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Top Tips for Optimal Battery Health

elecTED

Member
Jun 21, 2019
326
322
Bristol, UK
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There’s the 20/80 rule - unless needs dictate do not let battery charge go below 20% and do not charge beyond 80% on a regular basis.

What other ‘practical’ measures and behaviours can help keep the battery in good health and prolong its life?

The battery info in the manual is interesting. It states to keep the car plugged in, especially if you are not using it for several weeks. Does that mean you set it to 80% charge and then just leave the cable connected and in ‘charging’ mode if you will not using the car for a few weeks?
 

MaDProFF

Member
Jul 26, 2019
415
135
East Sussex
Do you mean WHERE's 20/80 rule? does not mention 20/80% it is what you are generally told by everyone, personally I have mine set to 90%, I asked about 90% and was told fine, when I picked car up it was preset to 90% but then I would practically never charge to 100%, and use car everyday, charge everyday at home, and probably once in a blue moon use a super charger, not used one yet, and do not see it soon.

If I was to leave the car for weeks with out use I would leave it plugged in if at home, and probably set to 80% but lets face it if you charge the car to 100% it is actually not at 100%, same as 0% it is not at 0% although at 0% if you leave it longer with out charging it will eventually drain everything to 0%
 

interbear

Member
May 27, 2019
729
634
Monmouthshire, UK
I was seeing mixed info on 80 or 90 so mine is currently set to charge to 85% :) I could easily lower it to 80% if that’s considered best practice as it would be more than enough for my typical needs.

One thing I’m not sure about is this - I work at home so some days won’t drive at all or will do very few miles. I read the “always keep your Tesla plugged in” advice and wonder whether I should still do this when I’m only down by a few percent ie at 70-75? Should I still plug in to top up to the 80-85% or leave it until it’s lower (not below 20 though)? Thus far I don’t, I’ve been plugging in only when capacity is around 40-50%, so once or twice a week.
 

NorfolkMustard

Active Member
Apr 18, 2019
2,214
2,204
M3P w/FSD
The guidance online and in the manual (same) seems pretty clear, even emphasizing in ALL-CAPS. If you can, keep it plugged in.

My charging level? 88 ;)
 
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MacPaul

Member
Sep 28, 2019
164
142
Aberdeen
I think the 80/20 rule is referring to the optimum rapid charging range as above 80% the charge speed tapers considerably.

IIRC Elon has said on Twitter to always have it plugged in and 90% is fine.
 

LukeT

Member
Apr 9, 2019
729
337
UK
I work on 80% except 90-95% twice a week when I do a journey that uses 70% of battery, which I expect to increase in winter. And except when going away for multiple days and long journeys, when if there's an opportunity to go higher immediately before a drive then I will.

I've covered nowhere near enough mileage to know first hand whether this is OK for battery health. And it concerned me. It still does a bit. But when I asked this question early on the answer tended to be "don't worry about it". So I make sure all >90% charges are right before a drive but I don't worry too much if I sometimes find I'm doing them a bit often. Longer term I'll try starting my 70% trip with only about 85% at the start but I haven't had the courage to do this yet! Now I have charging at the other end I think that'll change and I won't mind rocking up with 15%.
 

spon88

Member
May 2, 2019
571
314
Derby
I was seeing mixed info on 80 or 90 so mine is currently set to charge to 85% :) I could easily lower it to 80% if that’s considered best practice as it would be more than enough for my typical needs.

One thing I’m not sure about is this - I work at home so some days won’t drive at all or will do very few miles. I read the “always keep your Tesla plugged in” advice and wonder whether I should still do this when I’m only down by a few percent ie at 70-75? Should I still plug in to top up to the 80-85% or leave it until it’s lower (not below 20 though)? Thus far I don’t, I’ve been plugging in only when capacity is around 40-50%, so once or twice a week.
This is me exactly. I do relatively few miles as I work at home so charging once or twice per week is the norm. I haven't used a supercharger yet after 2 months of ownership. I charge to 80/85% and then come down to 45 ish before charging up again. I do leave it plugged in but with the charge level backed off so my "usual" charge time of 1am doesn't actually kick in. I was hoping this practice is satisfactory but maybe not? There doesn't seem to be a definitive answer? If anything my battery usage will actually come down as I'm knocking sentry off at night now we have new low level CCTV in place.

Maybe more fun runs are required!
 
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pgkevet

Active Member
Jul 1, 2019
1,470
1,306
mid wales
There's a difference between reality and practicality and another difference between what's best for you and what's best for Tesla.
Google tells us that a Lion Battery does best with the least number of cycles and storage percentage of 40% at 0degC.
Now whether Tesla Lion is quite the same is moot. It's also worth remembering that Tesla anodes swell by 300% (sounds so much more dramatic than 3x ) when fully charged so that is a lot of physical change per cycle. The final factor is charge rate - the slower then the less damaging.
Of course there's no point havng the darned car if it just sits in an a/c garage @ 40% on a trickle charge and doesn't get used - so simply put you charge it so you have enough for your daily needs with enough reserve for emergencies, road works and detours etc, In my case I generally top it up when it drops to 30-40% and put it to 60% because that's enough for an average couple of days for me.. more if I anticipate I need it.
From the Tesla viewpoint they want to emphasise convenience and range and reduce your use of superchargers and possibilities of folk getting stranded for lack of juice and keep instructions simple - so telling you to keep it plugged in helps with thickies that don't notice charge levels and telling you to charge to 90% reduces likely burdens at superchargers.
They then tell you the pack is warrantied for 8 years to keep you reassured but donlt tell you that it'll progressively degrade so by the time 8 years are up it's only circa 80% and any warranty will be a rebuilt pack of the same quality (otherwise the obvious move is to abuse it as much as possible and keep getting new ones)
 

