would mean, for example, that Rapid charging on a hot summer's day after a long drive would do the most damage. Is that what you are saying?
Hi levels of soc and allowing lithium plating to stay in situ for extended periods make it hard to breakdown.But this says nothing of leaving the battery for extended periods at a high SOC - it is my understanding this is worse for the battery than rapid charging per se.
In 99.9999999% of cases it will be, it's always the outliers that become big newsThanks for the explanations it all makes sense.
I'm going to continue to keep my car at 80% normally, 100% when I need it and rapid charge to any level needed. I'm confident that this will be fine long term.