iPad not charging on 1 percent

It will still charge but it will take a much longer time than usual.

FYI: It is never a good idea or to have a good battery life if it below 20% too often.

Do:

• Charge anytime you want
• Charge as long as you want (when is full, it will auto switch Off)
• Use it while charging

Don't

• Let battery goes below 20% often

Never

• Let battery dies.

Start here:

Charge and monitor the iPad battery - Apple Support

If your iPad won't charge – Apple Support