Balance functions have been measured in terms of relative pseudorapidity
($\Delta \eta$) for charged particle pairs at the Relativistic Heavy-Ion
Collider (RHIC) from Au+Au collisions at $\sqrt{s_{\rm NN}}$ = 7.7 GeV to 200
GeV using the STAR detector. These results are compared with balance functions
measured at the Large Hadron Collider (LHC) from Pb+Pb collisions at
$\sqrt{s_{\rm NN}}$ = 2.76 TeV by the ALICE Collaboration. The width of the
balance function decreases as the collisions become more central and as the
beam energy is increased. In contrast, the widths of the balance functions
calculated using shuffled events show little dependence on centrality or beam
energy and are larger than the observed widths. Balance function widths
calculated using events generated by UrQMD are wider than the measured widths
in central collisions and show little centrality dependence. The measured
widths of the balance functions in central collisions are consistent with the
delayed hadronization of a deconfined quark gluon plasma (QGP). The narrowing
of the balance function in central collisions at $\sqrt{s_{\rm NN}}$ = 7.7 GeV
implies that a QGP is still being created at this relatively low energy.