Battery balancing and battery life - fast or slow charging?

[Corindikev]

Nope, the wheels are still at the bottom not on the roof.

 

[Corindikev]

Slow is up to 11kW & fast above 11 to about 43kW & Rapid 50kW and above.

 

[Data]

Yes, that what your manual says. But over here it's Granny = slow
Fast charger = 7 to 22 kW
Ultra fast = 50 - 350 kW.

It's all meaningless as it makes no difference to anything.

 

[Rolfe]

Granny - slow
Fast - AC other than 13A plug
Rapid - DC
Ultra-rapid - DC above something like 100 kw

They're going to have to think of more names if they haven't already.

 

[Data]

Very interesting that the manual says the only way you can do a 'battery balance' is to slowly & fully charge the battery! Just as my garage & MG said. 80% doesn't do it.

 

[5teep]

My car is fully charged every night at 3.5 kW and balancing takes care of itself.

 

[Martinonline]

@GrayCat reported at post#81 on page 5 of the thread MG4 Balancing/Equalisation a photo of the screen showing balancing at 90%.

As I have posted before, see image below:

 

[Data]

That's rather interesting Martin. However, according to MG that doesn't do a full & proper balance. As per the manual & their technical support, that is only possible if it's charged to 100%. In reality I wonder how much difference it makes doing it at 90%?

 

[fred12345]

As long as the charge is not higher than 7kW, it's OK for balancing

 

[decrep]

Seems like we are still getting different models and different battery chemistry mixed up here.
With manuals saying different things also.
It's a tangled web of confusion, I apologise if I've started it.

 

[aleks57]

1 All AC is slow charging, all DC is fast charging. 2 Batteries are made by another manufacturer, mainly CATL and they also install BMS, MG only installs it in the car. 3 When I had MG MK1 balancing only occurred at 100% charge, this is a current of 350-400 mA power about 0.3 kW. Now I have MK2 and balancing occurs at 80% and at 90%, current 400 mA per phase and power 0.4 kW and time from 4 to 5 minutes. At 100% the same parameters only the time is longer. 4 For information, when charging 16A, the real current will only be 14.7A, 10A - 9.2A, 8A - 7.2A. The measurements were made on several cars and were the same everywhere.

 

[Data]

Seems like we are still getting different models and different battery chemistry mixed up here.
With manuals saying different things also.
It's a tangled web of confusion, I apologise if I've started it.

No, you didn't start it! This is a great thread. Very informative & we are hearing about lots of opinions & lots of facts. I've learned some stuff too.

Although I think there is one outstanding fact that folks keep missing & which is not only in the manual but is told to us by MG technical support & battery experts. That is you cannot do a full & proper battery balance unless you charge it to 100%. The battery has to be 'full' for this to happen. It then also not just balances the battery correctly but allows the BMS to properly calibrate your full range.

Of course some can balance at 80 or 90% but it's not a full & properly accurate balance & probably doesn't calibrate anything very well either, but better than nothing I'm sure. The battery experts are telling us this doesn't happen unless the battery is completely full. So far, I'm with the experts on this. Again, it's all very interesting.

 

[aleks57]

No, you didn't start it! This is a great thread. Very informative & we are hearing about lots of opinions & lots of facts. I've learned some stuff too.

Although I think there is one outstanding fact that folks keep missing & which is not only in the manual but is told to us by MG technical support & battery experts. That is you cannot do a full & proper battery balance unless you charge it to 100%. The battery has to be 'full' for this to happen. It then also not just balances the battery correctly but allows the BMS to properly calibrate your full range.

Of course some can balance at 80 or 90% but it's not a full & properly accurate balance & probably doesn't calibrate anything very well either, but better than nothing I'm sure. The battery experts are telling us this doesn't happen unless the battery is completely full. So far, I'm with the experts on this. Again, it's all very interesting.

you think correctly, only at 100%

 

[Martinonline]

@Data, you have stated that you have been told that to achieve a proper balance you need to have seen the low battery warning so that the BMS can control the charging and then take to 100%. You quote 20% as the trigger for the warning.

My Trophy has been down to below 10% in the past but I have never seen the warning in the 2 years I have owned the car. (Note I have never seen the battery level colour changes either.) Is this warning that which is referred to in the manual extract below?


The manual implies that if the BMS has not triggered the warning then equalisation must have occurred within the allowed time limit. I normally keep my car's battery between 30% and 80% allowing it to 'balance' every charging instance. I now don't do long distances so charging to 100% can be up to 6 months apart. I have not done a <10% to 100% charge in over a year but my GOM has been as accurate as I would expect it.

