So what range were you getting in recent cold weather?

[MickeySw]

I have just bought a new MG5 and am so far unimpresed with low temperature range, even at +10 degrees outside.

What kind of reduction in range are you seeing?

Both these 'explanations' (and probably countless others) would explain why the power output would drop in cold weather. That's not the same as range. If the reactions happen more slowly, that means less power but for a longer time. The total energy shouldn't be affected.

One important measure of battery performance is its capacity, which is affected by cold weather for the reasons stated.

 

[Jaumg]

I have just bought a new MG5 and am so far unimpresed with low temperature range, even at +10 degrees outside. I've now been reading various website explanations of this, but I don't agree with what they are saying. First quote from topgear.com:

and this from AutoExpress:

Both these 'explanations' (and probably countless others) would explain why the power output would drop in cold weather. That's not the same as range. If the reactions happen more slowly, that means less power but for a longer time. The total energy shouldn't be affected.

I just wish these sites would be more truthful about the reasons. Maybe it's just too difficlult to explain, but I hate seeing bad science on so many otherwise respectable places.

I have looked into this and the answer is seemingly that whilst the energy stored is the same in cold and warm weather, the usable energy is lower in cold weather because the voltage drops off more quickly in the cells so they can't be used.

This is partly caused by the slower reactions you mentioned, and partly by increased internal resistance within the battery, and it's the BMS preventing some stored energy from being used to protect the cells rather than there being less stored energy available (although the internal resistance in the cold does itself consume more energy along with other effects like higher rolling resistance, air drag, less efficient regen, using the cabin heating etc).

 

[Pebblefeline]

At 0 or below I get 150

At 5 degrees I get 175

at 10 degrees I will see 200 miles

At 15 degrees plus I will get 220 to 250

Some of this is due to using the heater, some is due to the battery heater being used by the car when the batteries are very cold

It also depends on my journeys,( if I do the school run in the cold it kills the battery, )my speed, (lose 20 percent at 70 as opposed to 60)
The explanations are fine as far as they go but we will all have different experiences depending on our driving style.

If you assume 1.5 miles per percent on the gom all year you will always be pleasantly surprised

 

[Paulie68]

At 0 or below I get 150

At 5 degrees I get 175

at 10 degrees I will see 200 miles

At 15 degrees plus I will get 220 to 250

Some of this is due to using the heater, some is due to the battery heater being used by the car when the batteries are very cold

It also depends on my journeys,( if I do the school run in the cold it kills the battery, )my speed, (lose 20 percent at 70 as opposed to 60)
The explanations are fine as far as they go but we will all have different experiences depending on our driving style.

If you assume 1.5 miles per percent on the gom all year you will always be pleasantly surprised

What discharge level are those figures based on please? say 100% down to 10%?, or other.

 

[quilkin]

What kind of reduction in range are you seeing?

Not done a full range test yet but yesterday got 3.7 miles/kWh on a 35 mile journey, +10 degrees, 40% at 40-50mph, 50% at 30mph, 10% in traffic / parking etc. Hardly used the heater, just a few short bursts of demist.

the BMS preventing some stored energy from being used to protect the cells rather than there being less stored energy available

That sounds a credible explanation, thanks

Does anyone have any data on the relative effect of the loss due to low temperature and the loss due to heating / demist etc?

 

[Pebblefeline]

So I keep an anal spreadsheet of consumption and charging. It’s a bit vague as it does work on distance and gom percentage but it gives a decent indicator of trends.

For instance I did 61 miles yesterday which used 35 percent, average temp was around 4 degrees and my total possible mileage based on that rough consumption (1.74 miles per percent) is 174 miles for a complete charge

In July however 33 percent took me 86 miles when the temp was 20 degrees or so giving me a total theoretical distance of 260 miles from 100 percent to zero at 2.61 miles per gom percentage or 4.54 miles per kWh

 

[dragon2611]

I totally agree with you it does seem strange but I would put my house on that there is no way I could get anywhere near 200 mls . My typical working day is around 6-7 hrs I only have the heating set at 22 degrees and the fan set on 3. I must add that I turn the heater off when I don’t have a customer in the car just to try and save the battery a bit but you soon get bloody cold. When I first bought the car I thought the miles I was getting wasn’t as good as my previous MG5. I bought it from an MG dealer so just to double check that everything was fine I booked it into another dealer and asked them to do a full check on the car they came back and said everything was fine. The car had 37 mls on the clock when I bought it. It’s a 23 plate.

I wonder if turning it off actually makes much difference as then it's just going to have to heat the car back up again.

 

[maskull]

I think the main negative effect is the battery temperature rather than running the heater permanently. Having said that, I'm dubious that it only loses 10 miles range that the car seems to indicate

 

[Pebblefeline]

As far as I can tell the initial heating slaughters the battery but maintaining it is not so bad

 

[quilkin]

I am still confused about this. Elsewhere I have read that the battery will warm up to 20 degrees or above on its own while driving for 15-20 minutes (because the chemical reactions during discharge are exothermic, and because of internal resistance losses.).
Ths suggests that, for a long drive (e.g. 200+ miles), the external temperature won't make so much difference in the range because the battery will already be warm for most if it.
I don't really care if the range is poor in the winter for short drives, because I can charge easily and cheaply at home. But if on a long trip and having to use expensive public chargers, I want the maximum range possible. Surely for a long drive it should only be use of heater / lights etc that affects the range (compared with the same trip in the summer)?

