How to choose a compact power bank for your MacBook

1. Look only at batteries with USB-C

Apple laptops officially work with small external batteries only with USB-C ports. These are the 2015 MacBook and newer, the 2016 MacBook Pro and newer, and the 2018 MacBook Air.

Sometimes there are options on sale for earlier Apple laptops, which are charged using the magnetic ports MagSafe and MagSafe 2. But the company does not certify such: their use can ruin the charging port and the built-in battery.

Instead of a compact external battery, in this case, it is better to take a large model with full-fledged sockets. You can connect a standard power supply to this one to charge your MacBook. But such a solution will not fit into a small backpack or city bag.

Power Bank for MacBook: Look Only at USB-C Batteries

A portable battery with USB-C is suitable for charging new MacBooks. It can be connected to a laptop using the supplied Apple cable. At the same time, a standard power supply is suitable for quickly charging the battery itself.

Only USB-C supports a new power standard called Power Delivery. Without it, the external battery won't have enough power to charge any of the newer MacBooks.

2. Check support for the new power supply standard

Look for the Power Delivery mark on the box, device case, official specifications on the manufacturer's website, or in reviews.

Power Delivery is the new standard for USB power supply with increased power. It is needed to charge laptops and other productive devices.

Popular external batteries Xiaomi ZMI 10, Hiper MPX20000, Aukey PB-Y7, InterStep PB2018PD and others work with it.

Power Bank for MacBook: Check New Power Standard Support

Using Power Delivery, the device requests the required power from the external battery. It can be different, depending on the intensity of work. If he manages to give it back, the device will fully charge.

Power Delivery can handle amperage up to 5A, voltage up to 20V, and power up to 100W. The standard was launched in 2012, and in 2014 they decided to use it only with USB-C ports. In external batteries, the standard began to emerge after the release of the new MacBooks in 2015.

3. Understand the maximum power

Manufacturers indicate the maximum power on the box or case of external batteries.

Usually it is far from 100W - the maximum value that Power Delivery supports. For example, an external battery Aukey PB-Y7 via USB-C can deliver no more than 30 watts.

The 12-inch MacBook and the new MacBook Air draw 30W at maximum load, the 13-inch MacBook Pro needs 61W, and the 15-inch needs 87W.

This does not mean that a 30W external battery cannot be used with a MacBook Pro.

Power Bank for MacBook: Understand Maximum Power

If you connect the Aukey PB-Y7 to your MacBook Pro at rest or under light load, the laptop can recharge. If you load it to the fullest, it will simply discharge more slowly.

If you connect such an external battery to a discharged MacBook Pro and then load the latter hard, the laptop will shut down. But you can wait until the computer is charged to 20-30%, and only then load it.

4. Determine the real capacity of the battery

Most often, manufacturers of external batteries indicate their capacity in milliampere-hours. It is called charge and is calculated based on the standard voltage for the batteries inside the device - this is 3.7 V.

At a voltage of 3.7 V, the Xiaomi ZMI 10 has 20,000 mAh. But if you increase it to 5 V, like the iPhone power supply, the charge drops to 12,000 mAh. But at 7.2 V it will already be 10,000 mAh. The higher the voltage, the less the charge, therefore, it is impossible to draw conclusions about the capacity of the battery on this basis.

When we do not know the voltage with which the external battery will be used, to estimate the capacity it is better to take not the charge, but energy. It is measured in watt-hours and is usually indicated on the case or box: the Xiaomi ZMI 10 has 72 Wh, the Hiper MPX20000 has 74 Wh.

Powerbank for MacBook: Determine the real capacity of the battery

If the manufacturer has not indicated the capacity of the external battery in watt-hours, you can roughly estimate its approximate value.

Battery capacity in watt-hours = charge in milliampere-hours × voltage in volts / 1,000.

These values should be indicated in the specifications of the external battery in small print.

The result in watt-hours will not be accurate, since external batteries do not provide the stated voltage stably, and it decreases during discharge. Nevertheless, this figure will allow you to estimate how many percent from scratch it will be possible to charge the MacBook.

When evaluating the capacity of an external battery, its coefficient of performance (COP) should also be taken into account.

Some of the energy will be spent on heating and will be lost during transmission, so no more than 70-80% will reach the MacBook in the end: we multiply the watt-hours of the battery by 0.7-0.8.

MacBook Battery Capacity:

MacBook 12 ″ - 41.4 W ∙ h;
MacBook Air with Retina display - 50.3 W ∙ h;
MacBook Pro 13 ″ without Touch Bar - 54.5 W ∙ h;
MacBook Pro 13 ″ with Touch Bar - 58 Wh;
MacBook Pro 15 ″ - 83.6 Wh.

Considering the efficiency, a 74 Wh battery can deliver 51.8–59.2 Wh.

It will fully charge a fully charged 12-inch MacBook and MacBook Air with Retina display. The batteries of other laptops when connected to such a battery may not reach from 0 to 100%.

5. Evaluate the additional capabilities of the device

When choosing a portable power bank for your MacBook, also look at the number of additional ports that come in handy for charging your smartphone and other mobile devices.

For example, InterStep PB2018PD, in addition to the Power Delivery standard, also works with the fast charging standards for Samsung AFC, Huawei FCP and Quick Charge 3.0 smartphones. You can pay attention to it if you use devices that support one of these technologies.