0% SoC

[hequals4]

Has anyone driven their MG4 down to 0% SoC yet? Or seen a review where this is done?

Obviously it's not something you really want to be doing but it'd be interesting to know how the car handles that. Does it have any spare miles in 'reserve' or is zero on the GoM really zero?

I know that Carwow do group tests where they drive the cars until they stop so maybe we have to wait and hope that the MG4 is included in their next one.

 

[Tight Git]

Yes - I managed it a few weeks ago!

With about 3 miles range it cut power and wouldn't go over about 15mph.

At 0% 0 miles range it flashed up 'park safely'!

Fortunately at that point I was 0.5 miles from home which was all downhill so managed to get home!

Not doing that again ??

 

[siteguru]

I've only had mine down to 6% SoC ... although when I recharged the kWh stored suggested that the real SoC may have been 24% ?‍

 

[hequals4]

Yes - I managed it a few weeks ago!

With about 3 miles range it cut power and wouldn't go over about 15mph.

At 0% 0 miles range it flashed up 'park safely'!

Fortunately at that point I was 0.5 miles from home which was all downhill so managed to get home!

Not doing that again ??

Thanks - useful to know. So it sounds as though zero might be zero with the MG4?

A friend with an ID3 got himself into a pickle last year and ended up running out of charge. He said the car went 4 miles beyond zero before it stopped.

 

[dave99]

I assume MG Assist will rescue you if you run out of charge? I've seen some insurance policies say they include out of charge assistance, but just noticed mine doesn't

 

[Cocijo]

It makes a bit of a farce of quoted range for any EV - most owners will never let their cars get close to 0%, for perfectly understandable reasons.
That’s another reason (as well as outside temperatures and driving conditions/type) that the quoted range on EV’s can be misleading. There is of course also a buffer at the top and bottom ends of the pack to protect it. (I think on the LR MG4 it’s about 2.5kwhr)
So it never really is 100% or 0% Even though it shows it as this.

 

[Ron61]

It makes a bit of a farce of quoted range for any EV - most owners will never let their cars get close to 0%, for perfectly understandable reasons.
That’s another reason (as well as outside temperatures and driving conditions/type) that the quoted range on EV’s can be misleading. There is of course also a buffer at the top and bottom ends of the pack to protect it. (I think on the LR MG4 it’s about 2.5kwhr)
So it never really is 100% or 0% Even though it shows it as this.

Agreed 25% is about as far as I'll let mine go for two reasons: -

1) I don't want the hassle of not being able to find a working charger with only a few % left.
2) It doesn't do the battery any good going really low.

 

[troopercooper]

Agreed 25% is about as far as I'll let mine go for two reasons: -

1) I don't want the hassle of not being able to find a working charger with only a few % left.
2) It doesn't do the battery any good going really low.

Someone told me a while back that at high and low charge capacity's, the battery's are pushed very hard to deliver the required power, so the golden zone is between 20% and 80% for optimal health. I don't know how true that is for the MG4... but figured its worth sharing. I didn't realise until watching a video yesterday that you can limit the battery charge capacity up to 80%, for these reasons.

 

[Cocijo]

MG4 has a different battery cell chemistry (I think only on the larger pack) that can withstand high and low SOC’s much better and apparently has an improved SOH over time.
I’m not too certain if the best practice guidelines around optimised charging have also changed - but I think that they might have.

 

[hequals4]

It makes a bit of a farce of quoted range for any EV - most owners will never let their cars get close to 0%, for perfectly understandable reasons.
That’s another reason (as well as outside temperatures and driving conditions/type) that the quoted range on EV’s can be misleading. There is of course also a buffer at the top and bottom ends of the pack to protect it. (I think on the LR MG4 it’s about 2.5kwhr)
So it never really is 100% or 0% Even though it shows it as this.

Well done for adding unnecessary complexity to a simple thread that that really didn't need it. You do know that you don't have to reply to every single thread on here don't you?

