Charging questions...

[demotrek]

I have a few charging questions I’m hoping you can help me with. I just picked up my ‘15 MS 85D last weekend and absolutely love this car.


1) From everything I’ve read it sounds like the ideal charge status is to stay between 30-70%. I currently charge my car to 69% every night and most days it goes down to around 45-50% sometimes down to 30%. Does this sound “ideal” or would 80% be better so I don’t hit the lower numbers often (30% ish)?


2) Is it good to run the battery to 100% at least a couple times a year or if you can avoid it all costs you should? Same with running it down to less than 5%. Is there any “reset” that’s good to do on the battery?


3) sometimes I come home for lunch 10-15 minutes. I plug it in since I’ve read to always charge when you can but does it hurt to have short 10-15 minutes charges?


4) My car is scheduled to get body work done on 2/11. This is an approved Tesla shop (they’re paying for it) but I don’t believe they have any chargers on site. They said they expect to keep the car 5-7 days. The body shop is about 10 minutes from me. How would you handle this? If I charge it to say 90% the night before and then create a profile where the temperature is 50 degrees and the car doesn’t auto lock, etc. would it last the whole week if I arrive there at say 85%? Any other ways to keep the battery draining while sitting?


I appreciate the help-

 

[shred86]

1) It depends how you define “ideal”. Following these simple steps will give you best balance between convenience and battery longevity:

• Charge somewhere between 50-90% for daily use.
  • Jeff Dahn recommends 70%. I wrote more about this in this thread if you’re interested. Regardless of what you choose, it will have very little impact on battery degradation unless you plan on owning the car for a very long time or drive a ridiculous amount of miles.
• Only charge >90% if needed for long range trips.
  • If you do charge to 100%, avoid keeping it at that level for an extended period of time. What I’d recommend doing is having the charge finish about the time you plan on leaving (look at how long it takes to charge and set a charging time).
• Keep it plugged in (i.e. don’t wait to charge, just plug it in when you get home).

2) There is zero benefit to charging any lithium-ion battery to 100% (in terms of battery health). There might be some benefit to charging >93% if your battery cells become “out of balance”. Above 93% appears to cause the cells to “re-balance”. Tesla’s battery management system (BMS) does an extremely good job of keeping the cells balanced (within milivolts of each other) so you really shouldn’t have to do this unless you’re experiencing problems. If you are experiencing problems, let the service center check it out. Also, since you mentioned it, there’s nothing wrong with going below 30% and there is no benefit in letting it get to <5%.

3) That’s exactly what you should be doing. Smaller depths of charge is better for reducing battery degradation than large depths of charge. There is a sheet that use to come with Tesla’s that says something along the lines of “A plugged in Tesla is a happy Tesla”.

4) Tesla’s typically lose about 1% per day (can be a lot more depending on the climate). You have absolutely nothing to worry about for 5-7 days.

Congrats on the purchase!

 

[demotrek]

1) It depends how you define “ideal”. Following these simple steps will give you best balance between convenience and battery longevity:

• Charge somewhere between 50-90% for daily use.
  • Jeff Dahn recommends 70%. I wrote more about this in this thread if you’re interested. Regardless of what you choose, it will have very little impact on battery degradation unless you plan on owning the car for a very long time or drive a ridiculous amount of miles.
• Only charge >90% if needed for long range trips.
  • If you do charge to 100%, avoid keeping it at that level for an extended period of time. What I’d recommend doing is having the charge finish about the time you plan on leaving (look at how long it takes to charge and set a charging time).
• Keep it plugged in (i.e. don’t wait to charge, just plug it in when you get home).

2) There is zero benefit to charging any lithium-ion battery to 100% (in terms of battery health). There might be some benefit to charging >93% if your battery cells become “out of balance”. Above 93% appears to cause the cells to “re-balance”. Tesla’s battery management system (BMS) does an extremely good job of keeping the cells balanced (within milivolts of each other) so you really shouldn’t have to do this unless you’re experiencing problems. If you are experiencing problems, let the service center check it out. Also, since you mentioned it, there’s nothing wrong with going below 30% and there is no benefit in letting it get to <5%.

3) That’s exactly what you should be doing. Smaller depths of charge is better for reducing battery degradation than large depths of charge. There is a sheet that use to come with Tesla’s that says something along the lines of “A plugged in Tesla is a happy Tesla”.

