Charging to 100% Question

[rafacq]

Does the Amperage you charge at make a difference in battery degradation when charging? If I need to charge overnight to 100% for a trip, will it be better for battery life to charge slower, like at 20A instead of 40A or 48A? How about my daily night charge, does it make a difference how fast you charge at? Since at night there is no rush, is a slower charge better? Is Supercharging to 100% more damaging to battery life than slower home charging? Any resources to learn more about charging? Thanks in advance!

 

[fasteddie7]

I think you'll come to find Tesla batteries and the accompanying software to be pretty smart and keep the worry to a minimum for the end user. The battery charges much like other devices where it is fast at first and tapers off. The heat generated by the speed and length of time at extremes (0% or 100%) are the real enemy. Elon has stated on multiple occasions the 100% is fine when you must, but you do lose efficiency (regen braking) and therefore should shoot for 95%. You can find articles that have similar and conflicting info, but my experience has been for long trips, and if you see there are superchargers along your route, arriving at a supercharger will less is better for times sake as you'll get more juice for time spent at the charger and i've found the in car supercharging navigation to be very accurate. As for rate of charge, I know quite a few p85 owners that have done nothing but supercharge for years with seemingly no extra degradation from those who have not.

 

[outdoors]

To answer the question regarding amperage at home. When you lower it significantly you start getting into terms like overhead. Long and short I would say less efficient. More degradation? Others with technical electrical expertise feel free to chime in.

Battery health wise. Well I would say let the battery management system handle it and charge what your connection at your location can provide safely. Some might give you some data that is many years old, and is not from Tesla saying if you do X you battery will last years longer or maintain itself better. I just remember those are things not in the manual. Many are not about the same types of batteries used in Tesla's either.

Supercharging to 100% again the BMS system will make the decisions for you and will lower the amps till charge is complete. Charging to 100% at a supercharger does take a really long time. Those resources might be in need of another person, so I don't do that. Only places I need 100% are at home starting on a road trip or some areas I travel in WY,MT, and Canada.

Edit add: Looks like a great read

Battery Degradation Scientifically Explained

 

[mswlogo]

Home charging amperages are all so low it doesn’t matter.

That said, I never charge to 100% unless I can immediately use it. I don’t consider immediate, the next morning. That would be to long at 100% SOC IMHO. I’d be more concerned about that than which amperage you use.

 

[jerry33]

Below 32 amps there are more losses between the wall and the car, otherwise it makes no difference. When charging to 100%, you should set the start time so that it finishes at the time you leave. Sitting at 100% (or very low %) is not good for the battery. If it only has 99% by the time you leave, that's okay. It's unlikely that the 1% difference will be an issue. A good plan is to start a trip going a bit slower than usual and then speed up if there is plenty of range left. The Nav system will also tell you if you need to slow down to complete your journey.

There are a lot of opinions, but from what people report, the changes that you can make (other than not leaving it sit at the very top or very bottom, and a plugged in Tesla is a happy Tesla) are going to be lost in the noise created by other variables such as driving conditions.

 

[ucmndd]

Does the Amperage you charge at make a difference in battery degradation when charging?

For any level 2 charging speed, no.

 

[ewoodrick]

Speed of home charging doesn't matter.
Charging to 100% doesn't damage the battery. Leaving it sitting at 100% for really long times (months) does decrease life a little.

The battery is designed not to be worried about, so don't worry about it.

 

[rafacq]

Thanks for all the answers. From your comments sounds like 24A or 40A does not make a difference. I’ve been charging daily to 90% but on an upcoming trip to Amarillo, the next Supercharger is 239 miles away. My S85D still shows 270 at full charge, so what I’m hearing is start charging so we leave as soon as the car hits 100%!

So next question, I’m retired now and may drive 40 miles one day, then 10 miles the next day and perhaps 50 the third day. Should I charge to 90% every day or drive without charging until the battery is down to 40% or 50% then plug that night so it charges to 90%? From the driving I’m doing it could be a week or more before I would need to charge! What’s the better option, daily or when battery drops below 50%?

 

[raptor5244]

So next question, I’m retired now and may drive 40 miles one day, then 10 miles the next day and perhaps 50 the third day. Should I charge to 90% every day or drive without charging until the battery is down to 40% or 50% then plug that night so it charges to 90%? From the driving I’m doing it could be a week or more before I would need to charge! What’s the better option, daily or when battery drops below 50%?

You will get different answers on this one. The manual will suggest you plug in the car whenever you are not using it. Primarily to protect against situations where you don't drive the car for weeks and wind up draining both the main and 12v batteries. Also, so that you always have range available if you need it. Some will suggest that if you don't need much range daily then set the charge limit to 50% or so and leave it plugged in. I tend to charge about every other day or two depending on my driving needs. I think as long as you don't run the batteries down to really low levels it does't really matter. I won't have the car 8 year or 120k miles from now so I am not overly concerned about it.

 

[TMThree]

Speed of home charging doesn't matter.
Charging to 100% doesn't damage the battery. Leaving it sitting at 100% for really long times (months) does decrease life a little.

The battery is designed not to be worried about, so don't worry about it.

Please stop giving advice about batteries. Maybe read the manual for the car while you're at it.

 

[Snowstorm]

Charging speed at any L2 charging speed is not going to be an issue. 24, 48 or even 72 amp is too slow to be a concern. Faster charging may be more energy efficient as the car spends less time on.

There are lots of opinion on 100% charge. I figure it isn’t terrible but not a great thing to do everyday. Sort of like eating a Big Mac. Once or even twice a week won’t hurt, but eat it everyday for lunch and dinner isn’t going to be good for your health over the long term.

Don’t sweat it, charge it to 100% if you think you need to, but keep max charge at say 80-90% normally for best longevity.

If you do charge to 100%, don’t let it sit at 100% for days. Next morning, is not an issue.

 

[aerodyne]

To the OP and his second question...

Elon has stated for the older Tesla's, SOC of 30-70% during operation is best for battery life, and for storage, 50-62%.

I keep my S85D at the middle of the strorage range stated above, 55%, and plugged in. Never been above 93%, or below 27%. This included a 5k mile road trip from LA to Chicago and return, SC all the way, average speed including stops 50-55mph.

Also retired, and 3 min from an SC, so if I have to go some where far on short notice it is not an issue.

My rated range has varied over the last 8 months and 10k miles from a high of 272 to a low of 265. Storage at lower SOC drops the range slightly, but when I charge to 70% or higher, goes back to 269.

The short version is still, don't worry about the battery pack, except avoid extremes and keep the car cool garaged or under shade if in a hot climate. But if you must worry, then get a copy of Teslafi, and use it to track you battery health.