Advice on a healthy battery

[Firespray31]

Hi everyone!

Long time reader first time poster.

I've ordered a MG ZS EV 2022 Standard Range. The average weekly mileage total is around 100 or so miles, with the longest round trip topping out at 52 miles.

I've been reading all the wonderful threads I can here around looking after the battery but had some questions!

-With the face-lift model SR, should I be charging to 80% or 100% battery?
-I understand that you can 'balance' the battery - what's the benefit and how often should a driver set this up?

Thank you all so much!

 

[DrTom]

With the SR being LFP battery technology, I think you are able to charge to 100% every time without doing any damage. In fact unless you stop it manually I don't think you have the option to stop it at 80%. I don't think either the app or the onboard software allows you to set the charge level on the SR model

 

[Les burrows]

Hiya and welcome to the forum you will find lots of different options on this subject may I advise you to go to MGs Webb site where you will find on line the handbook/owners manual for your vehicle which you have on order and read it very carefully before you get your car you have on order, it’s a good place to start IMHO mines a MG5 SR and the handbook says to do a balancing charge once a month but yours could be very different good luck
Les

 

[Firespray31]

Thank you both for the welcome and advice. That's great to hear and good to know I can get stuck into the owners manual in advance. I'll take a look! Got to pass the time somehow ahead of delivery...

 

[drmcw]

As you'll be charging to 100% then the pack will balance for you, so don't worry about it. The benefit of a balanced pack are that when you charge to 100% you'd expect about 50kWh of energy in the pack, if it wasn't balanced then you'd charge to 100% but maybe only get 40 kWh as an example.

 

[S17TTN]

I have a facelift SR and I charge it to 100% most nights and haven’t had a single issue - I think it’s only the LR that likes to be kept between 20-80% so charge away and enjoy!

 

[Maciej]

I have a facelift SR and I charge it to 100% most nights and haven’t had a single issue - I think it’s only the LR that likes to be kept between 20-80% so charge away and enjoy!

To be honest it's been short time so we won't really know the degradation till good few years into owning vehicle. MG manual says nothing about charging to full being bad. The only recommendation in manual is to balance battery once a month by charging to full on slow charge.

I expect charging to 80% will be marginally better than charging to 100% for long term battery life like degradation after day 7 years of ownership but is saving say 2 to 5% of battery life worth the hassle. For some it may be for others it won't matter especially if they don't intend to own a car for that long.

 

[Hotlush]

The biggest killer of batteries, across all manufacturers, is letting the battery get too hot or too cold for long(ish) periods.
In the UK it's very unlikely we would see any issues in that respect.

How often you charge, and the level, will have very little impact unless you're talking a battery that is out of, or near end of, warranty.

 

[jds1972]

To be honest it's been short time so we won't really know the degradation till good few years into owning vehicle. MG manual says nothing about charging to full being bad. The only recommendation in manual is to balance battery once a month by charging to full on slow charge.

I expect charging to 80% will be marginally better than charging to 100% for long term battery life like degradation after day 7 years of ownership but is saving say 2 to 5% of battery life worth the hassle. For some it may be for others it won't matter especially if they don't intend to own a car for that long.

In reality, when you charge the LR to 100% (68 kWh it is only 92-94% of total battery capacity (71kWh), charging to 100% is ok as long as you use it, Lithium does not like to be charged fully and left in that state for long periods (N.B. it doesnt like to be left with no charge for long periods either).
So i guess the best practice as a user would be to only charge to 80% for day to day use and only charge to 100% when you really need to, as the app states "Long Range mode". If your daily journey dictates that you need to use the full 100% on a daily basis then this in effect will also be fine because you will be depleting the charge and not leaving it at a full SOC.

Obviously it will effect the battery health over time if you are doing this on a daily basis, but all that really means is the available capacity will slowly drop over time, as with any battery. the batteries themselves will still be usable in 15-20 years time just with a reduced capacity.
Remember, with any battery, the charging and discharging cycles are obtained through Chemical reactions within the battery, the only major difference between all batteries is the chemistry, which in turn determines the capability.

 

[Gadget Geek]

I think it's similar to when I used to drive an ICE car. A full tank of petrol was extra weight you would carry around uneccessarily for day to day driving. I used to put £10 worth in (probably be £20 these days) and use that until it needed topping up. Full tank was for a trip to the seaside, (but I now live at the seaside so that would be a moot point). One thing the battery chemists can agree on is that rapid, deep charge/discharge cycles age the battery quicker than gentle cycles.

 

[jds1972]

I think it's similar to when I used to drive an ICE car. A full tank of petrol was extra weight you would carry around uneccessarily for day to day driving. I used to put £10 worth in (probably be £20 these days) and use that until it needed topping up. Full tank was for a trip to the seaside, (but I now live at the seaside so that would be a moot point). One thing the battery chemists can agree on is that rapid, deep charge/discharge cycles age the battery quicker than gentle cycles.

trickle charging is always better, just not always practical, but should always be done when you can, the faster the charge the more heat is generated in the battery.

 

[jds1972]

The biggest killer of batteries, across all manufacturers, is letting the battery get too hot or too cold for long(ish) periods.
In the UK it's very unlikely we would see any issues in that respect.

How often you charge, and the level, will have very little impact unless you're talking a battery that is out of, or near end of, warranty.

agree with the hot and cold to an extent, this affects the performance of the batteries at the extreme of temperatures more than anything.

with regards to the warranty, it is a misconception that the batteries will not last much more than the warranty, but this is not true. the Lithium cells themselves will last longer than the car probably will, the warranty covers a state of health to i think 75-80% for 8 years or 100,000 miles whichever comes sooner, it doesnt mean that they no longer function at this point, it just means that you only have around 75-80% of the range you had when they were new. and in reality, unless you have really abused the batteries during their life, after 8 years I would expect the SOH to be upwards from 85% generally

 

[Maciej]

agree with the hot and cold to an extent, this affects the performance of the batteries at the extreme of temperatures more than anything.

with regards to the warranty, it is a misconception that the batteries will not last much more than the warranty, but this is not true. the Lithium cells themselves will last longer than the car probably will, the warranty covers a state of health to i think 75-80% for 8 years or 100,000 miles whichever comes sooner, it doesnt mean that they no longer function at this point, it just means that you only have around 75-80% of the range you had when they were new. and in reality, unless you have really abused the batteries during their life, after 8 years I would expect the SOH to be upwards from 85% generally

I think that is a point of this discussion to establish what way of driving makes this 85% rather than 75% of range. Difference isn't huge but 20-30 more likes of range is big enough to matter plus it makes it easier to sell car with 85% SOH vs 75% SOH. My plan is to charge to 80% during week and to 100% for longer trips. My usual commute is rather short in a week so I am more than happy go to 80% and drop to 70% by the end of my usual day. On days when I need to go further I will top it up to 100% and it should ensure I can do return trip without needing fast charging. I don't expect to need fast charging more than maybe 5 times a year.

 

[Firespray31]

All great comments - what a welcoming forum, thanks everyone for the input. When delivery day eventually rolls around I'll be coming back to this for sure!