Speak EV - Electric Car Forums banner
1 - 12 of 12 Posts

·
Registered
Nissan Leaf 2016 Acenta 30kWh
Joined
·
29 Posts
Discussion Starter · #1 ·
Hi all, we bought our first Leaf30 Acenta back in October last year, so have only really known it as a winter car so far.

We found that a general battery use rule of thumb during the cold months seemed to be 20% battery = 15 miles. I'd seen that ratio on this forum somewhere, and it worked pretty consistently on our various length journeys.

Now that the weather has started to warm we've already noticed an improvement - my wife's standard commute has improved from 11% to 7%, and we're still only in March.

I was wondering what will happen as the weather improves more - do EV owners tend to see best mileage during Spring and Autumn, assuming hot batteries and aircon use reduce mileage again during the hottest months? Or is the summer the best point for mileage?

And any experienced 'rule of thumb' ratios we can use for April / May time as we plan trips to see family?
 

·
Registered
GOLF GTE PHEV
Joined
·
3,828 Posts
The improvement may be partially explained by less use of the heating.
On long journeys your average speed will have a larger impact.
Battery temperature mainly affects charging and max power delivery limiting for a hot battery although there maybe an optimum temperature for the most efficient energy production.
 

·
Registered
Joined
·
2,097 Posts
Even if you use the air conditioning it uses less power than heating, though it does still make some difference to range. Depending on the health of your battery, you can probably work with 1% = 1 Mile in the warmer months as a rough guide. That's mostly what I worked by in my 30kWh model.

Maybe play around with ABRP? Their planner takes into account lots of variables including degradation, as well as weather conditions. Trying different combinations should give you a good idea of what to expect. In my experience that's a very accurate tool.
 

·
Registered
30KW Tekna (2017)
Joined
·
1,122 Posts
Lol @Tandy0 this is normal uk temps for March!

Range depends on so many factors! Sped you drive, hills, heater and air on use.

I don’t use heating or air on unless necessary, and can manage 1 mile per % at this time of year.

Last week went right down, just before turtle and got 106 miles.

But I was driving on dual carriageways at 55 indicated.
 

·
Registered
GOLF GTE PHEV
Joined
·
3,828 Posts
I opted for a 62kw Leaf because its done 2miles/% over the last month with heating and slow single track country lanes. (The miles/kw improved from 2.5 to 3.2 last sunday (warmer) on a 60mph, 30miles trip to Morrisions & back)
 

·
Registered
Joined
·
63 Posts
We find temperature has little effect on range until it goes below 0 degress at which point it suddenly has a massive hit. When I was doing a regular commute to the office (remember them?) if it was really cold I would bang in a 10 minute rapid at Membury services which bought the battery temperature up and gave me back the full range again. Once the battery is warm it has a huge thermal inertia so won't get cold again during the journey.
 

·
Registered
Nissan Leaf 2016 Acenta 30kWh
Joined
·
29 Posts
Discussion Starter · #8 ·
Thanks all, that's useful. And on a separate note, what's a good speed to aim for on the longer journeys on dual carriageway or motorway - about 60mph is most efficient?
 

·
Registered
Joined
·
472 Posts
Air is much denser at colder temperatures so, regardless of aircon, the efficiency will be better at higher temperatures. Batteries like to be warm too so maximum range tends to be when air temperature is in the low 20s.
 

·
Registered
Joined
·
5,420 Posts
Hi all, we bought our first Leaf30 Acenta back in October last year, so have only really known it as a winter car so far.

We found that a general battery use rule of thumb during the cold months seemed to be 20% battery = 15 miles. I'd seen that ratio on this forum somewhere, and it worked pretty consistently on our various length journeys.

Now that the weather has started to warm we've already noticed an improvement - my wife's standard commute has improved from 11% to 7%, and we're still only in March.

I was wondering what will happen as the weather improves more - do EV owners tend to see best mileage during Spring and Autumn, assuming hot batteries and aircon use reduce mileage again during the hottest months? Or is the summer the best point for mileage?

