The H-T phase diagram and several superconducting parameters for the noncentrosymmetric system Li2(Pd1−xPtx)3B have been determined as a function of cation substitution x. Notably, the coherence length may be linear in platinum concentration. Despite the superconducting pairing state and band structure apparently changing fundamentally, the H-T phase diagram is essentially unchanged. Unusual aspects of the shape of the H-T phase diagram are discussed. The upper critical field Hc2(0) is not anomalously high for any Pt content, likely due to an absence of high carrier masses—in such a case, the value of Hc2(0) would not serve as a probe for novel physics.