Did you mean the L702X as I do not see an L7102X in the Dell support pages? If so then the batteries are not interchangeable but they both list the PA-4E adapter as compatible. At the Part-People site you can see the list of available adapters for both systems. Here and here. Also if you go to support and type in the service tag numbers of the units you will find under configuration the adapters that were included with the units. Obviously when you have both units in hand you can try the adapters compatibility in each unit.