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Plugged in Everyday?

Hi all

Trying to gather info on best charging practices and battery health.

I’ve read in places that the car should be plugged in when idle, even if not taking a charge. I’m also debating whether to do a small charge each night to top up what we’ve used that day, or just charge say once or twice a week through off peak hours, our weekly miles are only 100-120 MAX.

What’s the general consensus on leaving plugged in or not? Charging habits and patterns etc? Is it a case of each to their own or is there a definite proven method to follow?

Thanks.
 

Neilio

Member
Jul 8, 2020
994
626
Brentford
Hi all

Trying to gather info on best charging practices and battery health.

I’ve read in places that the car should be plugged in when idle, even if not taking a charge. I’m also debating whether to do a small charge each night to top up what we’ve used that day, or just charge say once or twice a week through off peak hours, our weekly miles are only 100-120 MAX.

What’s the general consensus on leaving plugged in or not? Charging habits and patterns etc? Is it a case of each to their own or is there a definite proven method to follow?

Thanks.
I think the phrase is a plugged in Tesla is a happy Tesla. I don’t have home charging at the moment but if I could I’d set the limit to 80% and yes charge it daily. From a battery point of view: if you don’t charge too high it should be fine and from a practicality point of view it’s perfect. You’ll always have range in case you need an emergency trip or fancy a random day out after lockdown
 
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Hi all

Trying to gather info on best charging practices and battery health.

I’ve read in places that the car should be plugged in when idle, even if not taking a charge. I’m also debating whether to do a small charge each night to top up what we’ve used that day, or just charge say once or twice a week through off peak hours, our weekly miles are only 100-120 MAX.

What’s the general consensus on leaving plugged in or not? Charging habits and patterns etc? Is it a case of each to their own or is there a definite proven method to follow?

Thanks.

Plug in, set limit to 50%.
When you have a planned journey set the limit to 50% + half the power required
 

Dre78

Member
Dec 16, 2018
307
303
Chicago, IL
Anecdotally, factors beyond charging affect battery life. For a year I was mostly Super Charging to 80%, lost some battery life. Then for the past year I've been mostly charging at home to 90%, lost some battery life. I think the cold, Chicago weather is to blame.

Screenshot_20210222-025217.png
 

Jason71

Active Member
May 8, 2019
3,429
3,616
Shropshire
I have home charging but only plug in when I need to charge it. which is only about 1, 4 hour charge a week at the moment!
I have heard the mantra ABC ( always be charging) but I don't really get it. I drive most days, all be it short distances at present constantly plugging in and unplugging seems pointless.
there is also the point that if I do that all my preheating will be from the mains at daytime prices not from the battery charged at night time prices!.
 

Battpower

Active Member
Supporting Member
Oct 10, 2019
2,233
2,274
Uk
I have home charging but only plug in when I need to charge it. which is only about 1, 4 hour charge a week at the moment!
I have heard the mantra ABC ( always be charging) but I don't really get it. I drive most days, all be it short distances at present constantly plugging in and unplugging seems pointless.
there is also the point that if I do that all my preheating will be from the mains at daytime prices not from the battery charged at night time prices!.

I think there are additional layers of subtlety that are either not generally known, published or understood. Also, as battery management can change from one update / set of bugs to another, its hard to track.

Also, the exact charging settings on a car make a difference, as might the type of charging outlet being used. So a proprietary Tesla charge outlet may (is likely to) behave differently from say Zappi or Polar. My charge outlet is on a timer so it can turn on and off independently of the car. From Teslamate data it looks very likely that with the car set to regular charge (MS R) and the charge lead plugged in but powered off, it appears that the car doesn't sleep correctly as it is always polling to see if the charge supply has powered up.

There is also evidence that for the battery to function optimally, it needs time powered off / completely shut down to monitor what happens to cell voltages.

I don't know if the car sleeps when left plugged in to a powered up charge outlet. At least in that case, the car will charge to the set SOC then idle according to whatever rules Tesla dictate, topping up SOC from time to time I expect.

My preference is to plug in and charge to somewhere between 60 and 80% SOC, then up plug. Teslamate reports stable battery readings and the car settles into a routine sleep pattern!

All that said, I haven't driven much in months, but I'm assuming that the OP is more interested in leaving the car plugged in when not in use.
 

Alistairuk

Member
Jun 25, 2020
608
444
Scotland
Everyone has different opinions on it and you can find arguments for all cases everywhere - but basically;

Tesla state leave it plugged in whenever possible. the car will manage its charge and battery health itself - if it needs to charge it will charge if it doesn’t it will sit there quite happily using tiny amount of power from ac to top up as required / run its systems. Just don’t charge above 80% if your not going to use it imminently.

Im not driving that much so mine sits happily on the driveway unplugged (charger is in the garage and in complete lack of forward planning was installed before the car arrived and the car can’t get up the ramp into my garage without bottoming out) - I charge it a few times a week down local park (cause it’s free) when I go for a walk although last few weeks it’s been parked at home doing nothing for 7-8 days at a time.

