The CH4 is an entry level charger and will charge most car and boat starting batteries overnight. It should not be left connected to a battery for more than 48 hours. Two LED indicators show when the unit is powered and when battery is fully charged. Not recommended for other than normal starting batteries. Please Note: The average life for automotive starting batteries in Australia is 36 months. As a general rule, do not charge deep cycle batteries at amperage greater than 10% of the battery amp hours.