AC Adaptor?

[Mr-Shutter]

A DC battery charger will NOT run your robot. It uses low current to charge the battery and is not advised to try and run you bot off of it.
Unless you have superior knowledge of AC-DC PSU construction, don't make your own.
Cough up the cash and buy a nice PSU.

For test boards, with little equipment

I mean, for a test board, running like 1-2 motors, use this! ( I doubt that the large motors use 40 amps)
http://myrcsupply.net/index.php?main... ucts_id=13383
or for 2-4 use this
http://myrcsupply.net/index.php?main... ucts_id=13008
They are equivalent to a car battery

Don't worry about blowing a fuse on the PSU's...

For the WHOLE robot

I like this one http://www.v-infinity.com/adtemplate...bcatky2=320934
It has what I believe to have sufficient current for the bot, and a lot of safety features built in, preventing damage top you, the bot, and the PSU.
Hook up a current meter to the bot and see how much current you draw with everything on. You’re going to want a PSU that can handle a little more then that amperage.