Can I limit charging to 80% and if so how?

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SDP79

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Can I limit charging to 80% and if so how? I have a MG5 LR exclusive. This is my second EV after a 40kw Leaf. There is much talk about charging regularly only up to 80%. I seldom do very long journeys so I could easily manage on this. I am with Octopus Go and my smart charger automatically charges during the low tariff period. But there seems to be no way either on the charger or the car to limit the amount of charge to 80%. I have looked through the car hand book and can not find a way to do this - have I missed it? On a personal note I have found that charging up to 100% regularly with home charger (around 6.5KW) makes little or no difference to battery performance. I tend to charge up every other day when car gets down to around 50%.
 
There is no communication between the car and AC charger which allows this.

Some users have said they calculate duration based on starting percentage and required final percentage e.g. 50% to 80% => 30% of 57kWh (usable) = 17.1kWh. This should take 2.59 hours (2 hours 35 minutes). Maybe!

So, trial & error combined with some maths should allow an educated guess at duration - if your charger allows this to be set.
 
My standard range gets about 50% added during a 4 hour Go charge so my routine is to charge when it drops below 30%. Simple enough for you to do the same although the figures will be slightly different with the bigger battery.
Crude but simple and it works.
 
Is there any real world evidence that charging to 100% each day has X amount of negative effect on the battery?

I ask as I will be charging to 100% each day because I don't know where I may be needed in my job, could be 40 miles or 200. Not got my vehicle yet unfortunately to comment on this in real world terms.
 
Ozzie1989 said:
Is there any real world evidence that charging to 100% each day has X amount of negative effect on the battery?

I ask as I will be charging to 100% each day because I don't know where I may be needed in my job, could be 40 miles or 200. Not got my vehicle yet unfortunately to comment on this in real world terms.
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I could be wrong, but I thought the issue was more related to keeping the battery fully charged (or discharged) for a period of time. I didn’t think charging to 100% (using AC supply) had a negative effect if then using the charge shortly afterwards?
 
The only thing I can find in the manual is about low SOC, nothing about high. Of course that doesn't mean it isn't true, I guess the vehicles aren't old enough yet to see any real long term affects.

Screenshot_20211102-224357-899.png
 
Maybe someday there will be a software update to allow control of this on the car side.

I have read over and over again that, regardless of Li Battery tech, only charging to 80% most of the time is the best for getting the full longevity from the pack. 20%-80% is best.

Well, many other variables as well, including charge and discharge rates, temperatures that you do these things at etc. etc.

I also never go more than about 150km per day, never use even 50% of capacity even if I hammer the car, so I would love to limit to 80% if possible.

The included 7.5kw charger supplied free with the MG EP here in Thailand does not have any obvious way to do this. There is Bluetooth on the charger that can be controlled by the iSmart app, but for some reason I cannot install the MG ismart app on my Android 9 phone, it says not available/compatible.

The charger must have SOME communication. When I use Fast DC charging, or even AC commercial chargers here, the state of charge of the vehicle is shown on the charger, and also on the payment/control app on the phone for the charger. So a 'smarter' charger should be able to stop charging at a chosen SOC.

For now, I'm just not going to worry about it. We have 8 years or 160,000km warranty here in Thailand. I will just continue to drive her and charger her like I stole her, and just enjoy the car I think, rather than stress about this. The BMS has to be smarter than I am!
 
I am with Octopus having switched to them at the beginning of October and I am still waiting for them to be able to connect to my smart meter so I can move to the Go tariff. I have an Ohme Home Pro charger and via the app it is possible to set how many miles you want to add and on my LR 80% charge seems to be about 200 mile range so I am able to simple add the miles needed to bring it to 200 miles - it’s not precise but it seems to get the charge to about 80%. Which smart charger are you using?
 
