Green newbie... Want to know so much

[Bleever]

Hi all, I just bought a 91 2300 and I've a few questions. 1 it came with a battery an a 1/2amp matainer that suddenly after many clicking noises stopped, battery dead..connected to shore tho an everything else is working...so I want to replace battery and charger/maintainer with new..suggestions?
Next... I've just ran across an read that the shoes has a grey water holding tank, correct? If so..are the following photos for that? The one to the right is connected to nothing, the one to the left is connected but, since I need new battery don't know if it works...or if so..how do I turn it one? The boat has an auto float bilge in engine area that when batt worked did come on..an manual did as well...does the grey water work off the same?
Back to battery.. Can I charge the new one while on shore power?
The fridge, an anything I plug in work... At one point so did all the lights, bilge switch an auto ( I tested it) but I understand until I replace batt they are dead in the water so to say...which by the way this boat is in the water... No engine..yet... Like I said work in progress. She's not taking on water... Thankfully...as stated any thing I can plug in works as fridge...an so did most everything else I tested.. I left the key on thinking it was needed to charge battery..not that it would kill it...live an learn.... Any ideas? Anything.... I know I am a baby boater but willing to learn, work hard an get it right... Ps my I hope once I get this battery thing concurred to connect to solar... But that's another's day for certain.... Last photo is my view this a.m.

[Bleever]

Photos

[shrew]

OK, a lot of stuff here.

The 12volt DC system runs off of the batteries. This includes the lights, pumps, starter (no engine so no starter). The battery charger would need to be plugged in and functioning.

A 1/2 amp charger sounds like a battery tender. If you want a fridge to run, you really need a actual battery charger, like a 15 amp.

The pump in the picture is a Bilge Pump to pump water out of the bilge. A Grey water tank is usually a holding tank which collects water from the sinks, which would drain into the grey water holding tank.

If you have no engine, then I assume the outdrive is connected to the boat. That will need to be removed before an engine can be installed, so you're going to need to haul toe boat in order to install a new engine and align it properly.

[mmwjr]

Grey water holding tank gets pumped out thru the waste deck plate at a marina.

12V runs lights and most other things.

Shore power run microwave battery charger.

The frig is dual volt and runs on shore power when plugged in and 12V when not.

To the right of the bilge pump is the float switch to turn it on.