And any experienced 'rule of thumb' ratios we can use for April / May time as we plan trips to see family?
We've had our Leaf 30 since last July so have had the chance to drive it in hot summer weather, (aircon needed) cool autumn weather (not much climate control needed if any) and winter right down to -8C.

In summer with A/C running we were seeing about one mile per percent or a little over 100 miles range. (just over 100 miles on the motorway at 60mph, about 4 miles/kWh, up to 110 in slower traffic suburban traffic, about 4.2 miles/kWh)

In the kind of weather we're having now (7-10C) with the heater on 22 range is around 85-90 miles. (about 3.3 miles/kWh reported) In -8C we saw real world range drop to about 70 miles, (2.9 miles/kWh) but we do multiple shorter trips (4 separate trips per day) which hurts range a lot more in winter than one long trip.

This is because you have to pay the "departure tax" of heating the car up multiple times instead of just once. The colder it is the more breaking your driving up into many smaller trips hurts, unless you do plugged in preconditioning. On a near freezing winter morning the energy to initially heat the cabin up to around 21C would carry you about 5 miles, so that's 5 miles range loss per trip if the cabin fully cools down between trips and has to heat up again from battery. So those doing multiple small spaced out trips over a few days will see a much bigger range hit in winter than those doing only one longer trip of the same mileage in a day, for example a cross country trip.

Hot batteries don't reduce range - if anything they increase it slightly as batteries work most efficiently when they are hot. (hot being up to about 40C, anything above that would be too hot) However hotter batteries experience increased degradation and higher statistical chance of having cell failures over time, so being slightly more efficient is not a good reason to let the battery get too hot. For longevity you want the battery kept cool. Below 10C batteries start to become slightly less efficient and below 0C a lot less, (and charging speeds will be reduced) so the sweet spot for battery temperature is around 10C to 30C to balance performance and longevity. (Keeping in mind that when driven or charged, battery temperature is always higher than ambient as the battery is somewhat insulated from the outside and is a heat generating source when driven and especially when rapid charged)

A/C theoretically reduces range in the peak of summer but the power needed for A/C is relatively small on a UK summer day so it makes little difference in practice, so I would say summer isn't really any worse than a 17C spring/autumn day. Cold weather and/or wet roads sap range far more than hot weather. We're not living in Texas here. :)
 

·
Registered
Joined
·
5,420 Posts
We find temperature has little effect on range until it goes below 0 degress at which point it suddenly has a massive hit.
Yes, I see a similar sudden step increase in consumption at a certain point approximately between -4C and +2C ambient.

From monitoring with Leafspy this is probably related to the balance of power drawn by heat pump and PTC heater. During initial warm up the Leaf runs the PTC heater and heat pump together as the heat pump alone can't warm the car quickly enough, however as the cabin reaches temperature the PTC heater is dialled back and usually stops leaving only the heat pump for most of the journey. (This use of PTC heater during initial warm up is one reason the cold weather departure tax is so high for multiple short trips, as that initial heat up process is less efficient)

However below a certain outside temperature the heat pump alone doesn't seem to be enough and the PTC heater remains partially on for the whole journey - the PTC heater of course uses a lot more power for the same heat output so consumption jumps up dramatically.

Another thing that can happen in very cold weather is the heat pump radiator at the front of the car can ice up - this has definitely happened to me twice that I know of (as Leafspy was running in the car at the time) in -5 to -8C conditions where it was very foggy. The heat pump started to run faster and faster (using more power and making more noise) and the radiator fan was running at high, then after a while it "gave up" and turned the heat pump off and used the PTC heater exclusively. Of course this would dramatically increase consumption.

On both occasions when this happened the heat pump wasn't working again until the following day as it was continuously below -5C ambient with no way for the radiator to thaw and I think the only thing that was able to thaw the iced radiator in the end was the overnight charging session. (which puts heat into the adjacent drivetrain cooling radiator and is probably enough heat to thaw the radiator.
 
1 - 12 of 12 Posts
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top