Just joined. ?

[PeteC]

I'm not sure that the balance charge is so important in the NMC as regards getting the GOM estimate right. It's particularly important in the LFP because the charging curve is so flat, so the battery can't see where it's at from the current voltage until it starts to drop off sharply as it nears empty.

The videos I found where people had managed to film themselves while (accidentally) running out of battery all featured this sharp reduction in GOM range towards the end (the guy in the Kia eNiro said never take this thing below 8%) and I was speculating that these were LFP batteries that hadn't been balanced recently. But the MG4 in that test was an NMC.

Agreed, not as important for the GOM estimate.

 

[Rolfe]

Which is why I was surprised that LR MG4's GOM turned out to be so unreliable.

 

[fnegroni]

Which is why I was surprised that LR MG4's GOM turned out to be so unreliable.

Tbh, we don’t know why yet.
I had that happen to me once when the car had less than 500 miles on the clock and it was the first time I had it reach below 25%. Never since. The presenter made some rather rookie mistakes anyway. Like going out of his way to choose a crappy charger instead of doing what his colleague did: pick the most convenient and don’t wait to charge until the last percent.
It’s true public chargers aren’t as good out in the wild, but there are way more of them.

 

[Rolfe]

I was also surprised by the difference in miles/KWh. I wonder if the Tesla driver was slipstreaming in that traffic and the MG4 driver didn't think of that.

 

[PeteC]

Which is why I was surprised that LR MG4's GOM turned out to be so unreliable.

Yes, me too. I did once get spooked into an extra charge on my way home from Scotland because the GOM seemed to be dropping faster than expected, even though I'd made the same journey without the extra stop several times before, including in mid winter, so I knew I should have no trouble getting home. Because the GOM is normally a good guide, when it was showing that it would be tight to get home I decided to believe it. There are no convenient chargers in the last 30 or so miles of the journey to fall back on!

 

[Rolfe]

I think if you look at the GOM and the remaining % charge and think about the terrain and speed of your last leg home, you can estimate things quite well.

 

[tsedge]

I was also surprised by the difference in miles/KWh. I wonder if the Tesla driver was slipstreaming in that traffic and the MG4 driver didn't think of that.

Teslas are much more efficient. They are more heavily optimised because people in the US drive so much father than us and range matters so much more.

However, for a lot of people here, you don't need more than 3.5-4m/kWh, that is actually plenty.

Which is why I was surprised that LR MG4's GOM turned out to be so unreliable.

Yes, it is a fair point that whatever the real curve the car should be able to make the range linear and predictable - but maybe the GOM is much more simplistic than we give it credit for?

Teslas use terrain, route and live weather to give a precise range estimate. Which is brilliant but also overkill.

 

[Rolfe]

Well, my SR seems to be able to do it.

 

[tsedge]

Well, my SR seems to be able to do it.

Yes, I agree it is odd that it isn't consistent. #shouldhaveboughtaSR ?

 

[fnegroni]

Teslas are from a drivetrain perspective still ahead of much of the competition.
But the efficiency of the MG4 isn’t that bad and better than many others at that price point.
I think the charge rates here in the UK are exaggerating the issue: I really struggle to understand why even with a fleet card from a well known energy supplier I will pay (as of November) 70p per kWh at an ultra fast charger where Tesla would charge me much less even at peak times.
Of course it must be said that Tesla chargers are cheaper to manufacture, and Tesla might be taking an optimistic approach to supply and demand by taking a hit on profits (a loss even)just so they can push their agenda forward.
Until recently Tesla charges were only open to Tesla’s. It remains to be seen if their rates will go up when they all open up to other vehicles.
I would also though expect some suppliers to cut their rates too in the not too distant future.

I am also not too fussed: I charge mostly at home for free… ?

 

[Rolfe]

Yes, I agree it is odd that it isn't consistent. #shouldhaveboughtaSR ?

What is surprising me is that I thought the issue of the GOM suddenly recalibrating and slashing miles off your estimated range was more of a problem in the SR with its flat charging curve than in the LR.

 

[tsedge]

What is surprising me is that I thought the issue of the GOM suddenly recalibrating and slashing miles off your estimated range was more of a problem in the SR with its flat charging curve than in the LR.

Quite. Which makes me think it isn't the battery chemistry which is the issue but the quality of the GOM programming.

 

[fnegroni]

What is surprising me is that I thought the issue of the GOM suddenly recalibrating and slashing miles off your estimated range was more of a problem in the SR with its flat charging curve than in the LR.

Tbh this different voltage curve between NMC and LFP seems a little exaggerated to me. All lithium-ion batteries are difficult to manage below 50%

 

[OriginalBigAl]

In a 203bhp LR , I have just had in 4 people and 75 kg of sheep food in the boot and on a steep uphill section of duel overtook a slower car and it pulled superbly and kept accelerating right to the top. I would think the X power would be more awesome , but don,t put the people in the boot!

