Equalisation charge - NMC battery

[wattmatters]

But does that still leave the question of whether balancing at 100% is better than at lower states of charge?

It is required every so often for a complete top balance. Cell capacity differences are really only evident from a full discharge/charge.

 

[decrep]

It is required every so often for a complete top balance. Cell capacity differences are really only evident from a full discharge/charge.

Maybe this is where some of the confusion is coming from.

 

[Data]

Maybe this is where some of the confusion is coming from.

I don't think so decrep. I was at a local MG EV meet a few weeks ago. There were just 6 of us consisting of 2 x ZS, 1 x MG5 & 3 x MG4's. All cars NMC except the MG5 & 1 MG4. The two LFP lads could easily equalise at 100%. One of the NMC MG4's could equalise from any soc as per what is being said by some on here. But the other guy with the MG4 was the same as us two ZS cars. He could only equalise at 100% & had to take the soc down to the low battery warning. The good news of course is that it doesn't need doing very often with NMC.

This being the case, it does show differences in how equalisation is achieved. It's not the same for everyone. So is this a fault with software on some cars, including mine? Well, my car has had a complete software upgrade to the newest for everyone of it's modules. Even before this, equalisation only took place at 100%. Since a full software upgrade, it's just the same so I do not think there is a fault. My car was brand new in January this year. Is it the same for all years or later models? I can't be sure but certainly some owners of later cars are having the same experience as me.

Does any of this matter?? I don't think so. It just means we need to acknowledge it's not the same for everyone when giving newbies advice because there is considerable confusion about how to do an equalisation charge amongst that group. I agree with Martin online that the manuals could also be clearer on this subject.

With my enquiring engineers mindset I've taken this as far as I reasonably can. I did this because I noticed several people on here reporting different equalisation experiences similar to mine. I do not agree with Martin online that this is a toxic subject. This forum is doing exactly what it should be doing...encouraging good robust debate & sharing of experiences. Trust me, I moderate on several engineering sites. In spite of my & others best efforts they are nowhere near as good as this site!
PS. This inability to equalise at any SOC may alter as the battery declines a little in health, it's been suggested by an MG tech. Will have to wait & see

It is required every so often for a complete top balance. Cell capacity differences are really only evident from a full discharge/charge.

Yes, it's better & is the only way to keep best range & best SOH.

 

[decrep]

@Data
Sounds like you know what you are doing, and not just quoting some UTube vid.
So I have to accept there are differences, which is rather weird, but we're getting used to weird with MG

 

[Jamesrr]

Yes, its better & is the only way to keep best range & best SOH.

Really?

I must admit I am very dubious about such a claim

You are asserting that the SOH of the battery after say 3 years and 60,000 KMs is dependant on how regularly you perform balance charging.

Are there any studies or even theoretical papers that support such an assertion?

You are suggesting that while going on a long distance journey my half hour charge will actually provide more range if I have previously performed regular balance charging than if I haven't.

I'm frankly sceptical in the extreme.

Please provide some evidence to convince me otherwise.

Sincerely,

James

 

[Data]

Really?

I must admit I am very dubious about such a claim

You are asserting that the SOH of the battery after say 3 years and 60,000 KMs is dependant on how regularly you perform balance charging.

Are there any studies or even theoretical papers that support such an assertion?

You are suggesting that while going on a long distance journey my half hour charge will actually provide more range if I have previously performed regular balance charging than if I haven't.

I'm frankly sceptical in the extreme.

Please provide some evidence to convince me otherwise.

Sincerely,

James

What car & what type of battery James? Why are you dubious? In case you didn't notice, I haven't made any suggestions.

 

[siteguru]

The car is an MG4 ER (77kWh NMC pack) ... he's included it to his Location info, like you did.

 

[Data]

Thanks siteguru.

