The shorepower charger is a Professional Mariner, Protech 1220. I looked through the manual and cannot find the capacity and their website is down. I previously contacted Professional Mariner and they say no problem adding a second house battery wired in parallel with the other house battery as long as the group size is the same. I could not identify battery manufacturer but the tag had part # DP27, CCA @ 0°f 625, CA @ 32°f 770, 23 amp ave 175 min. Since I'm using 2 identical batteries the group size will be the same.
The boat is 27' with a cabin
so it has a substantial DC house load (engine hatch
, trim tabs, refrigerator
, lights, stereo w/amp, etc). The boat has a generator
but we like to anchor
overnight, use the generator
for a couple of hours but not all night. On one occasion with anchor light, refrigerator
and misc other battery draw the CO detector started chirping during the night from low battery. I have a switch to parallel the batteries and that made the chirpping stop. Obviously, that made me concerned about draining both batteries.
The Mercruiser is a 496 Mag (2006) and Charging System spec is 65 Amp/917 Watt Alternator. I assume the alternator charges the battteries (house and engine) when the engine is running? It is not obvious to me how the alternator is connected to the batteries but I'm assuming that if I simply parallel a second house battery it will be connected to both alternator and charger in the same way the first house battery is connected.
I hope that more clearly identifies my situation and will help respond to my inguiry.
Thanks for the reply posts!