If you find that the card is short of balance when you get off the Shizuoka Railway train, you'll be asked to adjust the whole amount of the fare in cash (however, given the interoperation with TOICA, ICOCA can be recharged at JR Central stations in the vicinity).
静鉄電車降車時に残高不足となった場合は、全額現金精算となる（なおTOICAとの相互利用開始に伴い、周辺のJR東海の駅でもチャージ可能となっている）。