T&T: Battery question

[Laura]

Our current power set up is as follows (40 foot down east lobster boat, 3208
Cat single engine).



We have two sets of two 8D batteries  two dedicated to starting engine, two
for house batteries.  The average age is approx 5years old, and they are
probably getting tired. We have a xantrex true charge 20 amp multistage
charger, and an offbrand Vector 1200 watt (2400 watt peak) inverter.



As a test, we ran all our usual appliances (galley microwave, toaster oven,
lights, small refrig etc) for over 1 = hours.  The inverter began a high
pitched screaming noise, and eventually the power surged on and off then
stayed off. We used a tester to determine that one house battery was down to
12.16 volts, 5.97 miliamps and 542 cold cranking amps(42% capacity), the
other house battery was 3.69 milliamps impedance, 888 cold cranking amps
(76% capacity).



Questions:  Do either of the 8D house batteries sound salvageable, and what
you recommend to replace one or both?  It seems that in past discussions on
the list, the primary recommendation is for golf cart batteries.  Can you
recommend sources for golf cart batteries, if that is the way to go.  We
think we need to use flooded as our engine batteries are flooded and all are
charged through the same charger.



2. Recommendations as to an additional or replacement inverter  higher
capacity.



3          How can we use the inverter to run a 120 volt refrigerator  --
will the inverter know to switch between the battery and the 110 shore
power?  We currently have an older Norcold which switches itself, we would
like to switch over to  120 dorm size.



Any other comments or suggestions.



Artie & Laura Ortmann

NARCOSIS Downeaster

Long Island, NY