PROPELLER Ease. 3 SAFETY WARNINGS! improper use of batteries may Sad to overheating, breakage or leaking. -Do not mix oid and new batteries. -Do rot mix different battery brands. Install batteries with correct polarity. The fat side (negative terminal) of the battery should rest against the spring. -Remove dead batteries Immediately -Av old liquids, which can short circuit the batteries. -Never try to charge starless that are not rechargeable.