Charger for Legion Go S

I recently got a dock for my Legion Go S and I was wondering what chargers you guys have been using since I plan to keep on always connected to the dock and another close by. I know the charger that came with the handheld is 60w 20v. Does a charge have to be exactly 60w 20v or can one with a bit less power work but just charge slower? I don’t have much experience with handheld PCs so I don’t want to mess up the battery by using the wrong charger.