Reduced power mode at 23%

[SDP79]

I have to say that this sounds outrageous. Glad to hear that you are OK but service from all concerned leaves a lot to be desired. I have been reading this thread and am quite alarmed that the car decides to go to low power when if still has power left. Surely this is up to the driver? Like an ICE car does not got in to lower power or limp mode when the fuel light comes on! As for the comment from the dealer that you should not let battery go down below 40% and MG advise not charge to over 80%. Claimed range is 250 miles but according to this theory you can only use 40% so the range is effectively 100 miles. Quite clearly this rationale is total tosh!
I always charge to 100% over night with Octopus Go. I asked on this site if I could limit this to 80% and got told no and asked why I did not know this!
So where are we now? My experience with EV's - let me qualify this. - this MG5LR, is my second and the first a Nissan Leaf 40kw. Only once have I gone down to less than 10% battery charge - this was in the Leaf and there was no limp or lower power mode employed. I got home with my own judgement and great care. My wife has just returned home in the MG and the level was down to 39% - no low power mode employed.
I can only see the need for a low power mode if there is a fault with any of the car s systems - this would be very rare we must assume. Doing this on an ad hoc basis when there is low battery charge is, as described in the quote dangerous.
I am going to continue charging as I currently do. I definitely do not charge when there is 90% or more in the battery.
But I am worried about this sudden switch to lower power mode - Anyone brought this up with MG?

Have just charged MG5LR over night with Octopus Go. Was down to 39% so expected charging to go over the 4hour cheap rate. Surprised this morning to find that car has now gone into equalization/balance charging process! Not expecting this and there appears to be no warning that this was to happen - please tell me where I should be looking if indeed there is a warning. Only about 3 weeks since it did the last equalisation charge and covered around 600 miles. Now says charge will take another 3 hours and that range is currently 178 miles. I will have to stop charging as I need to use car!

 

[Kithmo]

Have just charged MG5LR over night with Octopus Go. Was down to 39% so expected charging to go over the 4hour cheap rate. Surprised this morning to find that car has now gone into equalization/balance charging process! Not expecting this and there appears to be no warning that this was to happen - please tell me where I should be looking if indeed there is a warning. Only about 3 weeks since it did the last equalisation charge and covered around 600 miles. Now says charge will take another 3 hours and that range is currently 178 miles. I will have to stop charging as I need to use car!

It always goes into balancing mode after charging unless you unplug it or turn the charger off.
You can unplug it while it's balancing, no problem.

 

[gaxx21]

Thanks for all your advice and taking the time to reply. In the future I will be a bit more cautious on letting the car get too low. I hadn`t planned it but a 20 minute journey turned into 1 1/2 hours in freezing conditions (taking the car for it`s software update) to the dealer only to be told I couldn`t wait as I hadn`t booked a waiting appointment so I booked one for the following day and was on my way home when the breakdown happened.
I wonder if anyone could verify another thing I ordered the boot mat and rubber mat set when I got the car was told after a couple of weeks they were on back order when I enquired what was going on with them the parts dept. said they had been discontinued?

 

[Alb]

I wonder if anyone could verify another thing I ordered the boot mat and rubber mat set when I got the car was told after a couple of weeks they were on back order when I enquired what was going on with them the parts dept. said they had been discontinued?

A few people have reported this but it doesn't sound logical.

 

[SDP79]

It always goes into balancing mode after charging unless you unplug it or turn the charger off.
You can unplug it while it's balancing, no problem.

Thank you for this, I did not know this and having checked my history on Octopus Go. I am not sure this is correct. The charging has stopped when full during the cheap rate period and obviously I have left the car plugged in. Twice now I have had the balancing experience and the car continues to charge at around 1kWh for several hours. Other times it just gets to 100% during the low cost period of my tariff then stops. Is it perhaps that the system tests itself to see if it needs a balancing/equalising charge? I would be great if the car could display the state of the battery and the need for this balancing charge. Many thanks

 

[Kithmo]

Depends how balanced it is as to whether it does it every time. If it's good then it might only take a few minutes, if it's not it could take hours.
The car will give a message on the dash when it really needs balancing, but MG recommend balancing once a month in the manual.
It's up to you whether you follow the manual or follow the message on the car.

