Texas Instruments TI-89 Titanium Short User Manual page 51

• Do not mix new and used batteries. Do not mix brands (or types
within brands) of batteries.
• Do not mix rechargeable and non-rechargeable batteries.
• Install batteries according to polarity (+ and –) diagrams.
• Do not place non-rechargeable batteries in a battery recharger.
• Properly dispose of used batteries immediately.
• Do not incinerate or dismantle batteries.
Getting Started 45