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Hi, Rita,

Calibrating your iBook's battery is an easy job...no big deal to do every month; calibrating your MBP's battery is, on the other hand, a pain in the butt procedure, but it should still be done several times a year. (If there's an optimal number that replaces several, I don't know what it is.)

As for running your iBook periodically, I know that computers can be stored for extended periods of time, but I have no idea if there's a limit. (Actually, Apple suggests that stored computers have their batteries run down to 50% beforehand, but I suspect that working it once a month will be a better life-extension procedure.)

V1's post is of no consequence to you, because portable Macs don't have PRAM batteries.

Hi, Rita,

Calibrating your iBook's battery is an easy job...no big deal to do every month; calibrating your MBP's battery is, on the other hand, a pain in the butt procedure, but it should still be done several times a year. (If there's an optimal number that replaces several, I don't know what it is.)

As for running your iBook periodically, I know that computers can be stored for extended periods of time, but I have no idea if there's a limit. (Actually, Apple suggests that stored computers have their batteries run down to 50% beforehand, but I suspect that working it once a month will be a better life-extension procedure.)

V1's post is of no consequence to you, because portable Macs don't have PRAM batteries.

V1's post is of no consequence to you, because portable Macs don't have PRAM batteries.

According to Mactracker no iBook ever had a backup (PRAM) battery. Instead they drew power from the main battery to retain the PRAM contents.

As for running your iBook periodically, I know that computers can be stored for extended periods of time, but I have no idea if there's a limit. (Actually, Apple suggests that stored computers have their batteries run down to 50% beforehand, but I suspect that working it once a month will be a better life-extension procedure.)

That's true of any device which has a lithium ion battery; Li Ion batteries (including lithium ion polymer, or "LiPo" batteries) always last lionger if they're discharged to 40-50% charge before storage.

Because of a quirk in the way lithium ion chemistry works, a fully charged lithium battery that is not used will permanently lose a certain percentage of its capacity each month. Lithium batteries really want to have the electrons keep moving. This applies to, for example, cell phone batteries, remote controlled toy batteries, BlueTooth headset batteries, (some) lithium power tool batteries, and anything else that uses a lithium power cell. (Some lithium power tool batteries--the larger, heavier ones--use a different kind of chemistry, lithium manganese oxide, that doesn't have this problem.)

Lithium ion batteries are also extraordinarily sensitive to heat. The permanent loss in capacity goes up very, very quickly as temperature increases. leaving devices like cell phones or cameras with rechargeable batteries in a hot car is a great way to wreck the batteries, as I discovered with my digital SLR camera.

Also I've read where you completely discharge it and then charge it back up. Today I read on the internet that draining it completely is known to ruin a battery! So much contradictory info. What'a gal to do?

Also I've read where you completely discharge it and then charge it back up. Today I read on the internet that draining it completely is known to ruin a battery! So much contradictory info. What'a gal to do?

...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.

There are several problems involved with information gleaned from the internet including:

1. There are a variety of batter types and within each type there are often multiple variations each with different requirements.
2. The specific battery type in your computer is often not easy to discover.
3. Much of the information available on the internet does not identify the battery type that it applies to apparently assuming all rechargable batteries are created equal. A bad assumption.
4. Much of the information available on the web is out of date and is undated making it difficult to even guess whether or not the recommendations are still valid.
5. Few users have either the time or the inclination to spen much, if any, time digging for the answers.

So what is a gal, or guy, to do?

1. First and foremost read the owners manual that comes with the computer. Hopefully that will provide the answer(s) you need straight from the horse's mouth — ie. Apple
2. Check HELP on the computer itself — although most of the information there is simply a copy of the contents of the printed Users Manual
3. Go to Apple Support and search the knowledge base but be sure you read the article(s) carefully to be sure you have found the one that specifically relates to your computer. If you are unsure what computer you have go to the Apple Menu > About this Mac > More info and verify the model there. By-the-way, you can get to the online support from there by clicking on "Support".
4. If all else fails look for answers on FineTunedMac

Draining a lithium battery completely destroys it instantly. That's not the same as draining it to the point where your computer says it is at 0% power and shuts down.

Lithium batteries contain tiny computers that monitor the battery and shut it off before it reaches complete discharge. So when your computer turns off, it isn't because you have completely drained the battery; it's because the battery has switched itself off with just enough charge left to avoid damaging it.

When Web sites talk about draining a lithium battery completely, they mean to 0% charge, which destroys it. When Apple talks about draining the battery completely, they mean down to the point where the battery switches itself off, which doesn't destroy it.

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.

Thank you. I did what you said and went to the support section via the About This Mac. Funny, in About this Mac it states I have an LCD display, and the manual it led me to says I have an LED display! Ha-ha! That's what I get for researching the heck out of stuff.

As with the "calibrate by draining the battery/draining a lithium battery destroys it," both of these are correct.

You have an LCD display. It's a flat screen display that uses a matrix of liquid crystals to produce color images.

It's also an LED display; the backlight that makes the display glow is an LED backlight, rather than the older florescent backlights that used more power and produced less even illumination. Technically, the full name of the type of display in your Mac is "LED-backlit LCD display."