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Charging everyday?

Petrlol

Member
Oct 16, 2018
405
550
Ohio
See below

upload_2019-10-30_15-39-21.png
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
Nov 28, 2018
10,839
12,567
Riverside Co. CA
Is it better to run the battery down to 20-30% before charging or charge everyday regardless of the SOC?

The quote in post number 7 is on page 122 of the manual (at least the version of the manual on my HDD). I suggest that all model 3 owners read this manual, even if they are not "car manual readers". There is a LOT of really good information in the manual. You can download a PDF version from your tesla account, and its also accessible from the touchscreen in your car.

Teslas official response is what you in post 7. They specifically state:

"There is no advantage in waiting until the batteries level is low before charging. In fact, the battery performs best when charged regularly".

Now, the discussion here always devolves to "what is "regularly" and "does tesla actually mean for you to plug in "all the time?". I personally feel the statement above is very clear, but others do not. What we know is, batteries are rated for number of charging cycles, and 1 full charging cycle might is quite different than several shallow charing cycles.

Its your car, do what you want, charge it how you want, but if you want to see what tesla recommends, its there in the manual for that (and a bunch of other very useful stuff)
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,807
8,422
Boise, ID
What we know is, batteries are rated for number of charging cycles, and 1 full charging cycle might is quite different than several shallow charing cycles.
You are confusing a charging event with a charging "cycle". In battery studies, a "cycle" is defined as the full capacity of the battery depleted and refilled.
That can be in one part: complete empty and refill, or
One fourth removed and refilled four times, or
One tenth removed and refilled ten times, etc.

So effectively this shows that the number of cycles corresponds pretty directly just to the amount of miles someone is driving, regardless of their charging habits. So someone isn't going through a different number of cycles if they refill a little bit every night, or if they refill a larger amount every 3 or 4 days by waiting longer.

But yes, most of the studies show that using smaller, more frequent charging events is generally a little better on the battery life. If it's small amount of differences, though, where you're only skipping a day or two and not going very low in the state of charge, it's not going to make much difference, and some people might weigh that against the wear of the frequency of use of the charge port and locking pin in the latch in the port, etc. So plugging and unplugging 3 or 4 times a day, whenever you pull into your garage is probably a little excessive and skipping a day of charging isn't a big deal.
 

TimothyHW3

Active Member
Jun 2, 2019
1,032
726
Germany
We just had this discussion on another post.

While I hate to go against the stream, I am not quite sure a lot of people understand what this part of the manual refers to.

If you read closely it talks about the car being left when "not using it" and when you are away (Tesla wants to make sure you don't drain the car due to bad setup and phantom drain like a lot of other people, just read this forum). I also think that the manual assumes that you drive at least 80-100 miles a day and not 10miles, so you are not just topping up 5% each day.

If they had to make a manual with all the graphs and charts for Li-ion batteries nobody will read it(not that they do now)

But from what I am seeing is that people have problems with their batteries when they follow this rule blindly.

If you only travel 50 miles a day, you will end up topping up the 60-90% daily. This is very, very, VERY bad for the battery and the BMS.

The optimal range for the battery is below 4V which on Model 3 is around the 60-70% mark.
(40%-75/80% gives the longest life to the battery)

The optimal charging for the BMS is the one where the BMS can go a little lower so that the car knows where is up and down.

In the other thread on a person loosing "range"(20miles) the most plausible reason is BMS miscalculation because he was charging exactly from 70-90% daily.

So there are two optimal charging strategies:
1. Good for the battery: 40%-80% daily and if you can't get to 40%, wait for whenever you can. This requires you to get the phantom drain in check see below video on zero to 1 mile phantom drain a day.

2. Good for the BMS: now and again(depends on how many miles you do, let's say after 2-3 weeks) 10%-90% or even 100% when you plan a long trip and can charge to 100% and unplug right away.

 
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TimothyHW3

Active Member
Jun 2, 2019
1,032
726
Germany
Pick your curve ;)

90-80 or 80-70 looks about the same as 75-65; The key is frequent smaller cycles are better the a few deep cycles...
You are missreading something about this chart. 90% is high SOC and is not good for the battery.

Also, small cycles are good for the battery itself, but is not good for the BMS, that actually calculates that capacity. So if the BMS is misscalibrated while never allowing it to go lower than 65%, all of these charts will not help you, since your BMS will think you only have 80% of the kWh available, even though there are more.

It is like having a full tank in reality, but the gas gauge thinking you only have 80%. Until you "reset" it, or change it in a gas car, you will never get the full range, even though it is there.

If you follow that graph and for a good BMS, I think charging between 30%-80% is the best middle ground.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,807
8,422
Boise, ID
90-80 or 80-70 looks about the same as 75-65; The key is frequent smaller cycles are better the a few deep cycles...
You are missreading something about this chart. 90% is high SOC and is not good for the battery.
Yes, that is misreading that graph pretty badly. All three of the best curves in that graph, which show the most long term retention of capacity in the battery are all three of the ones that only use 75% as their upper end of the charge range. All of the ones that use a higher limit are worse than those.
 

TimothyHW3

Active Member
Jun 2, 2019
1,032
726
Germany
Also, according to the website he got the graph from, 3.92V is the best to keep the battery at and this is almost exactly 60% (have to double check, but it is around there, maybe a little higher, 65%)

So keeping the Model 3 at 45%-75% will indeed be the best for the battery, but it will give the smallest miles per charge and it will probably mess up the BMS pretty badly.

I stand by my estimate of 30%-80% to be the best middle ground for battery and BMS.
Actually even 15-20% should be good as long as you charge right away when you stop and the car doesn't stay at 20% longer times.
Stay at 65% when idling for a while and or on vocation and charge from 10-90/100% now and again to reset the BMS.

And if possible slow charge at 2kW-4kW.
 

nwdiver

Well-Known Member
Feb 17, 2013
8,354
11,417
United States
You are missreading something about this chart. 90% is high SOC and is not good for the battery.

Elon has stated that 90% SOC isn't much worse than 80%. It's >90% that needs to be avoided and that's mostly time and temperature dependent. Charging to 100% isn't that bad so long as you don't sit at 100% for a long period of time.

Calibration is a bit different. Mis-calibration is a temporary issue that can mostly be remedied by a long trip or one deep cycle. Frequent deep cycles might be better for keeping the battery calibrated better but it causes more degradation and degradation is permanent.
 

SSedan

Active Member
Jul 24, 2017
2,948
2,589
Greenville Wisconsin
Also, according to the website he got the graph from, 3.92V is the best to keep the battery at and this is almost exactly 60% (have to double check, but it is around there, maybe a little higher, 65%)

So keeping the Model 3 at 45%-75% will indeed be the best for the battery, but it will give the smallest miles per charge and it will probably mess up the BMS pretty badly.

I stand by my estimate of 30%-80% to be the best middle ground for battery and BMS.
Actually even 15-20% should be good as long as you charge right away when you stop and the car doesn't stay at 20% longer times.
Stay at 65% when idling for a while and or on vocation and charge from 10-90/100% now and again to reset the BMS.

And if possible slow charge at 2kW-4kW.

What do you base the 2-4kw statement on?
10kw is slow charging compared to the 150 a supercharger can crank out.
 
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