AITRIP 6PCS 2A USB 18650 Lithium Li-ion Battery Charger Module Boost 3.7V to 5V 9V 12V Adjustable DC-DC Step Up Boost Module TP4056 DIY Kit Parts

It’s also fairly easy to install a gel pouch lithium ion battery into these things, and hook that up to charge from the 9V input. This has saved me an absolute ton of hassle, particularly since the kids love to play with these ones and aren’t great at switching them off. You’ll need something like this:https://a.co/d/01YoIgEu And one of these:https://a.co/d/0bqGOeXv And I found I need an LC filter (with a surprisingly meaty 2200uF capacitor) on the output of the battery module, since the sonicware inrush current was too high for the board itself. There is plenty of empty space inside so you can get a very chunky battery in there.