A multiple battery carriage comprising first and second battery carriages (111, 113), wherein each of the battery carriages comprises: first and second dual-contact assemblies (121, 123, 125, 127) each of which includes a positive contact (133, 143, 147, 153) and a negative contact (135, 145, 149, 155); wherein the positive contacts are each configured to contact a positive terminal (192, 196) of a battery (191, 193) and to be connected to a positive circuit connection, and the negative contacts are each configured to contact a negative terminal of the battery (191, 193) and to be connected to a negative circuit connection (173, 175); wherein one of the first and second dual-contact assemblies of the first battery carriage and one of the first and second dual-contact assemblies of the second battery carriage form a double-sided dual-contact assembly and share an insulator in common; wherein the double-sided dual-contact assembly is disposed intermediate to two peripheral dual-contact assemblies (121, 127); wherein at least one of the dual-contact assemblies of each of the first and second battery carriages comprises a spring-loaded dual-contact feature (133, 161, 153, 167) ensuring that a battery placed in one of the first and second battery carriages (111, 113) is resiliently and fittingly received between the spring-loaded dual-contact features (133, 161, 153, 167) and maintains continuous contact with the spring-loaded dual-contact feature (133, 161, 153, 167) on both sides of the one of the first and second battery carriages (111, 113); and wherein, when a battery is placed between an adjacent pair of the dual-contact assemblies (121, 123, 125, 127), the positive terminal (192, 196) of the battery (191, 193) is conductively connected with the positive circuit connection, and the negative terminal of the battery (191, 193) is conductively connected with the negative circuit connection (173, 175), regardless of which way the terminals of the battery are oriented relative to the adjacent pair of the dual-contact assemblies (121, 123, 125, 127). first and second dual-contact assemblies (121, 123, 125, 127) each of which includes a positive contact (133, 143, 147, 153) and a negative contact (135, 145, 149, 155); wherein the positive contacts are each configured to contact a positive terminal (192, 196) of a battery (191, 193) and to be connected to a positive circuit connection, and the negative contacts are each configured to contact a negative terminal of the battery (191, 193) and to be connected to a negative circuit connection (173, 175); wherein one of the first and second dual-contact assemblies of the first battery carriage and one of the first and second dual-contact assemblies of the second battery carriage form a double-sided dual-contact assembly and share an insulator in common; wherein the double-sided dual-contact assembly is disposed intermediate to two peripheral dual-contact assemblies (121, 127); wherein at least one of the dual-contact assemblies of each of the first and second battery carriages comprises a spring-loaded dual-contact feature (133, 161, 153, 167) ensuring that a battery placed in one of the first and second battery carriages (111, 113) is resiliently and fittingly received between the spring-loaded dual-contact features (133, 161, 153, 167) and maintains continuous contact with the spring-loaded dual-contact feature (133, 161, 153, 167) on both sides of the one of the first and second battery carriages (111, 113); and wherein, when a battery is placed between an adjacent pair of the dual-contact assemblies (121, 123, 125, 127), the positive terminal (192, 196) of the battery (191, 193) is conductively connected with the positive circuit connection, and the negative terminal of the battery (191, 193) is conductively connected with the negative circuit connection (173, 175), regardless of which way the terminals of the battery are oriented relative to the adjacent pair of the dual-contact assemblies (121, 123, 125, 127).