 

[SDP79]

Depends how balanced it is as to whether it does it every time. If it's good then it might only take a few minutes, if it's not it could take hours.
The car will give a message on the dash when it really needs balancing, but MG recommend balancing once a month in the manual.
It's up to you whether you follow the manual or follow the message on the car.

Thank you for this but I am still a bit confused. How does the car show it needs a balancing charge - I cannot recall seeing anything on the dash before this last balancing charge? Similarly what can I do to prompt the car to carry out this balancing charge? I would sooner do this once a month when it suits me rather than have it sprung on me as it has now? I have read what it says in the manual but again it says you must do this equalisation charge but does not say how , other than plugging the car in! Sorry if I am being a bit slow here but so far this balancing thing is very unpredictable from what I can see. Thanks again for your help

 

[Kithmo]

The message will only come up if it's not been balanced for a long time and is well out. If you leave it that long it will take hours to balance, whereas if you do it once a month it will probably take minutes. We only charge SWMBO's 5 about once a month so we let it balance each time we charge it and it usually balances for between 10 and 30 minutes, last time it was around 45 minutes but the temperature was around 0 deg C at the time.

 

[Biccys]

The message will only come up if it's not been balanced for a long time and is well out. If you leave it that long it will take hours to balance, whereas if you do it once a month it will probably take minutes. We only charge SWMBO's 5 about once a month so we let it balance each time we charge it and it usually balances for between 10 and 30 minutes, last time it was around 45 minutes but the temperature was around 0 deg C at the time.

That's reassuring. I guess a payday charge at home for a balance would be simple to remember! Charging everyday from work will be a godsend so the trigger to charge at home and do the balance on payday shouldn't be too tricky.

 

[djenson]

Thank you for this but I am still a bit confused. How does the car show it needs a balancing charge - I cannot recall seeing anything on the dash before this last balancing charge? Similarly what can I do to prompt the car to carry out this balancing charge? I would sooner do this once a month when it suits me rather than have it sprung on me as it has now? I have read what it says in the manual but again it says you must do this equalisation charge but does not say how , other than plugging the car in! Sorry if I am being a bit slow here but so far this balancing thing is very unpredictable from what I can see. Thanks again for your help

The Car will balance almost every time it get the opportunity (Where the charge to 100% has completed and it is still plugged in) It's very import that you let this process complete at least once a month, or more frequently if you rapid charge a lot to avoid scenarios such as what's been posted on here. What i highly suspect has gone on in some cases is the owner has not fully completed the balance charge regularly enough, and 1 or more cells have slowly fallen out of balance. I'm guessing the battery's used in the MG5 Are Lithium Ion cells, And as you already know, The car has many of these cells wired in a series configuration (So the packs total voltage is a sum of all the cell's individual voltages). Lithium ion battery's have quite a strange Voltage To SOC curve compared to "normal" battery, see this image from Scalable Lithium-ion Solutions & Storage System - PowerTech Systems :

As you can see, Normal battery's have quite a linier discharge curve, But Lithium Ion cells have a flat, followed by an extremely steep discharge curve. Now what does this mean for the MG?

Essentially although a cell in the pack might only be a few volts off compared to the other cells under light load, Under more load such as damaging the car to go up a hill, the cell might be asked for more than it initially seems it could handle. This one cell then goes down the steep curve seen in the graph, and lowers the entire pack's voltage significantly, Making the BMS freak out, see the one cell at a very low voltage and turn of the pack to prevent damage, or at worst a fire. Hopefully you can understand how important these balance charges are now.

