Which laptop power bank can be used with DC connectors?

There are some power banks charging laptops via USB Type C. How does it look if my laptop can only be charged via a DC barrel connector? A power bank with AC power plugs, as found in walls, will probably be extremely inefficient… After all, the power of the battery is brought to a higher voltage, and then converted from the laptop cable back to a lower voltage with high losses.

As far as I know, this is not because these holsteckerbuchsen or the charge control always need a certain voltage (17-20Volt)

USB - C needs a lot less.

Maximum it would be possible if you get a car battery, cigarette lighter and spannubgswandler. But how exactly that must be connected I do not know

Say everything, the link.

https://www.amazon.de/...B00XU9IR7G

The latest USB 3.x C charging techniques are a bit more complicated than they initially seem, because unlike regular USB, they work with multiple and sometimes variable charging voltages> 5.0 volts.

If you are interested in more about Quick Charge 4 and USB - PD:

https://www.teltarif.de/quick-charge-usb-pd-schnellladesysteme/news/76410.html

There are no fully compatible battery power banks, as they can still provide only 5.0 volts via USB.

For notebooks with a hollow plug - voltage supply, you must comply with the required rated voltage within a maximum of about 5% tolerance.

A power bank with AC power plug, as found in walls, will probably be extremely inefficient…

This can't be said so flatly, since it depends on it, with what efficiencies each of the DC / AC inverter and the original laptop - power supply work.

Both work with 90% efficiency, resulting in a total efficiency of 80%. If both converter circuits each only work with 80% WG, the total WG would actually only be 60%.

You must not forget in comparison to a normal USB power bank, however, that their internal battery voltage of about 3.6 to 3.7 volts must first be transformed to 5.0 volts high, which also only with a certain WG is working. In addition, USB 3.x according to the PC standard at 5.0 volts to max. 2000 mA limited.

There are now also specialized battery solutions (power banks) for notebooks with hollow plug voltage supply, which internally have several battery cells connected in series, thus keeping the conversion effort as low as possible. See, e.g. Here:

https://www.xtpower.de/DC-Powerbank-von-XTPower