How long can it sit at 100%

[drtimhill]

I don't think that's true. Keeping a lithium ion battery for long periods of time at either very high or very low levels of charge is non-optimal - at least for most chemistries (LFP clearly seems to be an exception here). Of course, what constitutes very high and very low, what constitutes long periods, and how much difference it makes

indeed but the Op was worried about an hour or two .. which is not going to make any difference

 

[Mrklaw]

Unless you're heading to darkest Wales (very few superchargers I hear) it is unlikely you need to set off with 100% anyway. As long as you can comfortably make it to a supercharger I wouldn't bother going over 90-95%.

plenty of trips that will be on the border of doable without charging - those are the ones I want to charge to 100% for. Eg on the SR+ maybe its 190-200 motorway miles. So a 100 mile each way trip to drop my son at uni, or visit my folks - each leg too short to need to stop, but no opportunity to charge at the destination. I’d like the choice to not have to stop if possible so I charge to 100%.

 

[NISFAN]

Don’t forget that high rate DC charge is also not good for the battery. I.e. superchargers.

So better to slow rate to 100% to avoid a supercharge en route.

 

[pdk42]

Plenty of very definitive answers here - which I find a bit perplexing since every single search I’ve done on similar questions reveals either a myriad of junk info on popular sites, or references to very academic papers, the conclusions of which are anything but definitive. My conclusion therefore is that there is no definitive answer to the OP’s question.

A more honest, but unsatisfactory answer, would be “no one knows for sure, so charge it to 100% as little as possible and leave it there for as short as possible”.

 

[Roy B]

Plenty of very definitive answers here - which I find a bit perplexing since every single search I’ve done on similar questions reveals either a myriad of junk info on popular sites, or references to very academic papers, the conclusions of which are anything but definitive. My conclusion therefore is that there is no definitive answer to the OP’s question.

A more honest, but unsatisfactory answer, would be “no one knows for sure, so charge it to 100% as little as possible and leave it there for as short as possible”.

Yup. Basically just follow the user instructions regarding trip/daily! Anything more than that is informed speculation at best.....

 

[Irata]

references to very academic papers, the conclusions of which are anything but definitive. My conclusion therefore is that there is no definitive answer to the OP’s question.

And using that reasoning, neither you own conclusion can be definitive. So we end up in a paradox.

At least that helps, maybe.

 

[Llama.]

Hi all

Thanks everyone for your responses to my OP. All much appreciated.

I charge my LR M3 to 100% for a road trip approx 1 time a month. And I do prefer to keep my charging to the off peak times.

I’m reassured by the comments about the general durability of the battery occasionally sitting at 100% for 4 hours before departing on a road trip.

I think I may split the difference and charge to 95% on off peak then top up the last 5% in the hour before departure.

Many thanks

Chris

 

[pdk42]

And using that reasoning, neither you own conclusion can be definitive. So we end up in a paradox.

Ha! I think "we definitely don't know" needs a qualification of "but we could be wrong!"

 

[Roy B]

Unfortunately @pdk42 is exactly right. Academic papers are all very well, but when we don't - with any degree of certainty - even know what chemistry our packs are using - it's difficult or impossible to apply the results of that research.

Tesla don't tell you what pack is in your car. They don't tell you what chemistry any particular pack uses. The sad fact is that Tesla choses to divulge as little as legally permitted about the battery packs in our vehicles and as a result we, basically, know nothing for certain (although we can make educated guesses).

 

[EVer Hopeful]

sometimes i'm not getting home until 2am or later

Not that it's any of my business, but ... 2am??? what do you do where you get home at 2am ... or is your commute just rreeeeeeeallly long?

 

[Billbrown1982]

Not that it's any of my business, but ... 2am??? what do you do where you get home at 2am ... or is your commute just rreeeeeeeallly long?

Truck driver mate and I work the late shift Don't normally start until around 2pm, and "usually" do a max of 10 hours and get home by half 12....but not always.

 

[Stranger Dings]

Truck driver mate and I work the late shift Don't normally start until around 2pm, and "usually" do a max of 10 hours and get home by half 12....but not always.

Then to you, sir, I would like to extend a sincere thank you.

A tough job, with very little thanks given. You guys keep this country running and I’m not sure you ever get the praise that you deserve.

 

[HenryT]

Don’t forget that high rate DC charge is also not good for the battery. I.e. superchargers.

So better to slow rate to 100% to avoid a supercharge en route.

I think the received wisdom is slightly different to that, in that high rate DC charging (such as Chademo) is potentially detrimental, but supercharging isn't because of the battery management employed.

See here.

 

[Jason71]

Yup. Basically just follow the user instructions regarding trip/daily! Anything more than that is informed speculation at best.....

So in summary after 2 pages of back and forth comments the conclusion is: RTFM

 

[Roy B]

I think the received wisdom is slightly different to that, in that high rate DC charging (such as Chademo) is potentially detrimental, but supercharging isn't because of the battery management employed.

See here.

I don't really believe this. The basic operation of DC rapid charging is the same, whether CCS or Tesla. In both cases, the car controls the DC voltage the that charger supplies to the battery.

Granted, there clearly are clearly differences in how Tesla implements both charging modes, as evidenced by different charging curves, but in any case the stress placed on the cells by high current charging is unavoidable. Just like the the stress placed on the cells by high *discharge* current is unavoidable - witness the controversy over Tesla limiting how many times you can use launch mode on a Model S.

 

[Llama.]

Bugger! I’ve charged up to 100% for the Mrs to drive to the in-laws and back. Now the trip is cancelled due to ‘dangerously high winds’.

What do I do with a car with 100% charge and nowhere to go?

I think I might just sit in the car all day with the climate and bum heaters on watching re-runs of Brooklyn 99.

 

[Billbrown1982]

Bugger! I’ve charged up to 100% for the Mrs to drive to the in-laws and back. Now the trip is cancelled due to ‘dangerously high winds’.

What do I do with a car with 100% charge and nowhere to go?

I think I might just sit in the car all day with the climate and bum heaters on watching re-runs of Brooklyn 99.

I have noticed that if I charge to 90, the following morning, i'm pretty much always at 90, or 89.

But on the rare occasion i've gone 100, if I've not set out quickly, its dropped by a few more percent than normal. Also seems to drop quicker when driving through that first 10%

I often wonder if there's some kind of management going on. Like my DJI Drone, if you charge the batteries to full but don't use them, after a few days they automatically start discharging themselves down to a storage level.

 

[T.W.R]

Yes I’ve noticed that too. I’ve done a couple of 220 mile (each way) trips, and have charged it to 100 each time. If it’s been sat for a few hours only, I’ve seen a 2 percent drop at the most so far !

 

[Mrklaw]

It’ll do no or very little regen at 100% as there is no space in the battery for it to go, so you’ll be less efficient for that first 10% or so

 

[MrT3]

What do I do with a car with 100% charge and nowhere to go?

Leave climate on for a few hours, or even just sentry mode.