Can MacBook Pro 13" run on AC mode without charging the battery?

The MBP and battery are smart enough to not charge when it is fully charged.

True Bassist said:

The MBP and battery are smart enough to not charge when it is fully charged.

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Is there actually proof of this ? I have more than enough products which when are finished charging, will automatically stop charging and the charge light will turn off.

But I doubt this is true of the MB or MBP given the fact that when the computer is turned on, it is draining the battery regardless of what it's doing, so the battery is never truly full. Try filling the battery and then unplug it. Test to see how long it takes for that light to turn red again.. Probably not long at all.

Other 'proof' to contradict this is that the port and the entire side near the charger is always hot when it's plugged in. Unplug it, and see how much cooler it gets within no time at all. If there were no charge going through it, it wouldn't be as hot.

Doug

I found this on Apple's Support site.

It is dated Aug. 2008, so I couldn't say for sure if it applies to the unibodies. But if I had to guess, I can't imagine it being any different.

If the battery is removed from a MacBook or MacBook Pro, the computer will automatically reduce the processor speed. This prevents the computer from shutting down if it demands more power than the A/C adaptor alone can provide.

Additional Information
Important: It is strongly recommended that you do not use your MacBook or MacBook Pro while the battery is removed. Accidently bumping the A/C adaptor could disconnect power and shutdown the computer. Any information that was not saved on your computer would be lost.

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I believe that when the battery is charged, the electricity bypasses the battery and the MBP is effectively running off AC power.

For the vast majority of circumstances the MBP will run entirely off the AC power when the battery is charged. However if there is a situation where it simply cannot get the power it needs from AC alone, it will tap into the battery briefly to make up for it. This is why if the battery is removed from a Mac notebook with a removable battery, the processor speed is throttled back, to prevent a situation where too much power is being demanded that the AC alone cannot provide.

You underestimate how advanced the technology in these notebooks really is. It is more than smart enough to manage the charging (and not charging) of the battery. Leave the battery in and forget about it, just remember to calibrate it occasionally.

Doug b said:

...

Other 'proof' to contradict this is that the port and the entire side near the charger is always hot when it's plugged in. Unplug it, and see how much cooler it gets within no time at all. If there were no charge going through it, it wouldn't be as hot.

Doug

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Sorry, but if the adapter is plugged in, the computer would be running off AC and would get warm whether you had a battery in the machine or not.

bobtomay said:

Sorry, but if the adapter is plugged in, the computer would be running off AC and would get warm whether you had a battery in the machine or not.

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Yeah, of course. Not sure of why I even suggested there would be no heat emanating from that side even if there were no battery present. I'd still love to know for my own sake though, at what point (if at all) when the battery is fully charged, does it go into smart mode and just stop charging ?

My logic dictates that it can not do this really, because if the Macbook were running off of the battery, you'd cease to see the fully charged icon and would see the battery life diminish, right ?

Or is it really possible to have the Mac run off of only AC power, while the battery remains attached ? That would of course, be ideal. And very smart. I know that when charging batteries on a stand alone basis, the case is that once they're fully charged, a switch is done internally, causing the charge to cease so that the batteries don't over heat. Guess I'm just looking for some hard core proof that our MacBooks are capable of this.

Doug

All modern notebooks have intelligent charging. The battery is charged when on AC power, up until the battery is fully charged. At that point, the machine runs solely on AC power. I'm not sure who is spreading these misconceptions, but if the battery was always being charged, it would explode.

Thanks cwa107 - better explanation than I could give!! =p

True Bassist said:

Thanks cwa107 - better explanation than I could give!! =p

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It's unreal how bunk like this gets spread on the Internet. People will believe whatever they hear I guess.

Up next "The sky is actually green, it's just that humans see it as blue".

cwa107 said:

It's unreal how bunk like this gets spread on the Internet. People will believe whatever they hear I guess.

Up next "The sky is actually green, it's just that humans see it as blue".

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The reason I have always personally believed this about the MB battery is because on both my MacBook Pro's (Unibody and 2008 Aluminum) the only part of the casing which gets hot, and I mean hot, not just mildly warm is the area directly above the battery (on the uni) and the battery its self (on the Aluminum).

I'd say that leaves a bit of room for speculation. I could see if it was the entire body/casing which got warm, or even the part which holds the magsafe adapter since electricity is always flowing through there.

And I'm sorry man, but just 'saying so' isn't enough proof to me that what you say is indefinitely true. Sure, it makes sense and all, given the technology we're dealing with, but there are things which point to other possibilities. I'd still really love to see some documentation about this.

I'm not saying you're wrong, but I can't say you're 100% correct, either.

Doug

Edit:

That kind of reminds me of a dialog found in the movie Reservoir Dogs:

MR. PINK
So who's the rat this time? Mr.
Blue? Mr. Blonde? Joe? It's
Joe's show, he set this whole
thing up. Maybe he set it up to
set it up.

MR. WHITE
I don't buy it. Me and Joe go
back a long time. I can tell ya
straight up, Joe definitely didn't
have anything to do with this
bull S.

MR. PINK
Oh, you and Joe go back a long
time. I known Joe since I was a
kid. But me saying Joe definitely
couldn't have done it is
ridiculous. I can say I
definitely didn't do it, cause I
know what I did or didn't do. But
I can't definitely say that about
anybody else, 'cause I don't
definitely know. For all I know,
you're the rat.

MR. WHITE
For all I know, you're the rat.

MR. PINK
Now you're using your head. For
all we know, he's the rat.

