Lithium Battery Aging Degradation

[Anonymous]

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[jerryt]

This info isn't very scientific (measured/controlled) but I purchased 2 lithium batteries for my camera (I believe it was 2 1/2 years ago). One battery is dead. It shows "green" on the charger but won't operate the camera. I didn't use it so I guess it died from aging.

The other one is in use in my camera and is charged periodically. I only use the camera periodically (probably 50 to 75 pictures over a 3 month period). The last 2 charges have not lasted very long.

 

[dogman dan]

Cell phone batteries tend to last a max of two years. But they are not lifepo4.

How fresh a battery are you getting could be part of the problem with some of these bargain 18650 packs. The lower than spec capacity could be from a few years on the shelf. FWIW, after 14 months, my ping seems to still have as much capacity as ever. I should have it totally used up in three years at this rate. I heard a lot of people talking about lifepo4 having a 5 year shelf life at least. So as long as your cost per ride is ok over that length of time.....

A whole different story with a $30,0000 car battery pack. I at least, couldn't absorb that over just five years. But if fuel goes up to say 8 bucks, then everybody is paying that kind of money. But I'll still be on an ebike, or small e motorcycle.

 

[liveforphysics]

To store lithium batteries, charge them to nominal voltage and no higher, and throw them in the freezer. This retards ageing a lot.

If you aren't storing them, avoid making a full charge until just before riding. For example, if you are going to not ride for a week, just bring them up to nominal voltage and wait until before you are going to ride, then top them off.

Try to always keep your packs in as cool of enviroment as you can when not in use.

 

[swbluto]

We'd all benefit from learning the Arrhenius equation.

To the point, lower temperature means slower chemical reactions including the ones that cause "aging", so cool those suckers down! Also, the equation is exponential, so it's, like, important. Basically, during the cold winter months when you're not going to use the batts, place them in the unheated garage - if your "cold winter months" consist of half the year, you could potentially get close to doubling your battery's "calendar life". Also, I've heard around 40-50% is an optimal SOC for lithium, so the two combined should optimize calendar life during periods of storage. I should be "storing mine" in a cool place right now but I don't have a cold place available to me during the summer.

Also, from the above link,

A historically useful generalization supported by the Arrhenius equation is that, for many common chemical reactions at room temperature, the reaction rate doubles for every 10 degree Celsius increase in temperature.

So, conversely, every 10 degrees celsius (18 degrees fahrenheit) decrease leads to nearly halving of the aging rate.

(Anyways, my current method is to leave the battery in its discharged after the last ride and charge it up shortly before my next ride. I typically plan my trips, so I just start charging whenever I get to the point of the planning stage or know I'm going to be out. I'm also storing my batteries in the basement, where it's 68 degrees fahrenheit. Not ideal, but about the best I can achieve.)

 

[OneWayTraffic]

I've got over 3 years from my cell phone battery, and it's lost about 2/3 of it's capacity, but still works well within it's limits. As I understand it, Lithium won't suddenly die from aging, it's a slow gradual decrease in capacity. So if you buy an oversized battery, use it well, and after 2 or 3 years go on shorter trips, it may squeeze out more life.

Of course if you have a fixed commute, you're round trip battery will eventually become a oneway battery and then a halfway battery....