Li-Ion batteries are practically everywhere. They are used for mobile phones, notebooks, even cars. But most people don’t really know about them and give out wrong hints on how to use and charge them. So here are two important facts about Li-Ion batteries you should know:
- The less the a Li-Ion battery cell is discharged, the more often you can charge it. Discharging 5% will allow you to charge it hundreds of thousands of times, while completely depleting it will drop the charging cycles to below 10 times. Luckily, most batteries will turn themselves off once discharged to 40%. Here is the thing about cheaper batteries promising to have more capacity than original batteries. Li-Ion cell’s power capacity is limited, so to increase the usable capacity, the manufacturer can either increase the battery size or allow deeper discharges. The second choice is a cheap way to buy “more” capacity by lowering charging cycles.
- A Li-Ion battery will go bad on its own. The only question is how fast. When a Li-Ion battery is fully charged, it’ll lose about 20% a year of its capacity when stored at 25°C, or 35% when stored at 40°C. Placing a fully charged cell in the fridge at 0°C will slow down aging to about 6%. A only 50% charged cell will only age for 2% a year at 0°C or 4% at 25°C. This is the reason why notebook batteries are always half-charged when shipped. Lower temperatures will slow down aging, but never cool them below -25°C, which will break the battery.
So the big question is how should one use their battery to get the most out of it. A lot of friends ask me this question, as most known battery hints are either for Ni-Cd or Ni-MH batteries and not for Li-Ion batteries. I usually tell them to charge when it is convenient and use when needed. The thing with Li-Ion is that charging cycles will drop when discharged deeply. But if you keep your batteries always full, they’ll age a lot faster. So when the best trade-off is to charge them fully and use them right afterwards and recharge when you know you’ll be using it again soon.