Balance Charging....AGAIN!!!!

[drmcw]

Is that because the Gen 1 has an LFP pack?

No the gen 2 SR has the LFP battery. I'd guess passive balancing is used and so only happens at 100% SOC irrespective of battery chemistry.

 

[Lovemyev]

Is that because the Gen 1 has an LFP pack?

No it has the older NMC chemistry on the original ZS EV ( Gen1 ).
Gen 2 has LFP on the standard range, but NMC chemistry on the long range.

 

[pollenface]

I'm not sure where in the manual it says not to use a granny cable.

Nowhere that i know of

 

[MG ZS EV WEST YORKSHIRE]

It doesn't need to be 100% to balance. If for instance you set the charge limit to 80% once it reaches 80% and is left plugged in and charging then it will carry on at very low power draw and balance all the cells to the same voltage but at 80% soc. It is recommended to balance at 100% once every so often I should add.

This isn’t right Andy?? The battery cells can only start to balance once the battery pack has reached its max 100% charge.

 

[AndyL61]

This isn’t right Andy?? The battery cells can only start to balance once the battery pack has reached its max 100% charge.

It is right. The cells can be balanced to a soc below 100% . My MG 4 Trophy balances at 80% or 90% . Definitely 100% right.

 

[Fluffykins]

If it reassures you about using the granny charger for significant charging, that's exactly what I do when I visit my son (just under 400 mile round trip). I plug in at his place with whatever is remaining in the battery, which is about 15% or thereabouts. Recharges to 100% in ca. 17 hours on the granny. I have a nifty little kWh meter from Alibaba.com that I've mounted in a plastic junction box, complete with a decent 13A plug and trailing socket all on 2.5mm² flex cable. The socket passes thru their letterbox. That lets me know how much of their leccy I've had and I can bung them an appropriate number of quids.
The socket and the granny charger I put inside one of those garden extension lead boxes from Lidl, which is water resistant and perfect for storage.

 

[Gadget Geek]

"Best pre-balancing method
The absolute best way to balance cells is connect cells in parallel that are at 80 % SOC or less, and then use a power supply (3.6 V for Phosphate cells, 4.2 V for LiPo or Cobalt cells) to slowly bring all the cells to 100 % SOC."

Ref: Li-Ion BMS - White Paper - Balancing cells by parallelling

 

[Mickky]

Manual says to charge below 3 kW when balance is needed.

I believe using the "granny" at home will solve your issue.

If you're charging on home point @ 7kw the car will get to near 100%then go down to 2.6 kW ISH then 300 Watts for as long as it takes to balance or it did on the MK 1 ZS

 

[MG ZS EV WEST YORKSHIRE]

It is right. The cells can be balanced to a soc below 100% . My MG 4 Trophy balances at 80% or 90% . Definitely 100% right.

How do you know that and where is your evidence the car does what you state ??

 

[AndyL61]

How do you know that and where is your evidence the car does what you state ??

Well I can see on the app when it's balancing. And it is a fact that NMC battery packs can balance at SOC below 100% .

 

[Gadget Geek]

Well I can see on the app when it's balancing. And it is a fact that NMC battery packs can balance at SOC below 100% .

Evidence?

From the handbook, page 181;

Indicative Charging Times for Battery Pack Type 1
Note: These times are only a guide.

From alarm status (the high voltage battery low warning displayed in the instrument pack message centre) to 100% (the high voltage battery state of charge displayed in the
instrument pack message centre) and equalisation, it takes almost 26 hours.

From alarm status (the high voltage battery low warning displayed in the instrument pack message centre) to 100% (the high voltage battery state of charge displayed in the
instrument pack message centre) and equalisation, it takes almost 11.5 hours.

Indicative Charging Times for Battery Pack Type 2
Note: These times are only a guide.

It takes approximately 18 hours to complete an equalisation charge for first use after the vehicle has been parked or stored for a long time.

It takes approximately 9 hours to complete an equalisation charge for first use after the vehicle has been parked or stored for a long time.

 

[Lovemyev]

Well I can see on the app when it's balancing. And it is a fact that NMC battery packs can balance at SOC below 100% .

The Gen1 ZS EV had the NMC battery and it will not commence the balance cycle until it hits 100% fully charged.
The Gen2 long range model has the same battery chemistry, so I am struggling to understand how the balancing process is different TBH.
LFP battery found in the standard range ZS EV Gen 2 actually benefits from charging to 100% because it finds it difficult to accurately predicted the remaining range in the pack.
Tesla Bjorn has made this observation on his many test drives of EV’s.

 

[Martinonline]

I suspect the evidence you require is empirical. I do not know about the ZS whose BMS may well be different to that of the Trophy. When I granny charge my Trophy to 100% and it reaches that level it continues to draw various amounts of current as indicated in the app and an inline power meter until it declares it has finished charging. If I set a lower battery charge limit then I see the same charging behaviour at the set limit. Hence I make the assumption that balance charging is being carried out at the level I have set (but not tested below 60%).

 

[Gadget Geek]

All the information I have found indicates that active balancing can only occur when the cells are brought up to 100% charge. What I have noticed on an 80% charge is that it reaches 80% and then trickles the charge in to 80.9%, which is why the percentage doesn't drop to 79% as soon as you drive off. I have no evidence that this is happening, so I might be wrong, it's just something I have observed in my ZS.

I will plug in my OBDII and use the Thai app next time to see if that gives any more information.