Hello again everyone. Thank you for all your replies. Pretty much as I thought - there is no way to make any setting to make charge go only to 80%. Once again bit of a fail for MG - having made recommendation and then giving no way of compliance other than best guess and experienced judgement. As I said I am not exactly a novice in the EV ownership stakes, I will carry on as before. Every once in a while let the battery run down to around 30% and then charge up - but of course this will take longer than my low tariff period! It would be nice to be able to limit charging to this! I have a ChargevEV smart charger. But smart is not the words I would use to describe it - surely something like this should be on the smart list of things to do! Once again thanks to all.
 
There's a wealth of information about battery health. The upshot is that the warranty is rather pessimistic so, even if you abuse the battery, it's unlikely to drop below the 70% capacity required to replace it. However, there are some tiny benefits (which will make a small difference to the overall capacity over a long period) from being slightly protective of the battery:

No need to do anything that will limit your utility of the car, just try to keep the car as close to 50% charged (and not below) as you can be bothered. Charge (and discharge) as slowly as you can be bothered. And generally keep the battery cool by parking in the shade on hot days and generally taking longer trips at a slower pace, if appropriate.

You won't notice any drop in capacity in the first year regardless as any degradation will be within the hidden buffer at both ends of the voltage range. But then it will slowly start to drop. It's inevitable that the capacity will go down over time, regardless of what you do.

Many people regard it as trivial so ignore it altogether. Some of us like to err on the side of caution. Ultimately, if you plan to keep the car long term, you might end up with a few more miles of range than some of the less careful owners. But I wouldn't worry too much about it, just ideally don't rapid charge every day.
 
SDP79 said:
Hello again everyone. Thank you for all your replies. Pretty much as I thought - there is no way to make any setting to make charge go only to 80%. Once again bit of a fail for MG - having made recommendation and then giving no way of compliance other than best guess and experienced judgement. As I said I am not exactly a novice in the EV ownership stakes, I will carry on as before. Every once in a while let the battery run down to around 30% and then charge up - but of course this will take longer than my low tariff period! It would be nice to be able to limit charging to this! I have a ChargevEV smart charger. But smart is not the words I would use to describe it - surely something like this should be on the smart list of things to do! Once again thanks to all.
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You say you are not a novice in the EV ownership stakes, and then criticise MG for not being able to limit a charge to 80%. Did you not do the appropriate research first? If not, the fail is with you. And apologies for being so blunt, but I am a complete novice with EVs, but I did know this limitation before I bought the car. It was pretty easy to find out.
 
SDP79 said:
Hello again everyone. Thank you for all your replies. Pretty much as I thought - there is no way to make any setting to make charge go only to 80%. Once again bit of a fail for MG - having made recommendation and then giving no way of compliance other than best guess and experienced judgement. As I said I am not exactly a novice in the EV ownership stakes, I will carry on as before. Every once in a while let the battery run down to around 30% and then charge up - but of course this will take longer than my low tariff period! It would be nice to be able to limit charging to this! I have a ChargevEV smart charger. But smart is not the words I would use to describe it - surely something like this should be on the smart list of things to do! Once again thanks to all.
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I'm interested as to where you've found the recommendation from MG that you should only charge to 80%?
 
Ozzie1989 said:
I'm interested as to where you've found the recommendation from MG that you should only charge to 80%?
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I’m not sure any manufacturer recommends only charging to 80% - this arbitrary figure seems to be based on the point where, roughly, charge speed begins to slow. I guess now one wants to include the slower charging percentage and make speeds look bad!

It’s mentioned several times in the owner manual when talking about time to charge from the point where low charge warning appears (20%) to this 80% value.

1636187460082.png
 
This is mentioned because the DC charging rate drops off after 80%.
 
I might be missing something, but doesn't the BMS take care of this already? The % indicated on the dash to the driver is not the full battery capacity, it's the percentage of the usable capacity...which is around 93% of the total capacity according to EV database. (Almost identical for LR and SR).

Yes, this is higher than 80% but I'd like to think that the manufacturers (of the car, battery and battery management system) have made sure this is the optimal balance of range and battery durability.
 
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