Is preheat killing my range or is this normal?

[Boss Hogg]

This looks normal to me. I used to do the exactly same pre-heat setup as you via timers and the battery is 100% is preheated to 13 degrees C every time using 2-5% of the battery (PB+) in winter when not connected to an EVSE. I stopped using the timers for this reason and just use the phone app for a 10min cabin heat but it will keep preheating as you drive however you have a short commute.

I have a CT 4S the same as you, the battery pre-heat may be specific to the CT as others don't seem to see the same behaviour. It would be good if you could choose what to preheat as it appears the feature is designed primarily for use when connected to a an EVSE.

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[Ross]

I am a north of England GTS driver.

First of all, always preheat when plugged in if you can. I always do at home in the morning.

Below a certain temperature (not sure what) the seat is nicely warmed up with one bar and the wheel is on and warm. Race Tex heated wheel is so nice, warm and fuzzy. I find a leather heated wheel a bit ‘sweaty palms’.

At work however I still preheat without being plugged in, for comfort, but it does use up the battery.

(Energy used preheating doesn’t show on the trip computer so you car looks more efficient)

In my experience a full hours preheat IS actively heating the battery for more efficient driving and cabin heating.
Not just a side effect of heating the cabin.

I preheated for an hour once
at -3 Centigrade when the car was NOT plugged in. It used a full 5% of battery power (4kw?) but the car was nice and toasty, the battery had gone from -3 to 10 degrees.

Preheating also works more efficiently in the morning if you are plugged in AND have charged overnight as a by product of charging is the battery warming up. Even if you just charge a bit for an hour before you want to preheat. Use the latent heat!

I also find that if you get in the car before the hour is up this always stops the preheat even if the App still thinks it is pre heating. When I open the App after a short journey it briefly shows Preheating is working but resets itself within a few seconds to show it is not.

If I forget to preheat in minus temperatures with a stone cold battery, in my massive 2.5 miles commute to work my consumption is
2 kw per mile which is the battery desperately trying to get to an optimally functioning temperature.

Don’t forget the 5 mins ‘Preheat when unlocking’ setting. Very useful. I never use the preheat in timer as it infuriates me if I forget to cancel and I preheat the car when not using it, wasting energy.
So of course I forget to pre heat sometimes.
If I unlock the car from inside the house and wait exactly five mins it definitely takes the edge off and my heated seat and wheel are on.
Very useful back up and doesn’t use much energy if not plugged in.

Hope this helps.

 

[Donlam]

with preheat
9 Feb 2024 12:34 00:55 h 18 km/h 17 km 27.4 kWh/100 km

without preheat
8 Feb 2024 12:01 00:43 h 17 km/h 12 km 37.0 kWh/100 km

I found preheat cabin and battery is more efficient than without preheat for my short journey. I have monitor these everyday.

Those stats are without AC plug-in . outside temp. +2 to +5C

Hope it helps.

 

[W1NGE]

This is not the case on my 2022 car. I did an experiment to check. If I set the timer for a percentage charge and a departure time I get an alert from the app 1 hour before that time telling me the car is charged and the dispenser current stops and the charge light goes white, then some time later - it seems entirely dependant on how cold the battery is - the green charge light comes on again and the dispenser shows around 5kW being supplied and the total during this hour was between 2.6 kWh and 3.6kWh supplied (I have only tested the procedure 3 times). The battery has been heated from cold to around 15C during this period.

I would imagine that in summer no battery heating would be required and when very cold it requires more, the software decides and whilst in winter this power use heating the battery is not negligible it does not explain the range problems.



See above.
Mine does.

Preheat of a battery requires somewhere in the region of 32C - 36C for faster charging not the lower temps reached when AC charging or using preheat of the cabin. Charging is a chemical reaction and of course the battery will get warmer but not significantly to be classed as "preheat".

I've tried timer controlled cabin preheat only and it looks like shore power is being used which when I've tried and then disconnected the EVSE the range will drop as if the battery has been the source of the energy to preheat the cabin. My conclusion therefore is that you can't rely on it. Same outcome on MY21 and MY23 cars I've had / have. Worth revising for sure.

It would logical to assume shore power would be used by default if EVSE connected but given my experience to date and the lack of a mention in the Owner's guide I'm erring on the side of caution.

 

[W1NGE]

This looks normal to me. I used to do the exactly same pre-heat setup as you via timers and the battery is 100% is preheated to 13 degrees C every time using 2-5% of the battery (PB+) in winter when not connected to an EVSE. I stopped using the timers for this reason and just use the phone app for a 10min cabin heat but it will keep preheating as you drive however you have a short commute.

I have a CT 4S the same as you, the battery pre-heat may be specific to the CT as others don't seem to see the same behaviour. It would be good if you could choose what to preheat as it appears the feature is designed primarily for use when connected to a an EVSE.

I doubt there's any difference across the model variants - that's probably the only constant here.

