First year battery capacity loss.

[PercyMinder]

MG4 SE SR

I have just had my first years’ service at 5,000 miles - it seems I have lost 6% battery capacity over the year. What are others owners experience?

 

[Jomarkh]

Do you do a lot of DC rapid charging and how often do you carry out a battery balance?

 

[MuzGB1970]

That's interesting that they performed a SoH check on your first service, on my service log it's listed for a B service (2nd year) only.

 

[PercyMinder]

Do you do a lot of DC rapid charging and how often do you carry out a battery balance?

Very little fast charging (I think 5 x in total). I try to balance each month but didn't start until it was about 4 months old.

 

[pollenface]

I'm not interested in SOH.

I don't want heart palpitations.

 

[Tight Git]

According to Tesla owners with the same battery type it drops quite a lot early on (first year or two) then slows down so I wouldn't worry too much about it!

 

[siteguru]

Very little fast charging (I think 5 x in total). I try to balance each month but didn't start until it was about 4 months old.

It is recommended to balance the SR (LFP) battery each week.

 

[Rolfe]

I balance it every time it's on an AC charger.

 

[PercyMinder]

It is recommended to balance the SR (LFP) battery each week.

ATM I'm only charging every week.

 

[Rolfe]

How are you charging? If you're on any sort of AC charger you should simply be leaving the car to get to 100% and then half an hour longer to balance, every time.

 

[spence7788]

That’s surprising, I’m sure nothing to worry about or indeed do we know just how accurate MG diagnostics are I’m not sure but you’d think they’d be using the same tools.

My August 22 built, Nov 22 delivered Trophy (Obv diff battery chemistry) was apparently at 100% SOH at 15 & 30k services, most recent 45k service it had dropped to 99% SOH, only seen a DC charger once mind & I charge to 100% daily however it’s just getting there when I leave, I’m pretty anal with battery SOC ?.

I’ve done this the last few years with my Leaf & MG5 and never noticed any degradation at all even with high miles.

 

[hharzel]

I didn't know not balancing weekly is detrimental to battery health. I thought charging it to 100% daily is worse, as is the case with all li-ion type batteries.

Can LFP be forced to balance below 100% ?

 

[SimonS]

The issue is not about charging it to 100%. It’s leaving it sitting at 100% that is the problem.

 

[hharzel]

The issue is not about charging it to 100%. It’s leaving it sitting at 100% that is the problem.

True, especially for NMC. In the manual it says that equalization should be performed monthly, however.

 

[PeteC]

MG4 SE SR

I have just had my first years’ service at 5,000 miles - it seems I have lost 6% battery capacity over the year. What are others owners experience?

My Trophy (different battery chemistry) was at 99% SoH at a year old and around 10,000 miles.

 

[Coulomb]

it seems I have lost 6% battery capacity over the year.

Remember also that degradation will appear worse in cold weather. You may get a lot of that back in summer.

I didn't know not balancing weekly is detrimental to battery health.

I'm pretty sure it's at least mostly reversible, at least. An unbalanced battery has lower effective state of health than a balanced one.

I thought charging it to 100% daily is worse, as is the case with all li-ion type batteries.

I think that's technically true, but I've stopped pointing it out. The effect is quite small with LFP because the voltage is so low (3.6 versus 4.2 V). 4.2 V is much further into the zone that gives the particles enough energy to do the bad things, and the effect is exponential.

Can LFP be forced to balance below 100% ?

I don't believe so, because at about 95% SoC, there is one of those nearly ruler-flat voltage versus SoC areas of the charge curve. From about 20% to 95%, apart from one very small rise at around 76% SoC, there isn't enough voltage change with SoC to figure out which cells need to be slightly discharged.

 

[Rolfe]

I didn't know not balancing weekly is detrimental to battery health. I thought charging it to 100% daily is worse, as is the case with all li-ion type batteries.

Can LFP be forced to balance below 100% ?

There is a genuine problem of people with LFP batteries reading advice meant for NMC batteries and thinking it applies to them. I thought the same until I was put right. Charging to 100% every time you charge (on an AC charger) will not harm an LFP battery in any way you'd notice, and it is what we are told to do by MG.

MG actually took the trouble to remove from the apps of SR owners the ability to set a charge limit, so as to stop them treating the batteries as if they were NMC.

There is no way I know of to balance an SR below 100% (in contrast to the LR). You can't set a charge limit below 100%, which is what you have to do to in the LR to get it to do a partial balance at 80%. And you wouldn't want to. You have a battery you can use the whole range of the whole time, and not worry about charging it up to full and leaving it there.

Watch this video. It's really reassuring for owners of LFP and NMC batteries alike.

 

[Archev]

There is a genuine problem of people with LFP batteries reading advice meant for NMC batteries and thinking it applies to them. I thought the same until I was put right. Charging to 100% every time you charge (on an AC charger) will not harm an LFP battery in any way you'd notice, and it is what we are told to do by MG.

MG actually took the trouble to remove from the apps of SR owners the ability to set a charge limit, so as to stop them treating the batteries as if they were NMC.

There is no way I know of to balance an SR below 100% (in contrast to the LR). You can't set a charge limit below 100%, which is what you have to do to in the LR to get it to do a partial balance at 80%. And you wouldn't want to. You have a battery you can use the whole range of the whole time, and not worry about charging it up to full and leaving it there.

Watch this video. It's really reassuring for owners of LFP and NMC batteries alike.

Excellent I must watch his Skye holiday video again. Where Euan and his lovely wife Travel to and around the Isle of Skye in a very low range car. That’s what convinced me to go electric driving.

 

[securespark]

What is this "balance" of which you speak?

I have seen a reduction in range once charged to 100%. It used to be 280, but has now dropped to 218.

Or is this a different thing?

Bamboozled by the wizardry of this new-fangled electrickery.....

 

[Archev]

What is this "balance" of which you speak?

I have seen a reduction in range once charged to 100%. It used to be 280, but has now dropped to 218.

Or is this a different thing?

Bamboozled by the wizardry of this new-fangled electrickery.....

The battery is made up of many individual cells which need periodical adjustment to ensure they can each hold the same amount of charge. The only way that can be checked and adjusted is via the BMS (Battery Management System). This bit of the trickery works away automatically in the background but can only ensure every cell contains roughly the same charge when it can see them all full. So every month or two it needs to be connected to the AC power supply (eg granny or house charger) So that it can methodically check the contents. It takes time to go round and balance each cell as close as possible to all the others.
So just leave it to get up to 100% occasionally and allow a bit of time beyond that and it sorts itself out. When you set off to drive press the OK button on the right hand side of the steering wheel (mk1MG5) for a few seconds and the range mileage will adjust to give a more accurate guesstimate of what’s available.
Then jump in and go for a long drive with maximum range - OR as I do - go off for a coffee and cake somewhere to bring it back within the 20 - 80% range.
So charge slowly to 100% - coffee and cake - car at 80%.