4) Tesla’s typically lose about 1% per day (can be a lot more depending on the climate). You have absolutely nothing to worry about for 5-7 days.

Congrats on the purchase!

Wow, this is extremely helpful and I appreciate the response. Thank you-

 

[David99]

1) From everything I’ve read it sounds like the ideal charge status is to stay between 30-70%. I currently charge my car to 69% every night and most days it goes down to around 45-50% sometimes down to 30%. Does this sound “ideal” or would 80% be better so I don’t hit the lower numbers often (30% ish)?

That's a good way to do it. If you don't drive much charging to 70% is just fine. Definitely better than charging to 80 or 90% daily, but the difference in degradation over the years is very small. If in doubt, always charge a little more. It's better not to run out of juice.

2) Is it good to run the battery to 100% at least a couple times a year or if you can avoid it all costs you should? Same with running it down to less than 5%. Is there any “reset” that’s good to do on the battery?

Yes it helps the BMS to recalibrate itself if you charge higher than 90% and then go down to 10% or lower. Charging to 100% is not bad when done here and there. Especially if you do so just before you go on a trip. You want to avoid charging to 100% often and letting the car it at 100% if you are not planning on using it. But if you need it, it's not a big deal. I charge to 100% several times a month for 5 years now. My degradation is right where the average is.

3) sometimes I come home for lunch 10-15 minutes. I plug it in since I’ve read to always charge when you can but does it hurt to have short 10-15 minutes charges?

It doesn't hurt the battery but it also doesn't help much. You can do it or not, either way is fine for the battery. I usually don't charge during the day because I prefer to use the cheaper off peak electricity at night.

4) My car is scheduled to get body work done on 2/11. This is an approved Tesla shop (they’re paying for it) but I don’t believe they have any chargers on site. They said they expect to keep the car 5-7 days. The body shop is about 10 minutes from me. How would you handle this? If I charge it to say 90% the night before and then create a profile where the temperature is 50 degrees and the car doesn’t auto lock, etc. would it last the whole week if I arrive there at say 85%? Any other ways to keep the battery draining while sitting?

They might need to move the car around, open and close door and windows/trunk and so on. I would charge it to 90% when dropping off. Give them the mobile charger with the normal 120 Volt plug just in case. If they want, they can plug it in over night on a normal outlet.

 

[whitex]

I've been charging our cars to 90% since 2013. I charge whenever the car is at home, even for few minutes; my wife mostly at night because she doesn't like to unplug the car on multiple trips hauling the kids around through the day. My MS is the older one from 2015, it might have lost a mile or two at 90% (charges to 225/226 at 90%, IIRC when new it was 227). The 2018MS is less than a year old, no noticable degradation. We never set the charge level to under 90%. Occasionally for trips I charge to 95, mostly to warm up the battery just before the trip. Only charged to 100% a few times. Oh, both cars have 24/7 2ch dashcams, and vampire drain seems about 3 miles per day, unless really cold and parked in windy outdoors. While in the garage, 2015 car cycles between 226-220.

 

[tstafford]

I've been charging our cars to 90% since 2013. I charge whenever the car is at home, even for few minutes; my wife mostly at night because she doesn't like to unplug the car on multiple trips hauling the kids around through the day. My MS is the older one from 2015, it might have lost a mile or two at 90% (charges to 225/226 at 90%, IIRC when new it was 227). The 2018MS is less than a year old, no noticable degradation. We never set the charge level to under 90%. Occasionally for trips I charge to 95, mostly to warm up the battery just before the trip. Only charged to 100% a few times. Oh, both cars have 24/7 2ch dashcams, and vampire drain seems about 3 miles per day, unless really cold and parked in windy outdoors. While in the garage, 2015 car cycles between 226-220.

Similar to what I've done with mine. 90% every night. I only charge at EOD because I'd prefer to only plug/unplug once a day. No issues whatsoever. I think it made sense to be concerned about battery degradation in 2012-14. But there aren't widespread reports of meaningful degradation and we are six plus years in to the MS. I'd say just enjoy the car and not worry too much about the battery.

 

[SSedan]

The port and plug can and do get dirty and worn. Plugging in for 10-15 minutes is harmful from that perspective.

Charging to 70-80% will cause the range estimates to decline over time, seems more stable if charging to 90%.

