Is ABC "Always Be Charging" bad for battery life?

[jboy210]

Hi,

One thing I have always heard about EV operations is ABC "Always Be Charging".

Since I often only drive a little each day, I have been driving and then plugging the car in when I get back home. Most of the time each trips starts at the 90% charge limit and goes down to 85% or at most 70% before I plug in again. Is this practice of always plugging in "bad" for battery life?

BTW, another reason for plugging in so often is because I am still waiting (and waiting, ...) on my Signature HPWC. So right now I am limited to 120V charging at a max 1 KW/hour.

 

[prash]

Hi,

One thing I have always heard about EV operations is ABC "Always Be Charging".

Since I often only drive a little each day, I have been driving and then plugging the car in when I get back home. Most of the time each trips starts at the 90% charge limit and goes down to 85% or at most 70% before I plug in again. Is this practice of always plugging in "bad" for battery life?

BTW, another reason for plugging in so often is because I am still waiting (and waiting, ...) on my Signature HPWC. So right now I am limited to 120V charging at a max 1 KW/hour.

Shallow depth of discharge is not bad at all. So you should be good. My recommendation in your case is to charge to 70 or 80% daily, instead of 90%. Charging to 70% is better than 80% charging which is better than 90%. But the differences are very minimal if any.

 

[DCGOO]

Hi,

One thing I have always heard about EV operations is ABC "Always Be Charging".

Since I often only drive a little each day, I have been driving and then plugging the car in when I get back home. Most of the time each trips starts at the 90% charge limit and goes down to 85% or at most 70% before I plug in again. Is this practice of always plugging in "bad" for battery life?

BTW, another reason for plugging in so often is because I am still waiting (and waiting, ...) on my Signature HPWC. So right now I am limited to 120V charging at a max 1 KW/hour.

Actually that is the preferred way to charge. I charge to 70% typically dropping 10% per day. I plug in every night.

You could be waiting for months for your WC. Why don’t you install the wiring, and use a 14-50 outlet while you are waiting? The 14-50 is a $10 part.

 

[jboy210]

Actually that is the preferred way to charge. I charge to 70% typically dropping 10% per day. I plug in every night.

You could be waiting for months for your WC. Why don’t you install the wiring, and use a 14-50 outlet while you are waiting? The 14-50 is a $10 part.

The signatures HPWCs are shipping out so I am hopeful. But, if it does not come in the next few weeks I might be forced to use a Nema 15-40.

2 years ago I had the panel wired with a 50 AMP breaker for a Nema 14-50 and wires run to a box with a blank plate as part of a remodel. Since I did not know what type of EV we would get, they wired it to where the front of the Tesla sits. The electrician is coming back out to do some more rewiring as part of phase 3 (or is it 4 ) of the remodeling in 4 weeks. My hope was that by that time I would have the Signature WC and he could move the wires from there to a left rear of the Telsa and install the WC.

But thinking about it, the Nema 14-50 might be best in the front where it can be used by any car since my wife may want the new Porsche EV or a electric bug or a ...

BTW, love your license plate!

 

[TexasEV]

@jboy210, the answer to your question is in the manual under “Battery”.

Hint: The early Model S came with a card inside showing the car plugged in that said “A connected Model S is a happy Model S”.

 

[Anzir]

Elon tweeted a while back that the sweet spot for the battery is between 30 and 80% so I keep mine at 80 max. But I've had the same concerns.

With the P100D on 22s I don't average any less than 400Wh/mile (well, sometimes it dips into the 300s) so I burn through battery like it's going out of style.

 

[jboy210]

Elon tweeted a while back that the sweet spot for the battery is between 30 and 80% so I keep mine at 80 max. But I've had the same concerns.

With the P100D on 22s I don't average any less than 400Wh/mile (well, sometimes it dips into the 300s) so I burn through battery like it's going out of style.

I figured it came from the factory set to 90% so that could not be too bad for it. After all they are on the line for battery replacement with the 8 year, unlimited mile warranty. And no company wants to swap a $15K battery pack unless they have to.

 

[Graffi]

Around the 50% mark is the sweet spot. Changing the charge level is soooooooooo easy that I leave ours at 70% unless a longer drive is expected, then increase it for that day and change it back to 70% when we return. For trips we start with either 90% or sometimes 100%, then change back to 90% before we get to our first Supercharger. Since we only charge enough to get to the next Supercharger, with a 15% to 20% reserve, we usually leave long before 90% is reached. If we have a long stop at the Supercharger (such as shopping or eating) and get the 5 minute warning on our phone we just increase the charge limit to 100% to give us more time to finish and get back to the car. When we leave I change it back to 90%.

We always park the car, then plug in. It stays plugged in until we leave again.

