Charging battery to full on regular basis or allow it to go down to 5 percent before topping up

[MoDolph]

How do people check the battery degradation? I know how to on my iphone, but not on the MG4.

Thanks!

An OBD reader and a suitable app. Car scanner and A Better Route Planner are the 2 current compatible apps

 

[Rolfe]

Something came up in another thread that's relevant to this. Plugging the car in every night so it's ready to go in the morning is a very attractive proposition. So is asking the car to turn on the heating and warm up for ten minutes before you go out in the cold.

Except apparently it won't turn on the heating remotely if the car is plugged into the charger.

<bangs head against wall>

 

[JDMB]

This was my thought. I have no doubt that all these articles by the learned electronics gurus are correct, but it's unclear how much difference their advice makes. Sweating over how to charge the SR to 70% when the app won't allow that to be done automatically? Is it worth it if the gain from doing it is minimal? Even if you plan to keep the car till it falls apart?

How about setting off with only 70% charge, so reducing your range by more than 30% (since nobody in their right mind is going to go down to zero)? How about holding off charging unitl the car is down close to 20%, and then discovering that you need to go somewhere, urgently, right now? All these are considerations that influence real world behaviour.

I'm inclined not to plug it in every night if I've only done short journeys, for the regeneration more than anything, but I'm not inclined to let it go below say 40-50% because I'd be screwed if something unexpected came up. I mean, a huge chunk of the advantage of an electric car is that you can begin every day with a full charge if you want to, and never have to worry about refuelling away from home unless you need to travel further than the range of the car. All these shenanigans significantly reduce the practical range that you're left with.

Certainly unless I have to race off right now, the car can always have half an hour or more on the rapid charger at the end of the road. But this really negates the advantage of being able to have it sitting ready to go, which is such a selling point.

@Rolfe See if this may help clear the muddied waters, The Puzzling Reason Why Tesla Misleadingly Recommends Charging the LFP Batteries to 100%

 

[Rolfe]

I just read it - someone else linked to it above. It only confused me more.

The app doesn't give SR cars the ability to stop charging at 80%. I don't want to have to set the alarm to wake up in the middle of the night to stop it manually (I don't have a wall box). I don't really want to limit myself to less than the range of the SR anyway - which is only 200 miles at the best of times.

Just how much difference does it actually make?

 

[JDMB]

I just read it - someone else linked to it above. It only confused me more.

The app doesn't give SR cars the ability to stop charging at 80%. I don't want to have to set the alarm to wake up in the middle of the night to stop it manually (I don't have a wall box). I don't really want to limit myself to less than the range of the SR anyway - which is only 200 miles at the best of times.

Just how much difference does it actually make?

As I mentioned before, I don’t think it’s something overly worth worrying about.

Here’s another good article, LFP Battery In Your Next EV? Tesla and Others Say Yes.

EDIT: and another illuminating article from 2022.

Tesla automatically setting LFP battery charge limits to 100% to prevent 12V Li-Ion batteries from failing

Earlier this week we told you about some new Tesla owners who were experiencing their 12V Li-Ion batteries failing when the vehicle’s main battery was at a low state of charge (SOC). The problem was […]

driveteslacanada.ca

They mention Tesla in both article, however the information in the articles is relevant to LFP batteries themselves rather than a specific Tesla quirk.

 

[profdraper]

As I mentioned before, I don’t think it’s something overly worth worrying about.

Here’s another good article, LFP Battery In Your Next EV? Tesla and Others Say Yes.

EDIT: and another illuminating article from 2022.

Tesla automatically setting LFP battery charge limits to 100% to prevent 12V Li-Ion batteries from failing

Earlier this week we told you about some new Tesla owners who were experiencing their 12V Li-Ion batteries failing when the vehicle’s main battery was at a low state of charge (SOC). The problem was […]

driveteslacanada.ca

They mention Tesla in both article, however the information in the articles is relevant to LFP batteries themselves rather than a specific Tesla quirk.

Yes, the various Tesla charging articles indicate that Tesla is more interested in the customer satisfaction side of the equation & so more accurate SOC with a 100% charge for LFP makes better sense than worrying too much about battery degredation on a chemistry which allows far more cycles than NMC.

I think the other matter to consider here is in the expectations and daily use requirements of many different owners & expectations. In my case for example, my 2022 ZS EV Essence SR LFP mostly gets used around town & for surburban short range commuyes - groceries, running the family around, the hardware store etc etc. On the more rare occasion we do a road trip, then sure, charge to 100%, do the usual plugshare scan etc.

Meanwhile, the literature clearly indicates that LFP chemistry still can suffer a little from degredation over time, just not as much as with NMC, plus the cycles available could well outlive the warranty period or the life of the car. LFP still needs battery equalization as well & this practically demonstrates the potential deterioration of the chemistry.

So I tend to charge as per my MK1 ZS EV habita mostly to 80-90% from a base of ~ 20%. Perhaps to 100% more regularly & a little math figures tells me how many hours to schedule if I don’t want 100% - that was second nature from the MK1 & of course any scheduling needed to be done at the wall box.

Finally, I think a lot of the weirdness around this comes from the fact that MG oddly dictated the SR can only be charged to 100% via the infotainment system or iSmart. Perhaps an sw update might rectify this in the future & where owners can set to whatever level they like, as in petrol with choosing to fill up or just put $10 in the tank.

