Facelift ZS EV LR battery type.

[drmcw]

There's a manual battery heater switch that I've seen on MG screen shots. Having an idea of pack temperature would be useful to know when best to switch it on, I'd guess?

 

[DrTom]

Firstly let me say again that I am no expert on battery technology but as far as I am aware, the main issue with thermal runaway is not ambient temperature but breakdown of the battery cathode.

The NMC811 has the lowest transition temperature of the NMCs in the attached graph.

Having said that the NCA, which is the battery technology that Tesla use, has a similar transition temperature.

btw NMC is the same as NCM

Anyway, I am sure that MG have all the bases covered and if kept mainly within the 40% -80% Battery Health Mode it will outlast an old git like me ;-)

 

[Gomev]

It is available for the Gen1 via an OBD2 app written by one of the members of this forum but I'm not sure if this will work with the Gen2 model.

Not sure if it is available with any of the other OBD2 apps - maybe someone can tell us.

whichever app you use you need an OBD2 dongle to get that information.

Battery temp is available on the Car Scanner app with a dongle for the Gen1.

 

[Dave]

Simple arithmetic. If the charger is only 50kW then it can and will only deliver (a max of) 50kWh in an hour and that is approx 66% of the battery total. Nothing to do with the car, simply the speed of the charger.

Now if you had said the cars maximum charging speed is only 80kWh, then that would be a little disappointing for a car with that battery size.

The LR ZS EV can charge at 100kW rate. I had a test trial in one before getting mine. On a 150kW charger I saw 82kW charging.
Modern EV batteries don’t degrade the way they used to do. Temperature controlled battery management systems look after them - unless you have a Leaf.

Batteries do degrade with the number of charge cycles performed on them. As such, the larger the battery, and the longer the range, the less it is affected by this phenomenon.

 

[Coulomb]

Batteries do degrade with the number of charge cycles performed on them. As such, the larger the battery, and the longer the range, the less it is affected by this phenomenon.

True. But calendar life, and especially temperature history, seem to be much larger factors.

The MG ZS EV SR seems to be LFP chemistry. Ideal for the subtropical climate where I live (Brisbane, Australia). It rarely (one or two nights a year) gets below freezing here.

 

[Dave]

True. But calendar life, and especially temperature history, seem to be much larger factors.

The MG ZS EV SR seems to be LFP chemistry. Ideal for the subtropical climate where I live (Brisbane, Australia). It rarely (one or two nights a year) gets below freezing here.

Agree, but charge cycles are as important. A longer range results in fewer charge cycles, giving less degradation than a smaller battery. The LFP batteries don’t suffer as much from 100% SOC charging than the NMC batteries. In the LR ZS the user is able to set a limit on the charge level, only going to 100% when needed for a long journey. I believe the SR version always charges to 100% SOC ?

It is generally accepted that Li Ion batteries lose between 15 to 20% of capacity over 500 charge cycles. I know the warranty on the batteries in the MGs is 80,000 while maintaining up to 70% of the original capacity (effectively range).

The SR has a range of around 200 miles.

80,000 / 200 = 400 cycles. Clearly they are expecting the worse and taking into account other issues that can cause degradation as the number of charge cycles is not a limiting factor for the warranty.

The LR has a range of 270 miles. This gives about 300 charge cycles.

Based upon 500 charge cycles:

SR is good for 100,000 miles before it loses 15% to 20% of its range due to charge cycling.

LR is good for 135,000 miles before it loses 15% to 20% of its range due to charge cycling.

The excellent BMS systems provided in BEVs limits other effects such as temperature. The new ZS EV allows the user to warm up the battery before charging as well. Unfortunately, it doesn’t show battery temperature anywhere :-(

Oh, and the Nissan Leaf has no thermal control of the battery other than limiting charge rates if it’s too hot or too cold. It also limits output power if too hot. RapidGate is a good thing to search on.

Here is some interesting reading..

Bjorn Nyland Tests 2019 Tesla Model 3 LR Battery Degradation

Here is an interesting battery degradation test of two years old 2019 Tesla Model 3 Long Range, conducted by Bjørn Nyland.

insideevs.com

 

[BarryH]

That was my disappointment the maximum charging speed , I have seen two articles that have stated a maximum charging speed of 76 kw which to my mind makes me think it's not going to charge any faster than the 1st generation ZS EV and if that is the case I know Bjorn Nyland will do his classic hand on head pose ? I only quoted the 80% charging speed using a 50 KW Charger as that's what MG have advertised , to my mind if it could reach 80% faster why not advertise that , surely it would be an extra selling point for the car. At the end of the day we don't actually know about efficiency and charging until the car has been fully tested , it was just an observation ?

I think you are oversimplifying the situation. You have to understand the Charging curve for your car and its BMS characteristics which varies the rate of charging depending on a host of factors. I have seen rates of 86 kW shortly after the start of a charge when the internal temperature of the battery and SoC have been just right but not with my current update of my BMS. However, if MG were to publish that rate of charge or claim a 30% - 80% charge time based on that rate they would quite rightly be hammered. I think it reasonable to quote a maximum rate at which the charge can be sustained for a reasonable period during the plateau of the charge curve to be reasonable. it would be good to have an indication from MG as to the charge curve so we could see whether our shortest journey times could be had by charging more frequently from 20% to 50% or 30% to 60% for example because I know for sure you'll spend significantly more time on the charger if you do one-stop from 20% to 80% than two stops from 20% to 50% although both would add as many kWh and miles in total.

Theoretically, (providing the battery pack temperature is correctly managed and all other things being equal) a 72 kWh battery pack should be able of supporting a proportionally higher maximum charge rate than a 44 kWh battery pack and therefore the 20%-80% or if you prefer 30%-80% for either size battery should be similar, ie same "C" value. However, this would ignore many other factors such as if the 72 kWh pack is physically the same size as the 44 kWh pack then there is a higher energy density and the cooling demands are higher. Also in the case of the MG ZS (Gen 1) and the MG ZS LR the larger pack has a different construction and a lower pack voltage which tends towards a lower "C" value and extends the charging time required.

[ note on the "C" value: in simple terms, as I understand it, if a pack has a "C" Value = 2 then the national maximum charge rate in kW is 2x the pack capacity in kWh ie 44 kWh pack could in ideal conditions charge at 88 kW and a 72 kWh pack could charge at 144 kW. So we might expect if everything could be scaled-up the ZS LR with around 64% bigger battery might charge at 64% faster rate, but because of the factors I mentioned above and the fact that the HV DC cables and the CCS socket are the same we typically find upgraded battery pack capacity will have a lower "C" value.]

 

[BrianG]

I wonder whether there is any more news on this?

I took to Google and found some interesting research papers which suggest:

NMC 811 batteries are sensitive to charging up to higher voltages, their life may degrade after 300 charges up to 4.5 Volts. much better to charge to 4.3 Volts. So if the LR is using this type it would be interesting to know what is the limit set on the BMS. It would also confirm the need to keep charge below 80% (which would obviously be a reduced voltage)

NMC 523 is more expensive to make and doesn't have quite the capacity of kWh per Kg. But has longevity but needs a BMS and cooling to stop runaway temperatures (NMC 811 also).

LPD is more useful for buses, it is heavier but also has not the ability to give a reliable state of charge. Neither does it work well at lower temperatures below -10. LPD doesn't degrade very quickly at all even after 3,000 cycles. Compared to NMC 811 at 300 full cycles. I couldn't find figures for NMC 523 in a detailed paper but the suggestion was good for 2,000 cycles before loss below 80%.

 

[malachi456]

The new standard range is LFP, while the extended range still uses an NMC battery.