Any issue Fast Charging with some Regularity when Battery at 50-60% ?

[GMan]

I have to wait for the electric company to quote out an estimate to bring another 100 amps from the grid to my house. In the meantime, I have no home charger (other than the 110v using the provided home charging cord) but I do have relatively easy access to a DC Fast Charging station. My preference is not to wait until the battery is 20% to charge.

So I would like to know if there's any long term battery issues/concerns with DC fast charging twice a week when the battery is 50-60%, bringing it back up to 80% each time?

Thanks

 

[borski]

There are plenty of threads on this exact topic. Pease do a search before posting; searching ‘fast charging’ brings up this as the first link, for example: https://lucidowners.com/threads/charge-only-with-ea-fast-charger.4114/

 

[GMan]

There are plenty of threads on this exact topic. Pease do a search before posting; searching ‘fast charging’ brings up this as the first link, for example: https://lucidowners.com/threads/charge-only-with-ea-fast-charger.4114/

I had searched and did not find a question like mine. There are plenty of DC Fast Charging questions in this forum of course and while I appreciate the link you sent, it does not address my question (although I did now learn there is a disadvantage to regularly using a DC Fast Charger, so thanks for that).

My question is specifically around plugging (on a level 3 DC Fast Charger) when the battery is not yet close to 20%, for example it's 50-60%. Is there a disadvantage plugging in at 50% versus waiting until 20%? That's what I'm after here and any info/insights will be helpful.

 

[SaratogaLefty]

Not really a disadvantage but its been my experience that the charging rate does drop off as your SOC increases above 50-60%.

 

[Tâm]

I had searched and did not find a question like mine. There are plenty of DC Fast Charging questions in this forum of course and while I appreciate the link you sent, it does not address my question (although I did now learn there is a disadvantage to regularly using a DC Fast Charger, so thanks for that).

My question is specifically around plugging (on a level 3 DC Fast Charger) when the battery is not yet close to 20%, for example it's 50-60%. Is there a disadvantage plugging in at 50% versus waiting until 20%? That's what I'm after here and any info/insights will be helpful.

A good read and graphs can be found at:

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

"Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine."

The depth of discharge between 50-60 is 10.

The depth of discharge between 20-60 is 40.

40 is worse than 10.

With the numbers you cited, if you do 20-80, that's the worst because that's the difference of 60!

 

[GMan]

A good read and graphs can be found at:

BU-808: How to Prolong Lithium-based Batteries

BU meta description needed...

batteryuniversity.com

"Similar to a mechanical device that wears out faster with heavy use, the depth of discharge (DoD) determines the cycle count of the battery. The smaller the discharge (low DoD), the longer the battery will last. If at all possible, avoid full discharges and charge the battery more often between uses. Partial discharge on Li-ion is fine."

The depth of discharge between 50-60 is 10.

The depth of discharge between 20-60 is 40.

40 is worse than 10.

So if I'm reading this right, it's actually better to regularly charge from 60-80% (depth of charge = 20), than waiting until the battery is at 20, and charging 20-80% (DoC = 60). Of course, I may have to charge more often at DoC = 20 but it sounds like the article is saying that's still better than charging less frequently at the larger DoC.

 

[Tâm]

So if I'm reading this right, it's actually better to regularly charge from 60-80% (depth of charge = 20), than waiting until the battery is at 20, and charging 20-80% (DoC = 60). Of course, I may have to charge more often at DoC = 20 but it sounds like the article is saying that's still better than charging less frequently at the larger DoC.

You got the idea.

I own a Tesla and it advises to plug in as much as possible. The benefit is shallower depth of charge.

If you monitor Tesla charging at home, you could see that it trickle-charges at a very shallow depth of charge. If I set the limit at 90% and it's done, it won't wait for the vampire loss to bring the battery down to 85% in order to trickle it back up again. It trickle-charges again repeatedly when it only goes down a fraction of a percent like 89.9% and brings it back up to 90%.

 

[Tâm]

So if I'm reading this right...

This is its chart:

Photo: Battery University

As you can see the top light orange line is best when charged/discharged for the 75-65% range: It retains more than 90% charge after more than 8,000 cycles.

The worst one is the black bottom line when charged/discharged for 100-25%: It could only retain about 75% after 4,500 cycles.

A good compromise would be the second-highest pink/purple line when charged/discharged for 75-45%: It retains almost 90% capacity after 6,000 cycles.

Nevertheless, the above is only educational in case you want to choose a best practice.

However, for practical purposes, I would not hesitate to use the worst practice if I had no choice in order to reach the closest charging station. It's only a difference between 4,000 and 8,000 cycles.

If I choose the worst practice and get only 4,000 cycles, let's say I use one whole full battery per day, that's 4,000 days or 10 years!

