My dad's cruiser has a standard 2 battery set up. Has shore power, an onboard electrical panel (AC, DC with all the functions, i.e. fridge, battery charger, stereo, etc.) a Guest "black box" and a Guest switch (off, 1, all, 2). #2 battery is the "house" battery and is a marine deep cycle. #1 is marine cranking. Both batteries are less than 30 days old.

#2 battery is dead as a proverbial door nail. Is warm to very warm (not super hot) to the touch. Not even enough juice to run engine alarm when the key is turned on.

AC comes into panel to AC main, battery Charger switch to "black box" to switch to batteries. Voltmeter on DC panel shows 16 volts (pinned) when battery charger is on and DC switch is thrown.

What gives here? I checked current (with probe- I don't have a multi-meter) from charger to black box to switch to batteries and current is there. Neither one of the meters on the charger are working- but there is current.

Help, anyone, SOS, hello? Thanks for any help.

my guess is you had a plate in your battery short out. a dead short battery will show no charge on a battery charger because it takes no charge. A hard jolt even to a new battery can break a plate loose.