 

[tsedge]

Look there are only two things recommended by MG:

1. Charge your SR to 100% once a week.
2. Charge your LR to 80% normally, 100% when you need it and at least once a month.

Outside this fretting about percentages, how often to charge, the mix of charger types, whether to do it in big chunks or small, all of this makes no practical difference to battery life in the real world.

You'll be second guessing the BMS anyway and probably wrong about the effects. Yes, experts will say each of these things will make some difference but it is very small.

All battery types will last hundreds of thousands of miles, the SR even more so. The evidence across all sorts of modern EVs is that batteries last much better than people expect.

Unless you plan to more than 200,000 miles in your car and keep it more than 10 years, none of this is worth worrying about.

 

[JDMB]

Finally, I think a lot of the weirdness around this comes from the fact that MG oddly dictated the SR can only be charged to 100% via the infotainment system or iSmart. Perhaps an sw update might rectify this in the future & where owners can set to whatever level they like, as in petrol with choosing to fill up or just put $10 in the tank.

From reading the second article I sent about Tesla, it seems they may be doing the same on some of their cars too.

 

[MoDolph]

You'll be second guessing the BMS anyway and probably wrong about the effects.

This is so true. The amount of contradictory information available means you can just about show anything you want. Here are BYD and Sony LFP cells showing worse life than Samsung NMC cells:

I do still try to keep the SOC as close to 50% as practical as this is almost universally shown to be beneficial. However, the car is there to serve me, not the other way around so if I need 100% then that's what it's getting charged to.

 

[profdraper]

From reading the second article I sent about Tesla, it seems they may be doing the same on some of their cars too.

Exactly, I agree - but they dont 'enforce' it like MGs sw.

 

[profdraper]

Yes we heard you the 1st, 2nd & 3rd times. I dont see anyone 'fretting' here so much, but rather an interesting & collegial discussion now based on a little empirical evidence and/or external expert opinion & less FaceBook-styled shouting. Has been nice to meet a few new ideas.

 

[okohll]

I do still try to keep the SOC as close to 50% as practical as this is almost universally shown to be beneficial. However, the car is there to serve me, not the other way around so if I need 100% then that's what it's getting charged to.

Yes that's basically my philosophy too. Usually I know at least a day in advance if I'm going on a long trip and if not, there's a 150kw charger just round the corner - not had to use it yet though.

 

[Rolfe]

Yes we heard you the 1st, 2nd & 3rd times. I dont see anyone 'fretting' here so much, but rather an interesting & collegial discussion now based on a little empirical evidence and/or external expert opinion & less FaceBook-styled shouting. Has been nice to meet a few new ideas.

I am slightly fretting, because I haven't yet come to a full understanding of the issues, so this conversation is helpful.

I'm inclined to Tsedge's point of view that these arguments make little practical difference in the real world. If some other part of the car is destined to fail catastrophically - maybe serious rust on the bodywork or something like that - long before battery degradation becomes an issue, why bother?

 

[Deleted member 9692]

Except apparently it won't turn on the heating remotely if the car is plugged into the charger.

If it’s plugged in and actively charging it will. If it’s plugged in and not charging then no pre heating for you. MG have been supremely helpful in explaining that “this functionality is not currently supported”

 

[Rolfe]

Oh great. So if you leave your car charging overnight, and it has finished charging, there is no way to pre-heat it without going out into the snow and disconnecting the charging cable. Isn't this likely to be how most people will want to use the facility?

I suppose if it's a LR battery and it's been programmed to go up to 80% then you could maybe start it charging again, then ask it to pre-heat? But with the SR and you're already at 100% I question if it would accept a command to start charging.

 

[Deleted member 9692]

Oh great. So if you leave your car charging overnight, and it has finished charging, there is no way to pre-heat it without going out into the snow and disconnecting the charging cable. Isn't this likely to be how most people will want to use the facility?

I suppose if it's a LR battery and it's been programmed to go up to 80% then you could maybe start it charging again, then ask it to pre-heat? But with the SR and you're already at 100% I question if it would accept a command to start charging.

Correct. It is an absolute pain. My car is back with MG dealer yet again next week. I’ve told them that “this functionality is not currently supported” is not an acceptable response to me. I would like to know if it ever will be supported and the likely time scale.

 

[Rolfe]

So, if you have a Trophy, and you've finished charging to 80%, you can't start charging again from the app for just long enough to heat the cabin?

 

[JDMB]

So, if you have a Trophy, and you've finished charging to 80%, you can't start charging again from the app for just long enough to heat the cabin?

That’s what I presumed. Haven’t tested it yet, though, however my Zappi and car had a bit of an argument the other day when I tried to change charging from 80% to 100% on the app while the car was charging, the app came up with an error message, then the charger and the car just stopped talking to each other, so I unplugged everything, left it for a while then plugged everything all back in again, and it was all happy again.

 

[MoDolph]

So, if you have a Trophy, and you've finished charging to 80%, you can't start charging again from the app for just long enough to heat the cabin?

Yes, it works like that for me

 

[siteguru]

If you have a "dumb" charge point (which doesn't care about communications protocols) then I suspect even being at 100% the charge point will still be available to provide a charge should the car want it, and so remote climate may well work OK. The problem I find is that my wall box gets told by the car to "stop charging" (i.e. turn off the charge feed) so it does ... thus it is plugged in but not charging, so the remote climate control won't work. (And trying to get the app to tell the car to start charging again won't work, because the SoC is already at 100%).