Poor efficiency (or is it just the cold?)

[hharzel]

Hi all,

Brand new MG4 SR owner here. As an EV newbie I'd like to know if its normal to have this low efficiency at this time of year. Below is a typical shot of my work trip that is about 12 miles, the average speed being 39mls/h with the energy consumption of 2.6mls/kWh. It's been quite consistent for the whole month I've had the car. Temperature's around 0-5 degrees celsius here in central Finland, no battery heating used, AC set to 25 celsius deg and fan set to 5, tire pressure normal.

Because every car is unique, how much variation is there in efficiency between different units (LFP batteries) of the same model in general, or is it so negligible that it makes no sense to even think about it? There's been some issues with the software so I really hope the hardware's OK.

 

[fnegroni]

LFP batteries don’t like the cold very much.
intelligent battery heating might even improve things or it might not. Worth a try.

LFP batteries don’t like the cold very much.
intelligent battery heating might even improve things or it might not. Worth a try.

What’s your commute like?
63 kph average over 20km on a straight flat motorway isn’t the same as a twisty hilly road

 

[Chasottmg4]

Judging by your picture your tyre pressure is low. This does make some difference. Try setting your driving mode to eco and heating to auto 25 celcius is ok. I suppose you get it colder earlier than we do in Ireland .

 

[dsimpkins]

Ambient temperature, driving in Normal instead of Eco, aircon/heating settings, tyre pressures, the topology of the commute, other traffic, and driving style will all affect the range.

My usual commute I average about 4miles/kWh but have seen this drop in the mornings due to the lower temperatures. It has got down to 2.6 miles/kWh on some mornings. Drive home in the evening is currently better as warmer in than the morning.

 

[Fogey]

I don't have an EV yet, but my neighbour's BMW i3's efficiency apparently responds hugely to preconditioning on cold (British) winter days - using mains energy to heat the battery while connected to the charger - before setting off. And, I believe, even using battery energy to precondition when not connected to a charger.

 

[tsedge]

Hi all,

Brand new MG4 SR owner here. As an EV newbie I'd like to know if its normal to have this low efficiency at this time of year. Below is a typical shot of my work trip that is about 12 miles, the average speed being 39mls/h with the energy consumption of 2.6mls/kWh. It's been quite consistent for the whole month I've had the car. Temperature's around 0-5 degrees celsius here in central Finland, no battery heating used, AC set to 25 celsius deg and fan set to 5, tire pressure normal.

Because every car is unique, how much variation is there in efficiency between different units (LFP batteries) of the same model in general, or is it so negligible that it makes no sense to even think about it? There's been some issues with the software so I really hope the hardware's OK.

View attachment 20720

Hard to say without knowing the route but this could be normal.

Remember during short trips the battery won't heat up properly so you can get efficiencies this low. The intelligent battery heating may help.

Unfortunately in colder countries the range will reduce more and the battery chemistry choice matters more.

 

[ukslim]

23 kWh/100km ~= 2.7 m/kWh

We've been getting 4 m/kWh ~= 16 kWh/100km in the mild British autumn (round about 17 celsius).

The battery works less efficiently at low temperatures, and it seems likely that 12 miles isn't long enough for its heater to warm it. You might benefit from pre-heating the battery (it's in the "schedule" screen in iSmart). The app recommends starting the pre-heat 90 minutes before your journey. You should be able to do it while plugged in.

 

[pollenface]

After reading about that person who put battery heating on while dropping the kids to school, I've been keen to try it.

 

[Tigger]

Ok, mine's a Trophy, but I got a shock today. A week ago it was a warm day, and I drove the 37 miles to Gatwick airport, and used 13% of battery power, at about 4.6m/kwh. Today I returned home from the airport, doing the same 37 miles in reverse. I used 19% of battery power, at 3.2m/kwh. Why? The only explanation is that the temperature today was 9 degress C.

That's a hell of a difference. Maybe there was less traffic on the road today, so I drove a bit faster, but even so . . .

 

[tsedge]

Ok, mine's a Trophy, but I got a shock today. A week ago it was a warm dy, and I drove the 37 miles to Gatwick airport, and used 13% of battery power, at about 4.6m/kwh. Today I returned home from the airport, doing the same 37 miles in reverse. I used 19% of battery power, at 3.2m/kwh. Why? The only explanation is that the temperature today was 9 degress C.

That's a hell of a difference. Maybe there was less traffic on the road today, so I drove a bit faster, but even so . . .

Speed makes a huge difference to efficiency. Low temperatures will cut efficiency 20-30%. Wind can make a big difference.

 

[the briggie]

If you had parked it at Luton Airport the batteries would have been prewarmed for you...

 

[Rolfe]

This happens to ICE cars too, always has. Maybe not to quite the same extent, but there's not a huge amount in it. I think we need to get over it and concentrate on securing cheap electricity.

If you had parked it at Luton Airport the batteries would have been prewarmed for you...

Ouch!

 

[siteguru]

Speed makes a huge difference to efficiency. Low temperatures will cut efficiency 20-30%. Wind can make a big difference.

Indeed it does. I did a 68 miles journey from Gretna services to home this afternoon with ambient temperature about 11°C. My average speed was 66 mph, and my efficiency was ~2.7 miles/kWh.

 

[tsedge]

With the hills around me, I am doomed to never win on the efficiency front. High 3s is the best I can do, only see 4s on holiday away from home.

 

[Rolfe]

I drove from Burton in Kendal services to Moffat one late evening with the ACC set at 80. I managed between 2 and 2.5 miles/KWh. After Moffat (well, the wells of Tweed) I did better than 4.

 

[the briggie]

It must be getting nearer winter as the drop in range hits all the EV forums again...

 

[Alb]

Although it's an MG5 rather than 4, you can see the impact of seasonal temperature for South West England on my average monthly energy consumption figures in the attached graph:

I think these variations are fairly typical.

 

[hharzel]

So I had this "Intelligent Battery Heating" feature on and switching it off greatly improved the efficiency, as well as toggling A/C off completely. At ~5 celsius I was finally able to go below 17kWh/100km efficiency. Getting slowly better at driving the vehicle too...

 

[fnegroni]

I never bother switching the a/c off. I like my cabin well dehumidified. At the cost of a bit of range.
Besides the heater is going to hurt more so I just keep the temperature low and wear an extra layer.

 

[GameZone]

26.4 kwh/100 km in Norway. 0 to -5C here