I would like to be able to drain a car battery down from fully charged at 12.6v down to between 10.5 to 11.9 volts without having to manually check it with a multimeter periodically, yet have some obviously visible sign that the discharge process has finished. Anywhere in that voltage range is acceptable, although closer to the higher end of the range is preferable.
The car batteries typically have capacities between 50 to 100 amp hours. I was planning to use one or two 12v 60watt ( 5amp ) car headlights as the load, such that the discharge time would be both reasonable, but not so fast as to damage the battery.
Is there some circuit design / device which could meet that goal and be implemented by someone with a basic knowledge of electronics?
OK, this ICStation Battery Low/Under Voltage Protection Kit is basically exactly what I'm looking for:
Obviously the easiest thing would simply be to mail order an item like this, however I'm not sure I could get it shipped to the country I live in. Would it be horribly difficult to build something like this?
OK, so here's a project suggestion for building something like this.