Check the end of your Ryobi 4V battery — if it has a button, then all you need to do is press it. The LED that is integrated into the battery will then either light up red, orange, or green.

Ryobi has a rotary tool available with 12V power, but it's a bit pricier at $80. Within the 4V battery line, the USB Lithium Rotary Tool is only $50. One of the main differences between them is ...