Q: Someone loaded his car with bags. A package of batteries fell out, but he drove off before I had a chance to alert him. What can I do with the batteries?

A: When a person would typically abandon hope of retrieving his lost item, e.g. there is no siman but he is unaware of the loss, this is called yei’ush shelo midaas. This is not considered yei’ush, and you may not take the batteries for yourself (B.M. 22b; C.M. 262:3).

There is a dispute about what to do if you pick up the batteries. Although some rule that once you already picked them up, you may use them meanwhile, Rema and most authorities rule that “Yehei munach ad sheyavo Eliyahu” — they should sit unused until Eliyahu Hanavi arrives. Moreover, you become responsible for them as a shomer, even after the owner subsequently notices his loss (C.M. 260:9-10; Shach 260:26).

One approach is to have intention not to become a shomer when you pick up the batteries. Then, when sufficient time passes that the owner will have unloaded his bags and realized his loss, you may keep them (Hashavas Aveidah K’halacha 5:4[18]).

B’ezras Hashem, next week we will mention another option.