powering a ring stick up cam battery...

I have two ring stick up cam batteries. I want to supply them with a power source instead of just relying on the batteries, because i have to borrow an extension ladder to recharge them. I have these cameras installed where an old alarm system had 12vdc power supplied via wires already ran withing the walls. I need to know what size barrel connector and what size DC volts I would need to utillize this exsisting wiring. I found the dc connector on the cameras. I assumn they are for solar power or for the plug in adapter you can purchase seperatly. I dont want to have to purchase these adapters and cut off the ends just make this system work. Thank you....