So enjoy your battery, and don't be overly concerned about it.

 

[Tâm]

From Lucid's manual on page 147:

"Preserving high voltage battery pack health
The most effective way to prolong the battery (when not driving) is to leave it plugged into a charging source. Setting the charge level to "Daily" usage helps preserve battery health.

CAUTION: When the vehicle is not in use for long periods of time, it's necessary to plug into a charging source and set the charge target to the minimum "Daily" value...

Battery pack life and performance are greatly improved by maintaining a healthy state of charge (generally between 40% and 80%)."

So according to Lucid, the practice in driving your car is 40-80%.

When it's in storage, plug in at the minimum "Daily" value, which I guess is 50%, the lowest you can set the limit to.

 

[Adnillien]

Below is the DE charging curve. You see that the charge rate continually drops when above 20% SOC. The Touring curve will be similar shape but lower due to the smaller battery. In your situation, I might try using 40% to 70% instead of 50% to 80%.

 

[borski]

My question is specifically around plugging (on a level 3 DC Fast Charger) when the battery is not yet close to 20%, for example it's 50-60%. Is there a disadvantage plugging in at 50% versus waiting until 20%? That's what I'm after here and any info/insights will be helpful.

Fair enough, and I totally apologize for misunderstanding your question!

 

[JJ_5]

This is its chart:

Photo: Battery University

As you can see the top light orange line is best when charged/discharged for the 75-65% range: It retains more than 90% charge after more than 8,000 cycles.

The worst one is the black bottom line when charged/discharged for 100-25%: It could only retain about 75% after 4,500 cycles.

A good compromise would be the second-highest pink/purple line when charged/discharged for 75-45%: It retains almost 90% capacity after 6,000 cycles.

Nevertheless, the above is only educational in case you want to choose a best practice.

However, for practical purposes, I would not hesitate to use the worst practice if I had no choice in order to reach the closest charging station. It's only a difference between 4,000 and 8,000 cycles.

If I choose the worst practice and get only 4,000 cycles, let's say I use one whole full battery per day, that's 4,000 days or 10 years!

So enjoy your battery, and don't be overly concerned about it.

Does this chart indicate that you get more cycles with a narrow 10% charge range, but you also get fewer total miles over the life of the battery?

 

[MHDave]

Does this chart indicate that you get more cycles with a narrow 10% charge range, but you also get fewer total miles over the life of the battery?

What the chart demonstrates is that your long term battery capacity (lifetime) depends on a combination of number of charges and the "strength" of the charge. It does not directly speak to how many miles you get on that battery, because your battery supplies power to the car for not only powering the wheels but many other things, and because so many other factors apply as to how much power will be spent on spinning those wheels. What it does directly answer is whether you should charge for a minimal number of deep charges, or a larger number of small cycles to keep the battery state of charge at a reasonably optimal level. You'll see opinions on whether that optimal range is between 20-80% or 30-70% or 40-60%. What the chart does not indicate is that internal (to the battery) "vampire" drain is substantially higher at high levels SoC.
Personally, if I weren't using the car every day, I'd set the charge target at 50% and leave it plugged in; for a long trip (>500 miles) I'd bring the SOC up to 80% the day before, then charge to 100%-ish before/while packing the car to leave, so that I'm spending that top level of the SoC immediately after unplugging. Then on the trip itself I'd plan for more frequent smaller charges, for the battery's benefit as well as my body's.

 

[Tâm]

Does this chart indicate that you get more cycles with a narrow 10% charge range, but you also get fewer total miles over the life of the battery?

Shorter drives are not as efficient as longer ones.

That means shallower charges can result in inefficient short drives and less miles.

However, more cycles such as the longevity of 8,000 vs 4,000 cycles will result in more miles.

Again, this is just an academic issue but not a practical one.

If I don’t have access to an electrical outlet at my apartment, the practical choice is no plug-in at home, enjoy your battery, and don't worry about it!

 

[GMan]

This is its chart:

Photo: Battery University

As you can see the top light orange line is best when charged/discharged for the 75-65% range: It retains more than 90% charge after more than 8,000 cycles.

The worst one is the black bottom line when charged/discharged for 100-25%: It could only retain about 75% after 4,500 cycles.

A good compromise would be the second-highest pink/purple line when charged/discharged for 75-45%: It retains almost 90% capacity after 6,000 cycles.

Nevertheless, the above is only educational in case you want to choose a best practice.

However, for practical purposes, I would not hesitate to use the worst practice if I had no choice in order to reach the closest charging station. It's only a difference between 4,000 and 8,000 cycles.

If I choose the worst practice and get only 4,000 cycles, let's say I use one whole full battery per day, that's 4,000 days or 10 years!

So enjoy your battery, and don't be overly concerned about it.

