What is the best charging and discharge plan to have the optimum whole life battery performance.

[Olly1bin]

As I understand it the lithium Iron EV batteries degrade because of five main reasons:

1) High temperature (leaving car in sunlight or charging when the battery has been used heavily, prior to charging)
2) Charging the battery above 90% regularly - which I think MG are advocating even with the new BMS (takes it to 95% I understand?)
3) Allowing the battery charge to drop below 20% charge regularly.
4) High charge or discharge - again the forum seem to suggest that rapid charging will not adversely affect the battery as long as it is rebalanced?
5) the number of charging cycles.

So given the freedom to choose how we drive and charge our MG ZS EVs do we have views on what is the best driving and charging plan that will make sure whole life battery performance is optimised? And Why?

Also if 1) is a real problem then why don't the public EV charging points come with a solar cell canopy to park under?

 

[Kithmo]

My view is that those things only matter if you're planning to keep the car for a long time.
MG guarantee the battery will be above 70% capacity for 7 years, with no special treatment or charging plans, apart from charging to full then balancing the battery once a month. The BMS looks after the battery for us.

 

[Olly1bin]

My view is that those things only matter if you're planning to keep the car for a long time.
MG guarantee the battery will be above 70% capacity for 7 years, with no special treatment or charging plans, apart from charging to full then balancing the battery once a month. The BMS looks after the battery for us.

I don't mean to argue Kithmo, but surely degradation in battery performance will affect charging times, rates of acceleration, the regeneration efficiency and range of your car? A degraded battery will affect your driving experience in a number of ways and hence in the resale value of your car too. And if MG only step in if the battery falls below 70% capacity that's a lot of degradation down to a range of c100 miles max.
I have no idea how well the BMS looks after the battery, but, if we can adopt simply least damage plan that would surely be beneficial?

 

[Mark Holmes]

I don't mean to argue Kithmo, but surely degradation in battery performance will affect charging times, rates of acceleration, the regeneration efficiency and range of your car? A degraded battery will affect your driving experience in a number of ways and hence in the resale value of your car too. And if MG only step in if the battery falls below 70% capacity that's a lot of degradation down to a range of c100 miles max.
I have no idea how well the BMS looks after the battery, but, if we can adopt simply least damage plan that would surely be beneficial?

I’ve completed over 17000 miles in a year and haven’t noticed any drop off at all in fact my reported SOH is still 100% and if you look at my post from the other day the road trip my volts are still at their maximum of 449 and I’m exceeding the WTLP by quite some margin, albeit it was between 5 and14 degrees out side on that trip...

 

[LiamWhales]

As I understand it the lithium Iron EV batteries degrade because of five main reasons:

1) High temperature (leaving car in sunlight or charging when the battery has been used heavily, prior to charging)
2) Charging the battery above 90% regularly - which I think MG are advocating even with the new BMS (takes it to 95% I understand?)
3) Allowing the battery charge to drop below 20% charge regularly.
4) High charge or discharge - again the forum seem to suggest that rapid charging will not adversely affect the battery as long as it is rebalanced?
5) the number of charging cycles.

So given the freedom to choose how we drive and charge our MG ZS EVs do we have views on what is the best driving and charging plan that will make sure whole life battery performance is optimised? And Why?

Also if 1) is a real problem then why don't the public EV charging points come with a solar cell canopy to park under?

As well as my MG, I've had a 2014 nissan leaf for about 3 years. We have always trickle charged it on a granny charger and don't often charge it to 100%. When we've had it checked over by Nissan, the mechanic said the battery was in the best state they had ever seen at that age. It's on 85% SoC at 7 years old and that's with older Li-Ion tech and no liquid cooling.

In response to your list of reasons for battery degredation, I thought ~I'd just add some details around why they cause degredation.

1) Lithium batteries operate best between +5C and +45C so summer weather in the UK isn't likely to be a problem and when you are using the battery it can be heated or cooled by the batteries coolant loop.

