Yesterday, by pure chance, I ended up reading an interview with a Li-Ion battery specialist. I was quite impressed (and scared) to hear that continuous full charge/discharege of the battery will ruin their life, and that is a best practice to plug it before it goes under 20% of the charge and unplug it when it reaches 80% charge.

I wanted to post a link to that source but in some way I cannot find it anymore. With google anyway I’ve found many trustable sources with suggestions on how to preserve the life of li-ion or li-ion polymer batteries. A short summary of their tips is listed below, I hope it can be of help to other people.

At the moment I am developing a small applet for Mac OSX that reminds me to connect and disconnect the battery when it reaches the proper level. I will upload it soon on github, if you are interested stay tuned.

Good practice in a nutshell

  • Optimal battery use is between 20% and 80%: aim to discharge to ~20% then charge to ~80%
  • Full discharges damage the battery: try to avoid discharging to below 10%
  • Keeping the battery at 100%, i.e. keeping it plugged in to the charger, damages the battery (through being at 100% and because it’s likely to be hotter when plugged in)
  • Humidity damages the battery: keep it dry
  • Heat damages the battery: keep as cool as possible at all times but above 0 degrees Celsius and avoid the fridge/freezer
  • Li-Ion batteries don’t have a memory: they don’t suffer from frequent small charges
  • To re-calibrate the fuel gauge of your battery (improve battery level reporting, not battery memory): fully discharge it approximately once a month, or once every 30-40 charges
  • It is better to charge the battery with the device turned off
  • If you need to store the battery without using it for a period of time, discharge to 40-50%

To remember to make a full discharge once a month Apple prepared a downloadable calendar event. Just open it in your favourite calendar application and it will set up a monthly reminder.

Hopefully these tips should help you to extend the longevity and the capacity of your li-ion batteries, on the other hand it seems pretty clear that these best practices are hard to follow.

####Sources

For additional informations have a look at the following links:


Update

The small program I promised above is ready. You can check the source code in its github repository or download it packaged as an app from here.

It’s just a status bar application for MacOSX 10.8+ that fires notifications to inform you when to plug or unplug the battery.


Update 2

Somebody made a sort of version with steroids of my app. IMHO it is quite expensive, but if you are interested, you can download it from the AppStore