7 Hour Universal Charger (230-0243) Hints and Tips Faxback Doc. # 17269 For best results, keep these hints in mind: Completely discharge the batteries before you charge them. Repeatedly charging batteries that are not fully discharged can shorten their useful life. It is normal for the batteries to become warm while charging. You can only charge a single AAA, AA, C, 9V, or D battery in a battery chamber at a time. A 9V battery is charged between two chambers and you can only charge one 9V battery between two chambers at a time. Do not overcharge a battery. Prolonged overcharging can shorten the battery's useful life. CAUTIONS: Charge only nickel-cadmium batteries in this charger. Charge batteries in an area between 60 and 85 degrees F. Batteries do not fully charge when they are cold. If the area is too warm, the batteries can permanently lose their ability to charge. Do not try to charge a battery size other than the sizes listed or by connecting the battery's terminals to the charging contacts with a piece of metal.