The thing i have against MG is there way of balance charging. As you might know, the ideal charge range for a lithium ion battery is 20-80%, Charging to 100% puts excess wear on the battery that isn't needed. On a tesla, you can set the target SOC for 80%, it will reach that charge level, then balance the cells, i believe it also does this process without charging. On an MG, you must charge and leave the pack at 100% in order for it to balance. You essentially are forced to unnecessarily damage the battery's in order to balance them. What a stupid design.

 

[SDP79]

The Car will balance almost every time it get the opportunity (Where the charge to 100% has completed and it is still plugged in) It's very import that you let this process complete at least once a month, or more frequently if you rapid charge a lot to avoid scenarios such as what's been posted on here. What i highly suspect has gone on in some cases is the owner has not fully completed the balance charge regularly enough, and 1 or more cells have slowly fallen out of balance. I'm guessing the battery's used in the MG5 Are Lithium Ion cells, And as you already know, The car has many of these cells wired in a series configuration (So the packs total voltage is a sum of all the cell's individual voltages). Lithium ion battery's have quite a strange Voltage To SOC curve compared to "normal" battery, see this image from Scalable Lithium-ion Solutions & Storage System - PowerTech Systems :
View attachment 5891
As you can see, Normal battery's have quite a linier discharge curve, But Lithium Ion cells have a flat, followed by an extremely steep discharge curve. Now what does this mean for the MG?

Essentially although a cell in the pack might only be a few volts off compared to the other cells under light load, Under more load such as damaging the car to go up a hill, the cell might be asked for more than it initially seems it could handle. This one cell then goes down the steep curve seen in the graph, and lowers the entire pack's voltage significantly, Making the BMS freak out, see the one cell at a very low voltage and turn of the pack to prevent damage, or at worst a fire. Hopefully you can understand how important these balance charges are now.

The thing i have against MG is there way of balance charging. As you might know, the ideal charge range for a lithium ion battery is 20-80%, Charging to 100% puts excess wear on the battery that isn't needed. On a tesla, you can set the target SOC for 80%, it will reach that charge level, then balance the cells, i believe it also does this process without charging. On an MG, you must charge and leave the pack at 100% in order for it to balance. You essentially are forced to unnecessarily damage the battery's in order to balance them. What a stupid design.

Hello djenson. Thank you for taking the time to give this very full reply. I agree that the failure to give the opportunity to limit charge to 80% is a fail by MG especially after recommending such a process. As I have said I always charge to 100% over night by use of my ChargedEV smart charger. I suppose you could limit the charge by using the "Granny" charger and using a timer - just make an educated guess about the time needed! Or of course I could set my alarm clock and get up at about 2am to switch off the charger - Yeah right! I have never rapid charged the battery - so far. We are all learning about EV charging and doing our best to understand what is perhaps best practice. So for me I intend to carry on charging to 100% - no choice really, the balance charge will kick in when ever it feels like and I will try to let this complete but there are times that I need the car and this cannot happen. Once again it would be great if the system could let you set a balance charge and therefore comply with their recommendation - come on MG how about it?

 

[Rocinante]

I agree that the failure to give the opportunity to limit charge to 80% is a fail by MG especially after recommending such a process. ..... Once again it would be great if the system could let you set a balance charge and therefore comply with their recommendation - come on MG how about it?

This relates to the New MG ZS EV, and doesn't specifically mention balance charge, but the increased functionality, at least shows MG is heading in that direction. If I was a betting man though I wouldn't bet on this functionality being back dated to older models.