If I charge to 100% at this time of the year 0C - 5C my battery gets to 13C.

Oddly, one morning this year 23C was reported after an overnight charge to 85%.

More poor coding / faulty sensors?

 

[f1eng]

Preheat of a battery requires somewhere in the region of 32C - 36C for faster charging not the lower temps reached when AC charging or using preheat of the cabin. Charging is a chemical reaction and of course the battery will get warmer but not significantly to be classed as "preheat".

I've tried timer controlled cabin preheat only and it looks like shore power is being used which when I've tried and then disconnected the EVSE the range will drop as if the battery has been the source of the energy to preheat the cabin. My conclusion therefore is that you can't rely on it. Same outcome on MY21 and MY23 cars I've had / have. Worth revising for sure.

It would logical to assume shore power would be used by default if EVSE connected but given my experience to date and the lack of a mention in the Owner's guide I'm erring on the side of caution.

I never expected the preheat of the timer to be to prepare the car for charging. That would be odd.

How much it heats the various elements of the car is probably programmed depending on their actual temperature.
In summer I feel sure it doesn't warm the battery or seats or rear window for example.
In winter mine certainly warms the battery far more than just charging it does. After I first noticed I checked it, only 3 times so not rigorous experiments, but enough to satisfy myself, if not anybody else, what was happening. I already knew why it was likely.

I understood it was a feature added during very low temperature testing when they found, unsurprisingly, if they set off with a very cold battery its max current capability is low and it discharges faster too.
By preheating the battery to a modest temperature - my car seems to target 15C - you get normal performance immediately since the current capability is then normal and better range (predicted and actual) because the discharge isn’t as fast.

 

[Scandinavian]

I do not have my car here at the moment, but this should all be visible in CarScanner app I think.

If you have the app connected to the car and start preheating in cold weather, you should be able to see the battery inlet temperature on the display. And you should also be able to see the PTC heater battery current.


I also have seen that my battery will get warmer if I preheat the car for the 60 minutes through the app. From minus 10 C to about plus 8 - 10 C in Norway during winter. But this warming of the battery is not the same as pre heating for charging at HPC.

 

[PedroJ]

Timer starts preparing the car usually an hour before time set. It warms the battery and the cabin.

So big battery drain is strange to me. However, SoC are not measured precisely. When I leave the can after the trip, battery temperature is usually above 20 C. After couple of hours on cold, the cold battery loses some %. My guess is its not a battery drain, its rather that cold battery can have lower voltage - which is recognized as a lower SoC.

 

[ct4s]

Thanks for all your replies - I now have a few options and settings to consider.

For the past week the timer has been turned off and the battery is lasting much longer.
Home charger is being fitted as I type this, so it shouldn't be a recurring issue after today. But I'll probably just turn on the preheat 10 mins before my commute rather than using the timer. And we're past the coldest weather already, so I won't need it at all after another couple of weeks.

I'll get the Car Scanner app and OBD dongle ordered at lunchtime to keep get a better grip on the data.
https://www.amazon.co.uk/gp/product/B088LW211V/ref=ox_sc_act_title_1?

 

[ct4s]

Don’t forget the 5 mins ‘Preheat when unlocking’ setting. Very useful. I never use the preheat in timer as it infuriates me if I forget to cancel and I preheat the car when not using it, wasting energy.
Hope this helps.

What's the 5mins preheat setting and where do I find it - in the app or PCM?

 

[Ross]

What's the 5mins preheat setting and where do I find it - in the app or PCM?

Go to Charging
Then Preheat/cool page
Tick the box
You get 5 mins conditioning.

As you can see bottom left. By the time I had faffed about getting the right page in the display to photograph just now there were
4 minutes remaining.

 

[ct4s]

Go to Charging
Then Preheat/cool page
Tick the box
You get 5 mins conditioning.

Great thanks.

 

[satchurator]

Preheating while not connected to a power source is going to consume an amount of energy from the HV battery proportional to the current-to-target temperature deltas for both the HV battery and cabin, plus the consumption from heating the steering wheel and seat(s). This total is going to vary primarily based on the ambient temperature in your garage / outside.

To speculate on range impact for this scenario means asking: 'is it normal to see this drop in range when preconditioning to a cabin temperature of 22°C without an external power source and an outdoor ambient temperature of X°C'.

IMO it's really not worth worrying about this - get your home EVSE installed and then precondition while connected to shore power.

Additionally, keep in mind that it might take a while for the car to update your projected range (since it remembers recent usage patterns).

 

[Gru]

Preheating while not connected to a power source is going to consume an amount of energy from the HV battery proportional to the current-to-target temperature deltas for both the HV battery and cabin, plus the consumption from heating the steering wheel and seat(s). This total is going to vary primarily based on the ambient temperature in your garage / outside.

Indeed.

I tested that at the end of this (long) post :

https://www.taycanforum.com/forum/threads/dissapointing-tacan-dc-charging.17484/post-287914

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