iPad battery lasts 3.5 hours from 80% charge

Getting only 3.5 hours of use from an 80% charge on a 2026 iPad (A16 chip) indicates an abnormal rate of drain.

While an 80% charge naturally yields less than the maximum 10-hour standard battery life, it should still provide roughly 7 to 8 hours of mixed use under normal conditions. 

Check this first

• Go to Settings > Battery > Battery Health.
• Look at the Maximum Capacity and the Cycle Count.

If your battery health is below 80% you might want to set up replacement

After that try this

• Look under Settings > Battery and review the "Battery Usage by App" chart for the last 24 hours and 10 days. If a single background app (like a social media app or browser) is consuming a disproportionate percentage, force-close it. 
• Disable Background App Refresh: Go to Settings > General > Background App Refresh and turn it off completely or restrict it to essential apps. This stops idle apps from draining your battery.
• Lower Screen Brightness: The display is the largest power consumer. Drop your brightness level to around 50% or ensure Auto-Brightness is active.