Battery equalisation on ZSEV Trophy LR

[Data]

Thanks guys. Yes, I should have mentioned the bit about BMS calibration happening also. The dealer mentioned that too. I want to do the whole thing as the car is 5 months old & has only ever been charged to 100% once in that time. I'm only covering about 6-7k miles per year so probably doesn't need it very often. The thing about all this stuff is the lack of clear written down instructions. The variable advice given by dealers & people in forums also. It's difficult to be sure of anything. Thanks!

 

[Roldorf]

You are worrying too much about it. I don't have home charging and mostly charge DC. Occasionally maybe once every 2 months I charge on my local AC street charger to 100% because it's a lot cheaper and I have never noticed it doing a balance charge. As soon as it gets to 100% it switches off and no more charge.

 

[Data]

Ok, further to my post above. Last night, having carried out a battery equalisation charge as per advice from the forum, I charged the car from 31% soc to 100%. Out of interest this morning the GOM showed 300 miles of range at 100% (483kms) in normal mode. Pretty good.

But here's the thing, practically no equalisation of the battery cells. It went to 300W to 200W & to charge ended in about 2 mins total. Thinking either the battery is in excellent condition even though I've been ultra fast charging for the last 3 months, or proper equalisation hasn't happened.

This was an entirely different experience from when I did a full battery equalisation & BMS calibration when I ran the battery soc down to 17% & then fully slow charged. On that occasion it took 12mins to equalise & calibrate.

Comments invited along with your personal experiences. Apologies to the original poster of this thread. Not my intension to hijack it. But there has been some good points made.

 

[Data]

You are worrying too much about it. I don't have home charging and mostly charge DC. Occasionally maybe once every 2 months I charge on my local AC street charger to 100% because it's a lot cheaper and I have never noticed it doing a balance charge. As soon as it gets to 100% it switches off and no more charge.

Thanks, but I don't actually worry about it. But I do want to keep the battery in its very best condition for a very long life. I know the battery will last a very long time even if I don't equalise regularly but my thinking is to do my best for the way I use the car to look after the battery. It's interesting to hear how you charge.

 

[Chris Law]

I perform a balance / equalisation charge monthly. Living in Portugal and with solar panels I use the granny charger at the weekend (cheap electricity for what is not covered by +/- 2 kW solar panels), starting from between 60-80% SOC. Once the SOC reaches 100%, charging continues at gradually reducing kW for up to another +/- 1 hour. As I understand it, this is what I should expect.

 

[Data]

I perform a balance / equalisation charge monthly. Living in Portugal and with solar panels I use the granny charger at the weekend (cheap electricity for what is not covered by +/- 2 kW solar panels), starting from between 60-80% SOC. Once the SOC reaches 100%, charging continues at gradually reducing kW for up to another +/- 1 hour. As I understand it, this is what I should expect.

It's kinda what I expected too Chris. But nothing really happened.

 

[fred12345]

This was an entirely different experience from when I did a full battery equalisation & BMS calibration when I ran the battery soc down to 17% & then fully slow charged. On that occasion it took 12mins to equalise & calibrate.

Few times I actually paid attention to it, once it took quite some time to balance (from memory, almost an hour) and the other time it was done fairly quickly, 15-20 min ... I use 3kW charger and balance on average once every 2 months.

 

[Data]

Few times I actually paid attention to it, once it took quite some time to balance (from memory, almost an hour) and the other time it was done fairly quickly, 15-20 min ... I use 3kW charger and balance on average once every 2 months.

Fred, what soc did you start from? Is yours an NMC battery pack?

Interestingly, I don't think my car equalised the battery cells at all. I set out on my journey this morning & found my regen (set to 3) was fully operational. Virtually one pedal driving just as usual right from the word go! Not at all like the last time I did a balance from 17% to 100% soc where there was no regen available. And today was with 100% soc. So pretty sure no balancing took place. I had anticipated the car would take 48.5 kWh to complete the job yet the charger pushed 54.75 kWh into the battery. It certainly was well charged & the range on my 55 mile journey was maintained really well ie: it didn't plummet down the scale.

The lesson for me is to do as the owners manual says. I'll take the soc down to the low battery warning area plus an extra couple of percent then do the BMS & equalisation charge. That really works.

 

[Chris Law]

Fred, what soc did you start from? Is yours an NMC battery pack?

