Battery Preheat - Down side

[piffmunday]

Hi All,

I had a small issue at the weekend, admittedly this was somewhat down to some poor planning with my charging and an issue with my overnight charge.

I was running low on charge on Saturday to the point I had to use a non-tesla charger. I put the destination in my satnav of the charger and it showed I would arrive with 3% battery remaining so I set off confident in the knowledge I would get there with battery to spare, I drove carefully to conserve range. I typically average around 220-230 Wh/mi but as I had put a charger as the destination, the car started to precondition the battery and my economy went up to 332 Wh/mi, my estimated % on arrival slowly went down until it hit 1% with 3 miles to go, at which point I cancelled the satnav as I knew where I was going, I arrived at the charger with 0% battery, high blood pressure and complete panic at the thought of the embarrassment when I told my family/friends.

Has anyone else found that this can happen, I am surprised there isnt something in the software to prevent preconditioning once you are below a certain percentage.

 

[AndrewGR]

I thought it wouldn’t do it if you were below 20% but maybe that has changed. It does seem to use (waste?) a lot of energy just to get you off the charger a few minutes quicker.

 

[Jonathan Mason]

Yes. to be honest, the amount of range the pre-heating was taking, and therefore the cost of it (at premium public rates) really didn't seem worth it, so I wont use the sat nav to charger option anymore.

 

[piffmunday]

Yes. to be honest, the amount of range the pre-heating was taking, and therefore the cost of it (at premium public rates) really didn't seem worth it, so I wont use the sat nav to charger option anymore.

It would be good if there was a prompt when you select a charger on the navigation to say 'Would you like to preheat the battery for faster charging?' I imagine that would be easy to add.

 

[AndrewGR]

The manual says this about preconditioning before a scheduled departure:
When Model Y is not plugged in, preconditioning operates but only when the Battery's charge level is above 20%.
Would be logical to do the same en route.

 

[UncleCreepy]

I thought it wouldn’t do it if you were below 20% but maybe that has changed. It does seem to use (waste?) a lot of energy just to get you off the charger a few minutes quicker.

It has changed. Just two days ago, I arrived at a SuC with 2% SoC left, and the battery was still preheating.

If you don't need to charge as quickly as possible, preheating has become a waste of money. This was different when we were charged by the minute. Now that we pay by the kWh, it just costs more money to preheat. Which also leads to SuCs being congested more often due to longer charging times.

 

[UncleCreepy]

The manual says this about preconditioning before a scheduled departure:
When Model Y is not plugged in, preconditioning operates but only when the Battery's charge level is above 20%.
Would be logical to do the same en route.

Not really. If the car knows that you can make it to the SuC (as in 10% left, 2 km away from the SuC), it might as well continue preheating the battery.

 

[ewoodrick]

Hi All,

I had a small issue at the weekend, admittedly this was somewhat down to some poor planning with my charging and an issue with my overnight charge.

I was running low on charge on Saturday to the point I had to use a non-tesla charger. I put the destination in my satnav of the charger and it showed I would arrive with 3% battery remaining so I set off confident in the knowledge I would get there with battery to spare, I drove carefully to conserve range. I typically average around 220-230 Wh/mi but as I had put a charger as the destination, the car started to precondition the battery and my economy went up to 332 Wh/mi, my estimated % on arrival slowly went down until it hit 1% with 3 miles to go, at which point I cancelled the satnav as I knew where I was going, I arrived at the charger with 0% battery, high blood pressure and complete panic at the thought of the embarrassment when I told my family/friends.

Has anyone else found that this can happen, I am surprised there isnt something in the software to prevent preconditioning once you are below a certain percentage.

I'm assuming that it was a relatively short trip to the DC Fast charger and very possibly cooler.

Those add up to a much higher than normal usage. The car shouldn't have been conditioning the battery, since the battery was too low.

But you had "confidant knowledge" of arriving at 3%? I'll admit that I push the lower levels quite a bit, but 3% doesn't really make me confidant.

If you were worrying about the preconditioning, why not just route to the address instead? And what was your "drive carefully to conserve range"? I'm assuming that it was about 30-35 mph.

 

[piffmunday]

I'm assuming that it was a relatively short trip to the DC Fast charger and very possibly cooler.

Those add up to a much higher than normal usage. The car shouldn't have been conditioning the battery, since the battery was too low.