 

[Martinonline]

@Data, I see you are back having previously stated you were done with this subject (#29). Makes me wonder if the ZS forum is not as interesting as this one. Perhaps you should get an MG4

By the way, you are not the only one with engineering experience. As for your enquiring mind you were given a great opportunity at you local MG meet. You make statements but don't amplify - what MG4 model could not equalise at below 100%, how did they know that, can they not set a battery level below 100%, what EVSE were they using? Did you ask them to join this site to add their experiences as it is different to many, if not most, NMC battery MG4 owners experiences on this forum?

This is critical information for those seeking MG4 information on this site.

In reply to your DM, I read the ZS manual linked from the app and it has the same words about equalisation charging as those in the MG4 manual except that it makes no mention of 'optimum equilibrium state' that is in the MG4 manual. You refer to the later pages in respect of the 20% start level but as I said in a previous post the tables are indicative charging times to 100% with no mention of being mandatory states to allow the car to equalise at 100%.

It is good that you now accept equalisation/balancing can occur at battery levels below 100% as I accept that this may not be true for all NMC MGs.

It would be good to hear from an MG4 owner with the car being unable to balance at less than 100% and/or need to start below 20%.

I think it would be beneficial that there should be no more posts as we wait for that one.

 

[Jamesrr]

Hi @Data ,

When responding to a comment re balance charging at 100%

It is required every so often for a complete top balance. Cell capacity differences are really only evident from a full discharge/charge.

You said

Yes, it's better & is the only way to keep best range & best SOH.

I expressed my scepticism re the effect on SOH.

What car & what type of battery James? Why are you dubious?

As noted an MG4 with NMC 77kWh battery.

I'm dubious because I've not seen any technical analysis that says balance charging is required to maintain the long term health of the battery.

I understand how the balance charging affects the accuracy of the BMS in determining if the system is "fully charged" and how much charge it may have remaining at any state of discharging, but you have said it will affect the actual state of health of the battery.

I'd like to understand what evidence there is for that.

In case you didn't notice, I haven't made any suggestions.

Haven't you suggested balance charging is "the only way to keep the best SOH" of the battery?

Cheers,

James

 

[Data]

@Data, I see you are back having previously stated you were done with this subject (#29). Makes me wonder if the ZS forum is not as interesting as this one. Perhaps you should get an MG4

By the way, you are not the only one with engineering experience. As for your enquiring mind you were given a great opportunity at you local MG meet. You make statements but don't amplify - what MG4 model could not equalise at below 100%, how did they know that, can they not set a battery level below 100%, what EVSE were they using? Did you ask them to join this site to add their experiences as it is different to many, if not most, NMC battery MG4 owners experiences on this forum?

This is critical information for those seeking MG4 information on this site.

In reply to your DM, I read the ZS manual linked from the app and it has the same words about equalisation charging as those in the MG4 manual except that it makes no mention of 'optimum equilibrium state' that is in the MG4 manual. You refer to the later pages in respect of the 20% start level but as I said in a previous post the tables are indicative charging times to 100% with no mention of being mandatory states to allow the car to equalise at 100%.

It is good that you now accept equalisation/balancing can occur at battery levels below 100% as I accept that this may not be true for all NMC MGs.

It would be good to hear from an MG4 owner with the car being unable to balance at less than 100% and/or need to start below 20%.

I think it would be beneficial that there should be no more posts as we wait for that one.

Actually Martin, if you read my earlier post about my meet with others, it's all explained about who could & couldn't equalise at below 100%. Read & digest! It's quite easy to understand so folks can see the facts. We discussed at some length the situation regarding these interesting facts. As for my engineering experience it is unimportant for many of the discussions we are having. And my experience all relates to ice engined vehicles, not EV's. That's why I'm here.

It's good you now accept not all cars seem to equalise in the same way regarding NMC packs.

The reason I'm still here Martin is because individuals, apparently including your goodself, don't understand or read my posts correctly or even the whole thread & go on to make inappropriate comments, assertions & remarks. It's a bit like some people seem to want to shoot the messenger. They commonly ask questions of me that have already been answered by me in earlier posts within the same thread. Many are oblivious to the context of the post they query or indeed the thread & the answers I give. If folks just read the thread properly mostly everything would be clearer for them. I do accept this is sometimes a 'thing' that happens on these forums, but....