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Let's put it this way - I have approximately 200 notebooks at the company I do support for. 90% of them are Dell, with a smattering of Lenovo and Acers thrown in. Granted, none of them are Apple.

The vast majority of them sit plugged in 24/7/365 as the users that have them do so because they are seen as a status symbol. I have never had a single batter faily outside of normal life expectancies. Not one in the 10 years I've worked there. Yes, I have had them fail within the first two years, but never one explosion (which is what would result of an overcharge condition), never one that didn't last at least 18 months.

I realize that these aren't Apple machines, but since Apple uses commodity hardware and batteries (evidenced by them suffering from the same Sony-related issues that the rest of the industry had a couple of years ago), I can't imagine that their charging circuits would be any different.

So, I can certainly understand if you wouldn't want to take my word for it, and I can't find anything out on Apple's site that says specifically reiterates what to me is a very obvious statement, but that's where the sentiment comes from. I would find it very hard to believe that this wouldn't be the case if Apple's opted to seal in their batteries.

With that said, I've never noticed my battery being warm when it's not being charged. So, if yours is, I'd imagine you've got a defective one.

cwa107 said:

Let's put it this way - I have approximately 200 notebooks at the company I do support for. 90% of them are Dell, with a smattering of Lenovo and Acers thrown in. Granted, none of them are Apple.

The vast majority of them sit plugged in 24/7/365 as the users that have them do so because they are seen as a status symbol. I have never had a single batter faily outside of normal life expectancies. Not one in the 10 years I've worked there. Yes, I have had them fail within the first two years, but never one explosion (which is what would result of an overcharge condition), never one that didn't last at least 18 months.

I realize that these aren't Apple machines, but since Apple uses commodity hardware and batteries (evidenced by them suffering from the same Sony-related issues that the rest of the industry had a couple of years ago), I can't imagine that their charging circuits would be any different.

So, I can certainly understand if you wouldn't want to take my word for it, and I can't find anything out on Apple's site that says specifically reiterates what to me is a very obvious statement, but that's where the sentiment comes from. I would find it very hard to believe that this wouldn't be the case if Apple's opted to seal in their batteries.

With that said, I've never noticed my battery being warm when it's not being charged. So, if yours is, I'd imagine you've got a defective one.

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I appreciate where you're coming from, and your sentiment is obviously warranted. I'm simply seeing this from my own perspective, that's all. Right now, the only thing that I can say, is that when picking up my unibody, there is a measurable difference in temperature when comparing the front side and back side, where the battery is (underneath of course).

The chances of my battery being faulty at this point I believe, is really small. I guess we'll have to agree to disagree, until the puddin' has been inspected and proven ? ;D I may actually attempt to contact Apple with this question at some point. I'm just so darned curious now !


Doug

The heat? Well... with the battery in, the system runs at 100%.. pull it out and it'll throttle back as a self-defense mechanism. The real heat down there is coming from the processor and GPU, which are right in that general location.

Historically, Li-on cells left in while the laptop is on AC have over time developed memory effect faster than laptop cells that were removed and set aside. The laptop makers know this, and because their sales team have recognised that when owners start noticing that a cell that used to take 5 hours to deplete, now only takes an hour to deplete, the owners either come back in and buy a new laptop, or buy a new cell. Ka-ching! Now we see why the laptop owners have such a disincentive to improve their product.

Previously, apple did have the decency to suggest that MBP owners remove their power cell for up to a month at a time if it was used on AC all the time and it was also important to prolong cell life, but with the current design, that is clearly impractical. Now they may have actually gone against the grain of the rest of the industry and actually done something effective to protect their laptop cells, but I'm a cynic and I think they are still hoping for people to come back in, and buy replacement cells about a year after their original purchase. What we need are some statistics from MBA owners on the life of their built in cells if we really want to be confident in how the unibody macs will fare.

If I was buying a unibody at the moment, I'd probably be looking to get the 3 year applecare as well, since then I'll already have paid for my replacement cells, and also anything else that wear out in the next three years. Apple's clever plan all along?

yes, it's all one big conspiracy...

I have had had my Unibody MBP for a year now and my use of the battery is probably one of the most intense you could find. I change between plugging-in to charge and running on battery so much each day because of University, out on business with clients, at home etc.

My battery capacity is still 100%.

There is no conspiracy =p

(trust me...I promise you that you can trust me)

True Bassist said:

I have had had my Unibody MBP for a year now and my use of the battery is probably one of the most intense you could find. I change between plugging-in to charge and running on battery so much each day because of University, out on business with clients, at home etc.

My battery capacity is still 100%.

There is no conspiracy =p

(trust me...I promise you that you can trust me)

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Actually, that type of activity sounds like the most ideal one for your use. But the point was aimed towards users such as myself whom keep their MacBooks plugged in on a constant basis, as a replacement more or less, for a desktop, and only occasionally take it with them for transport.

Previously, apple did have the decency to suggest that MBP owners remove their power cell for up to a month at a time if it was used on AC all the time and it was also important to prolong cell life, but with the current design, that is clearly impractical

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Yes, I do remember reading this from Apple at one point. So for all intents and purposes, I do agree with Cheesehole's sentiment.

Conspiracy ? No. Just business as usual is all.. Move along, nothing to see here !

Doug

Something we overlooked, something which tells the answer without the muss or fuss. Not sure of why I didn't notice this before.

So now I either have the choice of admitting that I'm simply a paranoid delusional, or that I'm wrong, period. Hmmmmmmm...... Man I hate these decisions !