I think the issue here is between "charging current" and "power supply maximum load". To avoid stressing the battery the current should be set to about 10% of the battery rated capacity, so for 7 Amps, 0.7A (700ma) is about right.
However, that is for charging under normal circumstances, if the battery is discharged , applying even 12V directly across it will try to make considerably more current flow and that small power supply will probably be overloaded and hopefully will shut itself down.
As advised, you need a higher voltage to 'pull the battery voltage up' to 12V, typically around 13.8 to 14V but you also have to limit the current to the C/10 value to protect the battery and PSU. That's why normal constant voltage chargers are not suitable for charging batteries.
Brian.