Toyota 2009 Tundra Owner's Manual page 632

Electrical system
Battery
Open voltage at
68°F (20°C):
Charging rates
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.
6-1. Specifications
611
6