2) The majority of the degradation in charging does come from charging from 80% to 100% of the total battery (not the usable) and the higher you go the more impact it has. It causes more degradation than the whole of the 0% to 80% charge. So if you can charge to only 80% or 90% you will get better life out of you battery. Having said that the hidden buffer that is built into the BMS will protect the car from most of the damage.

3) The lower end of the SoC runs the risk of over discharge, if this happens to a cell it may die completely and become unusable. Not really an issue as the BMS prevents it, as long as you don't leave the car for an extended time at a low charge level, it isn't a problem

4) High drain or high charge rates do impact on the batteries life. At higher current levels small lithium deposits form inside the cells, this reduces their effectiveness and overtime can lead to an internal short circuit and a dead cell.

5) Charging cycles cause degradation but the amount of degradation is related to how quickly the car is charged. I'm sure I heard somewhere that slow charging actually keeps the battery healthy more than having it sat doing nothing for extended periods. On the 2kW granny charger you'll be having minimal impact, even on a 7kW charger your not really putting the battery under strain (10% of it's max continous load). If you rapid charge on a regular basis there will be greater degredation over time but this would build up over years.

So all this into account my suggestions for maximising battery life would be,

1) If you can, only charge to 100% when needed, otherwise charge to 80%. Although an occasional charge to 100% has benefits in terms of rebalancing the cells

2) Only use rapid chargers when necessary, this is by far going to have the biggest impact. And when you do use them only charge to the level needed for the next leg of your journey (with some leeway)

A lot of the concerns around battery life are not there with the MG compared to our Leaf. Temperature isn't an issue with the liquid cooled battery. The Li-Ion tech is newer and the load to size of the battery is more conservative. The cars software will tell me if I need to balance the cells, with the Leaf I periodically have to check using leaf spy. So I really think you could quite happily rapid charge to 100% as your only method of charging and the battery would still hold out quite well.

 

[Mark Holmes]

As well as my MG, I've had a 2014 nissan leaf for about 3 years. We have always trickle charged it on a granny charger and don't often charge it to 100%. When we've had it checked over by Nissan, the mechanic said the battery was in the best state they had ever seen at that age. It's on 85% SoC at 7 years old and that's with older Li-Ion tech and no liquid cooling.

In response to your list of reasons for battery degredation, I thought ~I'd just add some details around why they cause degredation.

1) Lithium batteries operate best between +5C and +45C so summer weather in the UK isn't likely to be a problem and when you are using the battery it can be heated or cooled by the batteries coolant loop.

2) The majority of the degradation in charging does come from charging from 80% to 100% of the total battery (not the usable) and the higher you go the more impact it has. It causes more degradation than the whole of the 0% to 80% charge. So if you can charge to only 80% or 90% you will get better life out of you battery. Having said that the hidden buffer that is built into the BMS will protect the car from most of the damage.

3) The lower end of the SoC runs the risk of over discharge, if this happens to a cell it may die completely and become unusable. Not really an issue as the BMS prevents it, as long as you don't leave the car for an extended time at a low charge level, it isn't a problem

4) High drain or high charge rates do impact on the batteries life. At higher current levels small lithium deposits form inside the cells, this reduces their effectiveness and overtime can lead to an internal short circuit and a dead cell.

5) Charging cycles cause degradation but the amount of degradation is related to how quickly the car is charged. I'm sure I heard somewhere that slow charging actually keeps the battery healthy more than having it sat doing nothing for extended periods. On the 2kW granny charger you'll be having minimal impact, even on a 7kW charger your not really putting the battery under strain (10% of it's max continous load). If you rapid charge on a regular basis there will be greater degredation over time but this would build up over years.

