Best way to charge to prevent battery degradation?

[steph746]

We've just had our model Y for about a week and a half. I'd like to get into some good battery charging habits. Unfortunately, because I have had our Tesla Wall Connector installed yet, I had to supercharge twice for just about 50 miles or so each time.

My mobile connector just arrived last night. In general, is it best to charge with the mobile connector when possible?

Also, more longer-term, is it still better to charge with the mobile connector vs. the wall connector?

Thanks in advance.

 

[ATPMSD]

The Mobile Connector is limited to 32A (assuming a 40A or greater circuit). The Wall Connector will charge at 40A on a 50A circuit and 48A on a 60A circuit. Home charging is not an issue, charge at the highest rate you can as it is both more efficient and lets the car shut down the charging circuit and battery heater / cooler sooner.

SuperCharging is fine so long as it does not become a habit and keep the charge to sometime like 80% SOC or less. Of course always charge to what you need, if you need to.

Finally, as you received the mobile connector, use the 5-15 adaptor (for the 120V outlet) and charge using an outlet in the garage until you get the wall connector installed. Since you will be using a wall connector, do not waste your time installing a 14-50 outlet. Just keep the mobile connector in the car for when you may need it.

 

[jcanoe]

We've just had our model Y for about a week and a half. I'd like to get into some good battery charging habits. Unfortunately, because I have had our Tesla Wall Connector installed yet, I had to supercharge twice for just about 50 miles or so each time.

My mobile connector just arrived last night. In general, is it best to charge with the mobile connector when possible?

Also, more longer-term, is it still better to charge with the mobile connector vs. the wall connector?

Thanks in advance.

It appears you are using the Tesla estimated range value next to the battery icon and when charging. Many (most?) Tesla owners switch this to display the % state of charge (SOC) as the Tesla range estimate never matches real world range. To switch from estimated range tap on the range value on the Tesla screen or in the Tesla app and the % SOC will appear.

Charging at home (whether using the Tesla Mobile Connector, Tesla Wall Connector or other Level 1/2 charging station is more convenient and less expensive that charging at a Supercharger (unless you received free Supercharging through a Tesla promotion.)

If you plug the Tesla Mobile Connector using the 120V 5-15 plug adapter into a home 120V outlet you will be able to charge at ~1.0 to 1.4 kWh (3 to 4 miles of range added) per hour to the battery. That may be all you need if you drive less than ~33 miles day.)

If you decide to install a new 240V charging circuit get the Tesla Wall Connector as this is the better option (faster charging, longer charging cable, no expensive GFCI or receptacle needed.)

If you can charge at work then do so, especially if there is no cost to charge.

Don't overlook the Tesla J1772 charging adapter that comes with the Tesla Model Y. (Look for this small accessory in the rear hatch storage compartment.) The J1772 adapter will enable you to charge at any public Level 2 charging station. Download Plugshare onto your phone to locate nearby charging stations. You may even find some Level 2 charging stations that are free to use for a few hours while shopping or dining.

For daily use, when charging, set a maximum charge level somewhere between 50% and 90% (many choose to charge up to 80%, only charge beyond this before a road trip (even then 100% SOC is usually not needed as you will most likely be able to charge using the Tesla Supercharger Network while on your trip.)

 

[TesslaBull]

Charging to no more than 55% daily will result in the lowest possible battery degradation over time. Charging right before leaving(by using scheduled charging) for the day is also optimal. It keeps the battery at the lowest state of charge until needed, and charging gives some "free" preconditioning as it warms the battery a bit without wasting as much, if any, electricity for preconditioning.

 

[melmalinowski]

Charging to no more than 55% daily will result in the lowest possible battery degradation over time. Charging right before leaving(by using scheduled charging) for the day is also optimal. It keeps the battery at the lowest state of charge until needed, and charging gives some "free" preconditioning as it warms the battery a bit without wasting as much, if any, electricity for preconditioning.

On what do you base the first sentence?

