How do Li-ion batteries wear?

Just trying to maximize the useful life of my battery. A few questions came up..

Is battery wear only determined by total charge or discharge time?

Is there any difference between
1) discharging to 50% then charging to 100%
2) discharging to 75% then charging to 100% two times?

Are there any problems draining the battery to low power levels (~5%)?

Is it okay to leave the battery in at all times, even while plugged in and at 100%?

Anything else? Thanks everyone.

 

Here you go.

How to Prolong Lithium-based Batteries - Battery University

 

Good info in that link, but take it with a grain of salt. Laptops don't lose 20% a year if left in the laptop fully charged. Source: dozens of laptops I've owned over the years.

 

THey can under the right circumstances. My Inspiron 1720 started with a battery life around 4-5 hours. Now, fully charged and on powersaver, I can't get more then 45 minutes out of it. I've had the laptop for only 3 years. Basically, the heat and ALWAYS being charged kills Li-Ion batteries faster then anything.

 

It can, but after three years, the power will dissipate significantly after 3 years whether you use it or not. But I've had many laptops that are plugged in 90% of the time at full charge that only lost a few % in the first year. Heck I have two netbooks for over a year now my kids are using and plugged in most of the time, and shows 8% wear, and started with like 3-4% wear.

A lot of it depends on the design of the laptop and battery and battery charging algorithm. If it's getting high heat, then it's a bad design. But that kind of wear is NOT the norm.

 

I will agree with you there - battery bay and cooling system design REALLY come into play. And they will lose charge over time anyhow. But, it is possible. Rare, but possible. You make good points, though.

 

Thanks for the link Tinerbox.

It seems like the biggest avoidable problem with my use is that I constantly have my battery at 100% while plugged in. Whether or not that results in significantly increased wear rates, it still seems to be an avoidable factor.

My laptop automatically stops charging when it reaches 100%. Is it possible to change this? I'm thinking around 70% would be a good compromise. Most of the time I only leave my battery in for security against power interruptions, so the reduced runtime wouldn't be a big issue, and I could always resume charging if I know I'll need more soon.

 

I would use the laptop the way it's meant to be used (in other words, however it's convenient to do so) and just buy a new battery when mine no longer lasts as long as I need it to. $50-$100 for a new one isn't a lot in the grand scheme of things.

 

Li ion batteries like small charges all the time. Don't fully discharge and you'll be good

 

Don't fully discharge, but Li-Ion batteries also have a finite amount of charge cycles so if you are not going to use for a long period, read a couple months or more, then put it in cold storage. Otherwise, just leave it in the laptop. I do remove mine when i'm going to plug the laptop and leave it stationary for the day and put it back in when after shutting down the laptop.

 

i understand what you are saying, but i can't be bothered. My laptop will last probably 2 years tops before the next one comes, so in my case i can't be bothered lol

 

Well, we can only give advice. Whether you find it applies to you or not or you simply choose to ignore it is up to you. Given how often i change laptops, i don't bother with long term battery storage. Others do though, it is the same as removing the battery, some do it, some don't. I do it out of habit and also because like i said my laptop is plugged in so often that i prefer not having it inside, besides it sits right between my two fans so it could heat up a bit.

 

see if you all buy thinkpad T-series laptops then you could use the Power Manager that comes with the laptop to preset thresholds for charge and discharge of the battery. I have mine set to start charging when at 50% and stop at 95%, and my laptop is almost always plugged in.

to keep battery charged at 100% all the time is worst than having the cycle count increase. I wasn't using power manager in the first 2.5 years or so (though it only loads my system up) and my first battery died shortly after (could not hold for 5 min, lol) with very few cycles (like 40 or so). Now I have 3 other laptops here (well I just sold one so two actually) that are used somewhat for 3 years on and off, and all have their batteries charge to 100% of their design (and even a bit more), with low cycle count - one with about 100, and other two with about 35, and all three batteries are good. But power manager was running on those since the beginning.

I think for the last week to 10 days my battery dropped charge from 55% to 51% right now.