power supply for router

I have 2 routers a wrt54g and a wrt160n. I want to add a cooling fan to both. The cooling fans are 12v .82a. This will pretty much max out the linksys power supplies. I have a couple of laptop power supplies one is 16v 4.5a the other is 15v 5a could I use them in place of the linksys ps? I read that linksys routers can take up to 18 volts. Both of these routers are 12 volts. I'm thinking about soldering the cords directly to the boards as the connectors are different. Also will the extra voltage damage the fans? Thanks