...the apple website, they say you only have to calibrate the battery once. Which is it?
- Today I read on the internet that draining it completely is known to ruin a battery!
- I think I have a Lithium Polymer battery. Not sure how different that is from an ion battery.
In no particular order, and in addition to joemikeb's and tacit's comments I can add the following:
For maintenance purposes, there is no difference between Lithium-ion and Lithium-polymer batteries. You treat them the same way. This includes initial calibration and occasional subsequent recalibration: so there is no such thing as 'once' with these batteries.
The exceptions are built-in batteries: those don't require calibration (and, by inference
*) recalibration.
Periodic recalibration of 'eligible' batteries is recommended to reset the battery's internal circuitry's tracking of remaining charge, which over time can deviate from the actual number. The comment that built-in batteries don't require calibration and recalibration suggests that this deviation is not (much of) an issue here.
Draining a Lithium-based battery during normal use or calibration does NOT ruin it,
as long as you don't store it in that condition. Prolonged storage may cause a drained battery to lose the capability to hold any charge. On the opposite end of the charge scale, storing a battery at 100% charge may cause (only) partial loss of battery capacity, and hence battery life.
The critical question here is
how long a drained battery can be kept before it starts to deteriorate. As calibration entails holding a drained battery in that state for several hours before recharging, it's safe to say it'll take longer before problems arise. But since it's not clear
how much longer, I follow Apple's recommendation to charge such batteries ASAP.
If you do need to (re)calibrate, I find it helpful to run a WiFi utility that monitors WiFi access points in the vicinity. This literally sucks the juice out of your battery in a hurry, and makes sure the battery gets the required downtime after draining. But because of that downtime, I tend to run the recalibration overnight.
Some more useful links:
-
Apple - About Notebook Batteries-
Getting The Most Out Of Your Mac’s Battery – Part I*)
To be clear, I haven't found a single Apple suggestion that built-in batteries need re-calibration, only that they don't need (presumably initial) calibration. Likewise, it doesn't say anywhere that (re)calibration is detrimental to the battery. My guess is that it cannot hurt and may help.