From the MG website:
"An exciting addition to the infotainment system and ownership experience is the addition of iSmart. iSmart allows owners to control various vehicle features from a smartphone app. Pre-heating, charge scheduling, journey planning and vehicle status are just some of the many features of iSmart"

 

[marcopolomt]

The Car will balance almost every time it get the opportunity (Where the charge to 100% has completed and it is still plugged in) It's very import that you let this process complete at least once a month, or more frequently if you rapid charge a lot to avoid scenarios such as what's been posted on here. What i highly suspect has gone on in some cases is the owner has not fully completed the balance charge regularly enough, and 1 or more cells have slowly fallen out of balance. I'm guessing the battery's used in the MG5 Are Lithium Ion cells, And as you already know, The car has many of these cells wired in a series configuration (So the packs total voltage is a sum of all the cell's individual voltages). Lithium ion battery's have quite a strange Voltage To SOC curve compared to "normal" battery, see this image from Scalable Lithium-ion Solutions & Storage System - PowerTech Systems :
View attachment 5891
As you can see, Normal battery's have quite a linier discharge curve, But Lithium Ion cells have a flat, followed by an extremely steep discharge curve. Now what does this mean for the MG?

Essentially although a cell in the pack might only be a few volts off compared to the other cells under light load, Under more load such as damaging the car to go up a hill, the cell might be asked for more than it initially seems it could handle. This one cell then goes down the steep curve seen in the graph, and lowers the entire pack's voltage significantly, Making the BMS freak out, see the one cell at a very low voltage and turn of the pack to prevent damage, or at worst a fire. Hopefully you can understand how important these balance charges are now.

The thing i have against MG is there way of balance charging. As you might know, the ideal charge range for a lithium ion battery is 20-80%, Charging to 100% puts excess wear on the battery that isn't needed. On a tesla, you can set the target SOC for 80%, it will reach that charge level, then balance the cells, i believe it also does this process without charging. On an MG, you must charge and leave the pack at 100% in order for it to balance. You essentially are forced to unnecessarily damage the battery's in order to balance them. What a stupid design.

It is a stupid design i agree. leaf has the same such design. better not to charge to 100% but you need to do so to balance the cells.

im hoping the new zs will balance the cells when the charge limit is set. i generally avoid fully charging my leaf and just keep it between 40 and 80% for local driving. it used to get charged to 100% daily when commuting to work as there was no facility to stop charging remotely.

 

[SDP79]

.............. as there was no facility to stop charging remotely.

Is there any way to stop the MG charging remotely? I have questioned about limiting the MG 80% but I cannot do this from my charger and not from the car as far as I know.

 

[marcopolomt]

Is there any way to stop the MG charging remotely? I have questioned about limiting the MG 80% but I cannot do this from my charger and not from the car as far as I know.

There is with the new model.

 

[Petriix]

It's fairly trivial to work around the only balancing at 100% issue: just charge to 100% occasionally and time it so that you start your journey soon after it finishes balancing. You only have to do it once per month so it's hardly going to cause much damage, especially in comparison to those who charge to full every night.

 

[SDP79]

There is with the new model.

Thanks for this. Do you mean the slight revision that has just been released or the completely revamped model that will come out some time next year? My MGLR Exclusive was only registered in October and does not have this function.

 

[Biccys]

Thanks for this. Do you mean the slight revision that has just been released or the completely revamped model that will come out some time next year? My MGLR Exclusive was only registered in October and does not have this function.

That'll be the facelifted model hopefully coming next year, not the LR version.

 

[SDP79]

That'll be the facelifted model hopefully coming next year, not the LR version.

Thanks

 

[Bricktop X PWR]

I'm resurrecting this thread as it's what came up in my search before I started a new post.

Just a heads up as it caught me out and I was not impressed......

Car had 30% remaining yesterday but I did use 10% to charge my solar battery bank overnight.

So after pre heating the car this morning,
(Minus 2) I had 19% battery.
I forget the exact miles, but it was triple what I needed to reach the charger.

Half the journey is 70mph on the A40.

Not today it wasn't!!!

Nothing worse than asking for power and not getting it!!!
66, 64, 61, 59, fudge!
I thought it might actually bloody stop.

This was now at 6% but I had twice the mileage I needed to get charged.

All I will say is, that I will be very much more wary next time and take the back road to Carmarthen.

I do KNOW why it did it, (me, letting the range get so low in the cold weather) but I am still not amused.
(not amused so uses lol emoji)