 

[hequals4]

Agreed 25% is about as far as I'll let mine go for two reasons: -

1) I don't want the hassle of not being able to find a working charger with only a few % left.
2) It doesn't do the battery any good going really low.

Nobody is suggesting that you intentionally drive it down to 0% but own an EV for long enough and do enough long trips and there comes a reasonable possibility that you end up on a journey where things don't go to plan and, if that happens, it's useful to know how the car behaves. Ask me how I know

 

[Cocijo]

Well done for adding unnecessary complexity to a simple thread that that really didn't need it. You do know that you don't have to reply to every single thread on here don't you?

Don’t have to. But I try. You may think unnecessary and too complex for you - others may not.
You do know that you don’t have to read every Single thread on here don’t you?

 

[Ayoull]

Agreed 25% is about as far as I'll let mine go for two reasons: -

1) I don't want the hassle of not being able to find a working charger with only a few % left.
2) It doesn't do the battery any good going really low.

Point 2 only applicable with NMC and NCA batteries due to 80% depth of discharge, LFP have 100% depth of discharge with out degredation

 

[troopercooper]

Point 2 only applicable with NMC and NCA batteries due to 80% depth of discharge, LFP have 100% depth of discharge with out degredation

That's pretty interesting to know, do you know why MG therefore offer a charge limiter within their app? What's its purpose may be? I can't think of one asides from protecting the battery, which now seems redundant.

 

[Ayoull]

That's pretty interesting to know, do you know why MG therefore offer a charge limiter within their app? What's its purpose may be? I can't think of one asides from protecting the battery, which now seems redundant.

There isn't a charge limiter on the SE SR which is LFP, the LR models have the 80% limit as charging NMC and NCA to 100% does degrade the battery

 

[Cocijo]

That would make sense making the smaller battery LFP as it’s more likely to be fully charged more often and subject to more cycles than a larger pack. I’m guessing LFP technology is more expensive to produce?

 

[Ayoull]

That would make sense making the smaller battery LFP as it’s more likely to be fully charged more often and subject to more cycles than a larger pack. I’m guessing LFP technology is more expensive to produce?

No it's cheaper far cheaper than NMC and NCA as no cobalt involved but it's less energy dense so has to be heavier for the same power, so a 64kWh LFP battery would be around 20-40kg heavier than a 64kWh NMC or NCA battery.

Also LFP batteries pass the puncture test in that they don't ignite when ruptured where as NMC and NCA it's 50/50 if they do.

 

[Cocijo]

That’s really useful. Do you think LFP is the short term future for EV batteries? Will we see these on more and more cars, replacing the other types? Perhaps bringing down EV cost. Or is the weight issue a problem meaning the pack will have to stay relatively small?

 

[Ayoull]

That’s really useful. Do you think LFP is the short term future for EV batteries? Will we see these on more and more cars, replacing the other types? Perhaps bringing down EV cost. Or is the weight issue a problem meaning the pack will have to stay relatively small?

The technology is improving, and energy density is improving, Sodium-Ion batteries have started to be developed that use sodium extracted from sea water opposed to lithium, and these are showing similar densities to LFP.

The biggest issue with LFP outside of weight is the BMS issues due to how LFP cells discharge their power and hold the voltage stable for virtually all the discharge curve.

Tesla has invested heavily into LFP EVs with its model 3 SR models due to loss of NMC supplies.

Also CATL the world's largest battery manufacturer has spent alot on LFP technology but primarily for home storage systems, but the improvement here will filter into all LFP batteries but you need manufacturers to build EV specific BMS systems that account for the flat discharge curve and can account for weather impact on the energy discharge, which is all software algorithm based with LFP, where as NMC and NCA discharge at a predictable rate so no need for fancy software to work out how much charge is left.

 

[Cocijo]

Thanks. Great info. Don’t CATL supply SAIC?