storing battery

I primarily use my AAO plugged so I took the battery out.
Is it best to leave the battery fully charged or empty when not in use.

 

It's best to store it at 40% charge in the coolest place possible. That's what I know anyway.

 

coolest place? Put it in the fridge for some days and it may be dead because of ultra-low discharge. Keeping it in the machine is just fine. Yeah, you lose a little bit of lifetime opposed to handling it "with optimal care". But it's not worth the hazzle and you actually risk losing your battery if you don't know what you do. So, just keep it in place.

 

By "some days" you meant some decades. Lithium Ion battery looses about 2% charge every year at room temperature because of oxidation and electrical discharge. If the battery is charged at 40% and stored in freezer (provided that's no condensation), the battery will take 30 years to reach % and another 30 years to reach "ultra-low" discharge. Since the battery capacity loss and isn't linear, the less charge your battery has, the less % of energy it looses each year.

If i were you, i would just leave the battery in your laptop. It acts as a UPS incase the electricity went out. When you fully recharge and discharge your battery once every day( LIke i always do), expect to lose 25-30% battery capacity in the first year. Then an additional 25-50% in the next couple years.

 

I suggest you try that out, you may be up for a big surprise.

What I suggested

 

I do this all the time. I user 18650 and rcr123a li-ion batteries for flashlight.

 

The AAO seems to get hotter with the battery in place and on AC power.