Leaving a car plugged into 110 or not plugged at all?

[TexasEV]

I limit state of charge because every battery I've seen tested lasts longer at lower states of charge and temperatures. And while I love that the packs in the Model S are holding up well, we don't have decades of data on how well these batteries will hold up, and I would much rather have a pack that lasts 25 years instead of 15 years.

Having said that, if you're completely certain there will be no difference in lifespan by charging to 90% instead of 70%, I'd be happy to charge to 90% daily when you put up enough to cover the replacement of my pack in an escrow account.

Charge however you like, but new owners should know they don’t have to baby the battery. I will continue to charge to 90% every night, and 100% for trips, as I did with my Model S which only lost 5% of range in 5 years. I don’t think anyone has done substantially better than that by keeping lower states of charge. I also don’t plan to keep my car for 15 years, much less 25 years, and I doubt many people here would.

 

[David99]

Charge however you like, but new owners should know they don’t have to baby the battery. I will continue to charge to 90% every night, and 100% for trips, as I did with my Model S which only lost 5% of range in 5 years. I don’t think anyone has done substantially better than that by keeping lower states of charge. I also don’t plan to keep my car for 15 years, much less 25 years, and I doubt many people here would.

I hear you and it's true, charging to 90% is fine. Charging only to 70% when you don't need your car much is a little bit better for the battery. If you know you are only driving 30 miles a day back and forth to work setting it to 70% is not a compromise in any way and doesn't cost anything. It's like parking your car in the shade instead of the sun. You won't find shade often, the difference on the paint and materials over the years is small, yet it helps a little. I guess that's all I'm saying.

But at the same time, it's probably best to not put fear into new owner's heads that they need to worry about their battery.

 

[omgwtfbyobbq]

Charge however you like, but new owners should know they don’t have to baby the battery. I will continue to charge to 90% every night, and 100% for trips, as I did with my Model S which only lost 5% of range in 5 years. I don’t think anyone has done substantially better than that by keeping lower states of charge. I also don’t plan to keep my car for 15 years, much less 25 years, and I doubt many people here would.

If you're only going to keep the car for 5 years you probably won't see any differences, and at 10 years you might see a 5-10% difference. At 15+ I think the differences will really start to show. Granted, if Tesla has made some significant strides in battery lifespan, then average SOC might not matter as much as it did a couple years ago.

https://www.nrel.gov/docs/fy16osti/66708.pdf

Yes but we don't know if there are other mechanisms that the BMS uses to measure balancing. The BMS might take measurements in more than one way. My pack has 174k miles and is amazingly well balanced. I have gone months not charging beyond 90%. If the BMS would only look at cell balancing at 93% my pack would have gone without balancing for a long time yet it has never showed it (I'm looking at the CAN data). I think it's reasonable to assume the BMS has more than just one way.

Oh yeah, I'm fairly certain the BMS is always keeping an eye on the pack and balancing cells as needed.