Sudden range drop in MG4 Trophy LR

[MrLukus]

I got my MG4 a few weeks ago and I'm loving it. However did have a question regarding a trip I did the other day.

I drove up to London (Wembley) from Eastleigh (and back) on Saturday, which is 155 miles round trip. I left with 100% charge (from home charger), got to London fine, I think I had about 70% left. The drive back was mostly motorway (A40, M25, M3), doing 70mph, pretty wet and rainy and about 10 degrees outside. I noticed that between 40% and 20% the battery seems to be getting absolutely eaten up. Like 5 miles of range lost for every 1 mile I was travelling. Then once it hit 20%, it seems to go back to "normal". Is this a normal thing to expect? It's not really a problem, just was a little worrying as I saw the miles going down so fast. I turned off the AC and put it in eco to make sure I'd make it, but that might just be because I'm brand new to EVs and still have a bit of anxiety.

I made it home with about 30 miles left, so the range I actually got was probably about 185, which I think is probably about right at this time of year? I was just surprised at how differently the range seems to reduce at certain SoC. Is this normal? Will the range calculator get better at predicting this the longer I drive the car?

 

[tsedge]

It is called a Guessometer (GOM) for a reason! It will get more accurate if you have a single driver with a consistent style, otherwise it is a rough guide only.

It isn't a flat curve, typically the bottom half lasts less long than the top half but as you say the last bit at the bottom lasts well.

 

[Robf]

Make sure you have battery intelligent heating turned off

 

[MrLukus]

Make sure you have battery intelligent heating turned off

Interesting, I think I may have turned this on because it sounded cool... I will make sure to turn it off haha

 

[MrLukus]

It is called a Guessometer (GOM) for a reason! It will get more accurate if you have a single driver with a consistent style, otherwise it is a rough guide only.

It isn't a flat curve, typically the bottom half lasts less long than the top half but as you say the last bit at the bottom lasts well.

Haha, I did assume it was going to be somewhat inaccurate. But when I suddenly saw it drop from 40% to 20% in like 10-15 minutes I was pretty spooked as I thought that rate might continue and I'd not make it home. My 80 mile buffer was disappearing fast

At least it got me home with plenty at the end and was a much more comfortable journey than in my 1.2 Corsa (last car).

 

[Rolfe]

A drop from 40% to 20% in 10-15 minutes is very unusual and certainly not something I've ever seen. It would certainly spook me.

I think this may be an issue of battery balancing. Have you done the routine of charging the car to 100% on an AC charger and letting it sit at 100% until it's completely finished drawing charge? This is supposed to be done once a month on an NMC battery and one of the main reasons for it is to keep the GOM guessing reasonably accurately. I think doing that (if it hasn't been done recently) might sort this out.

Another thing that's supposed to be done is to let the battery get below 10% then charge all the way to 100% and balance in a single operation. The manual says to do this every three to six months.

I wouldn't have thought that a brand new car would be needing these things done so soon, but you didn't say if it was brand new. Anyway, something to try. There are various stories around of people running out of charge because the GOM dropped suddenly close to the end of the range, and the smart money is on the drivers not having balanced the pack recently.

 

[MrLukus]

A drop from 40% to 20% in 10-15 minutes is very unusual and certainly not something I've ever seen. It would certainly spook me.

I think this may be an issue of battery balancing. Have you done the routine of charging the car to 100% on an AC charger and letting it sit at 100% until it's completely finished drawing charge? This is supposed to be done once a month on an NMC battery and one of the main reasons for it is to keep the GOM guessing reasonably accurately. I think doing that (if it hasn't been done recently) might sort this out.

Another thing that's supposed to be done is to let the battery get below 10% then charge all the way to 100% and balance in a single operation. The manual says to do this every three to six months.

I wouldn't have thought that a brand new car would be needing these things done so soon, but you didn't say if it was brand new. Anyway, something to try. There are various stories around of people running out of charge because the GOM dropped suddenly close to the end of the range, and the smart money is on the drivers not having balanced the pack recently.

Yea was brand new, it's got 800 miles on the clock now.

I only got my home charger installed last week so I've not yet done a 10% to 100% balance charge and until last week I was relying on DC rapid public chargers only (40kw sometimes, 140kw others). Maybe this didn't help, I have read that rapid charging can throw the GOM off.

I did do an 80% to 100% on AC before the trip on Saturday before leaving the following morning. I think it did some kind of balance as I watched it in real time and the charge rate dropped to 0 but it was still charging for approx 5 mins before stopping completely.

Maybe I need to try and 10% to 100% charge and see if that helps the GOM.

