short commute and charging

[whitex]

According to the below research, charging to 75% dropping to 65% before recharging yielded the best life. The key takeaway for me is what you should always try to avoid, which is charge to 100%. I tend to follow about 75%-45% from a practicality standpoint based on my commute... which means I plug in about twice a week.

How to Prolong Lithium-based Batteries - Battery University

View attachment 235039

The only problem is that one LiIon batter is not the same as another. This study was not using Tesla batteries (or their charge management system, meaning controlling charge rates, discharge rates, and battery temperature - including cooling or heating the batteries). As an example, look at some research done comparing Nissan Leaf and Tesla batteries (both Lithium Ion) - it turns out what is optimum for one is not for the other, because of different chemistries and management systems. Bottom line for me, I trust Tesla on this when they say keep it plugged in to give the car the ability to do whatever it needs to in order to preserve the battery.

 

[AWDtsla]

According to the below research, charging to 75% dropping to 65% before recharging yielded the best life. The key takeaway for me is what you should always try to avoid, which is charge to 100%. I tend to follow about 75%-45% from a practicality standpoint based on my commute... which means I plug in about twice a week.

How to Prolong Lithium-based Batteries - Battery University

View attachment 235039

Seems like a very useless graph, the X axis should be total kWh roundtrip, not cycles. A 25-100 cycle is more energy than 65-75.

edit - with the exception of 50-100 and 25-75, which should be the same amount of energy per cycle, every other plot line is suspect.

 

[dhrivnak]

I drive infrequently but per Tesla's recommendations I keep it plugged in and charge to full on a standard charge 83% so the battery gets to balance EACH day. 9 1/2 years later my battery is still at 90% of new. I believe balancing is very important.

 

[Qbenjamin]

July 2013, 49k miles
90% 165 miles
100% 171 miles

Something is wrong, those numbers are very low...

 

[Mark Vallaster]

I did a lot of reading on this when I got my 85D a year and 1/2 ago. There were people posting about battery degradation and chemical properties and all sorts. there was one guy in another forum who actually bought a second tesla and took it apart to understand the battery configuration and makeup better.

The resolution was that whenever possible the car should be plugged in and the computer should manage the charge. Setting the computer to a charge level appropriate for your drive is best and the computer will turn the charge on and off. I set mine to about 60% most days (gives me 180 miles or so) which means any short trip plus any spontaneous trip is covered with given the reasonable access to superchargers in my area. I don't have reasonable access to chargers in the parking garages on which I frequent so it sits unplugged. When we are leaving for a trip, I set it to 95% the night before and then about 30 minutes before I leave I charge the last 5%. The trick here is monitoring it so when it hits 100% you unplug. Note that the estimate to complete the last 5% is always wrong. It significantly lowers the charging rate as it approaches 100% and when it hits 100%, it begins a battery alignment cycle that takes a few minutes. This gives maximum rage.

I've been following this method for over a year and have not seen any degradation. We do 8 - 10 long trips a year (aka more than 150 miles with the max being about 600 miles).

 

[TJtv]

Seems like a very useless graph, the X axis should be total kWh roundtrip, not cycles. A 25-100 cycle is more energy than 65-75.

edit - with the exception of 50-100 and 25-75, which should be the same amount of energy per cycle, every other plot line is suspect.

I came here to say exactly this, the graphs are silly. Your demand for energy is fixed - you have a set # of miles to drive per day, per week, whatever, and that consumes the same amount of energy regardless of how you recharge it. You can recharge the battery with that amount of energy many ways, 1000 cycles of 75-65 puts the same total energy into the batteries as 500 cycles of 75-55 or 200 cycles of 75-25. A battery that went through 1000x 75-65 charge cycles damn well better degrade much less than a battery that went through 1000x 75-25 cycles, but that doesn't really help us out considering we have a fixed amount of energy we need to use to get where we want to go.

 

[ABC2D]

Seems like a very useless graph, the X axis should be total kWh roundtrip, not cycles. A 25-100 cycle is more energy than 65-75.

edit - with the exception of 50-100 and 25-75, which should be the same amount of energy per cycle, every other plot line is suspect.

I came here to say exactly this, the graphs are silly. Your demand for energy is fixed - you have a set # of miles to drive per day, per week, whatever, and that consumes the same amount of energy regardless of how you recharge it. You can recharge the battery with that amount of energy many ways, 1000 cycles of 75-65 puts the same total energy into the batteries as 500 cycles of 75-55 or 200 cycles of 75-25. A battery that went through 1000x 75-65 charge cycles damn well better degrade much less than a battery that went through 1000x 75-25 cycles, but that doesn't really help us out considering we have a fixed amount of energy we need to use to get where we want to go.

You guys need to actually read the article - there is a definition of what constitutes a cycle and how cycles are counted based on depth of discharge.

 

[ABC2D]

Bottom line for me, I trust Tesla on this when they say keep it plugged in to give the car the ability to do whatever it needs to in order to preserve the battery

Well, Tesla also said "use superchargers as much and as often as you like - it will not degrade your battery", but we all know how that turned out. I think it wouldn't hurt to study other research on the matter instead of blindly taking Tesla's word on it.

 

[TexasEV]

Well, Tesla also said "use superchargers as much and as often as you like - it will not degrade your battery", but we all know how that turned out. I think it wouldn't hurt to study other research on the matter instead of blindly taking Tesla's word on it.

It turned out just fine. It's not "degrading the battery" which for most people means losing capacity (range). It's just the peak supercharging power needs to be a little lower after many uses, so as NOT to degrade the battery.