 

[tsedge]

In a 203bhp LR , I have just had in 4 people and 75 kg of sheep food in the boot and on a steep uphill section of duel overtook a slower car and it pulled superbly and kept accelerating right to the top. I would think the X power would be more awesome , but don,t put the people in the boot!

I imagine the XPower would do it with you towing the sheep as well! ?

 

[salty]

I imagine the XPower would do it with you towing the sheep as well! ?View attachment 20860

Spooky pic!

 

[Lovemyev]

I'm not sure that the balance charge is so important in the NMC as regards getting the GOM estimate right

I agree ?.
We charge from home 100% of the time, we find charging to 80% SOC suits our needs just fine.
From day one of ownership, the car has returned a predicted range of 212 miles at a 80% SOC.
Our Trophy LR is almost 18 months old and has covered about 15,000 miles.
I have only ever charged to 90% twice and 100% twice, so balancing has therefore never become a priority.
Having had problems with our previous Gen1 ZS EV regarding software bugs, then being instructed to constantly charging to 100% in order to help recover the battery.
But degradation after two years and about 20,000 miles was a real thing.
The predicted range was slowly reducing over time and other owners had reported very similar drops in range figures.
Constantly charging to 100% then balancing the pack after, I believe was part of the issue.
Pre BMS update the car would take between 30 minutes to 1 hour to balance.
Post BMS it would take 3 - 4 hours.
I tend to treat software updates with a lot of pessimism now TBH.
I am sticking with charging at 80% SOC unless we need to take a much longer trip.
NMC batteries benefit from regular charging between 20 - 80% SOC for better long term battery life, the extra range above 212 miles is available by charging to 100% SOC for the occasional longer trips.
LPF batteries DO prefer charging to 100% SOC on a regular basis due to the different battery chemistry.
I think choosing the correct size of pack, together with the right battery chemistry type, has to be matched carefully to the persons user case.
Everybody will be different of course.

 

[OriginalBigAl]

I imagine the XPower would do it with you towing the sheep as well! ?View attachment 20860

I,ve been looking for a suitable Shaun the Sheep sticker to grace my boot lid, but this may work

 

[tsedge]

I agree ?.
We charge from home 100% of the time, we find charging to 80% SOC suits our needs just fine.
From day one of ownership, the car has returned a predicted range of 212 miles at a 80% SOC.
Our Trophy LR is almost 18 months old and has covered about 15,000 miles.
I have only ever charged to 90% twice and 100% twice, so balancing has therefore never become a priority.
Having had problems with our previous Gen1 ZS EV regarding software bugs, then being instructed to constantly charging to 100% in order to help recover the battery.
But degradation after two years and about 20,000 miles was a real thing.
The predicted range was slowly reducing over time and other owners had reported very similar drops in range figures.
Constantly charging and charging, to 100% then balancing the pack after, I believe was part of the issue.
Pre BMS update the car would take between 30 minutes to 1 hour to balance.
Post BMS it would take 3 - 4 hours.
I tend to treat software updates with a lot of pessimism now TBH.
I am sticking with charging at 80% SOC unless we need to take a much longer trip.
NMC batteries benefit from regular charging between 20 - 80% SOC for better long term battery life, the extra range above 212 miles is available by charging to 100% SOC for the occasional longer trips.
LPF batteries DO prefer charging to 100% SOC on a regular basis due to the different battery chemistry.
I think choosing the correct size of pack, together with the right battery chemistry type, has to be matched carefully to the persons user case.
Everybody will be different of course.

Do you mean "constantly" charging to 100%? I assume you do mean that, which would indeed compromise the battery for the long term. Bizarre that this was the advice you were given, there must have been some major bugs early on.

 

[fnegroni]

I did a bit more research.
What I found out is this:
No battery prefers, per se, to be charged to 100%. Even LFP batteries benefit from being charged to less than 100%
The main difference is that the voltages at 100% and at 70% are not that different and generally the voltages are lower than say NMC batteries
However, the higher the SoC over a period of time the greater the degradation.
therefore the true advice for LFP batteries should be:
Store at less than 100% charge but more than 50%
Charge to 100% regularly but not daily to maintain a good GoM estimate without degrading the battery too much.
Moreover, DON’T charge to 100% until you need to use the car: schedule the charge to 100% to happen shortly before you need to drive (but do include the time to equalise the charge in this)

Example: I’m charging right now to 55%. Last time I charged to 100% was last week.
I don’t need to use the car tomorrow. Maybe the day after. Certainly on Thursday evening.
Therefore I will schedule a charge to 100% by Thursday daytime so it’s fully equalised by evening but not stored at 100% for more than a few hours. And if I do use the car in between I’ll just top up a little so that it won’t take a whole day to charge it back to 100%
But I will not charge every day to 100% unless I plan to drive it the next day.

Advantage of LFP: even if I forget all the above and charge to 100% every day, it will most likely last long enough not to be a problem.