Supercharging apparently degrades the battery over time (as per Tesla and others) but I assume this is mainly only a major issue for people who ONLY supercharge and who do it multiple times a week.

Basically do whatever works for you and don’t worry to much about it!
 
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tsh2

Member
Aug 27, 2019
317
95
Cambridge, UK
It seems that charging cycles anywhere between ~20% and ~80% are almost free in terms of battery wear. You might loose some accuracy in the tracking of absolute charge state, and maybe also some temporary capacity loss due to cells being out of balance (but these are hard to predict).

If I was worried about range for a specific journey, I might try to discharge down to about 10% a day or two before - but I have no idea if this is enough to re-calibrate the SoC. Probably better to plan the journey with some fall-back options anyway.

I don't think the car uses shore power for anything other than charging or preconditioning - you can't avoid the daily vampire drain going through the battery (unlike how you can keep a laptop plugged in, not charging and not using the battery given the right settings).
 

SergeyP

Member
Sep 10, 2020
66
57
London
Just don’t charge above 80% if your not going to use it imminently.
I got worried reading many comments in this thread advising max charging rate upto 80%. My M3P is plugged each day to a home socket (via Tesla portable charger that came with the car). I specifically asked Tesla representative when collecting my car abt what limit should I set. I was advised to set the limit to "Daily 90%" regardless if I drive the car or leave it for a few weeks (e.g. if I ever start travelling again). My M3P is from September last year. Till now I am following Tesla recommendation of Daily 90%, or should I drop the limit to 80%?
 
I have home charging but only plug in when I need to charge it. which is only about 1, 4 hour charge a week at the moment!
I have heard the mantra ABC ( always be charging) but I don't really get it. I drive most days, all be it short distances at present constantly plugging in and unplugging seems pointless.
there is also the point that if I do that all my preheating will be from the mains at daytime prices not from the battery charged at night time prices!.
This is similar train of thought to mine Jason. I’ve read the manual, yes it says plug it in when not in use but then immediately harps on about extended periods of the car being idle.

I can’t find anything in the manual where it states charging every night by small increments, is better or worse than having a decent charge once a week, depending on individuals usage etc.
 

Durzel

Active Member
Jul 17, 2019
3,938
2,909
Bath, UK
I think Tesla advise people leave the car plugged in because there’s less chance of it draining that way. If it just becomes a habit then it’s not something you have to put any thought into.

For what it’s worth I left my car plugged in for 2 weeks and it used absolutely no power from the charger at all. If it does do 12v maintenance etc then it doesn’t appear to need the charger to do it.
 
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Adopado

Active Member
Aug 19, 2019
4,938
3,752
Scotland
I got worried reading many comments in this thread advising max charging rate upto 80%. My M3P is plugged each day to a home socket (via Tesla portable charger that came with the car). I specifically asked Tesla representative when collecting my car abt what limit should I set. I was advised to set the limit to "Daily 90%" regardless if I drive the car or leave it for a few weeks (e.g. if I ever start travelling again). My M3P is from September last year. Till now I am following Tesla recommendation of Daily 90%, or should I drop the limit to 80%?

Don't panic, you're fine! There are reasonable assumptions made about some small advantage of using lower percentages because of how batteries with similar chemistry are known to respond when not in Teslas. However, nobody can really say for sure and Tesla is surely in the best position to flag up any issues with leaving the car at whatever state of charge. No matter what the advantage or disadvantage it's liable to be a small effect in comparison to the many other factors that will affect the battery over its life.
 
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SergeyP

Member
Sep 10, 2020
66
57
London
Don't panic, you're fine! There are reasonable assumptions made about some small advantage of using lower percentages because of how batteries with similar chemistry are known to respond when not in Teslas. However, nobody can really say for sure and Tesla is surely in the best position to flag up any issues with leaving the car at whatever state of charge. No matter what the advantage or disadvantage it's liable to be a small effect in comparison to the many other factors that will affect the battery over its life.

Thanks Adopado! I can sleep well now :)!
 

Adopado

Active Member
Aug 19, 2019
4,938
3,752
Scotland
Thanks Adopado! I can sleep well now :)!

!!

I suspect that we all acquire notions of how best to optimise battery life but it's almost impossible to know for sure how our own particular pattern of charging compares with someone else's over the long term. The only thing we know with some confidence is that routinely charging to 100% is not a good idea (though occasional is fine) and that running the battery down to a very low percentage and then leaving it uncharged is to be avoided. Another factor is that Tesla can (and does) tweak how the battery management system balances things up when they issue software updates but nobody outside of Tesla ever gets to know the details of what's going on "under the hood".

My own variation on charging schemes (which assumes that the battery management system is much more stupid than it really is) is to occasionally change the percentage point that I charge to. My "imagined" theory is that if I always charge to the same percentage point then maybe the same cells in the pack end up being fully optimised and others not. However if the BMS is doing its job then that shouldn't be the case at all ... so I'm wasting my time! There certainly appears to be some evidence that though none of this is likely to affect the overall future capacity of the pack it may actually affect how accurately the BMS "guesses" how much capacity is available... so it may vary in its accuracy.
 

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