I do also wonder if my anxiety about it means I might be exaggerating slightly as I didn't actually time it... I'll keep an eye on it and get some actual numbers when I next do a longish trip so I can crunch the numbers

 

[Rolfe]

Seems very weird to me. A car as new as that shouldn't be acting up like this even if it's never been balanced at all. Having an LFP battery myself I don't really know much about NMC behaviour, but I do know that my GOM was still spot on after three rapid charges in one day on a road trip. Twice. And it had never had a 10% to 100% charge at that point. (And it took me 130 miles at 80 on the motorway from 93% to 9%. That's the SR.)

I'm concerned that the car only seemed to balance for five minutes. The LFP balances for 30-35 minutes whenever it gets the chance (I've seen mine do it five days in succession) and I've heard NMC owners talk about longer balance charges than that - an hour and more. I don't think it could do anything much in five minutes, so either it barely needed balancing at all, or something's wrong.

It's worth documenting what's happening in a bit more detail, for example how many miles travel are you seeing for each 1% battery, and whether the battery % is dropping evenly or step-wise. A 10% to 100% charge is worth a try, but a new battery, especially an NMC, should not be needing this.

 

[fnegroni]

It happened to me the first time I took the car on a long trip, dipped below 40% and only had a few hundred miles on the clock. It had been balanced at 100% since it was brand new and just before that journey.
It’s the BMS learning about your battery. I never had that happening again since dipping below 40% on a regular basis and dipping below 10% once every three months.

 

[Tight Git]

Also prevailing weather conditions make a massive difference - rain and head wind on your return journey would really impact the range.

 

[tsedge]

Yea was brand new, it's got 800 miles on the clock now.

I only got my home charger installed last week so I've not yet done a 10% to 100% balance charge and until last week I was relying on DC rapid public chargers only (40kw sometimes, 140kw others). Maybe this didn't help, I have read that rapid charging can throw the GOM off.

I did do an 80% to 100% on AC before the trip on Saturday before leaving the following morning. I think it did some kind of balance as I watched it in real time and the charge rate dropped to 0 but it was still charging for approx 5 mins before stopping completely.

Maybe I need to try and 10% to 100% charge and see if that helps the GOM.

I do also wonder if my anxiety about it means I might be exaggerating slightly as I didn't actually time it... I'll keep an eye on it and get some actual numbers when I next do a longish trip so I can crunch the numbers

I think you are worrying a bit unnecessarily.

The NMC battery doesn't need balancing often and a quick (or no) balance indicates that all is well.

The GOM will not be that accurate unless you are the only driver and you have a very consistent driving style and routes.

I'd give it a bit longer before jumping to any conclusions.

 

[JonnyG]

As above, getting 185 mile range at 70mph in wet & rain is pretty good IMHO and nothing to worry about. The GOM was just probably having to (belatedly) adjust itself to you driving in these condtions. I would still do a <10% to 100% charge on your home charger asap though and leave it plugged in to fully balance.

 

[MrLukus]

Thanks for the advice guys, I'll keep an eye on it and try and do a 10% to 100% on AC soon.

Also will make sure I note down exact values so if I need further advice I have some solid figures

 

[MrLukus]

Also prevailing weather conditions make a massive difference - rain and head wind on your return journey would really impact the range.

It was raining pretty heavily and there was a lot of standing water. I didn't realise that would make much of a difference but seems like it does. Not sure if there was a head wind or not, but it's definitely possible

 

[Rolfe]

That could be the explanation. I hope so.

I'm surprised that people driving ICE cars often don't seem to realise the difference weather makes to their range. I always drove my Golf from 100% to 0% (hate going into petrol stations) and always made a note of how far I'd got in that time. I became acutely aware of how cold weather reduced the range, and also rain, driving on wet roads, and headwinds. I'd see anything from 370 miles in atrocious winter weather (with short trips) to 450 miles (long distance cruising on A roads in good weather).

I think the effect on EVs is more marked than on ICE cars, but I also think that the shorter range of EVs makes the issue more apparent. It's interesting to see how many people only notice it for the first time with their first EV.

 

[Tight Git]

I think the effect on EVs is more marked than on ICE cars, but I also think that the shorter range of EVs makes the issue more apparent. It's interesting to see how many people only notice it for the first time with their first EV.

One of the reasons that EVs appear to be more impacted by external factors such as temperature and rain is that an EV is far more efficient than an ICE car so the effect is much more noticeable on the EV. It almost seems counter-intuitive!

 

[fnegroni]

I can report that my ICE car doesn’t suffer as much in the winter. Most likely due to its mild hybrid drivetrain: cold starts are much less of an issue when you have a big 48v starter motor and electronic clutch that helps the engine when cold and disengages the clutch when cruising.
I think the bigger differentiator in the past has been the school run!

