What is the history of this device? You need to determine if this is a charge/battery issue or an overall logic board issue. Here are my suggestions if it is charge/battery related:
When troubleshooting charging issues, I would do the following (in order):
- Always try another Lightning cable and charger, preferably Apple original or MFi certified units.
- The Lightning cable 8-pin connector should be sitting flush with the housing and completely inserted. If it is not, there could be lint/dust/debris inside the port impeding a proper connection. You can clean it out with a toothpick, fine point tweezers or a dental pick. Just be careful not to damage the pins inside the Lightning Port.
- Change the battery. The battery is the weakest link in the entire device and certainly for charger related issues. Use a battery utility, such as coconutBattery (for Mac) or 3uTools (for Windows) to test the battery prior to removal. Anything less than 70% of design capacity will require replacement.
- If the battery is in good condition, you can use a USB Ammeter to determine if the device is really drawing current when it says it's charging. If it isn't drawing current, then I would change the Lightning/Charge Port. This requires micro-soldering.
- If a new battery and charge port still don't resolve the issue, then you either have faulty replacement parts (possible) or a logic board issue. On the iPad, it could be the Tristar IC (easy micro-soldering repair) or in some cases the PMIC (difficult micro-soldering repair).