Charge to 90% or 80% daily?

[djrodtc]

The key is simplicity.

I set mine to 90% the day I bought it, and leave it there. If I'm taking a long road trip, I bump up to 100%.

Otherwise, set it and forget it at 90%. Easy to manage, easy to understand, and my wife (who was a skeptic of EVs going in) is more than thrilled with it.

All the debate about battery health between 80% and 90% and drop down to 50% sometimes but more than others etc is just noise. It's not worth the brain cells you'll use thinking about it. It's just academic.

A little over a year in, almost 17k miles, and I'm showing 306 miles when full. Was 309 when I took delivery. (275 @ 90%.) No time wasted trying to outsmart the smart battery controller.


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At how many AMP do you charge? Do you charge your car as soon as you get home so the battery is still warm? Do you use scheduler charging?
Thanks!

 

[smatthew]

^^^ ive seen this happen when i SC my car to 100%. this is why it takes so much longer the last 5% or so to full.
the car will say "calculating..." and i sometimes saw the actual pak charge DECREASE - this is because of the bleed resistor doing its thing. then i would se charging and then "calculating..." and so forth.

In a model 3, the bleed resistors are not applied during charging. Even if they were, they are soo small that you would not see a change in the display. We're talking it takes 24 hours to move a brick 1mV i.e. from 4.200v to 4.199v. When the car says "Calculating" that's the BMS re-thinking things.

 

[dmurphy]

At how many AMP do you charge? Do you charge your car as soon as you get home so the battery is still warm? Do you use scheduler charging?
Thanks!

My HPWC is 48 amps. When I pull in, I plug it in. No schedule - just stays plugged in when I’m home. I try not to overthink it. Park the car, plug it in. No more “management” than that. Works well for our lifestyle - may not work for everyone. I understand that.

 

[lUtriaNt]

When the car says "Calculating" that's the BMS re-thinking things.

since you replied to me (im honored)

yeah boss I know what I see. the charge will DECREASE (As if the car is DISCHARGING or "BLEEDING" off a charge in a pack to equalize ) and then I would see "calculating" and then it would charge at like ~0-1kw or some such (its been weeks since I last SC'ed so going off memory) then "re-think" things.

if you are charging to 100%, doesnt it make sense for the car to make sure all the packs are charged at their full/100% charge so that you actually get 100% charge out of them all? some packs will charge faster than others and the system will see this, so it will bleed off (your term) a pack or so to better match other less charged packs, so at the end all of the packs are 100.

i mean im no battery boss like you are on these forums but that makes sense to me and i know what i see on the screen since im sitting in the car watching the charging (at a SC station)

 

[Hondo16]

I routinely only charge to 70% as ~20% of capacity is usually more than enough for my daily mileage (Model 3 LR RWD). Theoretically, physics dictates that keeping the battery closer to 50% will improve longevity. Realistically, I've read countless write-ups by high-mileage owners who have constantly charged to high states, ran it down to very low states, and supercharged frequently without any/much measurable effects.

My personal mentality is to charge the vehicle in whatever way doesn't cause undue stress on you, either by range anxiety or degradation anxiety.

 

[XLR82XS]

I routinely only charge to 70% as ~20% of capacity is usually more than enough for my daily mileage (Model 3 LR RWD). Theoretically, physics dictates that keeping the battery closer to 50% will improve longevity. Realistically, I've read countless write-ups by high-mileage owners who have constantly charged to high states, ran it down to very low states, and supercharged frequently without any/much measurable effects.

Improved longevity at 50% SOC? Maybe..... but I would think whatever the BMS is doing it's working well for Tesla vehicles. Will be interesting to see their advice on the Maxwell cells.

As I've stated before, follow the manual and plug in whenever possible and charge to 80-90%.

 

[Zoomit]

Improved longevity at 50% SOC? Maybe

It's really a balance between storing the car and using the car. You want to use it, not just own it, and that will routinely necessitate a higher charge. But there should be no question that there's improved battery longevity when the SOC is below 50%. As Tesla states on Page 17 of this EPA application:

"To maintain service life, the battery pack should be stored at a state of charge (SOC) of 15% to 50%."​

I'll be the first to say that the difference in service life that we're talking about here is likely small. I routinely charge my car high just to enable the best performance, irrespective of how far I'm driving.

 

[Raechris]

FWIW this conversation made me look up my MS75D battery stats and glad to find -1.6 % from new. When I charge it is at 3.3 kW/240v to 90%. I wonder if the slow charge rate helps with degradation.

 

[Rocky_H]

When I charge it is at 3.3 kW/240v to 90%. I wonder if the slow charge rate helps with degradation.

Well, kind of, but there are different meanings of "slow". For a battery that can take over 100kW recharging power, anything you can supply from your house is slow. 3 or 6 or 15kW are all slow charging from the battery's perspective.

 

[Raechris]

Well, kind of, but there are different meanings of "slow". For a battery that can take over 100kW recharging power, anything you can supply from your house is slow. 3 or 6 or 15kW are all slow charging from the battery's perspective.

Sure but there has been long term speculation that supercharging was poor for battery health. Not saying I agree with that but was pleasantly surprised by my stat after 2.5 years of ownership

 

[Rocky_H]

Sure but there has been long term speculation that supercharging was poor for battery health. Not saying I agree with that but was pleasantly surprised by my stat after 2.5 years of ownership

Well yes, not Supercharging--of course. But you were originally talking about how you only charge at 3.3kW, which is only 13A at 240V, and I have seen many many threads on here where people keep talking about how they are turning their charging amps down to 15 or 10 or 5 amps because they think it's "easier on the battery" than using 30 or 40 amps. And that extreme is just nonsense. But sure, using level 2 charging most of the time instead of constant Supercharging possibly does have benefit. So yes, I get it if that is what you meant.

 

[KenC]

Any AC charging rate is considered slow, and better for your battery than DC fast charging. There's been no evidence that charging at various AC rates has any benefits over any other AC rates.