Lithium NMC VS LIFEPO4

[PristDean]

So apparently the standard range MG4 uses LFP and long range versions use NMC.

Having read through some articles such as the one below, it appears LFP is the superior battery, Should we be concerned about long range models using NMC ?

LITHIUM NMC VS LIFEPO4 – HOW TO CHOOSE THE BEST ONE FOR YOUR NEEDS

 

[Cocijo]

Ayoull is very knowledgeable on this subject and has provided some extremely useful posts.

 

[Lovemyev]

Important to chose the size / type of HV battery that suits your usage pattern really.
E.G. - Why would you buy a long range model to consistently drive 20 miles per day.

 

[stevegus]

One thing ive learned. You can

1. Order your car and wait till it arrived and then enjoy it.

2. Research every possible problem, many of which are amped up in this forum, and worry about everything.


The NMC is proven technology used in current evs including teslas and you have an 8 year warranty and probably wont even have it 8 years

 

[Stageshoot]

We did 76k miles in our first Hyundai Kona. It was charged to 100% every night and rapid charged at least once every day

When it went back to Hyundai at 76k miles and 18months they did a battery report on it and it was still 100% with no visible degradation (like the Mg has a buffer that hides any initial degradation)

(And that was with a cooling fault that was stopping it cooling properly during rapid charging )

So I have no qualms using and abusing NMC full to empty

 

[PristDean]

Thanks all, just found the '0% SoC' thread with some very useful info in it, Ayoull is obviously very knowledgeable in this area and appreciate everyone's real world experience with NMC batteries too

 

[TheHypnoToad]

Having read through some articles such as the one below, it appears LFP is the superior battery, Should we be concerned about long range models using NMC ?

LFP may appear to be better, however NMC batteries offer higher current charging and discharging, and are lighter weight for the equievelent capacity, which is why the LR models use it.

 

[WalkingBootWeather]

So apparently the standard range MG4 uses LFP and long range versions use NMC.

Having read through some articles such as the one below, it appears LFP is the superior battery, Should we be concerned about long range models using NMC ?

LITHIUM NMC VS LIFEPO4 – HOW TO CHOOSE THE BEST ONE FOR YOUR NEEDS

No. It is horses for courses. If most of your driving is less than say 120 miles per day and you have convenient home or work charging then SR model will be fine. If you are regularly driving longer distances then the improved energy density and significantly higher real world charging speeds make the LR model a better option.

The most oft quoted reason why the LFP battery is superior is the quoted number of discharge cycles. In the case of the LFT around 5000 cycles is to be expected which with an average range of 100 miles per cycle gives a battery good for 500,000 miles. The NMC battery might show significant degradation after 2000 cycles but an average longer range of say 150 miles per cycle still means the useful battery life would be around 300,000 miles. Either would be more than enough for an owner to do 120,000 miles over a 10 year period. If you intend to keep your can for longer than 10 years or do more than 150,000 miles this may be an issue. For most people it won't be.

 

[Ayoull]

No. It is horses for courses. If most of your driving is less than say 120 miles per day and you have convenient home or work charging then SR model will be fine. If you are regularly driving longer distances then the improved energy density and significantly higher real world charging speeds make the LR model a better option.

The most oft quoted reason why the LFP battery is superior is the quoted number of discharge cycles. In the case of the LFT around 5000 cycles is to be expected which with an average range of 100 miles per cycle gives a battery good for 500,000 miles. The NMC battery might show significant degradation after 2000 cycles but an average longer range of say 150 miles per cycle still means the useful battery life would be around 300,000 miles. Either would be more than enough for an owner to do 120,000 miles over a 10 year period. If you intend to keep your can for longer than 10 years or do more than 150,000 miles this may be an issue. For most people it won't be.

It's also worth considering DOD (depth of discharge), as NMC only has a DOD of 80% before you begin to cause cell degredation where as LFP allows for 100% DOD with no degredation.

LFP in my mind will become the future of EV batteries until sodium-ion cells become more developed due to their increased cycle count and DOD in comparison to NMC/NCA especially as V2G becomes common place.

LFP is also far safer than NMC due to a higher thermal runaway point and due to them passing the rupture test where NMC doesn't

 

[TheHypnoToad]

It's also worth considering DOD (depth of discharge), as NMC only has a DOD of 80% before you begin to cause cell degredation where as LFP allows for 100% DOD with no degredation.

I've yet to see any type of rechargable battery which allows cycling without degredation, unless I've missed a recent breakthough.

 

[Ayoull]

I've yet to see any type of rechargable battery which allows cycling without degredation, unless I've missed a recent breakthough.

Now you're being pedantic, all batteries suffer degredation due to cycling, but NMC batteries suffer increased degredation if you go beyond 80% DOD, where as LFP don't suffer additional due to fully discharging the cells

 

[PristDean]

It's also worth considering DOD (depth of discharge), as NMC only has a DOD of 80% before you begin to cause cell degredation where as LFP allows for 100% DOD with no degredation.