But you had "confidant knowledge" of arriving at 3%? I'll admit that I push the lower levels quite a bit, but 3% doesn't really make me confidant.

If you were worrying about the preconditioning, why not just route to the address instead? And what was your "drive carefully to conserve range"? I'm assuming that it was about 30-35 mph.

It was about 15-20 miles to the charger, admitted I trust the % on the navigation as on the whole it is spot on. I wouldnt say it was cold (12-13 deg), I even turned the cabin temp down to 18 deg to help. I had already driven earlier and the reason I got so low was because I had an appointment pulled forward so it ruined my plans of using a charger much closer.

In terms of the pre-condition, I never knew it would have such an effect on range or I assumed that it probably wouldn't affect the range that badly.

 

[init6]

Being confident in 3% remaining is where you went wrong. Not a lot of wriggle room there

The preconditioning message does not mean that it's heating the battery all that time. It goes off an on depending on a number of factors.
What brand of charger did you use? Was it in the sat nav or did you manually add the address?

 

[zoomer0056]

complete panic at the thought of the embarrassment when I told my family/friends.

I read your story and it seems we've all learned something from it and the thread responses. However, it's the embarrassment caused by the ones that are supposed to support you that caught my eye. Electric cars are new and we're all figuring out the best ways to take advantage of this new tech. No embarrassment needed.

 

[piffmunday]

Being confident in 3% remaining is where you went wrong. Not a lot of wriggle room there

The preconditioning message does not mean that it's heating the battery all that time. It goes off an on depending on a number of factors.
What brand of charger did you use? Was it in the sat nav or did you manually add the address?

Instavolt, I used the satnav.

Its definitely a lesson, I got a little lucky. I am waiting a charger to be installed at home and at work so I wont be so reliant on granny charging. I will almost never use a public charger in the future. I sure as hell wont get this low again.

 

[piffmunday]

I read your story and it seems we've all learned something from it and the thread responses. However, it's the embarrassment cause by the ones that are supposed to support you that caught my eye. Electric cars are new and we're all figuring out the best ways to take advantage of this new tech. No embarrassment needed.

Its more the embarrassment in my piss poor planning

 

[Jwdrums]

Arriving at a supercharger with a stone cold battery will ultimately use the same amount of power as pre-conditining surely? The battery needs to be above a certain temp to charge efficiently. What you sacrifice in efficiency while driving to the charger with battery heater on, you gain in kWhs pulled from the charger. If you're one a one charge trip and have cheap rate at home then is it actually more economic to pre condition..

Having said that you would expect it to turn off under a certain SoC

 

[LoudMusic]

In the North American software you can tap on the text that says it's preconditioning to turn off the preconditioning.

Which also leads to SuCs being congested more often due to longer charging times.

Are you saying that preconditioning makes charging take longer because it's lowering the SOC?

 

[Big Earl]

In the North American software you can tap on the text that says it's preconditioning to turn off the preconditioning.

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Are you saying that preconditioning makes charging take longer because it's lowering the SOC?

Tapping the message makes it disappear but it does not stop preconditioning.

 

[ajmorr.is]

Arriving at a supercharger with a stone cold battery will ultimately use the same amount of power as pre-conditining surely?

The amount of power consumed on a charger is not related to the amount of time that you are plugged in - even 7kW chargers slow down massively as you get close to 100%. Pre-conditioning allows for a faster rate of charge on a DC rapid or ultra-rapid charger, but it comes at the expense of some stored power (around 4-5% in a MY LR from my experience). If you're not bothered about faster charge rates then no need to precondition and it would be beneficial as others have mentioned to have the choice to turn this off from the UI.

 

[UncleCreepy]

Are you saying that preconditioning makes charging take longer because it's lowering the SOC?

Nope, quite the opposite. Charging is way faster with a preconditioned battery. The comparatively low amount of energy it takes to heat the battery means next to nothing in terms of charging time, but the warm battery will make charging much faster.
Sorry if there has been any confusion.

 

[LoudMusic]

Tapping the message makes it disappear but it does not stop preconditioning.

Did it used to stop the preconditioning? I feel certain I could hear a change in the system when I did that previously. Like pumps turning off or something.

 

[adsheff]

If it was initially 3% then I wouldn't have gone with that - I need at least 10% on there to feel confident, preferably 15-20. Always seems to end up lower than it predicted.