 

[MG ZS EV WEST YORKSHIRE]

It will also balance at soc below 100% . 60, 70, 80 ,90. Will balance if set limit is reached and charger still left on.

I’d be keen to read the source of your knowledge if you could offer it up, oh and whilst you’re at it, what app are you looking at? Battery Power Online | Why Proper Cell Balancing is Necessary in Battery Packs

 

[Martinonline]

I also have noticed that my Trophy's charge does not drop immediately but that may be because I live on a hill and thus regen is active. But, of course, we do not know what the software considers a 1% drop. Is it rounded down or up? Is it Integer values only? More information would be useful.

 

[pollenface]

If you're charging on home point @ 7kw the car will get to near 100%then go down to 2.6 kW ISH then 300 Watts for as long as it takes to balance or it did on the MK 1 ZS

Ah okay. My home charger is only 1.5 to 3.4kw

 

[profdraper]

Well I can see on the app when it's balancing. And it is a fact that NMC battery packs can balance at SOC below 100% .

Can see why this thread has been named 'AGAIN'... very old story, eh?

Battery balancing or equalisation is required on any EV with NMC battery chemistry; a 'slow charger' is needed for this and is acheived by any AC charger, not just a 'granny' (that would indeed drive you nuts given the clacial rate). This can happen from 80-90% but as we see, MG recommends from 80% every six weeks or so. Most other manufacturers currently have this 'split' between LFP & NMC on SR vs LR cars (eg Tesla, Ford) & some manufacturers have NMC only models (eg Volvo XC40, C40).

To answer the question about 'proving' this, you can either sit there in the car and observe this when the charging rate drops to a trickle, or, simply look up the stats on a home 7Kw charger if you have one & this shows that decrease in charge level once past 100%; Wallbox Pulsar Plus 7Kw here and this is exactly what the app shows in a graph.

I owned a gen1 ZE EV (NMC) for a couple of years and that's how it worked like clockwork, charging overnight off-peak every two weeks to 80-90%, then to 100% and balance every 6-8 weeks. This was done by the Wallbox app & gave a record of the stats. When doing a battery balance, this awalys took 90mins or so beyond the 100% charge.

All of which is a bit of faffing about (but also applies to other NMC EVs; a bit silly really IMO - we pay a premium for a 'long range' car, but then find this to some degree crippled by the 80% charging rule). I susbsequenlty upgraded to a gen 2 2022 ZS EV SR LFP. What a brilliant thing - no more rubbish about battery charging rules, but also surprisingly much more refined than the gen 1 (suspension, soundproofing, sound system, motor, torque etc). From the same stats on the charger, it is also clear that it does a balance as well beyond 100% but doesn't seem to take all that long.

So I'm inclinded to stick with LFP chemistry, or forthcoming Sodium etc. BTW the only EV that I'm aware of that uses LFP chemistry right across the range is BYD, they're selling like hotcakes in Australia. The Blade battery is used for any and all ranges & the new Seal in particular now must have the longest range of any LFP battery on the market.

 

[MG ZS EV WEST YORKSHIRE]

Can see why this thread has been named 'AGAIN'... very old story, eh?

Battery balancing or equalisation is required on any EV with NMC battery chemistry; a 'slow charger' is needed for this and is acheived by any AC charger, not just a 'granny' (that would indeed drive you nuts given the clacial rate). This can happen from 80-90% but as we see, MG recommends from 80% every six weeks or so. Most other manufacturers currently have this 'split' between LFP & NMC on SR vs LR cars (eg Tesla, Ford) & some manufacturers have NMC only models (eg Volvo XC40, C40).

To answer the question about 'proving' this, you can either sit there in the car and observe this when the charging rate drops to a trickle, or, simply look up the stats on a home 7Kw charger if you have one & this shows that decrease in charge level once past 100%; Wallbox Pulsar Plus 7Kw here and this is exactly what the app shows in a graph.

I owned a gen1 ZE EV (NMC) for a couple of years and that's how it worked like clockwork, charging overnight off-peak every two weeks to 80-90%, then to 100% and balance every 6-8 weeks. This was done by the Wallbox app & gave a record of the stats. When doing a battery balance, this awalys took 90mins or so beyond the 100% charge.

All of which is a bit of faffing about (but also applies to other NMC EVs; a bit silly really IMO - we pay a premium for a 'long range' car, but then find this to some degree crippled by the 80% charging rule). I susbsequenlty upgraded to a gen 2 2022 ZS EV SR LFP. What a brilliant thing - no more rubbish about battery charging rules, but also surprisingly much more refined than the gen 1 (suspension, soundproofing, sound system, motor, torque etc). From the same stats on the charger, it is also clear that it does a balance as well beyond 100% but doesn't seem to take all that long.

So I'm inclinded to stick with LFP chemistry, or forthcoming Sodium etc. BTW the only EV that I'm aware of that uses LFP chemistry right across the range is BYD, they're selling like hotcakes in Australia. The Blade battery is used for any and all ranges & the new Seal in particular now must have the longest range of any LFP battery on the market.

My MGZSEVLRTC NMC battery only takes a short time to balance when compared to my mki zs EV too

 

[Lovemyev]

My MGZSEVLRTC NMC battery only takes a short time to balance when compared to my mki zs EV too

Our Gen 1 ( pre BMS update ) would take about 30 - 45 minutes on the balance cycle.
After the BMS update the balance cycle would take a minimum of 3 hours to 5 hours.