Generally ACDC chargers are limited to 50-60W of output power. Which for a lot of batteries is fine. You get power simply by volts * amps. It is this reason why all the high powered expensive chargers are DC only. This allows you to have a much higher amp input, allowing more output power, which is required to charge high voltage, high capacity batteries.

Some people convert unused computer power supplies, there are a few guides floating around on the internet. It involves opening up the psu, messing around with some wires, cutting etc, adding terminals to the 12V lines, blah blah blah. If you don't want to mess around then just get a good PSU. For your charger, try to input as much voltage as you are allowed. If the charger can accept a 24V input then try to aim for that.