Keeping the car connected to the charger

[HCS_UK]

If you are not planning to charge car, do you keep it still connected to the charger? I found that even car is scheduled for charging off-peak hours, car starts charging and stop on peak hours (very briefly like 4-5 minutes when I am inside). Which option is best for battery? MY24 RWD (2023 manufactured)

 

[Js1977]

Depends on what you are trying to do... going on holiday etc. Your car's battery chemistry is good for 100% charge every day otherwise for daily use.

If you are not planning to charge the car, then set it bellow to what the charge already is at (you can do this in the car or on the app) and plug it in.

Do you have a cheap/off peak electricity tariff?

 

[HCS_UK]

@Js1977 I have Octopus Intelligent Go.

4-5 mins charging does not important for electricity bill, I guess. I am worried about battery degradation. I also monitor car via Tessie.

 

[Js1977]

Plenty of posts about this here but in short 100% every day use. Dont worry about it even if you charged it to 100% and dont use it for say 2-3 days.

If you are not planning to charge car, its as ive mentioned above.

 

[Billbrown1982]

When I first bought the car old Elon said you can leave the car plugged in all day, every day and it will be quite happy. If I've charged the car and I don't go out there a couple days, I don't worry about it, but I certainly don't plug the car in if it doesn't "need" charging.

 

[WannabeOwner]

I found that even car is scheduled for charging off-peak hours, car starts charging and stop on peak hours (very briefly like 4-5 minutes when I am inside)

I would want to look into why that is (TeslaFi / Tessie / et al will likely give you some useful data)

Must admit I haven't checked recently, but my recollection is that the only charging I ever had was that Scheduled during Off Peak, except I specifically overrode for a "Daytime" charge

Maybe your car is waking up for something ...

If you are not planning to charge car, do you keep it still connected to the charger?

The saying used to be "ABC" - Always Be Connected

I want my car to charge, on schedule, if it needs it

I might want to pre-condition (off grid power) before going somewhere ... but that's old hat, nowadays it is usually cheaper to pre-condition off Battery, which was charged much cheaper during Off peak than Peak rate would be. Exception being if I am going on a long journey, have charged to 10)% and want max Range - so I want pre-condition to be "From Grid".

So : Come-home, Plug-in applies to me.

When on holiday I would leave it plugged in - in case it fell to a level where it needed to top up

But I worry that always-plugged-in could be a problem if there was a lightning strike.

Some people lower the LIMIT to (e.g. after a long journey / when returning home "empty") make sure that Off Peak charging does not continue beyond end of Off peak (and then further increase for "tomorrow night"). I use TeslaFi scheduler to STOP charging at end of Off Peak

So many choices ...

 

[Fursty Ferret]

From the owner's manual:

CAUTION
Tesla strongly recommends leaving Model 3 plugged in when not in use.

 

[12Pack]

I understand the BMS looks to balance the cells when the car is plugged in. This looks to ensure each individual cell is at nominal voltage levels, to prevent an individual cell staying low and eventually failing.

I also understand that while LFP batteries do not suffer as much cycle degradation as NMA/C ones, they still have worse calendar degradation at higher charge levels.

 

[HCS_UK]

I would want to look into why that is (TeslaFi / Tessie / et al will likely give you some useful data)

Must admit I haven't checked recently, but my recollection is that the only charging I ever had was that Scheduled during Off Peak, except I specifically overrode for a "Daytime" charge

Maybe your car is waking up for something ...



The saying used to be "ABC" - Always Be Connected

I want my car to charge, on schedule, if it needs it

I might want to pre-condition (off grid power) before going somewhere ... but that's old hat, nowadays it is usually cheaper to pre-condition off Battery, which was charged much cheaper during Off peak than Peak rate would be. Exception being if I am going on a long journey, have charged to 10)% and want max Range - so I want pre-condition to be "From Grid".

So : Come-home, Plug-in applies to me.

When on holiday I would leave it plugged in - in case it fell to a level where it needed to top up

But I worry that always-plugged-in could be a problem if there was a lightning strike.

Some people lower the LIMIT to (e.g. after a long journey / when returning home "empty") make sure that Off Peak charging does not continue beyond end of Off peak (and then further increase for "tomorrow night"). I use TeslaFi scheduler to STOP charging at end of Off Peak

So many choices ...

I have Tessie and it does not show any meaningful answer but, I have a theory that when I go in car, air condition starts working and use the energy from charger instead of battery.

I was using on board charging schedule but today I created an automation on Tessie to stop charging in off peak hours. We will see the result .

 

[MrBadger]

, I have a theory that when I go in car, air condition starts working and use the energy from charger instead of battery.

That’s exactly what happens. Our charge point has pulsing light when supplying electricity so easy to see when in use.