Interestingly, I don't think my car equalised the battery cells at all. I set out on my journey this morning & found my regen (set to 3) was fully operational. Virtually one pedal driving just as usual right from the word go! Not at all like the last time I did a balance from 17% to 100% soc where there was no regen available. And today was with 100% soc. So pretty sure no balancing took place. I had anticipated the car would take 48.5kwh to complete the job yet the charger pushed 54.75kwh into the battery. It certainly was well charged & the range on my 55 mile journey was maintained really well ie: it didn't plummet down the scale.

The lesson for me is to do as the owners manual says. I'll take the soc down to the low battery warning area plus an extra couple of percent then do the BMS & equalisation charge. That really works.

Data, one plausible explanation for your short equalisation duration is that your - relatively very new - battery cells actually need very little equalisation. OBD check to confirm/deny?

 

[wattmatters]

Comments invited along with your personal experiences.

2-12 minutes is pretty normal. If it's been a long time between equalisation charges then it can take an hour or more.

 

[Data]

Data, one plausible explanation for your short equalisation duration is that your - relatively very new - battery cells actually need very little equalisation. OBD check to confirm/deny?

Indeed, but the previous equalisation & BMS calibration that I did where I took the soc down to 17% produced a 'proper' equalisation lasting almost 12mins (quite a short time still) & no regen available afterwards until the soc dropped a little. That charge was carried out 3 months after getting the car from new.

This latest charge to 100% from 31% soc seems to have produced zero equalisation. The car still had regen available afterwards right from the word go. Yet the charge had fully ended at 100%. I'm told this indicates that equalisation didn't properly take place or didn't happen at all. I left it plugged in for over an hour afterwards due to phone calls etc but no further charge initiated. I fully expected the car to equalise for at least a short time especially as I've been ultra fast charging for the last 2 months. So I've spoken to my dealer (in the quest for knowledge) who tells me it's not uncommon for equalisation to not happen if you don't take the battery soc down to the low battery warning. He repeated what the car owners manual says that the only way to do it properly is to lower the charge to the low battery warning before commencing the equalisation. That is what they advise. Any other way often produces only partial or random equalisation, their words not mine.

I would add that even when I charge to 80% I've never experienced any balancing of the battery as others on here are saying they experience. I've deliberately been checking for this.

You can see why some of us get confused over this equalisation thing. Differing advice on the forum & differing results from car to car. I know others who have experienced what I have. And I have an auto tech background.

In my case equalisation won't need doing very often as my mileage is 7k pa tops.

 

[Chris Law]

Indeed, but the previous equalisation & BMS calibration that I did where I took the soc down to 17% produced a 'proper' equalisation lasting almost 12mins (quite a short time still) & no regen available afterwards until the soc dropped a little. That charge was carried out 3 months after getting the car from new.

This latest charge to 100% from 31% soc seems to have produced zero equalisation. The car still had regen available afterwards right from the word go. Yet the charge had fully ended at 100%. I'm told this indicates that equalisation didn't properly take place or didn't happen at all. I left it plugged in for over an hour afterwards due to phone calls etc but no further charge initiated. I fully expected the car to equalise for at least a short time especially as I've been ultra fast charging for the last 2 months. So I've spoken to my dealer (in the quest for knowledge) who tells me it's not uncommon for equalisation to not happen if you don't take the battery soc down to the low battery warning. He repeated what the car owners manual says that the only way to do it properly is to lower the charge to the low battery warning before commencing the equalisation. That is what they advise. Any other way often produces only partial or random equalisation, their words not mine.

I would add that even when I charge to 80% I've never experienced any balancing of the battery as others on here are saying they experience. I've deliberately been checking for this.

You can see why some of us get confused over this equalisation thing. Differing advice on the forum & differing results from car to car. I know others who have experienced what I have. And I have an auto tech background.

In my case equalisation won't need doing very often as my mileage is 7k pa tops.

Data,

My thoughts on your text.

I would add that even when I charge to 80% I've never experienced any balancing of the battery as others on here are saying they experience. I've deliberately been checking for this.

Equalisation as I understand it only takes place at 100% SOC. This from the owner's manual:

Equalisation Charging
Equalisation charging means that after a normal charging process the battery management system will enter a mode where it will attempt to equalise the charge of every battery cell.
This latest charge to 100% from 31% soc seems to have produced zero equalisation. The car still had regen available afterwards right from the word go. Yet the charge had fully ended at 100%. I'm told this indicates that equalisation didn't properly take place or didn't happen at all
Regen braking has nothing to do with equalisation but does have to do with SOC. At 100% there should be no regen braking - there is nowhere for the generated energy to go. I'm not saying you are wrong, just that this is the theory. This from the owner's manual:

Energy cannot be regenerated or is limited under some conditions, such as:

• N gear is selected (During driving do not coast in N gear) ;

• During torque intervention (SCS or traction control operation) ;

• High voltage battery pack is fully charged;

• High voltage battery pack temperature is too high or too low.

