add your checkbox to the add to cart form, and set the checked value top use the ID number for the battery.
Create a lookup recordset on your page that will query the products catalog and filter the ID column on the checkbox form element.
Go to the server behaviors panel, click the plus button and select eCart -> Add To Cart -> Add to Cart
Set the trigger to Lookup recordset not empty
On the bindings panel, bind each cart column to the corresponding column from the lookup recordset. Bind the quantity column to the quantity form element.