 

[mswlogo]

It appears you are using the Tesla estimated range value next to the battery icon and when charging. Many (most?) Tesla owners switch this to display the % state of charge (SOC) as the Tesla range estimate never matches real world range. To switch from estimated range tap on the range value on the Tesla screen or in the Tesla app and the % SOC will appear.

Charging at home (whether using the Tesla Mobile Connector, Tesla Wall Connector or other Level 1/2 charging station is more convenient and less expensive that charging at a Supercharger (unless you received free Supercharging through a Tesla promotion.)

If you plug the Tesla Mobile Connector using the 120V 5-15 plug adapter into a home 120V outlet you will be able to charge at ~1.0 to 1.4 kWh (3 to 4 miles of range added) per hour to the battery. That may be all you need if you drive less than ~33 miles day.)

If you decide to install a new 240V charging circuit get the Tesla Wall Connector as this is the better option (faster charging, longer charging cable, no expensive GFCI or receptacle needed.)

If you can charge at work then do so, especially if there is no cost to charge.

Don't overlook the Tesla J1772 charging adapter that comes with the Tesla Model Y. (Look for this small accessory in the rear hatch storage compartment.) The J1772 adapter will enable you to charge at any public Level 2 charging station. Download Plugshare onto your phone to locate nearby charging stations. You may even find some Level 2 charging stations that are free to use for a few hours while shopping or dining.

For daily use, when charging, set a maximum charge level somewhere between 50% and 90% (many choose to charge up to 80%, only charge beyond this before a road trip (even then 100% SOC is usually not needed as you will most likely be able to charge using the Tesla Supercharger Network while on your trip.)

Who cares if it’s not a perfect estimate. It’s easier to extrapolate with miles left than a percentage to know how far I can go. Many ICE cars switch to miles left when fuel is low. Wonder why they do that? But it’s just an estimate. Miles gives me more useful information than a percentage. In summer I can easily exceed its estimate unless I’m towing

 

[mswlogo]

Charging to no more than 55% daily will result in the lowest possible battery degradation over time. Charging right before leaving(by using scheduled charging) for the day is also optimal. It keeps the battery at the lowest state of charge until needed, and charging gives some "free" preconditioning as it warms the battery a bit without wasting as much, if any, electricity for preconditioning.

Charging right before you leave is also the most wasteful (needs the most battery Re-heating). Charging when you get home from a drive takes advantage of an already heated battery. Letting the battery cool and later reheat it, is pure waste.

Also letting the battery cool and reheating it causes more temperature swings. Heating and cooling cycles tends to age electronics quicker.

 

[GSP]

Charging right before you leave is also the most wasteful (needs the most battery Re-heating). Charging when you get home from a drive takes advantage of an already heated battery. Letting the battery cool and later reheat it, is pure waste.

Also letting the battery cool and reheating it causes more temperature swings. Heating and cooling cycles tends to age electronics quicker.

This is true, but charging just before you leave also has advantages: SOC over time will average to a lower value (more time spent at lower SOC). This results in a lower rate of cell degradation. Also your battery will be warm and ready to accept regen.

I like to finish charging shortly before I leave for the above reasons, and my off-peak electricity cost is very low, about $0.04/kWh, so the energy used to reheat the battery for charging is not a cost concern.

GSP

 

[GSP]

On what do you base the first sentence?

I believe @TesslaBear is correct about longer life at 55%, since lab testing of cells for calendar life always has the best results at 50% SOC. Cells kept at 80% or 100% SOC degrade faster, especially for the higher temperature tests. I have seen data for many different cell chemistries and they all have this characteristic.

However, cell life often is not what determines how long a battery pack will last. Other issues like water intrusion over time, corrosion, and circuit board failures are often the limiting factor.

GSP

 

[DanDi58]

Just follow Tesla's recommendations - keeping it between 20% and 90% for daily use. I charge to 85% daily, occasionally 90% if I have a lot of driving coming up the next day. 95% for road trips using Scheduled Departure. And I've been using the Mobile Charger from Day One, with a NEMA 14-50 outlet I had installed.