Trust me Martin, the ZS forum is just as interesting!

Hi @Data ,

When responding to a comment re balance charging at 100%

You said

I expressed my scepticism re the effect on SOH.

As noted an MG4 with NMC 77kWh battery.

I'm dubious because I've not seen any technical analysis that says balance charging is required to maintain the long term health of the battery.

I understand how the balance charging affects the accuracy of the BMS in determining if the system is "fully charged" and how much charge it may have remaining at any state of discharging, but you have said it will affect the actual state of health of the battery.

I'd like to understand what evidence there is for that.

Haven't you suggested balance charging is "the only way to keep the best SOH" of the battery?

Cheers,

James

Hello James. There is plenty of evidence that balancing your battery on a regular basis helps protect your HV battery SOH. In you MG4 MANUAL it states that equalisation preserves range & helps maintain your battery SOH. It actually helps extend your batteries life by preventing over or under charging of cells which can of course cause damage over time if not addressed. It allows the battery to actually 'fill itself up properly'. Of course there are many things that help preserve SOH. Equalisation is just one of them. It says this in my manual also. If you know something about EV batteries & their chemistry & how they work it's also fairly easy to understand that this is the case. If you do some further research there are articles on tinternet reinforcing this. Do your own research. It's there.

 

[Jamesrr]

Hello James. There is plenty of evidence that balancing your battery on a regular basis helps protect your HV battery SOH. In you MG4 MANUAL it states that equalisation preserves range & helps maintain your battery SOH. It actually helps extend your batteries life by preventing over or under charging of cells which can of course cause damage over time if not addressed. It allows the battery to actually 'fill itself up properly'. Of course there are many things that help preserve SOH. Equalisation is just one of them. It says this in my manual also. If you know something about EV batteries & their chemistry & how they work it's also fairly easy to understand that this is the case. If you do some further research there are articles on tinternet reinforcing this. Do your own research. It's there.

Well I have done quite a bit of research both before purchasing our MG4s and since.

Balancing did not come up as a significant determinant to long term battery health.

Not regularly charging past 80% and using DC fast charging only when necessary were the main recommendations.

I got Gemini to provide a quick summary....

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What does the mg4 technical manual recommend to maintain battery health?

AI Overview
+5
The MG4 Technical Manual recommends using slow charging whenever possible and only using rapid charging for long trips or emergencies to preserve battery health, and it also advises against leaving the vehicle unused for too long. However, the manual's specific recommendations vary by battery type: for the 51 kWh LFP battery, it's generally fine to charge to 100% regularly, though a full charge may be needed to balance the cells, while for the 64 kWh or 77 kWh NMC batteries, it recommends limiting regular charging to 80%. For long periods of inactivity, it's best to store the vehicle with the high-voltage battery at approximately 60% charge.

General Recommendations

Use Slow Charging:
Whenever possible, use a slower charging method to maintain the high-voltage battery's service life.

Use Rapid Charging Sparingly:
Reserve rapid (DC fast) charging for long-distance journeys or emergencies, as it can cause more stress on the battery.

Recommendations by Battery Type
For the 51 kWh LFP Battery:
You can typically charge to 100% on a regular basis without significant harm to battery health.

For the 64 kWh or 77 kWh NMC Batteries:
It is recommended to limit regular charging to 80% to preserve battery health.

For Long-Term Storage
Store at ~60% Charge: If you won't be using the vehicle for an extended period, store it with the high-voltage battery at around 60% state of charge.

For Long Trips
Charge to Full (if needed):
For long trips, you can charge either battery type to 100% to ensure sufficient range.

Perform Balancing Charges:
For NMC batteries, occasionally charging to 100% (and sometimes LFP batteries too) is beneficial for balancing the battery cells and ensuring accurate state of charge readings.
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Balance charging is useful for accurate soc readings rather than soh on my reading.

 

[DaveIJ]

All makes sense to me thanks for this