Can I charge my Macbook 2015 from a 2A 5V usb wall charger?

Hello:

For anyone interested in the details of Macbook 12" charging via 5V USB, here some data points.

Using an Orico charger with 2.4A (nominal) "Supercharger" port, and IOGEAR USB-A to USB-C charge cable (3.3ft), I record a power draw of 2.60A with a voltage of 4.72V (voltage drops from nominal 5.00 due to the strong draw).

Meanwhile, the Macbook (Coconut Battery) reports a discharge of <10mAh (less than 0.2% of battery capacity) per minute at this current and voltage, thus essentially keeping the battery level charged, while the Macbook is in operation.

With the Macbook being folded shut (i.e., sleep mode), the Macbook reports a charge of 50mAh for 3 minutes of charge. Thus, a total charge would take approximately 300 minutes or 5 hours.

In summary, a 5V/2.4A (12W) charger can keep a Macbook 12" operating almost continuously, but without charging it. Once the Macbook is in sleep mode, the 12W charger is able to charge the notebook in about 5hrs.

What about lower current chargers or portable batteries? It appears the Macbook attempts to draw at least 1.5A from its power supply. When it negotiates the power draw with the supply unit, and the power supply unit cannot provide the 1.5A at minimum 4.4-4.5V voltage, The Macbook discontinues its power draw. I found none of my 3 (cheap) portable batteries able to supply the Macbook, whereas a portable charger was able to charge the Macbook at 4.55V with 1.5A current.

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The attached photos show power draw from my Orico charger.

Hello:

For anyone interested in the details of Macbook 12" charging via 5V USB, here some data points (revised). Please ignore my earlier post, as I re-measured many of my earlier data points.

1. Charge with an Orioco 5V/2.4A Charger

Using an Orico charger with 2.4A (nominal) "Supercharger" port, and IOGEAR USB-A to USB-C charge cable (3.3ft), I record a power draw of 2.60A with a voltage of 4.72V (voltage drops from nominal 5.00 due to the strong draw). Meanwhile, the Macbook (Coconut Battery) reports a slight charge while in operation (playing a B&W movie) amounting to 0.077mAh per second, equivalent to a full charge in 19+ hours. With the Macbook being folded shut (i.e., sleep mode) and at 70-80% battery capacity, the Macbook reports a charge of 0.36mAh per second. Thus, a total charge would take approximately 4 hours (likely a bit more, due to the current drop-off when the battery is almost full).

In summary, a 5V/2.4A (12W) charger can keep a Macbook 12" operating continuously, charging it at the same time in slightly less than one day. In sleep mode, the 12W charger is able to charge the notebook in about 4-5hrs.

2. Charge with an Apple 5V/2A Charger

When charged with a 10W Apple charger, the Macbook draws 1.8A at 4.61V in my set-up, and reports a charge of 0.23mAh per second of charge in sleep mode. Thus a total charge would take about 6.5 hours (likely more due to the current drop-off near full charge). When watching a B&W movie in full screen mode, the 10W charger still provides enough power to charge the Macbook at a rate of 0.054 mAh per second, equivalent to a full charge in 27 hours.

3. Other Charging Methods

What about lower current chargers or portable batteries? It appears the Macbook typically attempts to draw at least 1.5A from its power supply. When it negotiates the power draw with the supply unit, and the power supply unit cannot provide the 1.5A at minimum 4.4-4.5V voltage, The Macbook discontinues its power draw. I found none of my 3 (cheap) portable batteries able to supply the Macbook, whereas a portable charger was able to charge the Macbook at 4.55V with 1.5A current. To note, from an old iPod charger (5V/1A) the Macbook will draw 0.5A at 4.86V (my set up). Also to note, a small wall charger (Apple style) at close to max capacity will produce considerable heat.

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The attached photos show power draw from my Orico charger.

same question, im using the powerbank to charge my macbook 12" 2016 through USB C to USB A cable. power system report that is 15 watts. i have 2 more questions:

1/ Can the lower power supply harm my device? apple said it need 29 watts to be charged. but my powerbank output is only 15 watts.

2/ Now im using powerbank like an AC power adapter, plug in all the time to keep the battery life better and minimize the cycle count. is it ok?

This would be perfectly fine.

If you do something really heavy on your macbook the power bank might not be enough though and the macbook battery will discharge as well but still at a lower rate.

I try to minimize the gear I carry, but even an iPhone adapter would add some hours during a whole day by decreasing the discharge rate. But remember that the macbook will increase the backlight when it receives power so maybe you end up with +/- 0 if you don't adjust the brightness. A high quality cable that is as short as possible also helps.

You do not have what was in the box?

If you look at the math, you're substituting a 29 watt power supply with a 10 watt power supply. So, if you don't mind waiting 3 times longer for the charge, it would probably work.

So far thats the best I can get - "Probably" !

Just try it and see, then you can report back.

Note: the USB-C cable that ships with the MacBook is for power only, not data.