 

[Rolfe]

One of the reasons that EVs appear to be more impacted by external factors such as temperature and rain is that an EV is far more efficient than an ICE car so the effect is much more noticeable on the EV. It almost seems counter-intuitive!

Yes, I can follow that.

What does annoy me is that whereas we're using ~95% of the electricity we buy to drive our cars, ICE owners are only using about 35% (?) of the fuel they buy to drive their cars and throwing away the rest of it as heat. And yet we're being charged as much per mile for electricity on the public chargers.

Even more inequitable, a huge % of what the ICE driver is paying is tax, far more so than the tax component of the electricity. If it weren't for the tax, petrol would be pennies a litre.

It does tend to suggest that fossil fuels are hugely underpriced for their energy content compared to electricity. Which I guess we knew all along and that's why we don't heat our houses with electricity. I don't actually want to pay any more for the kerosene that keeps me warm, but I do think electricity is hugely overpriced.

 

[fnegroni]

Yes, I can follow that.

What does annoy me is that whereas we're using ~95% of the electricity we buy to drive our cars, ICE owners are only using about 35% (?) of the fuel they buy to drive their cars and throwing away the rest of it as heat. And yet we're being charged as much per mile for electricity on the public chargers.

Even more inequitable, a huge % of what the ICE driver is paying is tax, far more so than the tax component of the electricity. If it weren't for the tax, petrol would be pennies a litre.

It does tend to suggest that fossil fuels are hugely underpriced for their energy content compared to electricity. Which I guess we knew all along and that's why we don't heat our houses with electricity. I don't actually want to pay any more for the kerosene that keeps me warm, but I do think electricity is hugely overpriced.

It’s not the fuel that is inefficient. It’s the engine fueled by it.
What is underpriced is the process and the impact on the environment that extracting oil and refine it and give you its byproduct.

Thinking about it, it would really be interesting to see exactly how much more would it cost to produce petrol compared to harvesting solar energy.
Carbon offsetting is an attempt to convince businesses to shift their source of energy by equalising the effect on the environment. Some processes are still way too expensive for sustainable energy harvesting yet drilling for oil is in a way still cheaper.
My hope is that producing renewable energy involves cheaper processes, plus the real issue of long term damage to the environment is priced more fairly.
This transition process is slow in order to make it sustainable at a global scale, but if consumers still don’t get why choosing EVs over ICE is a good way of accelerating the process, and therefore don’t push the demand for it, no wonder this is going to take a long time.

Installing chargers for EVs as opposed to fuel pumps has to make sense commercially for a huge company to make that shift and for them to justify it to their shareholders.
And begging consumers to compromise their lifestyle to save the planet makes as much sense as expecting everyone to stop eating fast food

That’s where governments are failing: by allowing this self fulfilling prophecy delaying the inevitable instead of accelerating it.

Anyone who thinks we will be driving ICE cars in 30 years time is either well meaning but deluded, or informed and has an agenda.

 

[Rolfe]

It’s not the fuel that is inefficient. It’s the engine fueled by it.
What is underpriced is the process and the impact on the environment that extracting oil and refine it and give you its byproduct.

Thinking about it, it would really be interesting to see exactly how much more would it cost to produce petrol compared to harvesting solar energy.
Carbon offsetting is an attempt to convince businesses to shift their source of energy by equalising the effect on the environment. Some processes are still way too expensive for sustainable energy harvesting yet drilling for oil is in a way still cheaper.
My hope is that producing renewable energy involves cheaper processes, plus the real issue of long term damage to the environment is priced more fairly.
This transition process is slow in order to make it sustainable at a global scale, but if consumers still don’t get why choosing EVs over ICE is a good way of accelerating the process, and therefore don’t push the demand for it, no wonder this is going to take a long time.

Installing chargers for EVs as opposed to fuel pumps has to make sense commercially for a huge company to make that shift and for them to justify it to their shareholders.
And begging consumers to compromise their lifestyle to save the planet makes as much sense as expecting everyone to stop eating fast food

That’s where governments are failing: by allowing this self fulfilling prophecy delaying the inevitable instead of accelerating it.

Anyone who thinks we will be driving ICE cars in 30 years time is either well meaning but deluded, or informed and has an agenda.

Yes, yes. That's exactly what I was getting at, thank you for putting it so well.

I listened to something on YouTube the other day that suggested that electricity could be almost cost-free in the future once durable installations to generate it were installed. Obviously there will be some maintenance costs, but if the solar panels and the wind and wave turbines are installed and generating away, the ongoing costs will be very small. Certainly compared to the costs of ongoing fossil fuel extraction.

I wonder how true this is? I don't wonder why some people are opposed to it.