The universal programmable Battery Guard (BG) prevents the excessive discharge of the battery (which would damage the battery) and protects electronic appliances against over-voltage. The BG40 battery guard has an “Automatic Board System Detection” -- the BG automatically detects the battery voltage (12 or 24V). The BG40 battery guard is capable of carrying 40 amps continuous load and 45 amps transient load. There is a choice out of 10 ON/OFF threshold voltage programs, for both 12V and 24V battery systems, which can be easily programmed.