Pre Conditioning for SuC - is this right?

[pdk42]

I did a long trip on Sun (to West Wales) and put the Aberystwyth SuC into the sat nav as the destination. Immediately after starting the drive, and with over 3hrs to go to the SuC, the message popped up on the screen telling me it was pre-conditioning for rapid charging. It eventually went off, but popped up again a while later. This repeated probably a half dozen times over the trip. Interestingly, the last 15 mins before I arrived there was no pre heating going on! Looking at the trip later on TeslaFi, it seems that battery heating was on for 31% of the trip. This doesn’t seem right, but maybe I’m misunderstanding how it works. Views?

 

[NewbieT]

I’ve noticed the same.

My thinking goes along the lines of: Is it actively heating for all of the time, or just not cooling. Is it running the heat pump or just not running glycol through the radiator and putting the energy into the pack instead. It may be more efficient to run the motor less efficiently and generate a little heat over a longer period and store it in the pack.

Has anyone logged CANBUS temps while pre-conditioning a 2021 recently?

 

[Gatsojon]

I noticed the same on a trip from Manchester to Bath at the weekend. It seemed to pop up at periods of more moderate driving say in the 50 and 60 speed limits. Perhaps it decides that if the rest of the journey were to be like that, then not enough energy is being drawn to preheat? Not sure really but it did seem a bit odd.

 

[Bantam]

I had a similar situation when travelling from Leeds to Bath earlier this month, first real long drive so put it down to normal behaviour.

P.S @pdk42 if the starting address is your home address, you may want to think about removing the address from the picture you posted.

 

[pdk42]

I had a similar situation when travelling from Leeds to Bath earlier this month, first real long drive so put it down to normal behaviour.

P.S @pdk42 if the starting address is your home address, you may want to think about removing the address from the picture you posted.

Thanks - but it’s OK. It’s a car park in Leamington. We did breakfast before heading off. Bebas - amazing place. If you’re in Leamington I’d recommend it!

 

[pdk42]

I’ve had the car 2 years now and this isn’t how it used to be. I guess Tesla do it for a reason.

 

[Jason71]

I’ve had the car 2 years now and this isn’t how it used to be. I guess Tesla do it for a reason.

agreed. I have had long trips in really cold weather and yes it would start pre-heating 20-30 minutes before getting to the SuC but it certainly didn't do it for the whole Journey.

 

[Jeeves]

I’ve had it too. It is different to how it used to be. No idea why, but presuming it isn’t a bug, I imagine Tesla have determined it is more efficient.

 

[Adopado]

I have seen this too. I was presuming (hoping) that though there was an early message about preconditioning that it was perhaps just acknowledging that it would be preconditioning when necessary rather than really starting right away. Whatever it is there is a change in behaviour.

 

[Dangerous Fish]

Yes, this changed a while ago. Unless you have ScanmyTesla or similar it's difficult to understand what it's doing, but it's a bit like central heating in that it's probably more efficient to get the pack temperature to where it needs to be over a longer period of time rather than trying to warm it up in one go immediately before arriving at the SuC.

 

[Louis0w]

Same here. It's been this way for a while now. Assumed pre-conditioning behaviour had altered to bring battery to temperature in a stepped manner, rather than in one go.

 

[Jason71]

it's a bit like central heating in that it's probably more efficient to get the pack temperature to where it needs to be over a longer period of time rather than trying to warm it up in one go immediately before arriving at the SuC.

is it though?

Martin Lewis explains why you should never leave the heating on low all day

Martin Lewis' MoneySavingExpert has revealed how to use your central heating this year.

www.dailyecho.co.uk

 

[Dangerous Fish]

It is in my house!

 

[Mr_Dave]

I did a long trip on Sun (to West Wales) and put the Aberystwyth SuC into the sat nav as the destination. Immediately after starting the drive, and with over 3hrs to go to the SuC, the message popped up on the screen telling me it was pre-conditioning for rapid charging. It eventually went off, but popped up again a while later. This repeated probably a half dozen times over the trip. Interestingly, the last 15 mins before I arrived there was no pre heating going on!

