Battery equalisation

[Museruk]

When I get home I will have to check to see if mine has done any balance charges since I went onto Octopus Intelligent a few weeks ago.

The other alternative is to get the granny charger out and do a balance charge between 11.30 and 5.00am.

I'm currently on a Connected Kerb 7kW and it's been doing a balance for about 50 minutes at 20 watts so it looks like it needed one!

I have now completed my tests to verify that using Intelligent Octopus Go (IOG) tariff (where the charge is typically allowed in 1/2 hr time slots during the night) and you set the MG4 to charge to 100% with sufficient charge add from the Zappi charger, it does not complete a balance charge i.e. have never seen it continue to charge at a low (50w to 200W) rate for a time period after completing the 100% charge.
However, to prove the point, I then did a Boost charge during the day on the Zappi, having charged overnight to give a battery charge level of circa 98% (I know - I'm a tight git when it comes to having to pay the full daytime tariff!).
The result was that it did a perfectly good balancing charge for approx. 40 minutes after 100% charge was reached.
So when I raised this issue with the Zappi support (MyEnergy), they insist that this is an MG issue and I should contact MG - whilst when speaking to the MG dealer (Stoneacre Derby) they stated that MG say that any AC charger, provided it is less than circa 11kW should be able to complete a balancing charge.
So they both deny there is a problem, even though I have sent the charge plots of both IOG charging to 100% (but no balance) together with the Boost charge plots during the day (balance charge, no problem)!

I guess that now we have the choice of doing what I did i.e. charge to just below 100% using IOG, then before setting off, first thing in the morning, add a boost charge to reach over 100%, whereupon the MG will perform a successful battery balance procedure or:
Simply use the granny charger to complete the balance during the low night-time tariff (both should work perfectly well).
Since the amount of energy used during the day to complete a balance is relatively small, this should not add a significant cost - however it's still very annoying that both Octopus / Zappi and MG seem to deny that there is an issue! Dohh!
Of course since I rarely use DC chargers, I should only need to do this procedure say once a month - hence not really a big issue. Just annoying that nobody at Octopus or MG seems to accept there is an issue with achieving a battery balance when charging with IOG!

 

[Tight Git]

I have now completed my tests to verify that using Intelligent Octopus Go (IOG) tariff (where the charge is typically allowed in 1/2 hr time slots during the night) and you set the MG4 to charge to 100% with sufficient charge add from the Zappi charger, it does not complete a balance charge i.e. have never seen it continue to charge at a low (50w to 200W) rate for a time period after completing the 100% charge.
However, to prove the point, I then did a Boost charge during the day on the Zappi, having charged overnight to give a battery charge level of circa 98% (I know - I'm a tight git when it comes to having to pay the full daytime tariff!).
The result was that it did a perfectly good balancing charge for approx. 40 minutes after 100% charge was reached.
So when I raised this issue with the Zappi support (MyEnergy), they insist that this is an MG issue and I should contact MG - whilst when speaking to the MG dealer (Stoneacre Derby) they stated that MG say that any AC charger, provided it is less than circa 11kW should be able to complete a balancing charge.
So they both deny there is a problem, even though I have sent the charge plots of both IOG charging to 100% (but no balance) together with the Boost charge plots during the day (balance charge, no problem)!

I guess that now we have the choice of doing what I did i.e. charge to just below 100% using IOG, then before setting off, first thing in the morning, add a boost charge to reach over 100%, whereupon the MG will perform a successful battery balance procedure or:
Simply use the granny charger to complete the balance during the low night-time tariff (both should work perfectly well).
Since the amount of energy used during the day to complete a balance is relatively small, this should not add a significant cost - however it's still very annoying that both Octopus / Zappi and MG seem to deny that there is an issue! Dohh!
Of course since I rarely use DC chargers, I should only need to do this procedure say once a month - hence not really a big issue. Just annoying that nobody at Octopus or MG seems to accept there is an issue with achieving a battery balance when charging with IOG!

It's not strictly necessary to use the granny to complete the balance charge - you can use the Zappi provided you can either start a boost charge at 11.30pm and just let it keep going until the car switches it off or take it off IO and just set it for a scheduled charge within the 11.30-5.30 cheap period.