 

[Data]

Can I ask what battery you have. NMC or LFP? Is your Trophy the ZS short range or long? Is it the MK2 facelift model?

I believe from your description you have a short range LFP model. If that's the case & you are slow charging most of the time then some amount of balancing of the battery will have been taking place. But it's not going to be a proper battery balance & calibration unless you fully charge the battery to 100% once & a while. A full & proper battery balance only takes place at 100%. It does say that in your manual somewhere. Strange you are not getting a low battery warning. This might mean your battery is very unbalanced &/or the battery BMS is very out of calibration. That may be the case if you haven't done a full & proper battery balance & calibration for a long time. LFP needs this more often than NMC. Would recommend you do that & purposely take your car for a good drive afterwards to avoid leaving it on 100% for too long. Let us all know how you get on if you do that please. Thanks.

 

[Martinonline]

As you can see from my profile I am driving an MG4 Trophy with an NMC battery.

I do not believe this discussion is limited to ZS owners so it may be that your understanding is limited to your car and mine is limited to my car.

I would have thought that if my BMS is wildly out of calibration then it would be clearly indicating it as set out in my MG4 manual extract above. Otherwise what is the purpose of that low battery warning requiring equalisation?

And if everything is out of kilter then the GOM would be showing irrational results but the percentage changes are matched with the displayed miles/kWh.

I will charge to 100% to see if it makes any difference but I am not yet planning a 54 mile journey to lose 20% so it will have to wait.

2 more images:

 

[siteguru]

Does your Charge Settings screen always show in km rather than miles?

 

[Data]

As you can see from my profile I am driving an MG4 Trophy with an NMC battery.

I do not believe this discussion is limited to ZS owners so it may be that your understanding is limited to your car and mine is limited to my car.

I would have thought that if my BMS is wildly out of calibration then it would be clearly indicating it as set out in my MG4 manual extract above. Otherwise what is the purpose of that low battery warning requiring equalisation?

And if everything is out of kilter then the GOM would be showing irrational results but the percentage changes are matched with the displayed miles/kWh.

I will charge to 100% to see if it makes any difference but I am not yet planning a 54 mile journey to lose 20% so it will have to wait.

2 more images:

View attachment 37272View attachment 37273

Thanks very much Martin for coming back. Unfortunately your profile doesn't show what car you have, just trim level, so I assumed you were a ZS owner as it's the ZS part of the forum. You are certainly right, no one is precluded from this thread about batteries. The more the merrier.

I do understand the type of battery your car uses. It's the LFP type & it require balancing quite often. Twice a month is fairly normal if you are doing average mileage (currently 7,800 in the UK) but you can do it less if your mileage is lower. I guess you'll have to try the 100% balance & recalibration to find out what effect it may have. For the rest of us it would be great to hear what you experience when you do that. I've heard previously that if you haven't done this regularly it can take two or three goes to bring the system back to full balance etc. My dealer has said to my MG5 owning friend with an LFP battery, balancing needs doing even if you think it doesn't need it. My friend is low mileage (4-5k per year) & they suggested doing a full balance & calibration charge to 100% every 4-6 weeks. You may find that after doing a full balance you will start to get the warnings at low soc.

Anyway, good luck & follow up on this if you can.

 

[Martinonline]

@Data, I do not think this thread is in the ZS Forum but rather it appears to me to be in the General Chat Forum. I note that the Similar Threads list at the bottom of the page does have a majority of ZS links.

I am confused by the first sentence of your second paragraph. Are you referring to my car's battery, or is it a typo that implies it and you are just making a statement about LFP batteries in general?

Lastly, could you please tell me how, other than seeing the the low battery warning message, that the car has been fully equalised? I will try in September when I'm due to travel over 50 miles in one go.

I thought my profile shows me driving an MG4 with Trophy Mk1 added to my location. Is that not what you see?

@siteguru, the images I posted are not from my car but from posts to the MG4 forum.

 

[siteguru]

Thanks very much Martin for coming back. Unfortunately your profile doesn't show what car you have, just trim level, so I assumed you were a ZS owner as it's the ZS part of the forum.

I do understand the type of battery your car uses. It's the LFP type & it require balancing quite often.

Erm ... this is the General Chat part of the forum.

And Martin's images show that he has a target charge level setting ... as he has an MG4 then his car has an NMC battery pack, not LFP.