Rechargeable Battery Do’s and Don’ts

Tips and charging suggestions for  Lead acid, nickel-based, NiCd, NiMH, Lithium-ion batteries.

Apple Notebook battery maintenance and energy consumption

Laptop battery health tips:

Nominally, LiIon and LiPo packs should be completely drained, and then recharged without using the machine until fully charged, once every 6 to 8 weeks.  This ensures the best possible longevity for the individual cells of the pack.  Not using the machine after a full drain, until it is full charged, is important.  It is because of how the machine is running from battery constantly; by not running it, the cells are given a smooth, constant recharge current, instead of being interrupted every few minutes as each circuit is engaged for use.


When you get the “Help! I’m running on emergency reserves!” alert, you have 2 to 5 minutes to save everything and shut down cleanly.  Say you have a 2010 15in MBP. The pack houses two circuits of 1.2V cells. Each circuit is capable of supplying up to 120 watts of current. The MagSafe for that model only supplies 85W max.  Every few minutes, the controller switches the active circuit over so that the cells being topped up become the active source. It’s like a see-saw.  With each swing, each circuit gets a progressively higher level of charge, until both reach maximum.

Expected life-span of any lithium-based battery pack in a modern laptop, provided regular full charge cycling is done, is three years.    Because most users never cycle their battery-pack properly, the actual average life of a LiPo pack is sixteen months.  Machines which are left on mains supply (AC power) adapter  almost permanently end up having the shortest life-span of all.

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