 

[Surfdog]

Glad you have came to the same conclusion as myself. A lot of owners think that by charging to 100%, a balance charge is automatically undertaken, which it is not. This issue has been discussed on IOG facebook forum and there does not appear to be a solution. As I previously said, my Ohme balanced charged no problem prior to IOG. IOG seem to have a minimum charge rate where if it falls below about 1kwh for more than a minute or so it stops the charge. Like you, I will now have to try the granny charger method which is a nuisance.
If Octopus allowed, say, 100w charging for a couple of hours after a 100% charge and this was a daytime charge slot, then they are going to have to provide you with off peak rates for this 2 hour balance charge period and would cost them income. This is just a theory I have as to why the do not allow charging below 1kw.

I have now completed my tests to verify that using Intelligent Octopus Go (IOG) tariff (where the charge is typically allowed in 1/2 hr time slots during the night) and you set the MG4 to charge to 100% with sufficient charge add from the Zappi charger, it does not complete a balance charge

 

[Museruk]

Finally achieved a balance charge using IOG overnight!
On this occasion I set IOG to put 50% charge into the car (it actually only needed circa just over 40%); this was to ensure that the Zappi charger didn’t terminate the charge rather than the car at reaching 100%.
Here is the charge plot:

 

[Museruk]

As far as I can make out, the only difference this time (where it worked and achieved a balance charge) is that Intelligent Octopus scheduled a much longer charge duration this time (I assume due to my request for a 50% charge to be added) as opposed to previous occasions when I only requested a relatively small charge add (10 to 15%).
So there was a good few hours allotted by IOG - and it then seems to work!

 

[Data]

I know this is an old thread but incase someone stumbles across it I thought I would add comment concerning battery equalisation using Octopus Intelligent Go. It's possible by now some other thread may already have disclosed what I am saying below. There is still some confusion on this subject so planting this info around the site may help.

Firstly, I use Octopus IG. It's great! However I've found that when about to do a battery equalisation charge it's imperative to turn off OIG smart charging. If you do not OIG may interrupt your charge at some point during the night for a short period & then restart (it's happened to many of us) which then cancels the equalisation charge even though the car may still charge to 100% but without an equalisation taking place. If switched on smart charging normally stops the charge as soon as 100% is achieved without the cars BMS being able to control the equalisation part of the charge. For a proper equalisation charge to happen the cars BMS must be in charge according to MG support, not OIG. Once 'Smart Charging' is turned off you can manually start the charge whenever convenient or schedule it in the MG app or your chargers app. The car of course will finish the charge in its own good time! This is what many of us have found. Hope this helps someone.

 

[Tight Git]

I know this is an old thread but incase someone stumbles across it I thought I would add comment concerning battery equalisation using Octopus Intelligent Go. It's possible by now some other thread may already have disclosed what I am saying below. There is still some confusion on this subject so planting this info around the site may help.

Firstly, I use Octopus IG. It's great! However I've found that when about to do a battery equalisation charge it's imperative to turn off OIG smart charging. If you do not OIG may interrupt your charge at some point during the night for a short period & then restart (it's happened to many of us) which then cancels the equalisation charge even though the car may still charge to 100% but without an equalisation taking place. If switched on smart charging normally stops the charge as soon as 100% is achieved without the cars BMS being able to control the equalisation part of the charge. For a proper equalisation charge to happen the cars BMS must be in charge according to MG support, not OIG. Once 'Smart Charging' is turned off you can manually start the charge whenever convenient or schedule it in the MG app or your chargers app. The car of course will finish the charge in its own good time! This is what many of us have found. Hope this helps someone.

My normal method of trying to prevent this is to set the end time at 04:00 and then just after 23:30 hit bump charge. However sometimes they do brief stoppages before 23:30 - I reckon probably 80% work properly without these brief pauses.

As an example I started a charge from 4% last week at 18:45 to add 100% by 04:00 (SE SR) and it did a full uninterrupted charge.

 

[Data]

I think there is also a bit of a difference in car software between the MG4 & ZS EV. My car is the ZS. My car requires charging all the way to 100% before the equalisation charge can start. Some MG4 owners say their cars can equalise at a lower soc, albeit it won't be a full & proper equalisation & BMS balance. It may also depend on the HV battery type ie: NMC or LFP. Anyway that's all another story. I am just talking here about switching off smart charging for the equalisation to properly taking place.

 

[dsr]

I am not a technical person, so my apologies if this is a stupid question, but is there a way of knowing whether a charge to 100% has balanced the battery or not balanced it?

 

[Tight Git]

I am not a technical person, so my apologies if this is a stupid question, but is there a way of knowing whether a charge to 100% has balanced the battery or not balanced it?

Most EVSEs will show you how much charge is going into the battery - if you look at mine from last night up to midnight the rate gas dropped down to about 200w from the normal 7kW and that is balancing happening. It can take up to about 40 minutes on the LFP battery.