So all this into account my suggestions for maximising battery life would be,

1) If you can, only charge to 100% when needed, otherwise charge to 80%. Although an occasional charge to 100% has benefits in terms of rebalancing the cells

2) Only use rapid chargers when necessary, this is by far going to have the biggest impact. And when you do use them only charge to the level needed for the next leg of your journey (with some leeway)

A lot of the concerns around battery life are not there with the MG compared to our Leaf. Temperature isn't an issue with the liquid cooled battery. The Li-Ion tech is newer and the load to size of the battery is more conservative. The cars software will tell me if I need to balance the cells, with the Leaf I periodically have to check using leaf spy. So I really think you could quite happily rapid charge to 100% as your only method of charging and the battery would still hold out quite well.

Totally agree with your summary and whilst I use my car for business I never charge to 100% unless it’s needed the next day and I need that range. I only rapid charge on the odd occasion and when I absolutely must as my alternative subject to time is to find another free 7 KWh charger and do some emails and calls before continuing with my journey.

 

[Kithmo]

Some people just worry too much about what ifs.

I don't mean to argue Kithmo, but surely degradation in battery performance will affect charging times, rates of acceleration, the regeneration efficiency and range of your car? A degraded battery will affect your driving experience in a number of ways and hence in the resale value of your car too. And if MG only step in if the battery falls below 70% capacity that's a lot of degradation down to a range of c100 miles max.
I have no idea how well the BMS looks after the battery, but, if we can adopt simply least damage plan that would surely be beneficial?

I don't disagree with anything you said, so there's no need to affirm your theories, you asked for views and that's mine.
No disrespect to you, but I personally just don't care about any of these things, I like to keep things simple, drive the car, charge the car, drive it some more, why add worrying to the equation.
If you enjoy faffing about that's your prerogative, I don't.

 

[LiamWhales]

Some people just worry too much about what ifs.

I don't disagree with anything you said, so there's no need to affirm your theories, you asked for views and that's mine.
No disrespect to you, but I personally just don't care about any of these things, I like to keep things simple, drive the car, charge the car, drive it some more, why add worrying to the equation.
If you enjoy faffing about that's your prerogative, I don't.

I see this as much the same as looking after any other part of your car. Just like with an ICE, don't hammer it from a cold start, don't leave it ticking over for ages, don't constantly start stop the engine. I also think that when it comes to selling the car, people will be very aware of battery degradation so If my battery is healthy my car will retain it's value better.

Sure If you don't care about it, that's fine it's your choice but Olly's question was around optimal battery maintenance not whether you care about it or not.

 

[Kithmo]

Sure If you don't care about it, that's fine it's your choice but Olly's question was around optimal battery maintenance not whether you care about it or not.

He seems to be already very knowledgeable about optimal battery maintenance and was asking for other people's views on it, which would include whether people care about it or not, and I gave mine.
FWIW, none of what you said about ICE cars applies to BEVs

 

[LiamWhales]

He seems to be already very knowledgeable about optimal battery maintenance and was asking for other people's views on it, which would include whether people care about it or not, and I gave mine.
FWIW, none of what you said about ICE cars applies to BEVs

The question was asking for opinions on what makes the best optimal plan for maintaining a battery not whether you think it is important.

And all that stuff I said about ICE cars was just about ways in which you look after your car, didn't mean they applied to BEVs, which they clearly don't, just that you take simple actions to keep your car running well, whatever the car runs on.

 

[Kithmo]

The question was asking for opinions on what makes the best optimal plan for maintaining a battery not whether you think it is important.

And all that stuff I said about ICE cars was just about ways in which you look after your car, didn't mean they applied to BEVs, which they clearly don't, just that you take simple actions to keep your car running well, whatever the car runs on.

I don't see anything in his post asking how to maintain an ICE car either, so your answer was more irrelevant than mine.
What's with all the negativity anyway ?

 

[AussiePete]

It’s a great question, however I suppose the answer will be there’s no simple answer. I say that as in many ways your charging regime depends on your driving regime. For example:

- if you do loads of short trips (say 30 miles a day) with just an odd longer trip every now and again you can afford to do 4 to 5 day trips before you recharge. You can also make all your charges slow (2kw granny or 7kw home charger) as you’re unlikely to need a big charge and you’ll be able to balance charge most times.

