NOVELTY - Pre-treated ion exchange resin (I), comprising at least 15% by total number of exchangeable groups comprising an ion, a Lewis acid and/or a Lewis base resulting from a heat transfer fluid component having a negative logarithm of acid dissociation constant (pKa) or a negative logarithm of base dissociation constant (pKb) of greater than 5 in an aqueous solution at 25degreesC, based on the total number of exchangeable groups, is new.    USE - (I) is useful in heat transfer systems, fuel cells and assemblies powered by an alternative power source (claimed).    ADVANTAGE - (I) simultaneously removes ionic species from a heat transfer fluid, maintains low conductivity in a heat transfer fluid and provides a beneficial property such as color to a corrosion inhibiting heat transfer fluid.    DETAILED DESCRIPTION - INDEPENDENT CLAIMS are also included for:    (1) an ion exchange resin (II) comprising at least 15% of exchangeable groups comprising a corrosion inhibitor, based on the total number of exchangeable groups;    (2) a heat transfer system, comprising a circulation loop defining a flow path for a heat transfer fluid having a conductivity of less than 10 muS/cm, and the ion exchange resin (II) positioned in the flow path;    (3) an assembly powered by an alternative power source comprising: an alternative power source and a heat transfer system in thermal communication with the alternative power source, where the heat transfer system comprises a circulation loop defining a flow path for a heat transfer fluid having a conductivity of less than 200 muS/cm, and the ion exchange resin (II) positioned in the flow path;    (4) a method of maintaining a conductivity of less than 200 muS/cm in a corrosion inhibiting heat transfer fluid, comprising: passing a heat transfer fluid through a heat transfer system, where the heat transfer fluid has a conductivity of less than 200 muS/cm and the heat transfer system comprises a circulation loop defining a flow path for the heat transfer fluid, and the ion exchange resin (II) positioned in the flow path;    (5) a method of making a treated ion exchange resin; and    (6) a fuel cell system, comprising: at least one fuel cell comprising an anode, a cathode, and an electrolyte; and a heat transfer system in thermal communication with the at least one fuel cell, comprising a circulation loop defining a flow path for a heat transfer fluid having a conductivity of less than 10 muS/cm, and an ion exchange resin (II) positioned in the flow path.