may include an indentation 90 fig3 located between the compartments 24 and 34 second end wall 78 may include an indentation 92 fig2 and 3 located between the compartments 28 and 30 in addition to the indentations 82 84 86 88 90 and 92 described above the battery case 20 may further include a pair of openings 94 and 96 which extend completely through the housing 20 as illustrated in fig3 the opening 94 may be bounded by the compartments 24 26 32 and 34 while the opening 96 may be bounded by the compartments 26 28 30 and 32 as shown the openings 94 96 may also be bounded by indentations formed between each of the bounding compartments opening 94 for example may be bounded by an indent 110 formed between the compartments 24 and 26 an indent 112 formed between the compartments 26 and 32 an indent 114 formed between the compartments 32 and 34 and an indent 116 formed between the compartments 34 and 24 opening 96 may be bounded by an indent 118 formed between the compartments 26 and 28 an indent 120 formed between the compartments 28 and 30 an indent 122 formed between the compartments 30 and 32 and an indent 124 formed.