I virtually never use the battery (System Battery: Built-in 77.5-watt-hour lithium-polymer) in my April 2010 15" MacBook Pro, so I've always followed (what apparently used to be) Apple's instructions to run it down once a month.

I just went looking to see what Apple's current take on the matter is, and I couldn't find a single doc that deals with it.

If there is such a doc, will somebody please point me to it, and if not, will somebody please fill me in on how to best care for my battery?

(I also looked at Battery University, but I couldn't find anything pertinent.)

Thanks.

Did you see this article from Battery University?
Or this Apple web page with links to

• Why Lithium Ion
• Maximizing battery Performance
• Servcie and Recycling your Battery
• Need To Power Your Accessories

Nowhere could I find a current mention,much less a recommendation, of periodic deep discharge/recharging cycles but everywhere there are precautions about the effect of excessive heat on charging Lithium Ion batteries, and in another context (motor home "house" batteries) I found Lithium Ion batteries will not take a charge at temperatures less than 32°F.

I started to write "I assume" but since everyone knows what happens when you assume I am rewording to say, "This leads me to surmise the old practice of periodically deep discharging and recharging batteries applies to NiCad and NiMh batteries but is no longer considered necessary for the current generation Lithium Ion batteries." Of course that is only what I surmise.

(Did I weasel word that enough? )

You did a pretty good job with the tools at hand!

Note: lithium-polymer and lithium-ion batteries are the same thing.

I went through every one of your linked docs and more before I posted, and you're correct that current batteries no longer require the deep discharge of recalibration.

But the topic of how to treat a battery that's virtually never used, which used to be prominently placed, is now absent (while at the same time the topic of long term storage, which is similar in nature, has been greatly expanded).

Even if "Apple wisdom" is that everybody who owns a portable Mac uses its battery on a daily basis, some guidance is still in order for those of us who aren't that wise (Yes, Apple, there are some! ): full discharge? partial discharge? how deep? how often?

In today's world, all roads lead to Cupertino, so I guess I'll head there later today. (Forgot about AppleCare. )

Lithium battery chemistry is fiddly and kind of temperamental. The advice I've seen for Li-Ion and LiPo batteries is that discharging or charging the battery all the way damages it, and this damage is cumulative. I know that most manufacturers ship and store batteries at about a 40-50% charge, which is the point at which the chemistry is most stable. With LiPo batteries, a fully charged battery will lose some percentage of its storage ability for each month it's left completely charged.

COMPLETELY discharging most any kind of rechargeable battery is very harmful, and often can chemically damage or brick the cells. (this includes all but marine "deep discharge rated" trolling lead acid batteries) But this doesn't refer to discharging it to where the battery is "dead", this is beyond that point. Modern battery packs don't allow you to dig that far down. Think of a battery's capacity as being able to go 5 to 10% into the red. The onboard controller in the battery won't let the computer drag it below zero. At that point it will say you are at 0% and will pull the plug. It's also saving some of that remaining charge to run the controller so it can "talk" with the computer and the magsafe (all three have a conversation when plugged in, before ANY power can be moved around) This conversation cannot occur if the battery is COMPLETELY dead, so it's important it never reach 'true bottom'. Otherwise it's bricked, regardless of the cells' condition.

If you discharge a battery to 0%, and then let it sit several weeks to months, it risks full self discharge and bricking by the above problem. When it gets to a certain point, (-5%?) it will start hibernating. This means you plug in the battery and power adapter and the computer outright doesn't see any battery, because the controller isn't talking. It's hibernating. It will wake up briefly every 5 minutes or so to see if anyone is tapping it on the shoulder. If so, it then gets to talking, and the battery starts accepting a charge, recovering it from hibernation. This is why if you have a deeply discharged mac battery you just have to plug it in and wait. Although I've seen batteries take 5-10 minutes to start charging, I've also seen them take several hours, so I'm speculating that at some point it shifts into "deep" hibernation, possibly only waking every 6-12 hrs, in a last-ditch attempt to save the battery. Several times I've left a computer with an undetectable battery on power throughout the afternoon with no appreciable effect, and then left for the evening, and come in the next morning to a fully charged battery. Those engineers are a clever bunch.

So discharging until it shuts off is still (afaik) Apple's periodic battery maintenance policy.

