Cold weather mileage.

[OriginalBigAl]

Charged to 70% overnight , temp -6c , then drove next day around 70 kms , temp around 1-2 c , heating on of course , levellish road normal driving in normal, used around 11% of the battery or 7kw the usage monitor was 15.5kw/100kms. Most likely a glitch ? The next trip might be massive usage just to balance out the figures.!

 

[Geoffree]

Charged to 70% overnight , temp -6c , then drove next day around 70 kms , temp around 1-2 c , heating on of course , levellish road normal driving in normal, used around 11% of the battery or 7kw the usage monitor was 15.5kw/100kms. Most likely a glitch ? The next trip might be massive usage just to balance out the figures.!

15.5kw/100kms = almost 4miles/kWh. I only get this in the summer!

 

[hojnikb]

With temps dropping below ~-5C and doing short trips with preheating, i'd be happy to get 100km of range on the 51kwh. Not having a heatpump kills efficiency pretty hard.

 

[LenEV2016]

With temps dropping below ~-5C and doing short trips with preheating, i'd be happy to get 100km of range on the 51kwh. Not having a heatpump kills efficiency pretty hard.

Beat pump doesn't help too much on short trips as the cabin always cools down and needs heated again, comes into its own on longer trips

 

[hojnikb]

Beat pump doesn't help too much on short trips as the cabin always cools down and needs heated again, comes into its own on longer trips

That may be, but you still need less power for a given unit of heat, compared to resistive heaters, which are always only 100% efficient.

Even if heatpump runs at 150-200% efficiency, thats still a lot better.

 

[OriginalBigAl]

15.5kw/100kms = almost 4miles/kWh. I only get this in the summer!

Me too , normally when the temps are above 20c , so as I said probably a glitch in the software . Although I do have a theory ? I charged when it was very cold ( 28% to 70% ) and in the morning the EVSE reported the total imported kWh. This was 3kw more than I expected which I put down to extra charging losses due to the cold . When on my journey after 14kms the percentage had gone up to 71% and only started to drop after that. If that 3kw had been put into the battery but had somehow due to the cold managed to squeeze in before the cut off point , then the 11% used plus the mystery 3kw ( around 10kw total ) would be more believable and nearer to the 15.5kwh/100kms figure. Still a somewhat fantastical figure for Winter I agree and I am not expecting it to be the norm for the remainder of Winter.

 

[T1 Terry]

With temps dropping below ~-5C and doing short trips with preheating, i'd be happy to get 100km of range on the 51kwh. Not having a heatpump kills efficiency pretty hard.

You are pushing the ability of a heat pump to not freeze the ..... in this case, condenser, out in the front of the car @ -5*C because the wind chill factor will pull it down lower as soon as you start driving .... not much heat capability trying to extract a heap of thermal units from a block of ice to raise the temp in the cabin above that same ice cold temp.

Using R290 as a refrigerant (propane) will get some cold weather improvement, but even propane has issues with the cold and not changing from a liquid to a vapour if it gets too cold.

T1 Terry

 

[LenEV2016]

You are pushing the ability of a heat pump to not freeze the ..... in this case, condenser, out in the front of the car @ -5*C because the wind chill factor will pull it down lower as soon as you start driving .... not much heat capability trying to extract a heap of thermal units from a block of ice to raise the temp in the cabin above that same ice cold temp.

Using R290 as a refrigerant (propane) will get some cold weather improvement, but even propane has issues with the cold and not changing from a liquid to a vapour if it gets too cold.

T1 Terry

You won't have that issue

 

[Bam Bam]

You are pushing the ability of a heat pump to not freeze the ..... in this case, condenser, out in the front of the car @ -5*C because the wind chill factor will pull it down lower as soon as you start driving ....

My guess would be that if it is -5 degrees you would have very low humidity so it would take a long time for the tubes to get frozen.

Particularly because the heat pump would also probably be scavenging small amounts of heat from other sources too.

 

[T1 Terry]

Snow, frost, all moisture, it only has to be in the area for the air to carry it .....
An example

The general technique is to block off the inside evaporator/condenser (depending on the cycle/heat or cool) and run the compressor to heat the refrigerant and continue to cycle it through the frozen outside unit, to melt away the ice so air again circulates.
In the old days, they would just switch the 2 way valve back to cooling and use the stored heat inside the house, bad enough in a large area, can you imaging the vents in the car, suddenly belting out very cold air?

The efficiency drops into the negative COP (electrical energy in/cooling or heating out, both measured in watts) while this function is in play, so that must be taken into consideration in the overall energy use compared to a straight resistive load type heater .....

T1 Terry

 

[Kithmo]

Pre-heating every day, short trips of 4 miles each way with the heater on 27C (22C real) I'm getting around 2 m/kWh. Gom is showing an optimistic 152 miles on 81% when in reality I'm getting around 130 from 100%.