Is charging past 80% really detrimental? 2013 S

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gringostar

Active member
Joined
Feb 17, 2015
Messages
28
Location
Santa Ana, CA
Hello

I have a 2013 S. Is it really detrimental to charge past 80% or is it just hog wash? I'd like to have more range. I do it sometimes of course. I live in Southern California near the beach.
 
gringostar said:
Hello

I have a 2013 S. Is it really detrimental to charge past 80% or is it just hog wash? I'd like to have more range. I do it sometimes of course. I live in Southern California near the beach.
Battery capacity is lost at high charge levels especially at high temperatures over time. Charge to 100% right before you drive the car is good practice, especially if it keeps your car out of very low charge levels.

What to avoid is charging to 100% and leaving the car parked for weeks. In summer.
 
You should also, when possible, avoid charging (and especially quick-charging) the car to 100% in hot weather, or whenever the battery itself is hot (7 or more temp bars on the gauge). So it isn't that you shouldn't charge to 100%, it's that you want to avoid leaving it sitting there, or charging that much when the battery is hot.
 
FWIW, thanks to https://www.chevybolt.org/threads/20-80.39572/, I found learned of a nice slide on page 8 of https://www.nrel.gov/docs/fy16osti/66708.pdf comparing degradation at 85% average SoC with 30% DoD vs. 55% average SoC with 90% DoD.
 
A battery ages. Depending on how you use it, it can age slower.

Very slow aging is possible if the SoC is set at 50% and the battery is placed at 45F temperatures. But that is not very practical so we try to avoid as much as we can, a high SoC at high battery temperature for extended times.

Want high SoC ? Try to avoid extended times and high battery temperatures
Want high battery temp ? Try to avoid extended times and high SoC
Want extended storage ? Shoot for 50% SoC and low battery temp
...
...

So is 100% SoC worse than 80%, all else being equal ? Yes
But if you want it, then minimize the damaging effects of duration and temperature. If you follow the advice above to only charge to 100% SoC for a short time and when the battery is not warm/hot (5 temp bars or less), then the damage is slight each time and you will still get decent life from the battery.

Conversely, the quick way to turn your battery to mush is to fast charge (thereby bringing the battery up to a high temperature), then charge to 100% SoC when you arrive home and leave the car in a hot garage. That ticks off all the boxes of how to accelerate battery aging.
 
LeftieBiker said:
You should also, when possible, avoid charging (and especially quick-charging) the car to 100% in hot weather, or whenever the battery itself is hot (7 or more temp bars on the gauge). So it isn't that you shouldn't charge to 100%, it's that you want to avoid leaving it sitting there, or charging that much when the battery is hot.

More a nit than a disagreement.

Quick charging is charging at higher than "1C". "C" is the ratio between the capacity and the current. "1C" is charging at the rate that will fill the battery in one hour. Or for the 24kWh LEAF, 24kW. Long before you get to 100%, the rate will drop below 1C, and while the car might be connected to a "quick charger" the car is no longer "quick charging". The most absurd case I've seen was someone with a "No charge to Charge" card charging a LEAF at 99%. Car was accepting about 1kW. The 120V cable would have been faster.


Quick charging heats the battery. Near full discharge, followed by a quick charge, then charge to 100% and store in a hot place for a long period of time, as Sage points out, does most of the bad things you can do to a battery for lifespan.

Charging to 100% just before departure when the battery is likely coolest is good practice. Store at lower SOC. Put vents in garage to keep it cooler.
 
WetEV said:
Quick charging is charging at higher than "1C". "C" is the ratio between the capacity and the current. "1C" is charging at the rate that will fill the battery in one hour.
By that definition I've never QC'd my 62kWh Leaf since every station I've been to was limited to 50 kW.
 
oxothuk said:
WetEV said:
Quick charging is charging at higher than "1C". "C" is the ratio between the capacity and the current. "1C" is charging at the rate that will fill the battery in one hour.
By that definition I've never QC'd my 62kWh Leaf since every station I've been to was limited to 50 kW.
Yep.

Warning, terms are somewhat loose, and vary with country. See also "fast charge", "ultra fast charge" and such. "Fast charging" a lead acid battery is much slower, and I'd expect even more confusion from solid state batteries.

In practical terms, 0.81C is close to 1C.


And "Quick Charge" is a Qualcomm trademark for power over USB that doesn't have anything to do with batteries.
 
Interesting chart, good find.

AC1775H.png
 
If I'm reading those charts correctly, the only real difference between them is the average SOC%. That's quite an amazing difference, especially since a 90% DOD is usually considered hard on the battery.
 
Wow - look at page 18 that shows the difference between letting the battery sit at 100 SOC% vs immediate driving, even after charging to 100%.

I think this is for PHEV but still, what a difference.
 
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