Without knowing what outboard you have and how/if it's connected, I can only speak in general terms.
First, is the outboard an elec start one? If it is, then the present connection will do provided they are in good condition. If it is a pull start, it may or may not (if a small hp) have the mean to recharge a battery.
The type of battery will depend on what it is use for. This topic has been discussed before in detail just do a search on battery/batteries.