 

[GaryMG4]

I think there is also a bit of a difference in car software between the MG4 & ZS EV. My car is the ZS. My car requires charging all the way to 100% before the equalisation charge can start. Some MG4 owners say their cars can equalise at a lower soc, albeit it won't be a full & proper equalisation & BMS balance. It may also depend on the HV battery type ie: NMC or LFP. Anyway that's all another story. I am just talking here about switching off smart charging for the equalisation to properly taking place.

If I'm doing a full calibration charge, <10-100% I turn off IOG and straddle the 6 hr 7p slot, although I'm not sure where the information came from that it needed to be uninterrupted. Normally I'll let the car stop the charge at 80%, this will do a cell voltage balance which is evident by the Zappi reporting a declining charging power of < 1kW whilst the car stays at 80%, this still happens if smart charge is off and I'm only using eco+ on the Zappi (solar only which usually does get interrupted by clouds). Whereas the Kia Niro will only balance at 100%, at 80% it just stops the charge.

 

[Data]

I am not a technical person, so my apologies if this is a stupid question, but is there a way of knowing whether a charge to 100% has balanced the battery or not balanced it?

There are no stupid questions dsr. Yes, as Tight Git says you can check your charging curve map on your charger or car. It will show a gradual reduction in kw's going into the battery from 7kw's gradually down to 1kw & 600w, 300w etc etc until the charge is completed. Mine takes 10-12 mins in total to do this part of the equalisation but can take longer if it hasn't been done for a while. Give it a try. On my ZS I have to drop the state of charge (soc) down to just below 20% soc & get the low battery warning before doing the equalisation charge otherwise the battery management system won't initiate the equalisation charge. On many MG4's & some earlier ZS's apparently you don't need to do that according to some on this forum, but check your owners manual on that. Good luck!

 

[ReintjeWA]

There are no stupid questions dsr. Yes, as Tight Git says you can check your charging curve map on your charger or car. It will show a gradual reduction in kw's going into the battery from 7kw's gradually down to 1kw & 600w, 300w etc etc until the charge is completed. Mine takes 10-12 mins in total to do this part of the equalisation but can take longer if it hasn't been done for a while. Give it a try. On my ZS I have to drop the state of charge (soc) down to just below 20% soc & get the low battery warning before doing the equalisation charge otherwise the battery management system won't initiate the equalisation charge. On many MG4's & some earlier ZS's apparently you don't need to do that according to some on this forum, but check your owners manual on that. Good luck!

The NMC batteries will balance the cells at whatever target is set for charging to stop, but a BMS calibration should still be <10% - 100% ideally. I think the MG4 with LFP only balance at 100%

 

[Data]

The NMC batteries will balance the cells at whatever target is set for charging to stop, but a BMS calibration should still be <10% - 100% ideally. I think the MG4 with LFP only balance at 100%

It seems to be the other way round now. This has been confirmed by the owners manual & MG tech support. I've tried it every way & the ZS has to get the low battery warning before the BMS will initiate an equalisation. I think the earlier ZS's were different & the MG4's seem to be a mix of results depending on battery type. I'd be guided by your owners manual whatever car you have.

 

[dsr]

There are no stupid questions dsr. Yes, as Tight Git says you can check your charging curve map on your charger or car. It will show a gradual reduction in kw's going into the battery from 7kw's gradually down to 1kw & 600w, 300w etc etc until the charge is completed. Mine takes 10-12 mins in total to do this part of the equalisation but can take longer if it hasn't been done for a while. Give it a try. On my ZS I have to drop the state of charge (soc) down to just below 20% soc & get the low battery warning before doing the equalisation charge otherwise the battery management system won't initiate the equalisation charge. On many MG4's & some earlier ZS's apparently you don't need to do that according to some on this forum, but check your owners manual on that. Good luck!

Thank you. I will give the charging curve map a look = something new for me.

 

[GaryMG4]

I wonder if there is a bit of a mix up of terminology here. An equalisation or balance charge is where the BMS will charge/discharge individual cells to balance the voltages across the pack. This is to ensure when discharging a.n odd cell doesn't go into deep discharge and potentially fail. With the MG4 NMC battery this will happen when the battery reaches the required %age, the car will continue 'charging' at a reducing rate until the car declares EV Full (Zappi message) and terminates the charge. During this time the %age and range do not change even though it may sit there for an hour 'charging'.
A BMS calibration charge is where you start from <9% (MG4 NMC) to 100%, this allows the BMS to know the actual capacity of the pack improving the accuracy of the GoM.
BTW this is not the case with 71 plate Kia which only does a balance ay 100%, so does appear to be BMS software dependent .