 

[father_of_6]

On what do you base the first sentence?

I've read this too... there are graphs posted somewhere on these forums of SoC studies that show higher degradation right around the 58% mark (oddly specific).

My first 6 months of ownership I charged exclusively at SuperChargers before I had home L2 charging installed (big project). As I got more and more comfortable with surviving off less range, I've dropped my SoC of charge down... to 50% now.

I don't have anything to contribute regarding degradation... sometimes my driving conditions get me rated range, sometimes they don't. Not sure how I'd even really measure this - seems like many times reduced range is actually caused by the BMS.

 

[ucmndd]

Charging right before you leave is also the most wasteful (needs the most battery Re-heating). Charging when you get home from a drive takes advantage of an already heated battery. Letting the battery cool and later reheat it, is pure waste.

Unless it’s very cold (like approaching 0 F) the car does no deliberate heating of the battery for L2 charging.

On the contrary, leaving with a warm battery from recent charging enables regen and almost certainly is overall MORE efficient.

 

[jcanoe]

Unless it’s very cold (like approaching 0 F) the car does no deliberate heating of the battery for L2 charging.

On the contrary, leaving with a warm battery from recent charging enables regen and almost certainly is overall MORE efficient.

Perhaps you meant 0C. The Tesla Model Y will not charge the battery when the battery temperature is close to freezing, i.e. 32F, starting at around 39F(4C).

While it is true that charging as soon as you arrive home may not require additional battery warming prior to charging if you are on a time of use rate plan it will be more efficient to wait until the off-peak period to charge.

Leaving home with a warm battery is not a guarantee of adequate regenerative braking. The Tesla Model Y's heat pump may use some of the heat from the warm battery coolant to warm the passenger cabin as soon as you start driving even if this means that regenerative braking may be reduced.

During preconditioning the Tesla Model Y no longer heats the battery as much as in the past. This saves energy and preconditioning takes less time. There is now a setting under Pedals and Steering to use the (friction) brakes when regenerative braking may be limited. Enabling this setting option further reduces the need for extensive battery warming.

 

[ucmndd]

Perhaps you meant 0C. The Tesla Model Y will not charge the battery when the battery temperature is close to freezing, i.e. 32F, starting at around 39F(4C).

Do you have any documentation of this? That's certainly contrary to my own experience in a Model S. My car will happily charge with the battery below freezing.

 

[jcanoe]

Do you have any documentation of this? That's certainly contrary to my own experience in a Model S. My car will happily charge with the battery below freezing.

Ambient air temp or battery temp?

Most lithium-ion batteries will be permanently damaged when charging when the battery is at below-freezing temperatures. A lithium ion battery cannot be charged at or below 32F (0C) without causing lithium plating in the form of tiny dendrites to form within the battery. Once dendrites form the damage is permanent resulting in decreased capacity and can lead to shorting within the cell.

Charging Your Lithium Battery Below Zero - DC Battery Technologies

The Best Battery For Cold Weather Applications

 

[turnbowm]

Who cares if it’s not a perfect estimate. It’s easier to extrapolate with miles left than a percentage to know how far I can go. Many ICE cars switch to miles left when fuel is low. Wonder why they do that? But it’s just an estimate. Miles gives me more useful information than a percentage. In summer I can easily exceed its estimate unless I’m towing

I feel the same way. Distance is measured in miles, not percentage.

 

[ucmndd]

Ambient air temp or battery temp?

Yes.

Most lithium-ion batteries will be permanently damaged when charging when the battery is at below-freezing temperatures.

I don’t believe that’s strictly true. Charging QUICKLY can certainly cause damage, but my car will absolutely charge at close to normal L2 rates with the pack below freezing. I was mostly responding to your claim that a Model Y will not charge AT ALL with the pack temp below 0C. That’s not my experience with my Model S.