 

[AWDtsla]

You guys need to actually read the article - there is a definition of what constitutes a cycle and how cycles are counted based on depth of discharge.

I did read the article, the closest it gets is this:

Evaluating battery life on counting cycles is not conclusive because a discharge may vary in depth and there are no clearly defined standards of what constitutes a cycle

Great!!! What's their definition? Who knows! But look, pretty chart, colors oooooh!

What's even worse is the selection of tests is just dumb. Why not compare 10% discharge at an even distribution of offsets, i.e. 100, 90, 80, ... 10, then 20% discharge 100, 80, 60, ... 20, then 30%, etc. They might get some data that shows a clear effect.

 

[roblab]

The only problem is that one LiIon batter is not the same as another.

Last time I checked, a year ago, there were 26 different "Lithium Ion" battery chemistries. Apples to Mangos.

 

[Tesmotorfaqcom]

As M3 is being push out and SC being built to enable urban driving it will become more common for people to own Tesla without home charging the sale people would never discourage any potential owners from buying a Tesla without a home charger right? Just because they can't plug in overnight ?

 

[vesder21]

Had my car in the other day and the official word from the service center is to not plug in daily and drain the battery down a bit and then recharge.

I also had a sales rep say to set the charge to 50% so that the car is in a plugged in state, but not charging.

Think I'm going to go with recommendation 1.

 

[TexasEV]

Had my car in the other day and the official word from the service center is to not plug in daily and drain the battery down a bit and then recharge.

I also had a sales rep say to set the charge to 50% so that the car is in a plugged in state, but not charging.

Think I'm going to go with recommendation 1.

I wouldn't call what one service rep says as "the official word", especially when it contradicts what Tesla says in writing. And certainly not a sales rep. There's been too much misinformation from ill-informed Tesla people to go by what one says. I wish I could find the thread we had here a few years ago of stupid things Tesla people have said.

 

[kort677]

Had my car in the other day and the official word from the service center is to not plug in daily and drain the battery down a bit and then recharge.

I also had a sales rep say to set the charge to 50% so that the car is in a plugged in state, but not charging.

Think I'm going to go with recommendation 1.

A connected Model S is a happy Model S

 

[DarkMatter]

When I want to leave the car plugged in but not charging I'll set it to 50%. It works great.

 

[appleguru]

As M3 is being push out and SC being built to enable urban driving it will become more common for people to own Tesla without home charging the sale people would never discourage any potential owners from buying a Tesla without a home charger right? Just because they can't plug in overnight ?

This is exactly my situation. I live in the city and do NOT have a place to plug my 75D model s in overnight. I can only charge at work, at superchargers, and at destination chargers. This was one of my biggest concerns buying an EV, but I was encouraged by the sales people to buy my model s, and in the end decided to dive in,

While this has occasionally been a minor inconvenience, it really isn't that bad. I typically charge to 90% every day. Which leaves it with roughly 80% when I park it in the city at night, and roughly 70% when I get back to the office to charge again. About ~3hours on level 2 charging adds back the lost ~20% and I do it all over again.

I usually charge up to ~100% for weekends (especially if I know I will be driving long-ish distances). And I try and "top off" at a supercharger coming home from weekend trips so I start the cycle over again on Monday (though, this week for example, I made it into the office on Monday with 45miles of range left... Had to make it back in time for GoT on Sunday, so only could SC for 10minutes ).

 

[vesder21]

I wouldn't call what one service rep says as "the official word", especially when it contradicts what Tesla says in writing.

i agree but have also experience my battery decrease in mileage (charge capacity) by driving a few miles and leaving it plugged in at night. i'll try the "use up a a greater percent and then plug in every few days method" and report back in half a year.

 

[David99]

A few things that were mentioned here that I feel are worth commenting on.

Keeping the car plugged in does not activate the battery management system. It is working ALL THE TIME regardless of being plugged in or not.

The car will not draw power from the grid to keep the battery healthy or things like that. Everything the battery needs to do to stay healthy and balanced, it does on it's own independent of being plugged in our not.

According to Jeff Dahn, a battery expert that works directly with Tesla, it makes no difference to degradation if you charge for example 30 miles every day or 120 every 4 days.

If you use the app to cool or warm your cabin before you drive, the car will draw the necessary power from the grid so you are not loosing battery level. So it is a good idea to keep the car plugged in all the time even if you are not charging.

Battery capacity cannot be easily measured unless you full charge and discharge the battery. They have a clever algorithm to estimate the remaining battery level at any point in time. This estimate is by nature less accurate of you keep partially charged. Discharging the battery to a low point and charging to a high point will recalibrate the algorithm. Sometimes this leads to getting a higher rate range. It's not balancing, it's just the car's estimate getting recalibrated after a long period of partial charge.

Higher state of charge causes more degradation on the battery. Avoid 100% unless you need it. 90% or lower is fine. If you only need few miles on a daily basis, charging to a lower level can help a little with degradation. The difference is diminishing the lower the level.

Many thing affect degradation but Tesla's battery management system is taking care of it as best as possible. Not much to worry about and not much to do on our end. I would charge the car at night when the grid has little load and electricity is cheaper.

The difference in degradation between cars that see little use and those that get used a lot and are in hot climates and Supercharge a lot isn't big. Maybe 3-8 miles difference after 3 years. Considering how little the difference is I would say, don't worry, enjoy the car and use it as it is convenient to you.