These are serious chargers and will charge at a fast rate slowly reducing the current with the increase in charge but should not be left charging indefinitely. Charging figures from a quick test were 2.5A charge @ 11V, 2A charge @ 12.4V and 0.4A charge @ 14.9V. These chargers are 118mm L X 66mm H X 84mm W and weigh 1.4Kg. In side they have a 3300uF cap and what seems to be a 5A bridge rectifier and have Australian approvals.