What's really interesting about this graph is the following:

What dominates longevity is actually:
First) The lowest max charge level, and then only after that factor
Second) the Depth of Charge (e.g. the range between low and high charge level)

We can see that the optimal lines (in order) are:
1) Any with a 75% max charge level (3 of them),
2) Followed by the one 85% level, and finally,
3) The three which charge to 100%

Now, within the top group (e.g. the 75% max), the best outcomes are then dominated by DoC, with
1) Yellow line has DoC = 10%
2) Purple line has DoC = 30% and finally,
3) Light Blue with DoC = 50%

This chart is highly insightful and thanks for sharing it. I know it's also in the link you provided along with a great deal of additional technical info. Thanks again!

 

[EVCar]

Just to add to my confusion, Mercedes officially recommends letting the SoC below 20% periodically to prolong the battery life.

 

[Tâm]

Just to add to my confusion, Mercedes officially recommends letting the SoC below 20% periodically to prolong the battery life.

It's done every 6 months, which leads me to suspect it's for the Battery Management System to calculate the capacity more accurately. I don't think it is about prolonging the longevity but it's about practicality: If the BMS is inaccurate, the car could be stranded.

 

[JJ_5]

What the chart demonstrates is that your long term battery capacity (lifetime) depends on a combination of number of charges and the "strength" of the charge. It does not directly speak to how many miles you get on that battery, because your battery supplies power to the car for not only powering the wheels but many other things, and because so many other factors apply as to how much power will be spent on spinning those wheels. What it does directly answer is whether you should charge for a minimal number of deep charges, or a larger number of small cycles to keep the battery state of charge at a reasonably optimal level. You'll see opinions on whether that optimal range is between 20-80% or 30-70% or 40-60%. What the chart does not indicate is that internal (to the battery) "vampire" drain is substantially higher at high levels SoC.
Personally, if I weren't using the car every day, I'd set the charge target at 50% and leave it plugged in; for a long trip (>500 miles) I'd bring the SOC up to 80% the day before, then charge to 100%-ish before/while packing the car to leave, so that I'm spending that top level of the SoC immediately after unplugging. Then on the trip itself I'd plan for more frequent smaller charges, for the battery's benefit as well as my body's.

I was just doing some quick and dirty math in my head, looking at the total number of cycles where there are approximately 8400 cycles (orange line) times multiplied by the depth of the cycle, 10% percent of capacity, in comparison to 4500 cycles (black line) multiplied by 75% percent of capacity. You make a good point about vampire drain. I also realize that the total kWh capacity in the battery with the deeper charges declines more quickly so that by 4000 cycles the black line shows about 79% retention while the orange line shows 94%. So the comparison isn't as simple as 8400*10 compared to 4500*75; 10% in the orange line isn't the same as 10% in the black line. But it still seems like you might be able to get more total kWh out of a battery with deeper charges. Does this make any sense? Am I misreading the chart?

 

[EVCar]

It's done every 6 months, which leads me to suspect it's for the Battery Management System to calculate the capacity more accurately. I don't think it is about prolonging the longevity but it's about practicality: If the BMS is inaccurate, the car could be stranded.

Thanks for the info.
I haven't had time to re-read the manual and kind of relatively uninformed about this subject .

 

[Tâm]

I was just doing some quick and dirty math in my head, looking at the total number of cycles where there are approximately 8400 cycles (orange line) times multiplied by the depth of the cycle, 10% percent of capacity, in comparison to 4500 cycles (black line) multiplied by 75% percent of capacity. You make a good point about vampire drain. I also realize that the total kWh capacity in the battery with the deeper charges declines more quickly so that by 4000 cycles the black line shows about 79% retention while the orange line shows 94%. So the comparison isn't as simple as 8400*10 compared to 4500*75; 10% in the orange line isn't the same as 10% in the black line. But it still seems like you might be able to get more total kWh out of a battery with deeper charges. Does this make any sense? Am I misreading the chart?

Now that you have done the maths, I stand corrected: I falsely assume that many shallower discharges would yield more kWh, miles...

However, those advantages come at the expense of longevity.

Let's compare the choice of orange line 75-65% discharge/recharge range or 10% a day to charge daily with

Waiting for it to fall down from 100% to 25% or 75% for 7.5 days (black line) before charging up instead of the above daily charging.

After 8,400 charges or days, the daily orange method would use 84,000% while

The other black line method only used only 1,120 charges because it takes 7.5 days to spend 75% or 10% per day or 1,120 charges x 7.5 days = 8,400 days. 1,120 cycles x 75% is also 84,000%.

The black line uses fewer charges: 1,120, but the degradation is below 90% capacity.

The orange line uses more charges: 8,400, but the degradation is down only to above 90% capacity.

For real-life situations, just enjoy your car even if there's definitely there's an academic difference.