 

[Data]

Data,

My thoughts on your text.

I would add that even when I charge to 80% I've never experienced any balancing of the battery as others on here are saying they experience. I've deliberately been checking for this.

Equalisation as I understand it only takes place at 100% SOC. This from the owner's manual:

Equalisation Charging
Equalisation charging means that after a normal charging process the battery management system will enter a mode where it will attempt to equalise the charge of every battery cell.
This latest charge to 100% from 31% soc seems to have produced zero equalisation. The car still had regen available afterwards right from the word go. Yet the charge had fully ended at 100%. I'm told this indicates that equalisation didn't properly take place or didn't happen at all
Regen braking has nothing to do with equalisation but does have to do with SOC. At 100% there should be no regen braking - there is nowhere for the generated energy to go. I'm not saying you are wrong, just that this is the theory. This from the owner's manual:

Energy cannot be regenerated or is limited under some conditions, such as:

• N gear is selected (During driving do not coast in N gear) ;

• During torque intervention (SCS or traction control operation) ;

• High voltage battery pack is fully charged;

• High voltage battery pack temperature is too high or too low.

Hello Chris, yes to all of that. Am aware of what the book says regarding regen & equalisation etc but so many folks on here are telling me that their cars equalise at more or less any soc. This I had never heard of (at any state of charge) & my dealer was somewhat skeptical of this. Yet some folks are telling me & some others it happens. It's never happened ever on my car though unless I've charged to 100% after getting the 'low battery' warning at 20% soc or less. The fact I still had regen available indicates the battery could be out of balance as energy was still able to be stored.

My thoughts are that the owners manual is totally correct & a proper battery balance cannot be guaranteed to take place unless the soc is at or below the low battery warning level. Preferably just under so as to make sure all the battery cells drop below 20%. I'm going to do another 100% charge shortly but I'll take it down to just under the battery low warning figure. I'll let you know how it goes.

Thanks for your input Chris & everyone. Bye for now.

 

[wattmatters]

Hello Chris, yes to all of that. Am aware of what the book says regarding regen & equalisation etc but so many folks on here are telling me that their cars equalise at more or less any soc.

My MG4 with an NMC 64 kWh battery will do an equalisation no matter the upper SOC setting used. e.g. If I set the battery to charge only to 70%, it will end the charge session with a typical short period of equalisation.

You can do that with NMC cells. Not the case with LiFePO4 which definitely need to be taken to 100% to perform any cell equalisation.

 

[Data]

My MG4 with an NMC 64 kWh battery will do an equalisation no matter the upper SOC setting used. e.g. If I set the battery to charge only to 70%, it will end the charge session with a typical short period of equalisation.

You can do that with NMC cells. Not the case with LiFePO4 which definitely need to be taken to 100% to perform any cell equalisation.

I'm left wondering if there is a software difference that prevents equalisation on the ZS MK2 later models happening at any state of charge? Mine is NMC too yet no equalisation unless I get the low battery warning first before charging to 100%.

Do you have to take your battery down to the low battery warning before charging in order to get it to equalise at 70%?

 

[Coulomb]

Do you have to take your battery down to the low battery warning before charging in order to get it to equalise at 70%?

No, I often charge my MG4 extended range to 80%, and it equalises just fine, even if I haven't gone below 70% since the last charge.

Of course, the ZS facelift model may be different, but I would not have thought so.

 

[aleks57]

No, I often charge my MG4 extended range to 80%, and it equalises just fine, even if I haven't gone below 70% since the last charge.

Of course, the ZS facelift model may be different, but I would not have thought so.

I have a 23 year old ZS with a 72 kW battery and equalization occurs at both 70% and 90% but more time at 100%

 

[fred12345]

Fred, what soc did you start from? Is yours an NMC battery pack?

Mine is 2022 standard range so it should be LFP battery. I only managed to do 10%-100% twice in the past 18 months (got the car second-hand), the rest was from about 30%. I decided not to bother too much with balancing, I'll just do it when convenient - considering I'm still using 3-pin granny charger and not even on full 3kW to avoid burning the socket ...

 

[wattmatters]

Do you have to take your battery down to the low battery warning before charging in order to get it to equalise at 70%?

Nope.