I know that road into Aberystwyth well and the last stretch of the drive toward the town drops from just under 1050ft above sea level at Bwlch Nant y Arian visitor centre to about 25ft above in less than 10 miles so I wonder if this might account for the lack of preconditioning in the last 15 mins, as there’d be a lot of regen going on which heats the battery (or sufficiently keeps the temps up).

As far as what’s most cost effective, am I wrong in thinking that (for those of us that actually pay for supercharging) we only pay for what actually goes into the battery? So when preheating, energy comes out of the battery, but when actually supercharging, the extra energy needed to warm the battery (or having the HVAC on) comes from the charge point. Therefore, while it will take longer to charge, as the battery will be relatively cold, it may be cheaper?
I’m fully willing to admit I’m completely wrong about this though as it’s just a theory in my brain.

 

[Jeeves]

I think the aim of preconditioning is to minimise time spent charging, rather than cost, so journey and charger occupancy times are shortened.

 

[NewbieT]

…and to minimise battery degradation.

 

[Jason71]

I know that road into Aberystwyth well and the last stretch of the drive toward the town drops from just under 1050ft above sea level at Bwlch Nant y Arian visitor centre to about 25ft above in less than 10 miles so I wonder if this might account for the lack of preconditioning in the last 15 mins, as there’d be a lot of regen going on which heats the battery (or sufficiently keeps the temps up).

As far as what’s most cost effective, am I wrong in thinking that (for those of us that actually pay for supercharging) we only pay for what actually goes into the battery? So when preheating, energy comes out of the battery, but when actually supercharging, the extra energy needed to warm the battery (or having the HVAC on) comes from the charge point. Therefore, while it will take longer to charge, as the battery will be relatively cold, it may be cheaper?
I’m fully willing to admit I’m completely wrong about this though as it’s just a theory in my brain.

Not correct I'm afraid. It used to be the case but they changed it about 18 months ago. Now you pay for all DC that the car consumes.
Which is fair to be fair and still better than everyone else who charges for the AC consumed by the charger so you end up paying for the conversion/transport losses. You always need to add 10% to everyone else's prices when comparing to SuC

 

[Drew57]

On a recent journey from Cheshire using the M6 Rugby superchargers the car preconditioned frequently and Wh/m went from ~250 to ~370 during those periods (some quite lengthy). Overall consumption was 322 Wh/m.

For the next journey I set the destination as Rugby Services and charged without preconditioning. The journey used 271 Wh/m and although road and other conditions were similar, temperature was lower.

Both journeys started with the same 90% SOC & I'm not sure if the slightly longer charging time for the second occasion used more energy overall or not. The first used more during the drive but less from the supercharger, the second consumed less while driving but more from the supercharger.

If preheating assists in reducing battery degradation I will always use it, if it doesn't then on many journeys a slightly longer charging time means very little to me.

As it stands now, I don't really understand (preconditioning) consequences for overall energy consumption/cost or battery life. I would rather believe that Tesla is promoting it mainly to reduce the inconvenience of waiting while charging.

 

[Adopado]

If preheating assists in reducing battery degradation I will always use it, if it doesn't then on many journeys a slightly longer charging time means very little to me.

I would be surprised if there's any degradation benefit. If the battery is too cold to take the higher Supercharger rates it will surely just throttle back accordingly. I would have thought that the only penalty would be that charging to target percentage will take longer. (Just an opinion)

 

[Louis0w]

This is what the manual says about preconditioning when navigating to a Supercharger. No mention about mitigating degradation; it's purely for convenience and, I'd imagine, increasing throughput at the chargers:

From Scan My Tesla, optimal battery temperature appears to be in the mid 40'c range. Unless the ambient temperature is very high (something we're not used to!) it takes a lot of effort and many hours of driving to get anything close to the optimal temperature without the auto preconditioning.