Many folks think this is degradation but if you do a few deeper discharges like down to 5% and then back to 95% you gain estimated miles back. Not everything but some.

 

[f205v]

I usually charge to 80% every night at home.
Charge to 100% only for long travel, and usually start the journey immediately after reaching 100%
Only once I got down below 5%, usually I plan travel to get to a charging station between 10% and 15%

 

[whitex]

The port and plug can and do get dirty and worn. Plugging in for 10-15 minutes is harmful from that perspective.

Do you have any data on that, published by Tesla or even anyone reporting reporting having a worn down plug or port needing replacement? Do the busy superchargers require periodic (if so, how often) replacement of plugs? While I understand the idea of wear, if the difference between plugging in 3 times a day vs. once means for example that the plug and/charger will last 300 years instead of 100 years, then it makes no practical difference.

 

[SSedan]

The UMC to car plug with my 80k mile car was getting warm, cleaning it with electronics cleaner and brushes helped.
I installed a wall connector and at 72 amps it runs cooler than my UMC does at 40 or even lower.

A rational reasonable person capable of simple reasoning will attribute this to wear. It is a mechanical connection that is manipulated frequently, it is completely irrational to argue it won't wear.

 

[Brian-MS90D]

@demotrek , congratulations on your new car! Tesla has great batteries and battery thermal management system. This means that, for the most part you are worrying and thinking way too much about charging. That being said, I understand that some people are more engineering minded than others and want to geek out on the topic. From my informal research over the years and my own personal experience, do whatever makes you feel comfortable and peaceful between 60% and 90%. Never be afraid to charge to 100%, but don't leave it that way too long (12hrs or more?) and try to schedule it so that's it's ready comfortably before you depart.

In other words, just remember to enjoy one of the supreme conveniences of an electric car compared to ICE: Easy refueling at home w/o range anxiety. Don't stress yourself out over the minutia. I was in your shoes and it was wasted effort

 

[bob_p]

There are many different strategies on charging strategy, though it appears that charging regularly below 90% doesn't seem to have much impact on long-term battery degradation (which has been surprisingly low).

Best advice for new owners - KEEP IT SIMPLE:

• Tesla recommends plugging in the vehicle for charging whenever possible
• Charge above 90% only when needed for a road trip, and try to do this only immediately before leaving on a road trip
• While on a road trip, use the recommendations of the onboard navigation software to help set the target charging level when leaving a supercharger - only go above 90% at a supercharger if absolutely necessary to get to your next charging stop, since supercharging slows down significantly above 80%
• Try to keep the back above 5-10% charge, since depleting below 5% often could degrade the pack
• Fast charging at Tesla superchargers appears to be safe, while Tesla has limited some vehicles when using 3rd party fast chargers

WARNING - if you do set the charging limit above 90% - that setting stays in effect until you manually set it back to 90% or below. So if you do charge to 100%, make sure you reset the charge limit before plugging in for the next charge, otherwise you may find that you've charged your vehicle to 100% the next time, and left it for an extended period at 100%, which may not be good for the battery.

 

[boonedocks]

+1 +1 +1 for 90% daily charging and always leaving your car pugged in when at home. Early 2017 MS100D charged daily to 90% with very rare over 90% charges. Daily commute ~100 miles and the weekend warrior car for family. 64,400+ miles and just barely over a 3% drop in battery capacity. My S85D was treated the same way and had almost 60k miles when I sold it with almost the exact same 3% battery loss.

 

[Icepucks]

I'm picking up my 2015 S70 (13,800 miles) this afternoon in West Palm Beach. This information has been very helpful. I can't wait to hear what Tesla recommends at delivery.

 

[David99]

Do you have any data on that, published by Tesla or even anyone reporting reporting having a worn down plug or port needing replacement? Do the busy superchargers require periodic (if so, how often) replacement of plugs? While I understand the idea of wear, if the difference between plugging in 3 times a day vs. once means for example that the plug and/charger will last 300 years instead of 100 years, then it makes no practical difference.

Yes the whole part is made from plastic and will eventually wear out, but I totally agree it is not a concern when it comes to charging habits. Plug in as many times as you want. You can get a charge port from eBay for $100 and it takes less than an hour to replace it. It's like saying, turn off the AC so the compressor doesn't wear out. Every part on the car will wear out with use.

