Power Bank for a 2015 MacBook Air (MJVM2LL/A)

tibbi wrote:

Any idea if it's possible someone makes a power bank that the ac adapter can plug into?

There was one once upon a time - that provided 100V AC and plugged right into the "duckhead" connector on Apple modular power adapters. It was basically a battery with inverter, and had a setup where the modular AC connector went on the other end to plug into AC power to charge the battery. It was really strange looking and was discontinued at least a decade ago.

However, I looked it up and there are power banks that provide AC power. I guess they would be like a self contained battery/inverter combo. It's not going to be terribly efficient though with all the losses in converting AC to DC to charge it, then back to AC to power your adapter and charge/power your Mac. But some are pretty big. Here are a few:

https://www.ravpower.com/products/rp-pb054-pd-20000mah-80w-ac-portable-charger

https://www.amazon.com/Portable-Universal-31200mAh-External-Notebook/dp/B07S4DJTZG/

The main issue I see with these is that they charge through USB-micro-B or possibly USB-C, although I don't know what rate they charge at. If USB-C input works, then they could possibly be reasonably fast if they have it rigged to accept higher voltages with a high-output USB-C power source.

John Galt wrote:

👍 Nice find.

There is an allegedly new one for sale on a popular auction site.

I wouldn't buy anything that old (OK - discontinued maybe 2015?) with a lithium-ion battery that hasn't been regularly charged. Self-discharge would mostly likely kill it with deep discharge.

There are some newer ones that have an AC outlet, which would make them better suited for this sort of duty.

I've tried some oddball rigs before. I think one of those portable car jump starters with a 12V outlet might work to supply lots of 12V power before conversion to AC. I used mine to charge my phone with a 12V lighter adapter. Not sure if one might be a fuse or circuit breaker limited though for the outlet (they're really designed to work through battery clamps except for small 12V devices). I have a 100W rated inverter about the size of an iPhone, although the separate plug/cable itself is about half the size. I figured that I might use it to charge my Mac in a pinch from my car. The thing buzzed like crazy and I'm sure that the output isn't close to a pure sine wave.

Not that this is practical because of weight, but you'd be better off buying a deep cycle battery (marine, golf cart, industrial or etc.) and getting an inverter to convert (invert?) that battery's output to AC so the Apple charger be used. That's what I have as a backup for a piece of medical equipment I have. But that little device is life sustaining.

I've just never seen the advantage of carrying around a battery you have to keep charged to be able to augment the battery on a portable device you have to keep charged anyway.

y_p_w wrote:

tibbi wrote:

Any idea if it's possible someone makes a power bank that the ac adapter can plug into?

There was one once upon a time - that provided 100V AC and plugged right into the "duckhead" connector on Apple modular power adapters. It was basically a battery with inverter, and had a setup where the modular AC connector went on the other end to plug into AC power to charge the battery. It was really strange looking and was discontinued at least a decade ago.

OK - it was the Lenmar Chugplug.

That MacBook Air requires an ac power adapter.

About Mac power adapters - Apple Support:

45W MagSafe Power Adapter with MagSafe 2 style connector

• MacBook Air models introduced in 2012 through 2017

You can any MagSafe Power Adapter with a MagSafe 2 style connector though, such as the 60W one you're using.

I've built inverters, transformers, switching power supplies .... at least one of them all at one time or another.

Use the supplied charger. That's going to be the cheapest, most efficient and easiest to come by or replace.

Neither would I. A deep cycle marine battery as ku4hx suggests plus an inexpensive inverter would cost more or less the same, at the cost of some bulkiness and inconvenience.

The Chug Plug was nice and elegant. Not much capacity though. Its "up to" 3 or 4 hour endurance was probably optimistic even back then.

John Galt wrote:

Neither would I. A deep cycle marine battery as ku4hx suggests plus an inexpensive inverter would cost more or less the same, at the cost of some bulkiness and inconvenience.

The Chug Plug was nice and elegant. Not much capacity though. Its "up to" 3 or 4 hour endurance was probably optimistic even back then.

Some bulkiness? Have you seen what happens when a flooded lead-acid battery is tipped over? At least my portable jump starter used a sealed lead-aside battery. Heck - I remember using a Sony cordless phone from the 1990s that included a small sealed lead-acid battery. Not sure why that when most still used NiCad or even NiMH by that time. I don't think it's necessarily about cost, but there are practical considerations that mean that lead-acid batteries are not really all that practical. And have you seen the price of lead-acid batteries these days?

Are you saying I can't use any power bank at all with my laptop. That it only charges with the ac power adapter?

Yes.

👍 Nice find.

There is an allegedly new one for sale on a popular auction site.

I've just never seen the advantage of carrying around a battery you have to keep charged to be able to augment the battery on a portable device you have to keep charged anyway.

The marine / aviation batteries I have in mind are designed for sustained inverted flight and are non-spillable.