Panasonic Corp’s initial investment in Tesla Motors Inc’s (TSLA.O) battery factory will amount to “tens of billions” of yen, the Japanese company’s chief executive said on Tuesday. Chief Executive Kazuhiro Tsuga also told reporters that he did not think the yen’s current exchange was “bad”, as long as it remained stable. California-based electric car maker Tesla has been hammering out the final details of the plant that will produce cheaper and more efficient battery packs for its vehicles.