 

[Rolfe]

I have not found a problem with a normal balance charge at the end of a charging session even if Octopus has interrupted the charge. I can't see why that would make any difference.

The <10% to 100% calibration charge ought to be performed in one single charge because of the hysteresis curve. If the charge is interrupted the car doesn't know whether it's on the charging or discharging side of the curve. Octopus gets in the way of this if it decides to interrupt the charge.

Another forum member told me how to get round this and still get the 7p rate for the whole charge. I plug the car in at my convenience, but have Smart charging turned off in the Octopus app. I want it to start at 11.30 because this is convenient for the way I run my system, but you could start earlier if you want. I make sure the Zappi's own scheduled charge is deleted. At 11.30 I turn on Smart charging and ask for 100% to be delivered by 7.30am. This always works. Asking for less than 100% doesn't work.

This is for the 51 kwh battery, you probably need to set a longer window for the larger batteries. Also, check from the iSmart app when the charge is set to end. If it's too close to the end of the Smart charge window so that balancing might not complete, simply set a scheduled charge on the Zappi from a time before the end of the Octopus Smart charge window, and going on for maybe an hour to make sure it all happens. The car takes so little while it's balancing that it doesn't matter if this is at peak rate (in my case it will take it from the home battery).

 

[ReintjeWA]

It seems to be the other way round now. This has been confirmed by the owners manual & MG tech support. I've tried it every way & the ZS has to get the low battery warning before the BMS will initiate an equalisation. I think the earlier ZS's were different & the MG4's seem to be a mix of results depending on battery type. I'd be guided by your owners manual whatever car you have.

Not sure why it seems to be the other way around now. In the MG4 the NMC batteries can equalise at the set finish %, and the LFP can’t set a % other than 100%, which is where the battery can equalise its cells.

This is the MG4 forum so confusing the facts with other models seems counterproductive.

 

[Data]

I wonder if there is a bit of a mix up of terminology here. An equalisation or balance charge is where the BMS will charge/discharge individual cells to balance the voltages across the pack. This is to ensure when discharging a.n odd cell doesn't go into deep discharge and potentially fail. With the MG4 NMC battery this will happen when the battery reaches the required %age, the car will continue 'charging' at a reducing rate until the car declares EV Full (Zappi message) and terminates the charge. During this time the %age and range do not change even though it may sit there for an hour 'charging'.
A BMS calibration charge is where you start from <9% (MG4 NMC) to 100%, this allows the BMS to know the actual capacity of the pack improving the accuracy of the GoM.
BTW this is not the case with 71 plate Kia which only does a balance ay 100%, so does appear to be BMS software dependent .

Yes, that's all correct Gary for many of the MG4's & some earlier ZS cars. I have the long range ZS with an NMC battery (72.6kwh). I bought mine new at the start of this year. These cars are unable to equalise or balance unless the low battery warning comes on at 20% soc. Best to take it down to 18% soc to be sure all cells are below the threshold. After that the BMS takes full control of the charge. Interruption of the charge at anytime prevents the BMS from controlling the equalising charge as when the power comes on it won't remember what it was asked to do, surprisingly I thought. From experience, this seems to be the case. No equalisation if the charge is interrupted on these cars. It seems the software on these later ZS's is somewhat different to MG4's & earlier ZS's. However, it's not a problem & easy to do.

This is the MG4 forum so confusing the facts with other models seems counterproductive.

Only came about because some folks were making incorrect sweeping statements. The aim was to inform that some MG4's don't seem to equalise at any soc according to other battery equalisation threads & I made the point it was similar in the ZS world. Some cars can & later cars cannot. What software the cars have seems to be the key, especially for the NMC batteries.

 

[ReintjeWA]

Only came about because some folks were making incorrect sweeping statements. The aim was to inform that some MG4's don't seem to equalise at any soc according to other battery equalisation threads & I made the point it was similar in the ZS world. Some cars can & later cars cannot. What software the cars have seems to be the key, especially for the NMC batteries.

The most recent incorrect sweeping statement was you saying that it seems to be the other way around (supposedly confirmed by MG tech support), i.e. NMC can only equalise at 100% and LFP at any set percentage, which is absolutely inaccurate for the MG4. This may be a correct statement for the ZS, but again, that's not helpful for MG4 owners looking for the right information.

The only thing I can recall that may have been confusing, is that some SE SR owners saw an option to set their charge percentage but this was identified as being a bug, and software updates fixed this as far as I'm aware.