LukeT

Member
Apr 9, 2019
729
337
UK
That’s what I do too. Battery target set at @65% when I get home from work, plugged in.

at midnight, teslafi ups the target to 88% to make use of cheap overnight leccy

This is pretty much what I do in lower usage times. Teslafi 55% and 80% limits scheduled with a higher one timed for a long drive as and when. I also think a daily teslafi trigger is a neat way to ensure charging returns to "best practice" methods after a manual override.
 
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Mikeoneuk85

Member
Oct 13, 2019
58
13
Droitwich Spa
I have a 70 mile round trip for my commute and planning on charging to 80% overnight and when waking up changing the charge to 90% to warm the battery up and also to get a bit more range as I know there is going to be allot of battery loss as the colder weather kicks in.

This will be for an SR+. Does this seem like a good plan?
 

gangzoom

Active Member
May 22, 2014
1,348
1,206
Uk
From the Tesla viewpoint they want to emphasise convenience and range and reduce your use of superchargers and possibilities of folk getting stranded for lack of juice and keep instructions simple - so telling you to keep it plugged in helps with thickies that don't notice charge levels and telling you to charge to 90% reduces likely burdens at superchargers.

They then tell you the pack is warrantied for 8 years to keep you reassured but donlt tell you that it'll progressively degrade so by the time 8 years are up it's only circa 80%

Tesla say to keep the battery any where between 50-90%, and using rapid DC charging is the quickest way to kill a battery.

Tesla is one of the few EVs where you can actually set the charge limit on the car, in an iPace/Leaf when you plug in your charging to 100% regardless, where as on the Tesla you can set it to a set % safe in the knowledge it'll never over charge.

80% degredation on any Tesla is massive, and short of pack issues (like some 85s) pretty much unheard off.
 

pgkevet

Active Member
Jul 1, 2019
1,470
1,306
mid wales
Tesla say to keep the battery any where between 50-90%, and using rapid DC charging is the quickest way to kill a battery.

Tesla is one of the few EVs where you can actually set the charge limit on the car, in an iPace/Leaf when you plug in your charging to 100% regardless, where as on the Tesla you can set it to a set % safe in the knowledge it'll never over charge.

80% degredation on any Tesla is massive, and short of pack issues (like some 85s) pretty much unheard off.

Battery tech will keep evolving but please point me to statsitics showing how well 8 yr old Tesla packs are averaging. You cna also exect degradation to be exponential and afaceted by local climate.
 
Jul 5, 2019
176
134
Sussex, UK
It's also worth remembering that Tesla anodes swell by 300% (sounds so much more dramatic than 3x ) when fully charged so that is a lot of physical change per cycle.

Where did you hear that?!

It may be true for Silicon anodes -

"It’s easy enough to make anodes from chunks of silicon; the problem is that the anodes don’t last. As the battery is charged and lithium ions rush in to bind to silicon atoms, the anode material swells as much as 300%"

But Tesla anodes are hybrid silicon/graphite -

Tesla’s Batteries have gone through 3 stages: Stage 1 was from 2009-2012 found in the Roadster and Model S. Stage 2 was from 2016-2018 and powered the Model S Gen II, and the Model X. Stage 3 starts with the Model 3 in 2018.

Stage 1 batteries were constructed with 18650 cells, which are 18 mm wide, and 65 mm tall. They had a NCA formulation that required 11kgs of Cobalt in the cathode, per car. They had a pure graphite anode, with no Silicon.

Stage 2 batteries used the same 18650 cells, but reduced the amount of Cobalt required in the cathode from 11 to just 7kg/car. They also introduced a small amount of silicon into their anode.

Stage 3 batteries are new for Tesla, and first shipped with the Model 3. Stage 3 batteries have further reduced the amount of cobalt to just around 4.5kg per vehicle. They also have a hybrid silicon/graphite anode, and while proprietary and unreported, probably higher silicon content than their stage 2 batteries.
 

Cogarch

Member
Apr 27, 2019
246
180
Loches
My situation is similar to @NorfolkMustard and @LukeT ’s (my Tesla is left embarrassingly idle for several days at a time) except that we also have an Evezy Zoe competing for the charger. It is made still more complicated by the fact that we have an Ohme smart cable with an Octopus Agile electricity tariff. This is set to come on in the small hours when there’s a car plugged in.
 

pgkevet

Active Member
Jul 1, 2019
1,470
1,306
mid wales
I make no pretence of being a battery expert. Whether the anode is silicon or something else I guess the same number of lithium ions has to be moved around to hold the charge - whether one keeps them in silicon or some spongy matrix of carbon nanotubes. Technology moves on.
 

MaDProFF

Member
Jul 26, 2019
415
135
East Sussex
I do know that it will fully charge to my setting 90% when told do, then it will recharge to full again some hours later if left connected with a constant feed, the 2nd charge seems to always be 2 miles range less than the initial long charge to full 90%.
 

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