My charging routine

[dendenyc]

I've read that the best way to preserve longevity of the cells is to charge frequently to 80%. However with my daily driving habits this is not practical. I drive about 8miles a day which doesn't take much energy out the battery so I've opted to fully charge the car to 70% on Sunday night and run it down to about 30% throughout the week. I basically charge only once a week on NEMA 14-50 service. Will this routine damage my battery over the long term?

 

[bluetinc]

dendenyc, You don't mention why you are only charging once per week, if it takes extra work to go to the charger, or if you just aren't plugging in to the charger sitting there. So, I'll say that if it's the latter, charging up to 50%, driving a couple miles a day, then plugging in that night to charge back up to 50% is going to show the least degradation over time. Now if it's the former, then I would say that what you are doing sounds just fine, and you will not see unusual degradation from it. In fact, with that use case, I would say I would expect that never see any degradation that will effect your batteries to do what you want them to do, (drive 50 miles a week), over the lifetime of the car. -- Peter

 

[dendenyc]

There's rally no good reason why I only charge once a week besides the convenience of hopping in and get going. I felt that the constant cycling every day thats only putting back a few % in the battery would have been worst overall for the cells as opposed to letting them deplete to 30% before charging them back up.

 

[bluetinc]

No, with Li-Ion, it's the other way, in that shallow cycles are much better for the battery than deep discharges. Of course with anything, there are diminishing returns. There are some decent stories out there of Li-Ion batteries sitting at 40% charger kept cool in the fridge for years and years with no signs of degradation. Here is a decent resource to see the effects of temperature and charge on Li-Ion capacity, though I will note that the advanced formulas that Tesla uses are significantly better than they show, for example my battery is about 5 years old will over 100k miles on it, and has less than 5% degradation. -- Peter

BU-702: How to Store Batteries – Battery University

 

[bluetinc]

No, with Li-Ion, it's the other way, in that shallow cycles are much better for the battery than deep discharges. Of course with anything, there are diminishing returns. There are some decent stories out there of Li-Ion batteries sitting at 40% charger kept cool in the fridge for years and years with no signs of degradation. Here is a decent resource to see the effects of temperature and charge on Li-Ion capacity, though I will note that the advanced formulas that Tesla uses are significantly better than they show, for example my battery is about 5 years old will over 100k miles on it, and has less than 5% degradation. -- Peter

BU-702: How to Store Batteries – Battery University

 

[TexasEV]

This says all you need to know:
A connected Model S is a happy Model S

For more details, RTFM, especially the battery section. What you feel is right is the opposite of what Tesla recommends.

 

[Cosmacelf]

Honestly, the difference between charging 8 miles a night and doing it once a week is so minor in terms of battery life, I doubt you’d notice a difference either way.