Winter efficiency?

[Deleted User 2312]

A bit of unscientific testing from me this week, two identical commutes with nearly identical weather/temperature and similar traffic. Commute is 40 miles of dual carriageway and motorway.

Day 1 - no pre departure heating, averaged 3.1 miles/kWh
Day 2 - pre departure heating (plugged in), averaged 3.8 miles/kWh

Unscientific for sure but the pre heating certainly made a difference. Unsure if it's the battery preheating or just the cabin temp or both. Suspect both as after pre heating the regen bar was fully available whereas half available the day before (both same SoC)

How were you preheating for this?

Starting climate from app using ‘start’?
Climate timer?
Charging location timer + climate timer?

[Ken3966]

It’s not as simple as that. Even at the lower efficiency you have more than enough range to do your commute and get home again.

If you charge overnight at an off peak rate of say 7.5p a kW, why on earth would you want to preheat before setting off at 29p a kW?
The saving in consumption by preheating is surely lost by higher electricity costs for the preheating.

Personally I unplug my car before preheating if I will still have enough range for the days trips. I would only consider preheating whilst plugged in if I knew I was destined to use a fast charger away from home to complete the trip.

[EVSJ]

How were you preheating for this?

Starting climate from app using ‘start’?
Climate timer?
Charging location timer + climate timer?

This was a timed departure charge from the app the night before.

It’s not as simple as that. Even at the lower efficiency you have more than enough range to do your commute and get home again.

If you charge overnight at an off peak rate of say 7.5p a kW, why on earth would you want to preheat before setting off at 29p a kW?
The saving in consumption by preheating is surely lost by higher electricity costs for the preheating.

Personally I unplug my car before preheating if I will still have enough range for the days trips. I would only consider preheating whilst plugged in if I knew I was destined to use a fast charger away from home to complete the trip.

Agreed, purely from a cost perspective it may not make sense. Although I saved 2.5 kW or so during the trip it's probably outweighed or equalled by the kW for preheating. This was more an experiment for my own interest.

That said I do longish day trips of 200+ miles which may then make the initial preheating beneficial if it stops having to recharge on the way home. Sometimes the range outweighs the cost, similar to why I added the heat pump, it's not going to save me money but the extra range at times may help in the winter.

[Dav00]

Agreed, purely from a cost perspective it may not make sense. Although I saved 2.5 kW or so during the trip it's probably outweighed or equalled by the kW for preheating.

It's all about different driving & travel patterns and external conditions so I'm not questioning the figures above but I think that the loss of efficiency due to poor thermal management of the battery can be (easily) far worse than the 1.5-2.5kW you can use for battery conditioning.
I have experienced that over the past few days, with lower temperature: despite having very good performance up to the moment, we eventually experienced a sudden drop, a sudden and significant drop. Only a few days ago I was reporting these figures, viewtopic.php?p=23882&hilit=range#p23882
I think we have lost 1/3 of the range since then!
I don't have hw and sw to monitor the system but clearly there are tresholds and once you cross them, it's a leap into a world of inefficiency.

And let's be honest, these are not even real "low temperatures". If you look at forums/posts from other European countries, e.g. on the official Facebook group managed by Skoda, the problems pile up as soon as you hit some non-extreme winter conditions: poor efficiency inc. very low regen, very slow charging processes etc. A terrible mix.

[orrery]

If you charge overnight at an off peak rate of say 7.5p a kW, why on earth would you want to preheat before setting off at 29p a kW?

Because it makes for a more pleasant experience, getting in a warm car and not having to scape the ice off?
It gives you more range - how much is your time worth?
... and, as you said, it may save you from having to charge at 60/70/80p on a public rapid.

[ricky10]

Warner condition this week has yielded above 4miles/kwh efficiency.

May the warm weather continue

[Ken3966]

If you charge overnight at an off peak rate of say 7.5p a kW, why on earth would you want to preheat before setting off at 29p a kW?

Because it makes for a more pleasant experience, getting in a warm car and not having to scape the ice off?
It gives you more range - how much is your time worth?
... and, as you said, it may save you from having to charge at 60/70/80p on a public rapid.

You misunderstood me.
By all means preheat, but do it from car battery which was charged at 7.5p a kW. If plugged in still it will be at 29p a kW.
I regularly preheat, did it this morning, but car did not need to be plugged in as loads in battery.
Forgot for return trip and we had to wait in car a few minutes for it I warm up and windows to demist.