That being said, battery technology has made significant progress in terms of capacity, usable cycles, and memory. The somewhat recent shift from an expected 300 cycles to an expected 1000 cycles still amazes me. (people complain about non-replaceable batteries don't seem to understand, the battery is probably going to outlive the computer) Memory effects have been dropping steadily with time as well. Look at NiCD, and then NiMH, and LiIO, how that progression has gone. LiPO have very little problem with memory now. It wouldn't really surprise me if Apple stopped recommending periodic cycling, because a combination of increased mobile use and decreased sensitivity to memory are making it a rare/minor issue.

Coincidentally, I just finished up with AppleCare, and after much digging and consulting with "an expert on the subject" the tech told me that the common wisdom remains to run down even a Li-io battery once a month if you don't use it otherwise, and he doesn't know why that's been taken down from Apple's website.

(Note that my old type battery ran completely down, i.e. my deuced Mac(hina) shut down, and I had to hit the power button after I plugged the MagSafe in, whereas my Li-io battery apparently retains a power reserve such that the black screen I see doesn't indicate a complete shut down, rather my dM restarts - from the chime - by itself when I plug the MagSafe in.)

Your info, saying both "discharging or charging the battery all the way damages it" and "a fully charged battery will lose some percentage of its storage ability for each month it's left completely charged" gives some direction, but isn't definitive. (After about 30 months, my battery has run through 39 run-down cycles and still takes a 94% charge, so I dunno.)

So my question remains technically remains unanswered.

Edit: Posted before I saw V1's post. (More later)

Thanks for another enlightening post!


As I reported, that's what the tech told me, but it's nowhere to be found on their website.

Edit: It should be noted that we're (I'm, anyhow) talking about maintenance of an almost never used battery.

It is not necessary to calibrate a Li-ion battery.

Bingo! This comment just sparked my memory. With NiCad batteries it was necessary to periodically fully discharge them to prevent a chemical "memory" that would eventually only allow the battery to discharge to a certain level. NiMH batteries did not have to be deep discharged so often but in their case it was not a "chemical" memory rather it was to "recalibrate" the electronics in the battery that controlled the charging and depth of discharge. In fact that was what the process was referred to in the documentation Li-Ion batteries do not have a "chemical" memory and, as you said, do not need to be re-calibrated.

In spite of their higher cost the lighter weight and much higher energy density of Li-Ion batteries are causing them to be used more and more used in high end solar power installations and as "house" batteries in RVs. Periodic deep discharge cycles are specifically NOT recommended in those applications because it reduces Li-Ion battery life. In fact expensive controllers are used to prevent discharging below a given point to prevent permanently damaging the batteries.

Maybe that is why the periodic deep discharge cycling recommendation has been removed from Apple's web site.

Another "Bingo!"?

I wonder if Apple has perhaps thrown out the baby with the bath water, taking down the instructions for now potentially dangerous to your battery's health recalibration and, in the process, forgetting that it's a healthy thing to do for a little-used battery?

In view of the input I've gotten from the AppleCare tech (who, as opposed to some of his compatriots, was particularly knowledgeable), V1, and you, and factoring in the fact that I've been discharging my deuced Mac(hina)'s battery 'til "shutdown" monthly for three years with no observed ill effects, I'm going to assume that the lack of guidance for users in my situation is an oversight on Apple's part and continue discharging.

Thanks to all for the assistance.

If you are comfortable with your decision that is fine — the swollen battery issue caused by keeping MacBooks always plugged in seems to have been solved — (were those Li-Ion or NiMh batteries?) — so your routine is unlikely to do any harm. But you might want to explore this further. Given the literally tens of millions of Li-Ion batteries Apple has out there between the various PowerBooks, iPods, iPhones, iPads, and now wireless keyboards, magic mice, and wireless trackpads it seems unlikely they would overlook anything important in prolonging the battery life in all those devices.

I dunno!

It's possible that Apple operates on the assumption that their devices are being used as "expected", so my situation may very well have flown beneath the radar. (I once read that they "expect" laptop users to work their batteries "n" hours/day, and if so, I imagine that it's a fair guess that the same goes for their other devices...that, compounded by their well known hubris.)


"Partial discharge" is the key there, because it doesn't address the possibility of zero discharge.