Get in car, HVAC comes on, charge point starts supplying power. It won’t then stop until you have left car and it’s locked itself.

You can however stop it early when sitting in the car by turning off HVAC from main screen.

I’ve never bothered to check energy consumed, but if it’s similar to pre conditioning it’s not insignificant.

 

[WannabeOwner]

I have Tessie and it does not show any meaningful answer

I've not used Tessie, but using TeslaFi I would check (raw data) for when charging occurred to see if I could see a pattern ("Every hour on the hour" or "When I opened the car door [but didn't drive anywhere]" and whether anything else is happening at same time (climate on, battery-heater, ...). If there is a pattern (e.g. one day to next) it might be something scheduled in an APP that has been used at some time - If there is that possibility I recommend changing Password (which will prevent all such APP access), re-set the password in Tessie, only, and see if it still logs short-charges.

You would have to, also, make sure that Tessie is not waking the car ... (TeslaFi has a means of checking the car is awake, without actually asking the car - which, Natch!, will wake the car. I presume Tessie has similar).

 

[father_of_6]

Plenty of posts about this here but in short 100% every day use. Dont worry about it even if you charged it to 100% and dont use it for say 2-3 days.

This is not great advice. Charging any lithium battery to 100% stresses the cells. Leaving it sitting at 100% will increase degradation.

 

[father_of_6]

Laugh all you want, but this it just not good advice. It's researched, data-driven, and well known that it's less healthy for your battery to sit at a high state of charge.

There are many, many posts about this including data visualizations from those that have done the research.

For a battery that costs $15-20k, it's irresponsible to tell people to "charge to 100% and let it sit". If you want to take care of your battery, including minimizing degradation, then don't leave it sitting at a high state of charge.

 

[HCS_UK]

View attachment 1005769

Laugh all you want, but this it just not good advice. It's researched, data-driven, and well known that it's less healthy for your battery to sit at a high state of charge.

There are many, many posts about this including data visualizations from those that have done the research.

For a battery that costs $15-20k, it's irresponsible to tell people to "charge to 100% and let it sit". If you want to take care of your battery, including minimizing degradation, then don't leave it sitting at a high state of charge.

As I understood, @Js1977 shared Tesla's official recommendation. LFP batteries more durable than NCA/NMC batteries against degradation like 1 to 4. Moreover, LFP battery has very flat voltage difference between 100% to 0% (Less stressed than NMC/NCA). For this reason, Tesla's BMS cannot measure correctly if you don't charge the car to 100% in specific periods (at least once a week according to Tesla).

I could not decide that should I keep 100% every time like Tesla recommends or follow traditional charging pattern (80% daily and 100% once a week).

Thank you all members for their contributions. The main point is should we follow Tesla's recommendation or our hunch and previous experiences about lithium ion batteries

 

[NikoV6]

For another view, my Model S pack currently has a 12% mismatch between cells. Tesla has asked me to charge to 90% for a couple of weeks while leaving the car plugged in. This will allow the car to balance the pack, drawing power as required.

We are on Octopus Intelligent and Tesla are seeing pack imbalance because Intelligent effectively turns off charging, rather than leave the car capable of charging/balancing. Will report back if this balancing works

 

[yessuz]

@Js1977 I have Octopus Intelligent Go.

4-5 mins charging does not important for electricity bill, I guess. I am worried about battery degradation. I also monitor car via Tessie.

if this is Intelligen Octopus, then car starts to charge once pluged in and stops by instruction from Octopus. it can take some time to algorythm to kick in. This is standard IO behaviour

alternatively, you can set to start the charge at 23:30 in your car.

 

[MrBadger]

Thank you all members for their contributions. The main point is should we follow Tesla's recommendation or our hunch and previous experiences about lithium ion batteries

Tesla do change their recommendations from time to time, even for the same battery pack.

Eg they use to suggest (incl in app prompts and limit lines) it was OK to daily charge to 90% for non trip purposes but recently changed that to 80% and updated in app prompt. I guess they have more historical info now to base their recommendations on.

 

[yessuz]

This is not great advice. Charging any lithium battery to 100% stresses the cells. Leaving it sitting at 100% will increase degradation.

except if that is LFP battery then tesla recommends to charge to 100% daily.
MY RWD is LFP

 

[MrBadger]

alternatively, you can set to start the charge at 23:30 in your car.

Watch out for scenario where battery SoC is at a value where IO does not need to charge, eg IO limit < SoC. In this case car will start to charge at scheduled car time and not stop until it hit the in car limit - ie exactly the same as car and battery schedule/limit. This may not be what was desired.

 

[Js1977]

it can take some time to algorythm to kick in. This is standard IO behaviour

FYI - I dont have any experience with cars controlled directly to IO but my connected charger is pretty much instant every time.