- if you’re daily trips are long ones - say over 100 miles, you may be forced into rapid’s or ultra rapids whilst doing your journey. You may do an overnight charge on granny or home, but it’s unlikely to include a full balance. If you’re lucky you might balance charge once a week on weekend

- if your driving is sporadic (like me) and your journeys could be short or long, you’re likely to charge all the time as tomorrow could need a full charge for a trip. As such I plug in most nights (unless I’ve only done a handful of miles that day - say under 20) and let it top up and rebalance.

So even if there was a formula for best battery management it’s unlikely the majority would be able to follow it. I do think there are some tips which will help (ie slow charge with a full rebalance once for every 10 rapid charges), however I’m not sure these are proven to extend the life of the battery.

 

[LiamWhales]

I don't see anything in his post asking how to maintain an ICE car either, so your answer was more irrelevant than mine.
What's with all the negativity anyway ?

The ICE talk was only to mention a point that changing how you use your vehicle to ensure that it has a good long life is normal.

I did not start the negativity you came on and basically said you didn't care about maintaining your battery. That's fine but it's like coming onto a post about how to look after a puppy and saying you don't like dogs, doesn't really lend much to the conversation.

 

[Kithmo]

The ICE talk was only to mention a point that changing how you use your vehicle to ensure that it has a good long life is normal.

I did not start the negativity you came on and basically said you didn't care about maintaining your battery. That's fine but it's like coming onto a post about how to look after a puppy and saying you don't like dogs, doesn't really lend much to the conversation.

Talking about ICE cars has no relevance whatsoever on maintaining a BEV battery.
I was talking about your negativity towards me and my view, it seems your one sided view is the only one allowed in your eyes.

 

[LiamWhales]

Chill out, I am not saying your views are wrong, I am saying they are not relevant to the question asked.

ICE Cars are a good reference frame for talking about BEV's. Most people are new to BEV's but used to ICE cars so talking about differences and similarities between them makes sense. Like I said and will now repeat a third time, my only point was that you use a machine in a certain way in order to keep it running well, whatever that machine is.

Again, like I said before, you started the negativity when calling the whole idea of looking after your battery as faffing and pointless. I am only trying to point out to you that the original question of this post was HOW to look after your battery not whether you care about it.

 

[AbuG]

I find it bewildering how people are on a car enthusiast forum and enter a thread and say "I don't care about these things".

Why enter the thread at all if your not enthusiastic about topic of the thread?

I'm not criticising, just trying to understand.

 

[Kithmo]

Having a dig at me is not answering the original post is it, so please return to the topic instead.

 

[LiamWhales]

Having a dig at me is not answering the original post is it, so please return to the topic instead.

Well said, on that note I realise in my reply I never addressed driving style to lengthen the life of the battery.

Generally the less power you draw from the battery the less degradation so gentle acceleration and deceleration is going to be the kindest to the battery. But having said that the pack is capable of a peak load of 115kw from the motor and usually for Li-Ion batteries, if they can deliver that power they can generally do so for around 5 min without much issue. So unless you put your foot to the floor for a solid 5 mins on a regular basis, your driving style will have little effect on the life of the battery.

 

[Bazzer44]

Having a dig at me is not answering the original post is it, so please return to the topic instead.

Hey Kithmo
Thee and me are Yorkshiremen we can still talk and disagree lol

 

[Dave53]

I don't mean to argue Kithmo, but surely degradation in battery performance will affect charging times, rates of acceleration, the regeneration efficiency and range of your car? A degraded battery will affect your driving experience in a number of ways and hence in the resale value of your car too. And if MG only step in if the battery falls below 70% capacity that's a lot of degradation down to a range of c100 miles max.
I have no idea how well the BMS looks after the battery, but, if we can adopt the simply least damage plan that would surely be beneficial?

Let's face it if you buy a car of this price as a petrol or diesel car its value is scrap value after seven years with the new MOT emissions tests, the only noticeable issue is the range and for me, in 10 years my range will be noticeably shorter nevermind the cars.