2009 Toyota Tundra Owners Manual - Page 636

6-1. Specifications Electrical system Battery Open voltage at 68°F (20°C): 12.6 ⎯ 12.8 V Fully charged 12.2 ⎯ 12.4 V Half charged 11.8 ⎯ 12.0 V Discharged (Voltage checked 20 minutes after the key is removed with all the lights turned off) 5 A max. Charging rates 6 Vehicle specifications 611