Portable Power Bank That Provides 12 Volts DC

What is the intended purpose of the power bank? If you don't need 120VAC, just 12V, A much smaller option would be one of these:

https://www.amazon.com/dp/B0CH159X56/ref=sspa_dk_detail_1?ps...

This one uses DeWalt tool batteries but there are similar products for other brands as well.

It provides USB ports, a 12V 2.1A power jack and even a flashlight.

I use it with a DeWalt 12AH battery and it provides a stable 12V supply for electronics. It also charges smartphones and other devices via a USB port.

I have a collection of DeWalt tools and always have charged batteries available. I keep two of these adapters around and find them very handy.

If you do need A/C, and your wattage requirements aren't excessive, this adapter uses the same DeWalt tool batteries:

https://www.amazon.com/dp/B0CKSMFSVH/ref=sspa_dk_detail_6?ps...

The cost of both adapters plus a DeWalt battery is considerably less than a power bank.

While this unit does work to use the dewalt battery to power an inverter there is no protection to stop it from completely draining and keeping a load on the battery after drained. This causes the battery to go to an unreadable state with the Dewalt charger and will not charge the battery. So you must only use this for a short time or until the battery is drained and then remove it immediately so it doesn't overdrain your pricy battery. When you fail to do this the way to get your battery back from the dead (depending on how dead) is to jump-start it which is hard with those little pins just enough so it has enough charge that the charger will recognise the battery. This is, obviously, bad to do repeatedly to the battery so the only thing to do is to keep your eye on this device at all times to safeguard your investment in batteries.