Best Charging Habit

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Most of my daily drive is a 50 mile (round trip) commute. With keeping battery level between 20% and 80%, I’d have to plug in after 2 days. OR, I can charge to 90% and eke out 3 days. What’s better for battery life; charging more often, or charging above 80%? Or should I not worry about it (only really applies in cold weather months when range drops).


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hoo boy.... here we go.

Kia says to charge to 80%

There's more wear on the battery discharging deeper... so between the 2 proposed habits, are you discharging to the same level? 20%?

If so, there should be little difference in lifetime of the battery.

If it was me, I would charge every 2 days, since battery manufacturers (Kia does not manufacture batteries, it assembles them from packs from the manufacturer) tell you that lithium batteries will give more lifetime watt hours if you do not discharge as deeply and thus charge more often.

But many of the experts here will disagree.... but there is no "alien technology" in our batteries, they are the same as in your laptop, phone and all your other toys. Look to the experience and recommendations for those.

Greg
 
Greg Elmassian said:
hoo boy.... here we go.

Kia says to charge to 80%

There's more wear on the battery discharging deeper... so between the 2 proposed habits, are you discharging to the same level? 20%?

If so, there should be little difference in lifetime of the battery.

If it was me, I would charge every 2 days, since battery manufacturers (Kia does not manufacture batteries, it assembles them from packs from the manufacturer) tell you that lithium batteries will give more lifetime watt hours if you do not discharge as deeply and thus charge more often.

But many of the experts here will disagree.... but there is no "alien technology" in our batteries, they are the same as in your laptop, phone and all your other toys. Look to the experience and recommendations for those.

Greg
Click to expand...

Yep. Striving to not go below 20%.


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I would add that, with pandemic lockdowns when the car may not be driven for days or even weeks, it's best to keep the state of charge between 40% and 60% during those periods.

Sent from my Pixel 3a using Tapatalk
 
This can go on for pages and pages...

1. people confusing "long term storage" SOC levels with 2 days of non-use, even overnight
2. reading that keeping your battery between 60 an 80% (you pick the numbers) and never charge to 100%
3. people believing that charging to xx% "magically" equalizes all the batteries lifetimes, and all batteries will charge to exactly the same voltage "balancing"
4. some people believing that this or that battery pack is a unique formulation, or something else that makes these ordinary li-ion batteries act differently from the rest of the millions in use.

On and on...

The reality that charging beyond about 95% or so harms nothing because:
a. the charging rate is lowered above a certain SOC
b. your car never really lets you get to 100%, they play with numbers

and there's more.

This is my third EV in 6 years, it's about 1/2 year old. I charge to 100% when my range is not sufficient for the trips I take. My previous ones had less range and needed to be charged every night, and the range did not decrease (the actual miles on a charge) in the 3 year time period.

"battery charging angst" is really a waste of time, other failures are more common, in the battery itself and other systems.

Greg
 
Greg Elmassian said:
This can go on for pages and pages...

1. people confusing "long term storage" SOC levels with 2 days of non-use, even overnight
2. reading that keeping your battery between 60 an 80% (you pick the numbers) and never charge to 100%
3. people believing that charging to xx% "magically" equalizes all the batteries lifetimes, and all batteries will charge to exactly the same voltage "balancing"
4. some people believing that this or that battery pack is a unique formulation, or something else that makes these ordinary li-ion batteries act differently from the rest of the millions in use.

On and on...

The reality that charging beyond about 95% or so harms nothing because:
a. the charging rate is lowered above a certain SOC
b. your car never really lets you get to 100%, they play with numbers

and there's more.

This is my third EV in 6 years, it's about 1/2 year old. I charge to 100% when my range is not sufficient for the trips I take. My previous ones had less range and needed to be charged every night, and the range did not decrease (the actual miles on a charge) in the 3 year time period.

"battery charging angst" is really a waste of time, other failures are more common, in the battery itself and other systems.

Greg
Click to expand...
Well said!
 
If you are asking me, my recommendation was to 100% no matter what. (next to last paragraph in my post)

I have no "battery charging angst" :D
 
Jim Colwell said:
So if I happen to drive a bit farther and the battery is depleted to 14% I should then charge to 100% instead of 80%?
Click to expand...
No idea, but for me I'd just charge back up 80%. Then every 2000 miles or 2 month, I'd charge to 100% at least once. Kinda taking the manuals advice of monthly charging to 100% at least once.
 
The issue with trying to hold to the 80% max charging "rule" in this instance, is that it is more damaging to the battery with the deeper discharge than 100% charging. (starting at 100% is less percentage discharged for his commutes).

