If it is a steady orange light it may be a dud. If it is a flashing orange (amber) light it may indicate a pairing problem that can be fixed by resetting and repairing them. I had the same problem and doing that worked for me. At the time I found an article online about it that helped. This may be it but I'm not sure . . .

https://www.imore.com/how-to-troubleshoot-reset-airpods

It seems like my new airpods are always on an orange battery light no matter how little I use them. Just used them for 20 minutes after a full nights charge and they were already blinking orange when I put them in the case. Did I get a dud?