An excerpt from one of your articles:

The Best Battery For Cold Weather Applications

“The damage to the battery when charging at colder temperatures is proportional to the charging rate. Charging at a much slower rate can reduce the damage, but this is rarely a practical solution. When temps fall between 32 degrees and 14 degrees Fahrenheit, batteries cannot be charged at higher than .1C. When temps fall between 14 degrees and -4 degrees Fahrenheit, batteries cannot be charged at higher than .05C”

That seems more in-line with my observations between 14-32 degrees F. A 75kwh battery charging at 7.5kw on a L2 charger is at that 0.1C threshold - plenty slow to not cause any significant damage.

 

[Rocky_H]

I don’t believe that’s strictly true. Charging QUICKLY can certainly cause damage, but my car will absolutely charge at close to normal L2 rates with the pack below freezing. I was mostly responding to your claim that a Model Y will not charge AT ALL with the pack temp below 0C. That’s not my experience with my Model S.

Your Model S isn't different from all of the other Model S's. I think the miscommunication here is that people are saying the phrase "at" freezing, which sounds like exactly AT 32.00 degrees Fahrenheit, and then you're getting hung up on that 32.00 degrees number.

The cutoff point may not be exactly at 32 degrees. I'm not sure where it is. It may be at 30 or 28 or 25 or something, but there is a point where your car, my car, and other people's cars will simply not charge the battery AT ALL because it is too cold. The car will just sit there attempting to warm the battery pack up some before it will even begin charging.

And that is that other point you mentioned, where it does scale. Below some point, there is no charging. But then at some point it is warm enough to take a little bit. And then that's a rising curve, with temperature increasing, the amps can increase too.

 

[ucmndd]

Your Model S isn't different from all of the other Model S's. I think the miscommunication here is that people are saying the phrase "at" freezing, which sounds like exactly AT 32.00 degrees Fahrenheit, and then you're getting hung up on that 32.00 degrees number.

The cutoff point may not be exactly at 32 degrees. I'm not sure where it is. It may be at 30 or 28 or 25 or something, but there is a point where your car, my car, and other people's cars will simply not charge the battery AT ALL because it is too cold. The car will just sit there attempting to warm the battery pack up some before it will even begin charging.

And that is that other point you mentioned, where it does scale. Below some point, there is no charging. But then at some point it is warm enough to take a little bit. And then that's a rising curve, with temperature increasing, the amps can increase too.

Agree on all counts. As I said in my first post, my understanding of that threshold where the car simply WILL NOT CHARGE is closer to ~0F than 0C (reality is very likely somewhere in the middle and scales down as you say). But I generally maintain my response to mswlogo's assertion that "charging right before you leave is also the most wasteful." I don't believe there's any evidence to support that claim in most/all cases (possibly excluding as I said when it's "very cold").

 

[TesslaBull]

Just follow Tesla's recommendations - keeping it between 20% and 90% for daily use. I charge to 85% daily, occasionally 90% if I have a lot of driving coming up the next day. 95% for road trips using Scheduled Departure. And I've been using the Mobile Charger from Day One, with a NEMA 14-50 outlet I had installed.

This is not the correct answer to the question posted by the OP. The question was:

"Best way to charge to prevent battery degradation"​

The question was not "how does DanDi58 charge his battery".

Keeping charge rate at or below 55% *optimally* minimizes degradation over time, and this is based on the best scientific research available on the subject.

You *can* charge to 80 or 90%, and for many people this will be fine, but it does not optimally minimize degradation. I plan to keep my car for 10 years or possibly longer. For me personally, minimizing degradation i.e. maximizing the amount of range that I keep for my car matters a lot. My daily commute is only 60 miles, so why on earth do I need to charge daily to 280 miles or whatever 80-90% gives me if there is some benefit to not charging to such a high level daily? I can optimally minimize degradation while retaining about 190 miles of range with my 55% daily charge rate. Even if I forget to charge one night I still have plenty to commute an can charge some when I wake up. This adresses the ops question.