I was told to never let your battery run all the way to zero before you recharge.
Hi
Thomas - Lithium Ion battery technology is complicated and a number of contradictory comments have been made regarding charging schedules, discharge levels, storage, etc. - below is a listing that I put together a while back from a number of sources (much from
HERE).
Just to emphasize a few points: 1)
Charge holding - the reason in the last half dozen years or so that I replaced all of my old cordless woodworking tools w/ older battery technology w/ those using Li-Ion batteries; 2)
No memory effect - thus, partial discharges/recharges are fine; 3)
Cycles (see my post previously on cycles and battery health) - Apple's batteries can handle 500 - 1000 complete discharge cycles while maintaining 80% or so of their health (NOW - I've had a few duds, so do not trust those numbers w/o reservation); 4)
Needs computer for management - about once a month, a Li-Ion battery should be nearly completely discharged (I go down to 5%-10% charge left), then recharged to reset the battery monitoring technology for more accurate reporting on the battery's stats; and 5)
Prefers partial to deep discharge - as you state, discharging the battery completely should not be done - this will shorten and degrade the battery.
Now there are plenty of articles on battery management, if those interested want to do some googling - Apple has many KB articles - we've also had a LOT of threads in this forum on battery management (a number of which I've left posts). Hope this helps - Dave
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Lithium Ion Battery Technology
Pros
- Much higher energy density (i.e. lighter)
- Hold their charge (lose 5%/month vs. 20 NiMH)
- No memory effect (complete discharge not needed)
- Handles hundreds charge/discharge cycles
Cons
- Degrade as soon as made (not based on use)
- Sensitive to high temperatures
- Ruined if completely discharged
- Needs on-board computer for management
- Small chance of bursting into flames
Prefers partial to deep discharge - don’t go to zero DC
Age from start even if unused (manufacturing date!)
Avoid heat