How to charge my MacBook Air from an external battery
December 29, 2015 5:34 PM Subscribe
I bought an external battery (20800 mAh) for my oldish Macbook Air. But there is one thing I didn't think of: How do I plug my Macbook into an external battery that only has USB outputs?
Response by poster: Nooooo! Please don't say that! It's non-refundable.
posted by Triumphant Muzak at 6:23 PM on December 29, 2015
posted by Triumphant Muzak at 6:23 PM on December 29, 2015
USB power is not even close to being adequate to charge a laptop.
posted by ryanrs at 7:04 PM on December 29, 2015
posted by ryanrs at 7:04 PM on December 29, 2015
You do have a nice tool to charge a tablet or phone though.
posted by rockindata at 7:10 PM on December 29, 2015 [1 favorite]
posted by rockindata at 7:10 PM on December 29, 2015 [1 favorite]
I think newer Mac laptops can charge via USB-C (though the battery needs to supply enough amps or whatever - and non Apple USB batteries are not officially supported - but I've seen some reviews of people doing it), but older ones need a battery pack capable of DC output. They either come with, or you can buy separately, a cable to go from your laptop to the DC port.
posted by bluefly at 7:11 PM on December 29, 2015
posted by bluefly at 7:11 PM on December 29, 2015
USB power is not even close to being adequate to charge a laptop.
Not true. The latest Macbook with a USB-C connector can be charged by any USB external battery. Charging rate will be slow, but overnight it should do okay.
posted by JackFlash at 10:09 PM on December 29, 2015
Not true. The latest Macbook with a USB-C connector can be charged by any USB external battery. Charging rate will be slow, but overnight it should do okay.
posted by JackFlash at 10:09 PM on December 29, 2015
Yes, the most recent new model, called the MacBook, has a USB-C port that is used for charging but that's the only one so far. All the others, including all the current and previous MacBook Airs charge via their MagSafe connector.
So, if you can find an adaptor that say, takes 2 USB inputs and outputs via MagSafe then you might get maybe 25 watts if everything was working in your favour. This is based on the fact that Apple ships 12W USB chargers for iPads.
The Airs come with a 65 watt power supply though, so even that is a long way from what you would ideally have and you may not be able to get that much power if they are standard USB outputs, which are limited to 5W each I believe.
posted by mewsic at 10:17 PM on December 29, 2015
So, if you can find an adaptor that say, takes 2 USB inputs and outputs via MagSafe then you might get maybe 25 watts if everything was working in your favour. This is based on the fact that Apple ships 12W USB chargers for iPads.
The Airs come with a 65 watt power supply though, so even that is a long way from what you would ideally have and you may not be able to get that much power if they are standard USB outputs, which are limited to 5W each I believe.
posted by mewsic at 10:17 PM on December 29, 2015
These exist, and there have been others on kickstarter/elsewhere(which i cant find right now) but they're very expensive.
I've never, ever seen one that was less than $200 with the magsafe adapter. All the ones here are about $200 too.
What do you need a battery for? Just a backup in your bag, or to use the macbook stationary in a place for a long time where there's no outlets? You'd be WAY ahead spending 1/4 the cash, buying the cheapest car jump starter with an inverter built in(look for one that says "120v AC outlet") that your local sears/autozone/etc has. Should be like $50, and it'll run your macbook far longer than almost any of those battery packs.
Only buy one of those if this needs to fit in your backpack. They're actually sort of a ripoff, and that wont be solved until more laptops support USB-C charging.
posted by emptythought at 11:08 PM on December 29, 2015
I've never, ever seen one that was less than $200 with the magsafe adapter. All the ones here are about $200 too.
What do you need a battery for? Just a backup in your bag, or to use the macbook stationary in a place for a long time where there's no outlets? You'd be WAY ahead spending 1/4 the cash, buying the cheapest car jump starter with an inverter built in(look for one that says "120v AC outlet") that your local sears/autozone/etc has. Should be like $50, and it'll run your macbook far longer than almost any of those battery packs.