The biggest enemy of lithium ion batteries is the deep discharge. That wears out the battery much faster than anything else except outright abuse. It's on the Internet published by the people who make the liion cells... not the people who assemble them into packs (who have a different agenda), nor the car company who bolt the packs into the car (who have yet another agenda).

If you actually research about batteries, and get past all the "experts", and realize that the "Battery University" site is comparatively "Battery Kindergarten", and gain enough knowledge, you will find graphs from the companies who make the individual cells that show how much longer a pack can produce over a lifetime by being recharged when it is 50% down vs recharged when it is 80% down.

In the case here, the OP is running the battery down pretty low by necessity.... no way out of his deep discharge, therefore starting at a higher initial SOC will result in a "less deep discharge" and the battery will have a longer lifetime (watt hours produced).

Greg
 
Maybe I'm wrong here, but I suspect it also depends on HOW you're charging.

I only go to 100% with a Level-1 charging (110v, 1.4kw). After I got my car I discovered that the 220v dryer outlet in my leased duplex was wired for 110v. I only have one long drive a week (San Diego area to Los Angeles) and while there I typically do Level-1 at work and Level-2 at WholeFoods (VOLTA).

If I end up doing Level-3 (EvGo, Electrify America) I'll limit to 80%.
 
Remember that it's the "charger" in the car that limits current, end of charge, and watches battery temp.

It sounds reasonable that higher current chargers will heat the battery more and be "rougher" on the battery. How much? I'd like to see a scientific study. The fact that Kia says to limit DC charging may reflect this idea.

Greg
 
Greg Elmassian said:
The issue with trying to hold to the 80% max charging "rule" in this instance, is that it is more damaging to the battery with the deeper discharge than 100% charging. (starting at 100% is less percentage discharged for his commutes).

The biggest enemy of lithium ion batteries is the deep discharge. That wears out the battery much faster than anything else except outright abuse. It's on the Internet published by the people who make the liion cells... not the people who assemble them into packs (who have a different agenda), nor the car company who bolt the packs into the car (who have yet another agenda).

If you actually research about batteries, and get past all the "experts", and realize that the "Battery University" site is comparatively "Battery Kindergarten", and gain enough knowledge, you will find graphs from the companies who make the individual cells that show how much longer a pack can produce over a lifetime by being recharged when it is 50% down vs recharged when it is 80% down.

In the case here, the OP is running the battery down pretty low by necessity.... no way out of his deep discharge, therefore starting at a higher initial SOC will result in a "less deep discharge" and the battery will have a longer lifetime (watt hours produced).

Greg
Click to expand...
So Greg,
If I follow you correctly the most important aspect to reduce the number of times my commute deep discharges. If I charge to 80% and end commute at 14%
( using 66% of battery, 5x a week) I should charge to 100% so the 66% of use comes from 100% down to 34% and lessens how deeply the batteries are depleted?
Is this what you're suggesting or have I gone off the rails somewhere?
Oh and I'm a bit over 30K miles so far, with no discernible degradation in mileage.
thanks
Jim Colwell
 
Yes, it can be difficult, but you can see the lifetime watt-hours based on depth of discharge on the manufacturers site for any lithium ion/polymer battery.

The really salient point is that it is non-linear... 500 discharges to 50% is much more wearing than 1000 discharges to 25%... same total watt-hours produced, but much worse on battery life, that is the real point, it is a non-linear relationship.

Older style chemistries we not as negatively affected, in fact deep discharge would often cover up the sins of a poor charging system, but that is another discussion, not the same for lithium.

Back to our batteries, you can look at the curves on the manufacturers sites and make your determination of what % of charge is your "target limit". Most people draw the line at 50%, it's a variable thing, so the more "topped up" you keep the battery, the more lifetime watt hours. There is really no danger of "overcharging" our batteries, too many safeguards, and if you do some more reading, it seems the 100% indicated is really 90-95% of full charge.

My personal line is 50% is where I recharge, but I have lots of short trips, so it's very rare a single trip would take me to 50%. For people with commutes that eat like 30% per day, then you would have to choose between charging at 70% or 40%.... in that case I would charge when I hit 70%, but that's just me, have only been using lithium batteries for about 35 years in multiple applications ;)

Greg
 
I geeked out on this with some others in this thread some months ago.
I concluded 20%-80% would be my target (which is actually more like 15%-70% since there are a few kWh of unused reserve capacity.)

It really is splitting hairs. If the test study I found applies, my battery pack retains 80% capacity at several hundred K miles, likely longer than the life of the vehicle.
 
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