They are not. To meet applicable USA and EU safety standards, and to make sure your child doesn't accidentally ingest a coin cell battery, the batteries are sealed for safety. To us, safety is by far the most important, and we want to make sure your child is safe with our product. Even though the Pals are not replaceable, we have worked hard to find a balance between battery life, safety, and price. Each Glo Pal Light Up Cube costs less than $2.75 ($11.00 for a pack of four Light Up Cubes) and each Light Up Cube is warrantied to last a minimum of 30 days from the date of purchase, but typically last much longer when cared for properly.