 

[TexasEV]

Around the 50% mark is the sweet spot. Changing the charge level is soooooooooo easy that I leave ours at 70% unless a longer drive is expected, then increase it for that day and change it back to 70% when we return. For trips we start with either 90% or sometimes 100%, then change back to 90% before we get to our first Supercharger. Since we only charge enough to get to the next Supercharger, with a 15% to 20% reserve, we usually leave long before 90% is reached. If we have a long stop at the Supercharger (such as shopping or eating) and get the 5 minute warning on our phone we just increase the charge limit to 100% to give us more time to finish and get back to the car. When we leave I change it back to 90%.

We always park the car, then plug in. It stays plugged in until we leave again.

You’re treating yourself, not the battery. After many years your car will not have a MEANINGFUL difference in range compared to one that remains set at 90% for daily use and 100% for occasional trips. Statistically significant difference maybe, but not a meaningful difference. Remember the slider was put there to get around the EPA averaging the daily and trip ranges— with a slider there aren’t two numbers to average— not because it’s really necessary to set the car below 90%. The early Model S firmware just had 93% and 100% settings.

I just don’t want new or prospective owners to think they need to obsess over the battery like this. It’s ok if you want to, but it’s equally ok to keep it at 90%, increase to 100% for trips, and just enjoy the car.

 

[Eclectic]

You’re treating yourself, not the battery. After many years your car will not have a MEANINGFUL difference in range compared to one that remains set at 90% for daily use and 100% for occasional trips. Statistically significant difference maybe, but not a meaningful difference. Remember the slider was put there to get around the EPA averaging the daily and trip ranges— with a slider there aren’t two numbers to average— not because it’s really necessary to set the car below 90%. The early Model S firmware just had 93% and 100% settings.

I just don’t want new or prospective owners to think they need to obsess over the battery like this. It’s ok if you want to, but it’s equally ok to keep it at 90%, increase to 100% for trips, and just enjoy the car.

This is my experience as well. We've had Teslas since 2013 and put well over 100,000 miles on the two cars. We supercharge frequently and also charge to 90% and above on a regular basis. We drive a lot and don't want to put battery life above peace of mind on the road. We've never seen any evidence that either of our cars had a material drop in battery range over the years. I think it's a lot like people who take great pains to avoid dings, scratches and other cosmetic imperfections...if you're trying to preserve the car to a state that it looks factory fresh, and that means something to you, then be concerned with how you charge. If you bought the car to drive and enjoy, don't worry about how you charge.

 

[Anzir]

I guess I should clarify that my charge limit depends on who is paying. I charge to 80% at home, 90% at my office or at superchargers.

 

[bob_p]

We've had a Tesla since January 2013 - charging on a combination of 14-50 or 80A HPWC, and now have an S 100D and X 100D.

We've always followed the advice in the user manual - keep the car plugged in whenever possible, letting the cars charge to 90% - and haven't seen any significant range loss (and what loss we have seen may be due more to software changes than to actual degradation).

When plugged in, the car will charge up to 90% - and then slowly lose a little charge before deciding to charge back to 90% again. This means the charger isn't constantly trying to keep the battery pack at exactly 90%, instead, the "vampire drain" is slowly discharging the battery - and then causing the charger to periodically recharge. And this doesn't seem to cause any problems.

As eclectic has said above - follow the advice in the manual and don't worry about keeping the car plugged in whenever you can.

It's always nice to leave in the morning with a "full charge" - and not having to get in line for a gas pump...

 

[jboy210]

... and not having to get in line for a gas pump...

What is a gas pump?

 

[bob_p]

Seem to recall seeing gas pumps in Zoolander 2...

 

[jboy210]

Those gas pumps are dangerous. Especially when they start smoking.

 

[David99]

If you only have 120 Volt for now I would say yes charge more often. But in general it is not beneficial for the battery to be topped off all the time there is a chance. What matters to battery life is the state of charge over time. If you top it off all the time you have a higher state of charge than when you wait for a day or two and then charge. Yes it does make a difference. Every battery study with lithium cells shows that the higher the state of charge the faster the degradation. OTOH you want to drive your car and you want to always have a decent amount of range just in case. If you drive as little as you describe I'd definitely set the charge limiter to 70% and top off more often.

 

[jboy210]

If you only have 120 Volt for now I would say yes charge more often. But in general it is not beneficial for the battery to be topped off all the time there is a chance. What matters to battery life is the state of charge over time. If you top it off all the time you have a higher state of charge than when you wait for a day or two and then charge. Yes it does make a difference. Every battery study with lithium cells shows that the higher the state of charge the faster the degradation. OTOH you want to drive your car and you want to always have a decent amount of range just in case. If you drive as little as you describe I'd definitely set the charge limiter to 70% and top off more often.

Do you have some reference quantifying the effect if higher SOC on battery life. I would be great to know what the optimal max is .

Everything I have read from various sources show Depth of Discharge (DoD) (difference in starting and ending charge) as being the main culprit in reducing battery life. This would seem to imply charging as often as you can do minimize depth of discharge, and running the battery down too far has a detrimental effect. So that is good for my operations of charging it all the time.