Hi Rod,
I'm happy to help here! The 510-808/901 adapter should be exactly what you need. I'm posting a link to the product below. Please make sure to select the adapter that is 510 to 808/901 battery - as the other option is the opposite of what you need.
http://www.smoktek.com/510-808901-adapter-808901-510-adapter_p_126.html
Best regards,
Brad