New Nifty tool! - Best practices for battery charge level for long battery life

[Khan3]

I've updated the charger list - more voltage/current options

 

[JZtheHW]

I spent an hour watching one of the Li-ion battery professor talking about the topic "Why do Li-ion Batteries die ? and how to improve the situation?" He actually built a through, complex, and precision test system to acquire all kind data to quantify the difference of all kind batteries and the conditions leading to battery degradation.

My conclusion: Tesla did their homework to pick the best technology to build and operate the battery, so take easy, the leading cause of battery degradation is fully charged cell in a high-temperature situation. Keep following principle in mind will prolong your Tesla battery:

1) Avoid fully charge situation as much as possible, especially in the high-temperature situation like summer in Nevada, keep the maximum level as low as practical for your usage at anywhere between 50 to 90%. e.g. for me, a southern California resident, 70% in summer and 80% in winter. As long you keep this principle in mind, pick the maximum level of charge between 50 to 90% suites for your need, and your Tesla battery is in good hand.

2) Keep the charger plugin whenever, why? the Tesla battery has thermal management to maintain the optimal interior temperature, you want to use the electricity from the grid to cool/warm your battery, not the energy from the battery itself. Make sense?

Hopefully this help to ease your concern. Enjoy your Tesla!

 

[David Haynes]

Here is an interesting video on this subject. Looks like 70% charge level is best for day to day charging. Come from a very reputable source.

Thanks

 

[SageBrush]

1) Avoid fully charge situation as much as possible, especially in the high-temperature situation like summer in Nevada, keep the maximum level as low as practical for your usage at anywhere between 50 to 90%. e.g. for me, a southern California resident, 70% in summer and 80% in winter. As long you keep this principle in mind, pick the maximum level of charge between 50 to 90% suites for your need, and your Tesla battery is in good hand.

Your advice is missing the low SoC target you should typically not exceed.

My perusal of the science suggests keeping SoC above 20-25% in general.
I'll add below 90%, in general.

Anything better is an optimization with diminishing returns. But if that is important to you, cycle around the midpoint.

It is interesting to consider that for a Model 3 SR with a nominal range of 220 mile a reasonable typical maximum range between charges works out to 220*(0.9 - 0.25) = 143 EPA miles.

 

[David_Cary]

Plugging in all the time is certainly not required or helpful most of the time. Tesla keeps it simple for the masses. In a majority of garage situations, the temperature management is not working. It kicks in above 110 degrees - probably not common outside of Nevada and Arizona. On the cold side, I can't find the reference but the car has to be pretty cold. Better to insulate your garage a bit more....

People like simple and there is a huge bias for that. Charging a phone to 100% every night is probably fine since you will replace the phone in 2 years. But it is absolutely not ideal. The hope is that a Tesla will last 20 years or more. At that point, the difference between losing 1.5% a year vs 2% a year (for example) becomes an issue.

Charge what you need to stay above 50% when you get home. Most important in the summer. Cold temps are so protective that it probably does become inconsequential. Battery damage is pretty significant at 90 degrees. But hey - we may be wrong but why take a chance?

 

[golfpilot]

Thanks for all the great feedback!

@C141medic - I do plan to put all these tools into an easy to use app that model3 owners can keep closeby. Lookout for this towards end of the year around when deliveries should ramp up and we have a lot more reference data to support the tools.

@Zoomit , thanks for the charger list, i'll update mine to match - what page did you find that image on?

Per the video relating to the learned Prof's response, I did review it as part of my research and find it totally consistent with what I found. The professor provided a simple answer to the simple question posed, given that the question had no context for the driving range requirements or context. If you look at the research link, they found that the battery life is maximized when used in the 65 - 75% range (i included diagram below - the yellow band). So it's totally consistent for the response to the question to be "keep it at about 70%" .... HOWEVER ... that answer will definitely change if your daily range need is 120 or 140 miles a day ( in which case your daily DoD will significantly do more damage than raising your charge to 80%).

Given the opportunity for a more robust discussion i bet the Professor would respond along the same lines.

View attachment 245575
source : https://www.researchgate.net/public..._Battery_Degradation_for_Cell_Life_Assessment

Am I reading this right? If you go from 75% to 25% and recharge you would have to do that 5000 times to degrade 10%. In a model 3 that is 750,000 miles

 

[Khan3]

Am I reading this right? If you go from 75% to 25% and recharge you would have to do that 5000 times to degrade 10%. In a model 3 that is 750,000 miles

Assuming the car is a perfect machine with 100% efficiency, then those numbers should be right.
There is a lot of data out there to back this up for owners that charge in the more aggressive 10% to 90% range:

Tesla Model S battery degradation data
Tesla battery predicted to have 80% capacity after 840,000 km (521,000 mi)

(NOTE: Model 3 battery chemistry is different from Model S which this data represents, but I expect Tesla to have improved battery metrics in the model 3 vs the model S since its newer technology)

 

[ReddyLeaf]

Am I reading this right? If you go from 75% to 25% and recharge you would have to do that 5000 times to degrade 10%. In a model 3 that is 750,000 miles

Yes, that is the real protective aspect of Tesla batteries: size. That’s one of the reasons that Tesla provides an unlimited mileage warranty for certain models. Temps, avg SOC, and depth of discharge are scientifically important but everyone is forgetting another very important parameter: time. These scientific studies are done on small batteries with rapid charge-discharge cycles, typically over a few months, to get the data collected and the report written. They cannot easily do the same research on large, 60-100 KWh batteries over decades. The only real world data on extremely high miles is Tesloop and other Taxi companies. In this situation, one should expect 500,000+ mi with most large batteries, even the same cells that are in the ill-fated 2011 Leaf. The key is battery size and continuous use to achieve the highest mileage in the shortest time. Several Leaf taxis exceeded 100,000 mi (2000 cycles) without temperature control and continuous fast charging. Scaled up, a 75-100 KWh 2001 Leaf would have easily gone 300,000 - 600,000 mi in taxi service. In real world non-taxi use, all large batteries ( >60 KWh) should easily last the lifetime of the car, unless damaged or improperly installed.