I'm trying to Bild my own boombox with an 2*50W Bluetooth amplifier and 10 18650 cells with 3,4Ah each. I habe bought a tp4056 charging board. The question is if i use 10 betteries connected in parallel and connect the minus and plus to my tp4056 board if it would be able to charge the safely. Or do I need a balance charger?
You theoretically don't need anything, but there are drawbacks:
The charging will be 10 times slower compared to a single cell charged from a TP4056
A damaged cell will cause the others in the pack to drain and you'll never be able to charge or maintain the pack at full capacity.
A damaged cell will also cause even more slower charging.
So if you make sure all cells are good, you should be fine for a while.