Edit: Also, note that it only says "does not need periodic full discharge cycles", not that they should be avoided, as I'd expect if they're dangerous.

Bottom line, then... After considering all the input I've gotten both here and from AppleCare I'm going to stick with once a month "full" discharges for a reason that seems to me to make sense: I've got about 5 months left on my AppleCare, so if the 39 "full" discharges I've done so far have damaged my battery (which doesn't appear to be the case) I'm best off continuing and hoping it tanks while I'm still covered. And if it still doesn't show any damage after 44 "full" discharges, why switch to not discharging it at all, which may actually damage it?

Edit: I'm going to keep tabs on this issue in the hope that the tech to whom I spoke escalates it and elicits an authoritative response.

slolerner,

Your branch of posts regarding an iPad battery has been detached from this topic and now appears as iOS Battery Question.

First, an update: since I last posted I've spoken to three AppleCare associates and a Genius, and all four have advised me that a monthly full run-down is proper care for a battery that never gets used otherwise.

Annd... THE PUNCH LINE: I was running my battery down on the 4th (four days before the expiration of my AppleCare) when it all of a sudden decided it wouldn't discharge past about 35%.

I charged and discharged it a coupl'a times, and when it became apparent that the condition was permanent I called AppleCare, opened a case, and took my deuced Mac(hina) on an excursion to the Genius Bar.

Well, it turns out that my Mac went "Vintage" at the end of February and Apple will no longer work on it; they sold me insurance on which they couldn't fully deliver!

My next step is to call customer service.

If anybody's got any experience or other input to pass along I'll be extremely grateful for it.

Thanks.

The MBP with the issue that I originally posted is under Applecate, but only if the friend I bought it for gets her act together and brings it in.

If it's in warranty and they can't fix it, you get an (equal or better) replacement. The End.

Call AppleCare and lean on them. I've seen this on several occasions and it always ends the same way. Customer either flat out gets a replacement computer or gets a serious credit toward a new one.

Call corporate. At first they may offer a refund on your AppleCare but what they did sounds a lot like fraud.

Thank you SOOO MUCH, V1!

I was hoping that you'd have an insight into my problem, and your response is (of course) what I dreamt about.

Yeah, I expect that an AppleCare refund will be first on their list, and it really WILL NOT be adequate.

But no, rather than having been defrauded; I think I just slipped into a crack.

I'll guess that it's most unusual for Apple refurbs to hit the market so long after their discontinuance and that my situation has just never been contemplated (Edit: or is unusual enough that dealing with it properly would be more cumbersome...perhaps even more costly than gambling).

Fingers crossed!

More later.

That is what my old cell phone battery used to do. Was wondering about that. Thanks.

never seen that happen. they can't just refund the price of your insurance to avoid paying out on it. that'd be all kinds of illegal.

(That's slolerner whom you quoted, not me.)

My first thought was a full refund of AppleCare, but I quickly realized that I'm entitled to a fully functional Mac.

If they can engineer a battery replacement, so it goes, but if not, a new computer is the only really acceptable answer; the very significant discount on a new Mac that you suggested doesn't really cut it.

I've heard the 'significant discount' is usually around $300.

Naaah! That's less than AppleCare costs when they sell it to you. (B&H really deep-discounts it...$275, I think I paid.)

They discount AppleCare? Good to know.

Right now, AppleCare for a 15" MBP is $349 from Apple and $299 from B&H.

I was shocked to discover that B&H was so much cheaper.

B&H is almost always the best place to buy mac accessories. I was quite surprised to find that out

That's because you don't live in NYC.

On the other hand, my daughter just told me about B&H's labor relations issues.

That's one way to keep prices low. :∞P

Well, what ultimately happened?

They took care of business as expected.

Yay!!

I run in to weird stuff like that from time to time. A few years back I bought a new (Canon PowerShot S3IS) digital camera... from DELL. *shrug* $260 instead of $399 iirc. No idea why. Did not care.

To the small extent that I look, it looks like B&H's prices have gone up since they were unionized.

LA Computer is the cheapest I've found.

Their price for AppleCare for your new MBP is now $199.00; I think it's gone up in the past coupl'a weeks?

I guess so. I paid $189.00. I thought I'd better get it right away in case it went up. It went up!! Still cheaper than anywhere else at this point.