Apple Care

See the following footnote from AppleCare Products - iPad - Apple

1. Service coverage is available only for iPad, its original included accessories, one compatible Apple Pencil, and one compatible Apple‑branded iPad keyboard used with your iPad for protection against (i) defects in materials or workmanship, (ii) batteries that retain less than 80% of their original capacity, and (iii) up to two incidents of accidental damage from handling of your iPad, Apple Pencil, and Apple‑branded iPad keyboard every 12 months, each incident being subject to a service fee of $49 for iPad and $29 for Apple Pencil or Apple‑branded iPad keyboard, plus applicable tax. Any unused accidental damage incidents will expire and you will get two more accidental damage incidents to use within the next 12 months of continued coverage. Replacement equipment that Apple provides as part of the repair or replacement service may contain new or previously used genuine Apple parts that have been tested and pass Apple functional requirements. AppleCare+ coverage begins on your AppleCare+ purchase date. See terms for full details.

First, Apple doesn't actually replace the battery in iPad. If an iPad battery is defective and needs to be replaced during the warranty period, you'd get a replacement iPad, which is most often a refurbished device. If you mean does the standard one year Apple Care warranty provided with all iPad's cover the cost, the iPad would be replaced under warranty ONLY if Apple determines there is a verified issue/defect with the battery.