 

[tkmaxx5]

That’s what I’m getting with my FL5 Trophy. Doesn’t help doing the 10 minute remote heating each day from sub zero to toasty. Can take a couple of % off the battery.

My car lives outside in Sheffield.

Just out of interest, what process are you using for preheating? I can't get the app to send hot air to the onboard heater. It turns on the AC but seems to always blow cold regardless of the temp. I have a FL SE trim.

 

[kevin ellard]

Just out of interest, what process are you using for preheating? I can't get the app to send hot air to the onboard heater. It turns on the AC but seems to always blow cold regardless of the temp. I have a FL SE trim.

My Trophy did something similar for a while when they updated the app. It is fine now but during that time the solution was to change the temperature setting after turning the HVAC on. I would click it up one degree and then back down again the next day.

 

[tkmaxx5]

Thanks will give it a try

 

[Jaumg]

I am still confused about this. Elsewhere I have read that the battery will warm up to 20 degrees or above on its own while driving for 15-20 minutes (because the chemical reactions during discharge are exothermic, and because of internal resistance losses.).
Ths suggests that, for a long drive (e.g. 200+ miles), the external temperature won't make so much difference in the range because the battery will already be warm for most if it.
I don't really care if the range is poor in the winter for short drives, because I can charge easily and cheaply at home. But if on a long trip and having to use expensive public chargers, I want the maximum range possible. Surely for a long drive it should only be use of heater / lights etc that affects the range (compared with the same trip in the summer)?

The battery does get warmer with use, and more energy is lost to heat the colder it is, but even so when it has cold air being whipped past at 70 miles an hour, it stays cold*. That's why there's a battery preheating option to be able to charge quickly when it's cold, even if you're on a long drive.

*the heat losses rise in proportion to the square of the current, so I suppose it could be possible to constantly accelerate and brake to maximise amps to heat the battery, but I don't think anyone would ever advise you do that!

 

[Pebblefeline]

Longer trips do get better inefficiency I. The winter but you will still lose 20 percent over the warmer months.

I assume I will lose around 40 miles per full charge compared to the summer

Not bad tbh

 

[MickeySw]

I am still confused about this. Elsewhere I have read that the battery will warm up to 20 degrees or above on its own while driving for 15-20 minutes (because the chemical reactions during discharge are exothermic, and because of internal resistance losses.).

Yes and no, yes the cells will warm up during (heavy) usage but no they won’t reach 20 deg on their own:

The MG5 is constantly pumping the battery ‘heating” fluid trough a heat exchanger which is only bypassed when the cell temperatures are lower than 10deg.
This effectively keeps the battery around 10deg or ambient, whichever is higher.

Ths suggests that, for a long drive (e.g. 200+ miles), the external temperature won't make so much difference in the range because the battery will already be warm for most if it.

Not on an MG5, unfortunately

I don't really care if the range is poor in the winter for short drives, because I can charge easily and cheaply at home. But if on a long trip and having to use expensive public chargers, I want the maximum range possible. Surely for a long drive it should only be use of heater / lights etc that affects the range (compared with the same trip in the summer)?

The battery is artificially kept at @ 10 deg which is 20 deg below optimum hence the reduction in range

*the heat losses rise in proportion to the square of the current, so I suppose it could be possible to constantly accelerate and brake to maximise amps to heat the battery, but I don't think anyone would ever advise you do that!

That’s exactly what you need to do if you want max DC charge speeds, apart from flooring the accelerator as our German colleagues are legally able to do (10min @ max speed will do wonders for rapid charging)

 

[quilkin]

The MG5 is constantly pumping the battery ‘heating” fluid trough a heat exchanger which is only bypassed when the cell temperatures are lower than 10deg.
This effectively keeps the battery around 10deg or ambient, whichever is higher.
Not on an MG5, unfortunately
The battery is artificially kept at @ 10 deg which is 20 deg below optimum hence the reduction in range

Thank you for the details. Do you know why it's kept at +10 degrees, rather than higher? Is this unique to the MG5? Does this mean that loss of cold-weather range for the MG5 is worse than other EVs?

 

[MickeySw]

Thank you for the details. Do you know why it's kept at +10 degrees, rather than higher? Is this unique to the MG5?

No idea, one of these MG quirks?

Does this mean that loss of cold-weather range for the MG5 is worse than other EVs?

Not according to below

NAF – New winter range record in the world’s largest electric car test - FIA Region I

A record was set for how far an electric car drives in winter in NAF (Norwegian Automobile Federation) and Motors’ large winter range test.

www.fiaregion1.com

 

[quilkin]

Not according to below

NAF – New winter range record in the world’s largest electric car test - FIA Region I

A record was set for how far an electric car drives in winter in NAF (Norwegian Automobile Federation) and Motors’ large winter range test.

www.fiaregion1.com

Excellent article! So MG5 is near the best of the bunch, Good to know. I will perhaps find out for myself when I drive 280 miles each way either side of Christmas.

 

[MickeySw]

I will perhaps find out for myself when I drive 280 miles each way either side of Christmas.

Get yourself an OBD dongle/app and then you’ll be able to see exactly what’s going on under the hood…