Per my reply to your post earlier today...
Your iPad will suffer no ill effects through being connected to its Power Adapter for extended periods. Your iPad will automatically regulate and optimise charging - and will not overcharge the battery.
When used in retail or kiosk applications - where external power is connected for extended periods of time - the iPad may automatically modify its charging strategy and limit battery charge to ~80% of maximum. This modified charging strategy is designed to reduce chemical ageing that might otherwise occur if 100% charge is maintained at all times.
Nominal 100% charging will be restored when a normal charge/discharge routine is restored.
More information about iPad’s battery management can be found here:
About iPad and iPhone Charge Management Feature – Apple Support