Minimum power (watts= volts x amps) wall charger.

Hi noelvh,

Thanks for posting. I understand you have a question about power adapters and charging your MacBook Air, and I have a resource that should provide an answer, titled Find the right power adapter and cable for your Mac notebook:

"You should use the appropriate wattage power adapter for your Mac notebook. You can use a compatible higher wattage power adapter without issue, but it won't make your computer charge faster or operate differently. If you use a power adapter that is lower in wattage than the adapter that came with your Mac, it won't provide enough power to your computer."

For your model of Mac, you'd need to make sure you're using a charger like the one below:

"Apple 30W USB-C Power Adapter and USB-C Charge Cable

• MacBook Air models introduced in 2018 or later"

I hope I've answered your question. Take care.

Nothing will damage it as long as everything used is of acceptable quality. Even using a 5W iPhone "cube" power adapter and a USB-A to USB-C cable should be fine. It will be painfully slow. It may not even be enough for net charging of the battery if the current usage is high enough. But it should be able to handle it without any damage to the battery or power management system.

Here's the battery information sheet for basically every battery powered device sold by Apple since 2010:

https://www.apple.com/legal/more-resources/docs/apple-product-information-sheet.pdf

The only description is "lithium-ion" although technically that could include lithium-polymer.

I've played around with my wife's 2019 MBA just out of basic boredom. I've tried all sorts of things starting with the 30W adapter that came with it. You can check System Report > Hardware > Power to see what it's currently coming up with for wattage. It won't say what the voltage is however. Obviously for USB-PD devices - those can communicate their power rating and I've seen it display "65" when that Lenovo 65W USB-C power adapter was connected. For a 5W USB-A power adapter, computer port, or USB power bank, those don't actually broadcast anything.

When I plug in to USB-A in I've seen anything from 2.5 to 12 listed in System Report > Hardware > Power. I've also tried the same adapter more than once and they might show up with different wattages, so maybe it's sampling them differently. 2.5 makes sense because a standard USB-A computer port is rated at 500 mA at 5V. I've tried my Mophie USB-C power bank with a 5V, 3A rating and it comes up as 15W which makes sense.