Battery preconditioning

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electric beagle
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Battery preconditioning

Post by electric beagle » Thu Feb 25, 2021 12:00 pm

Is there any way to force the car to condition the battery whilst plugged in?

I generally charge my car using off peak at 5p a kWh at home so before departure it is generally already fully charged. All my attempts to add a departure time when the car is fully charged have failed. Is there any way to do this?

I know that the car needs to be plugged in (and it was) and that power needs to be enabled (so switched off my Andersen timed charging). But still no dice.

Is there any way to enable departure preconditioning without giving up a control of charging costs?
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kermit68
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Re: Battery preconditioning

Post by kermit68 » Thu Feb 25, 2021 12:25 pm

electric beagle wrote:
Thu Feb 25, 2021 12:00 pm
Is there any way to force the car to condition the battery whilst plugged in?

I generally charge my car using off peak at 5p a kWh at home so before departure it is generally already fully charged. All my attempts to add a departure time when the car is fully charged have failed. Is there any way to do this?

I know that the car needs to be plugged in (and it was) and that power needs to be enabled (so switched off my Andersen timed charging). But still no dice.

Is there any way to enable departure preconditioning without giving up a control of charging costs?
It should be possibile. Charging and preconditiong should not be related, at least according to what I read in JLR documentation.
The basic idea is that if you set a departure timer AND the battery temperature is below 13C AND there is enough time/power to reach 100% SoC before departure time AND before the amount of time needed for the battery to reach the optimal temperature, then you'll get the preconditiong.
Of course there are a lot of "AND" but in your case you should have all of them as far as I've understood from your post as the car should be already at 100% SOC which makes easier to have available the needed time for precon.
Last edited by kermit68 on Thu Feb 25, 2021 1:10 pm, edited 1 time in total.
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electric beagle
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Re: Battery preconditioning

Post by electric beagle » Thu Feb 25, 2021 12:33 pm

Any idea how long it takes to achieve an optimum temperature after a full charge I was allowing 90 minutes which felt reasonable.
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Captain.Plummet
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Re: Battery preconditioning

Post by Captain.Plummet » Thu Feb 25, 2021 12:56 pm

Depending upon outside air temperature and wind chill it can take a long time and a lot of power to precondition the battery. In cold weather several preconditioning sessions may be needed to overcome cooling through the chassis. The heating element in an I Pace is a plate under the cell pack, unlike Teslas where the temperature control is threaded between the cells. Heat loss through the battery subframe and baseplate is high.
Since the car is using the battery to precondition it can use what it needs. It is charging at the same time of course, but available power is being drawn from the wall socket. It's quite possible to use 15kW when preconditioning in cold weather and still not have the battery up to temperature.
If the car is standing outdoors, preconditioning is accelerated if you use a car cover that extends to the floor. By far the best and cheapest solution is to use a garage if possible. Even better if the garage is insulated and can be heated economically.

electric beagle
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Re: Battery preconditioning

Post by electric beagle » Thu Feb 25, 2021 1:21 pm

I do plan to move the car to the garage but need to do a complex piece of work first to replace the current 2 stupid rather small standard doors with a much larger double door. My garage is pretty well insulated if not heated and that will be better still once the new door is fitted until then I am stuck with it being outside.

Is the battery preconditioning worth the cost in terms of added duration? If it costs 15Kwh of power that would need to add at least 40 odd miles of range (at my own driving pace) to break even.

Also the power I would use to precondition would be almost 3 times the cost of the power I normally use to charge. That may be worthwhile for the convenience but I would be interested to know how much difference it is likely to make. To give context an extra 40 miles would be about 25% of a normal full charge distance.
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Captain.Plummet
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Re: Battery preconditioning

Post by Captain.Plummet » Thu Feb 25, 2021 2:00 pm

The battery begins to heat internally once you are driving and a balance between internal heating and external cooling is established within a few miles. Once that point is reached the range has nothing to do with how much you preconditioned. During the first few miles it will always look as though consumption is startlingly high, but tha is misleading because the battery curve is S shaped. The voltage drops quickly at first and then establishes a stable on-load voltage which it maintains until it begins to decay quickly at the end of the discharge cycle. Obviously Jaguar don't let the car get to the point where the voltage avalanches, so there are always a few kW left in the battery when everything goes dark. In the first few miles you are using no more power to move the vehicle than later in the drive, but you are losing voltage very quickly and bringing the battery up to temperature.
Preconditioning is really about two things a) preparing the cabin for comfort and b) lifting the battery temperature to get more charge into the cells.
a) takes less than 30 minutes in most cases but b) takes hours from cold in winter and costs a fortune. To improve battery capacity you are far better off putting the car on charge as soon as you get home at night when the battery is warm and charging it to 100%. Leave the car plugged in and you can precondition for 20minutes before departure in the morning to warm the cabin. Don't worry about 80% charging, it's a red herring. the I Pace is designed to be charged to 100% without affecting battery life.

electric beagle
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Re: Battery preconditioning

Post by electric beagle » Thu Feb 25, 2021 4:33 pm

Interesting thanks so I have had no issues with cabin preconditioning which as you say even in the cold normally sorts things in less than 30 mins but I have only once tried to set a departure time with the aim of maximising range and that failed perhaps because I was too close to the departure time.

I am reading that there is little real point in preconditioning the battery as that is disproportionately expensive and time consuming? Shame that JLR didn't change the battery warming design for the 21 which might have made it more efficient and effective. Having heating and cooling between the cells seems to be a no brainer.
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jpbates
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Re: Battery preconditioning

Post by jpbates » Thu Feb 25, 2021 8:44 pm

As I understand it you need to allow for upto 4 hours for battery pre conditioning. So you need to allow time to fully charge battery plus 4 hours before departure time set. So if using eg Zappi or Anderson you will need to set it to allow charging outside the 4 hours for eg Octopus Go.

So leave at 9 am then Charger needs to allow from 12.30 to 9 am
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Captain.Plummet
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Re: Battery preconditioning

Post by Captain.Plummet » Thu Feb 25, 2021 8:48 pm

electric beagle wrote:
Thu Feb 25, 2021 4:33 pm
Interesting thanks so I have had no issues with cabin preconditioning which as you say even in the cold normally sorts things in less than 30 mins but I have only once tried to set a departure time with the aim of maximising range and that failed perhaps because I was too close to the departure time.

I am reading that there is little real point in preconditioning the battery as that is disproportionately expensive and time consuming? Shame that JLR didn't change the battery warming design for the 21 which might have made it more efficient and effective. Having heating and cooling between the cells seems to be a no brainer.
Redeveloping a battery pack takes years of work. Jaguar cannot change a design on the fly.
The benefits of preconditioning are so dependent upon circumstances and duration, but they come with a cost. You are better off charging from warm even at peak rate than charging from cold and preconditioning when all of the incoming power cannot keep up with the loss incurred trying to heat three quarters of a ton of battery to a reasonable temperature.

dernotte
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Re: Battery preconditioning

Post by dernotte » Thu Feb 25, 2021 11:39 pm

You can clearly see of this graph what happen when you set the preconditioning with a full battery, and and plugged car.
I monitor the car since 9am, and the departur time was set for 2pm. At 12:30, the car decided to pre warm the battery (red, green, yellow line) for min,max,avg temperature of the battery, probably warmed by the hot coolant (line green and orange), It took one 1 hour to raise the battery temp from -10c to +20c. It seems that preconditionning always stop at 20c for the battery. And then at 1:30pm the car started to precondition the cabin for 30 min, and you can see the cabin temperature (blue line) reaching 20c.

Capture d%u2019écran, le 2021-02-13 à 17.52.02.png


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