LFP in my mind will become the future of EV batteries until sodium-ion cells become more developed due to their increased cycle count and DOD in comparison to NMC/NCA especially as V2G becomes common place.

LFP is also far safer than NMC due to a higher thermal runaway point and due to them passing the rupture test where NMC doesn't

Thanks, as the EV market place develops, the thermal runaway sits in my mind as something that insurance companies may.. just may pick up as a reason to increase premiums for LR cars with NMC.

 

[TheHypnoToad]

Now you're being pedantic, all batteries suffer degredation due to cycling, but NMC batteries suffer increased degredation if you go beyond 80% DOD, where as LFP don't suffer additional due to fully discharging the cells

I wasn't trying to be pedantic - while LFP does deal with 100% DOD better than NMC, I'd still only use 100% DOD when needed, 80% DOD will result in longer lasting batteries, be it LFP or NMC.

 

[Cocijo]

Does it make any difference to battery packs if you drive aggressively and use full power a lot of the time?
I know it might be incorrect but it doesn’t feel quite right using full power especially when first starting out. This is probably a hangover from ICE when it was advisable to let the engine warm up.
I wondered if battery packs might last longer if less power is used - E.g. gentler driving.
Or is this just twaddle?

 

[PristDean]

Does it make any difference to battery packs if you drive aggressively and use full power a lot of the time?
I know it might be incorrect but it doesn’t feel quite right using full power especially when first starting out. This is probably a hangover from ICE when it was advisable to let the engine war up.
I wondered if battery packs might last longer if less power is used - E.g. gentler driving.
Or is this just twaddle?

I see where you are coming from. This was one thought about 'running in' an EV car. 'Training' the battery and taking appropriate care initially could only be a good thing in my view.

 

[Ayoull]

Does it make any difference to battery packs if you drive aggressively and use full power a lot of the time?
I know it might be incorrect but it doesn’t feel quite right using full power especially when first starting out. This is probably a hangover from ICE when it was advisable to let the engine warm up.
I wondered if battery packs might last longer if less power is used - E.g. gentler driving.
Or is this just twaddle?

I don't know of any impact but it isn't something I've looked into I know home battery storage systems have a peak output rating and a continuous output rating, which is controlled by the battery management system.

But in an EV I wonder if it is tied down to the continuous opposed to peak as can't see a benefit of it

 

[Ayoull]

I wasn't trying to be pedantic - while LFP does deal with 100% DOD better than NMC, I'd still only use 100% DOD when needed, 80% DOD will result in longer lasting batteries, be it LFP or NMC.

Agreed.

You could argue based on the DOD that the trophy only has 80% of its 61.7kWh battery as useable which is 49.4kWh, with a range in the SE SR of 224mi where as the SR can do 218 with no increase in degredation over that caused by cycling.

 

[Cocijo]

I know the bms will reduce output if cells are significantly out of balance (or low on charge) to protect them but there doesn’t seem to be any (or minimal) limitations on, for example. driving off on a very cold pack at full load. Or perhaps there is, in extreme sub-zero temperatures?

I know driving very hard can lead to a power reduction, but I think that this is more from the bms detecting the heat of the pack?

It’s interesting to compare for example a pack that is subject to high speed autobahn usage day in and day out and another that has mostly city driving.
So, I’m guessing that the high rate of discharge in one case has no adverse impact compared to the slower discharge in the other.

 

[Macadoodle]

Does it make any difference to battery packs if you drive aggressively and use full power a lot of the time?
I know it might be incorrect but it doesn’t feel quite right using full power especially when first starting out. This is probably a hangover from ICE when it was advisable to let the engine warm up.
I wondered if battery packs might last longer if less power is used - E.g. gentler driving.
Or is this just twaddle?

Fast charging or discharging will degrade a pack more quickly but possibly not enough to worry about.
Low temperature does hamper any battery's ability to move electrons so probably a good idea not to thrash it in initial running in winter IMO.

 

[Ayoull]

I know the bms will reduce output if cells are significantly out of balance (or low on charge) to protect them but there doesn’t seem to be any (or minimal) limitations on, for example. driving off on a very cold pack at full load. Or perhaps there is, in extreme sub-zero temperatures?

I know driving very hard can lead to a power reduction, but I think that this is more from the bms detecting the heat of the pack?

It’s interesting to compare for example a pack that is subject to high speed autobahn usage day in and day out and another that has mostly city driving.
So, I’m guessing that the high rate of discharge in one case has no adverse impact compared to the slower discharge in the other.

Fast charging or discharging will degrade a pack more quickly but possibly not enough to worry about.
Low temperature does hamper any battery's ability to move electrons so probably a good idea not to thrash it in initial running in winter IMO.

Logical assumptions, given the BMS does take pack temperature into account when charging and using regen you'd assume that it would do the same when discharging.