Power bank for laptop, adapter?

I have a Lenovo Yoga 530 with a power supply 65W / 20V / 3.25A. I would like to buy a power bank so that I can charge it in the university if the battery runs out.

1. Question: Is it worth using a power bank at all? I'm not yet in university and do not know how many plugs there are in the library / in the rooms etc.

2. Question: the laptop is charged via a DC connection, I would need an adapter to USB to find a power bank more easily: what should I watch out for when looking for such an adapter?

I wouldn't buy a laptop power bank, usually there are enough connections there, remember others have to charge their laptops too. But what could help a simple power strip then you have an extension and several people could connect their laptops.

There's no adapter for usb for the charging cable of your laptop and also no suitable USB power bank, because the laptop can't tell you what voltage it needs via the connection that it has.

there are special power banks that output the correct voltage: https://www.amazon.de/...B00YP823NA

But at the price it would then be more worthwhile in my opinion to operate the laptop in egg saving mode or to hang it here and there for a short time