Only buy one of those if this needs to fit in your backpack. They're actually sort of a ripoff, and that wont be solved until more laptops support USB-C charging.
posted by emptythought at 11:08 PM on December 29, 2015
ExtremeTech summarizes this messy situation.
There are four USB specifications; USB 1.0, USB 2.0, USB 3.0, and USB 3.1
USB 1.0 can draw .5 amps
USB 2.0 can draw .5 amps
USB 3.0 can draw .9 amps
USB 3.1 can draw 1.5 or 3 amps (depending)
There are several specifications for USB connectors. The USB-C connector used with USB 3.1 is what is found on the current 12" MacBook. All previous MacBook Air computers use the old style standard USB-A connector.
Your old style MacBook Air draws on the order of 1.5 amps (according to the label on the power brick.) Old style USB-A connectors cannot provide that much power.
You cannot use an external battery pack with only USB ports, to charge a MacBook Air. Sorry for the bad news, but that isn't a possible tool for the job you want to do.
posted by blob at 8:42 AM on December 30, 2015
There are four USB specifications; USB 1.0, USB 2.0, USB 3.0, and USB 3.1
USB 1.0 can draw .5 amps
USB 2.0 can draw .5 amps
USB 3.0 can draw .9 amps
USB 3.1 can draw 1.5 or 3 amps (depending)
There are several specifications for USB connectors. The USB-C connector used with USB 3.1 is what is found on the current 12" MacBook. All previous MacBook Air computers use the old style standard USB-A connector.
Your old style MacBook Air draws on the order of 1.5 amps (according to the label on the power brick.) Old style USB-A connectors cannot provide that much power.
You cannot use an external battery pack with only USB ports, to charge a MacBook Air. Sorry for the bad news, but that isn't a possible tool for the job you want to do.
posted by blob at 8:42 AM on December 30, 2015
The chargers are probably so expensive because you're paying for Apples licensing fees on MagSafe or Lightning connectors.
posted by rhizome at 2:11 PM on December 30, 2015
posted by rhizome at 2:11 PM on December 30, 2015
Old style USB-A connectors cannot provide that much power.
Not exactly, you can plug a USB-A male connector into a Quick Charge supply (which is, technically, probably not actually USB-A standard). Quick Charge can supposedly do as much as 30 Watts, which is a lot better than the USB 2.0 standard. Some batteries support some variation on Quick Charge, but more like 16 Watts, not 30. It's still not enough power for a Macbook Air, the Macbook power supply can give 45 Watts.
USB3.1 can draw up to 100 Watts, which is why it can be used to charge laptops. It looks like there will be another generation of Quick Charge which will handle up to 60 Watts, probably happily using USB-A like the previous iteration did.
posted by BungaDunga at 5:49 PM on December 30, 2015
Not exactly, you can plug a USB-A male connector into a Quick Charge supply (which is, technically, probably not actually USB-A standard). Quick Charge can supposedly do as much as 30 Watts, which is a lot better than the USB 2.0 standard. Some batteries support some variation on Quick Charge, but more like 16 Watts, not 30. It's still not enough power for a Macbook Air, the Macbook power supply can give 45 Watts.
USB3.1 can draw up to 100 Watts, which is why it can be used to charge laptops. It looks like there will be another generation of Quick Charge which will handle up to 60 Watts, probably happily using USB-A like the previous iteration did.
posted by BungaDunga at 5:49 PM on December 30, 2015
Which is all well and true, but a MacBook Air cannot recharge itself with USB Quick Charge
posted by zachlipton at 12:47 AM on December 31, 2015
posted by zachlipton at 12:47 AM on December 31, 2015
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You don't. USB 2.0 isn't designed for high power uses. There are external battery packs for the MacBook Air; a simple search will show examples.
You need to return this product and get something suitable for your desired purpose.
posted by blob at 6:01 PM on December 29, 2015 [2 favorites]