Toyota Prius Owners Manual
12 volt battery recharging precautions
During recharging, the battery is producinghydrogen gas.
Therefore, before recharging:
1. If recharging with the battery installedon the vehicle, be sure to disconnectthe ground cable.
2. Make sure the power switch on therecharger is off when connecting thecharger cables to the battery and whendisconnecting them.
Always charge the battery in an unconfinedarea. Do not charge thebattery in a garage or closed roomwhere there is not sufficient ventilation.
Only do a slow charge (3.5A orless). Charging at a quicker rate isdangerous. The battery may explode,causing personal injuries.
Never recharge the battery with thehybrid system on. Also, be sure allaccessories are turned off.