What exactly happens when..

the battery is 100% and you're plugged in to the AC? does it use 1% of the battery and charge it up again at 100% or does it cut the battery usage and use full AC power?

 

It should stop charging the battery all together. Generally, though, you don't want to leave a lithium ion fully charged for long periods of time. You should store it at 40% to 50% charge.

 

@100% it bypasses the battery and runs from AC power.

 

As they mentioned, it cuts the power to the battery and runs from the AC power. A lot of people will actually remove the battery altogether if it is at 100% and you are going to be running off of AC power for an extended period. It seems to help the life of the battery,

 

I heard otherwise, I thought there was a trickle effect on these?

 

trickle effect was on the older generation of lithium ion batteries.

 

This is true, my old ASUS W1N laptop's battery only stores 2% charge now because I kept in the AC Charger at all times, the battery just simply died.

 

Ouch!

Note, it's not a memory effect like NiCds had, but an actual failing of the cells. With a good battery conditioner, you could work through a memory effect.

Heat kills lithium ion batteries.

 

Yup, and charging the laptop produces quite a bit of heat. My Macbook Pro only heats up when I'm charging it, and boy it gets hot. I can't feel the heat as much on the Alienware or P170HM, but that's because being a gaming laptop, it'll be plugged in for the most part and they need good airflow on them.

 

here is a good article on LION batteries.
How to Prolong Lithium-based Batteries - Battery University.

 

It's not the heat that kills Laptop Li-ion batteries. It's the trickle charging.
Bad charging circuits, and older laptops, keep trickle-charging their Li-Ion batteries while plugged and at 100% charge.
Trickle-charging causes plating on the electrodes inside the batteries, reducing their effectiveness and thus the maximum current and capacity.
As mentioned, newer laptops and/or batteries cut the charging when the battery is at 100%. The last generation of Clevos shouldn't have problems with trickle charging since they call their batteries "smart", which should indicate internal protection circuits.

Edit: Heat is also bad for batteries, but we're talking about 80c + applied to the battery.

 

Cool - learn something every day. Thanks for the info. I thought it was the heat that caused the wear. What you say makes sense, since the recommendation is to run the battery through larger charging/discharging cycles even if it's only to 40% or so. That avoids the tricke-charge effect then.

 

As there is no official confirmation if the battery has smart charging designed to avoid trickle charge (like higher end notebooks and lenovo notebooks, etc.) I remove the battery. Trickle charging will slowly reduce your battery's capacity over time.

The bigger deal for me is that storing your Lithium Ion battery at 100% for long periods of time is also harmful to it. I discharge mine to 55% and remove it at all times. I pop the battery in for a minute or two when I need to move it around and then take it out again.

 

and what is a "long period of time" 2 days? 1 month?


edit:

Besides common aging, a Li-ion battery can also fail because of undercharge. This occurs if a Li-ion pack is stored in a discharged condition. Self-discharge gradually lowers the voltage of the already discharged battery and the protection circuit cuts off between 2.20 and 2.90V/cell. Some chargers and battery analyzers (including those from Cadex) provide a wake-up feature, or “boost,” to re-energize and recharge these seemingly dead Li-ion batteries.


got it from the website which was posted. Does this mean that taking it out when discharged (55%) is bad?

edit 2: nevermind I found on the same site that for lithium-ion batteries that it is the best to get it out at 40%