Old ipad charging indicator comes on but doesn't hold a charge. Doesn't build charge either? Any suggestions already tried cable and new transformer.
It could simply be the battery in the iPad no longer holds a charge due to age and cycles. You may try to replace the battery yourself:
Looks like its time to replace the battery unfortunately. Will cost $99USD. Check out this link to attempt to resolve or diagnose the issue further first though: https://www.apple.com/support/ipad/repair/battery-power/