I want to power a "suitcase boombox" amp using 4 Li-Ion 18650's. To charge these batteries I'm thinking TP4056, because they're small cheap and have nice charging features.
From what I have read so far that even at first glance having multiple TP4056's with their own DC-DC isolation seems weird, it's alledgedly not a bad way to mitigate some of the battery balancing downsides.
- Are there any pitfalls of this approach? Apart from DC-DC isolation (see next question)?
As discussed on the internet and here on EE, to charge the batteries using multiple TP4056's, one needs isolation. Commonly mentioned is the isolated 0505S DC-DC converter. Big downside is that it's only rated for 1W. To get most out of the charging process you'd want more like 5W.
I'm not finding any cheap/small/simple DC-DC buck converters, but I do see some AC/DC 220VAC>5VDC converters that claim to have isolation, such as this one: https://www.aliexpress.com/item/AC-DC-5V-700mA-3-5W-Power-Supply-Buck-Converter-Step-Down-Module-for-Arduino/32451069599.html (or will this burn down the house?)
- Do these AC-DC converters provide the required isolation (or how to tell?)