14 A t fr s t g lanc e char ger s and ba t t er ie s do no t s eem t o b e e sp eciall y imp o r tan t ac c e ss o r ie s P er haps they do no t s eem wo r th pa ying a t t en tio n t o f o r quality o r o r ig in E xp er ienc e shows the o p p osit e Ins tr umen ts and their elec tr o nics r e ac t s ensitiv el y and need a r eliable p ower sup pl y in all envir o n men tal c o nditio ns B a t t er ie s and char ger s ar e als o exp os ed t o the s e c o nditio ns s o me will f unc tio n o ther s mig h t and s o me no t f o r lo ng o r no t a t all under c er tain c o nditio ns T ha t is wh y the quality and e ffciency o f the o r ig inals als o c oun ts f o r ba t t er ie s and char ger s o ri ginal Ba tteries an d Chargers F o r r eliable ins tr umen t f unc tio n 14