Battery with AC outlet charges laptops


Hm, what’s the most efficient way of converting DC to AC? It’s been a long time, but I seem to remember every method had a lot of loss. Or has the internet solved that problem?

1 Like

When will the Internet learn that x,000 mAH is the same as x AH?


The standard way is to make a switching power supply whose output is either +150V, 0V or -150VDC, then alternate between those 60 times a second in the sequence 0 + 0 - 0 +… to make something that appears to be a 60 Hz sine wave. In reality, it’s only three voltage levels.

Considering the battery itself is DC and the laptop requires DC, yes, skipping the inversion to AC (at the 120V household outlet) and then back to DC (at the laptop’s power adapter) would be most efficient.

If only such a solution existed…
Oh wait:


There are a zillion Anker-like solutions out there (many of them are actually rebadged Ankers). For DC connections, yes, the Anker seems a great solution. But the item under discussion here also has an AC outlet, which is what makes it interesting.

1 Like

I don’t know how many different laptop power connector types there are on all the laptops sold today, but it’s probably in the dozens. It’s really a shame that the laptop industry hasn’t standardized on a power connector, as the Android phone industry has done with Micro USB. This product would be a lot more efficient (nearly 100%) if so.


The solution is at hand in USB 3.1, which allows for, IIRC, 100Watts. If we can just get everyone to agree to the Type-C (reversible) connector, a lot of cable woes are going to fall by the wayside in one swell foop.

1 Like

I just spent way too much time trying to find out anything technical about that USB 3.1 spec with its Type C plugs.

The 100W is available only in USB PD mode (power delivery) in which the 5V power cable pair is jacked up from 5V to 20V, and run at 5 amps (which makes more ohmic voltage drop, but at 20V, who cares.)

See page 30.

If you can get 20V from USB, then all laptops could run that 20V as is to their battery charging circuits!

USB 3.1 spec is 41 megabytes. Just the power delivery spec is 534 pages. This stuff is not for the faint of heart.


True that. Even something as simple as 5.5/2.1mm barrel jack would do the job well. I standardize on that one, including modding some equipment (or making an adapter; my Thinkpad power supply got such connector added inline, so I can use it for the netbook too, or for feeding a Li-ion battery charger (with hacked-in switchable diode drop, so the box does not complain that it is getting more than 18 volts).

The more mix-and-match we can do with our toys, the better. And the fewer boxes we have to haul around.

1 Like

I don’t see why the government doesn’t standardize a single small DC wall socket. They do for AC. Sure I’d need an adapter from it to my laptop, but I’d much prefer having the DC power supply in the wall than carrying it around with me.

Instead we have dozens and dozens of DC ports from a cigar lighter sockets to SAE connectors to XLR connectors.

I mean, almost every single one of my devices that plugs into the wall runs on DC. USB plugs in wall might be great, but they’ll never power my television.

Do they now.

For which the suggested use is a laptop AC to DC adapter.

When your 1 Gb drive can store more and yet less than a billion bits.

The underlying problem is that the plebs has little knowledge of the tech, despite the astounding ability to keep up to date on celebrity gossips and telenovels.

In that setting, thousands of milliwhatevers look optically as more than just whatevers without the zeroes.

It’s not that nobody knows they’re the same, it’s that plenty of things are measured in sub-AH fractions. Sure, it’s easy enough to see that 12500 mAH is a larger number than 12 AH, but keeping the unit scale consistent makes it even easier. Similar reason one doesn’t express a person’s height as “1m, 8dm, 7cm” or “18,700,000,000 Å.”

My height is measured as 5’11". So there.

The bigger problem is that they don’t specify the voltage of the battery, so an amp-hour rating is making a big assumption. It would make more sense for these things to use a series stack of batteries for better conversion efficiency, but then the same mAH rating would mean several times the total energy available, so it gets messy.

Watt-hours is the best unit for this product. Good luck getting that used! (Actually, W-H is the TSA’s guideline for allowing it on board an airplane, so there’s hope.)

Look man, just because you’re a midget doesn’t mean you need to get all defensive.


Feel free to buy this, but don’t expect it to live up to its promise of capacity. It appears to be about 50% short of promised capacity when charging a Macbook Pro. Yes, some loss is expected from DC-AC-DC conversion, but both sizes of this battery pack were sold with the promise of fully charging a Macbook Pro; even the large battery is unable to do so.

1 Like

Given that most batteries these days are in the amp-hour range, the best “consistent scale” values would be in the format like 0.85 Ah, 1.2 Ah, 12.5 Ah…

The 0.025 Ah batteries for pocked quadcopters could maybe deserve milliamp-hours but can do without, too.