I don't know if this USB Charger will work for my personal project

First of all hello, I'm new in the arduino community so don't be bad with me ::slight_smile: , so the problem is that I'm planning to make a bluetooth speaker powered with a phone battery which is Li-Ion 3.7V and I'm looking for Li-Ion usb chargers for 3.7V and I found this but as I'm new in this, I don't know if this will work, or if it will make my battery die, so I'm so glad If you can help me :-[ The usb charger is this:

Li-Ion battery charger USB

Another thing is...In case this work how should I connect the battery, I mean for charging I know It will be B+ and B- but If I just want to use it to power the speakers I should solder again another cable from the positive of the battery to OUT+ and from the ground og the battery to OUT- :sweat_smile: ?

Thanks for read and sorry if this is a newbie question :wink:

I'm planning to make a bluetooth speaker powered with a phone battery

What will the Arduino do?

You can in effect buy this project for about $5.00 on eBay, it is not very practical to implement this with an Arduino.

What I guess you really need (can't fully understand what you try) is a powerbank.

Batteries are not something to mess around with if you don't know what you're doing. Small mistakes can have serious consequences (such as setting your batteries on fire).