for a battery that is energizing or charging, the voltage across its terminal will be greater than its emf. this result can be expressed as Vterm= E + Ir w

connect a single, very old battery to oppose two other newer batteries. the pair of batteries across CD will determine the direction of the current since their combined emf is 3.0 volts while the battery being energized across points AB has an emf of only 1.5 volts.