 

[whitex]

Yes the whole part is made from plastic and will eventually wear out, but I totally agree it is not a concern when it comes to charging habits. Plug in as many times as you want. You can get a charge port from eBay for $100 and it takes less than an hour to replace it. It's like saying, turn off the AC so the compressor doesn't wear out. Every part on the car will wear out with use.

My point was that you are unlikely to ever need the port replacement from Tesla or Ebay, unless you have a defective part from the start.Tesloop taxi did 400k miles, charging often, without wearing out the charge port.
Tesloop’s Tesla Model S Surpasses 400,000 miles (643,737 kM)
So, yes the part wears out, but it wears out slower than the rest of the car even if you charge multiple times a day.

 

[AwlBidnz]

1) The Master says periodic 10% and 90% charges are OK and won't harm the battery. Forums seem to say 20-80% is best practice. Nothing wrong with 30%ish when home. The ideal charge rate for our batteries is slow (NEMA 14-50).

2) Only bad I here is continual super charging. Good is "ABC" Always Be Charging". No one says it's good to charge to 100%. Of course you need to for trips, but it ain't "best practice". Yes there is a reset..most of the forums have search capabilities now & you will find it's a run to 0%, charge to 100%, repeat, "reset", eventually. Keep doing this when your battery be comes unbearably small, all the while trying to convince the SC to replace your battery under warranty ;0-

3) ABC

4) You will expend approximately 1% per day IF you can resist from continually checking your babies condition. You may want to consider valet settings for those test drives that will need to be taken ;0)

 

[Joelgjr]

My advice after a year of ownership: don’t over think it. Plug it in at night, charge to 70%. Charge it more for longer trips and drive what is convenient not worrying about going below 5 or above 93 percent for short periods of time.

Before I took delivery I thought owning and driving an EV would basically require me to operate as an expert in batteries. I wrote out all these plans and bought 100’ of RV power cable and every single 240v plug that exists, plus the chademo adapter
What ended up happening is I just let it charge at home with the mobile charger using the 14-50 adapter it came with, and have only ever used my wires and adapters twice and didn’t actually NEED to, and primarily use the supercharger network with little to no thought when traveling.
I drove x- country from Boston to San Diego and literally put a San Diego address into the nav when leaving Boston and left with 69% charge. My stops were short enough that we almost never waited for charging to finish (between everyone using bathroom and walking dog / eating meals)

I’m sure it’s different with shorter range EVs, but I could not give this vehicle less thought when planning. No matter what anyone says about all the “Tesla killers” coming out, while they may compete with specs (7 years later!!! The model s came out in 2012 remember) no one has a high speed charging network like Tesla does, and that makes a HUGE difference in the practical usability of the car. Anything over 100kw charging makes the car essentially ICE-practical. The current 50kw fast chargers out there are not fast and are the single reason why EVs aren’t more widely adapted.

 

[Mike Robinson]

When I took delivery of my new 2018 MS 100D on 12/21/18, the delivery specialist pointed out that the charging percentage was set to 90% and that I should leave it set at 90% for daily charging. I specifically asked him if it wouldn’t be better to only charge to 70% or 80% daily, and he said “no”. He said charging to 100% for trips was fine.

 

[shred86]

When I took delivery of my new 2018 MS 100D on 12/21/18, the delivery specialist pointed out that the charging percentage was set to 90% and that I should leave it set at 90% for daily charging. I specifically asked him if it wouldn’t be better to only charge to 70% or 80% daily, and he said “no”. He said charging to 100% for trips was fine.

It depends how you define “better”. For the vast majority of customers, 90% is the best balance between convenience (maximizing available range) and battery health (minimal degradation), hence it being a common recommendation. I highly doubt the delivery specialist understands the science behind lithium-ion batteries and what actually causes degradation. Not to mention even if he did, he probably wouldn’t give you any other recommendation than what he did. Why? Because it works just fine and the difference in battery degradation from say 60% SOC versus 90% SOC is going to be fairly minimal over the course of 8+ years and 250k+ (or more) miles. I’m not claiming I am an expert on lithium-ion batteries, just re-stating what experts like Jeff Dahn and the folks at batteryuniversity.com have written articles, made videos and published white papers about. The science suggests/shows there is in fact a difference with varying levels of charge states. It also shows the difference is very minimal for the expected life span of a typical EV. In 5-10 years from now, the difference will probably become more apparent with the early year Teslas, if the battery pack hasn’t already been replaced.