Replacing 5KW generator on 32' Belzona power boat

[Rusty car]

The 5kw Onan gen set on my boat failed. I am looking to replace it with batteries and an inverter. 90% of the time the boat will be at the marina hooked to shore power.
While underway I would like to charge the batteries from the alternator on the engines. The boat has two Mercury 300 Verados.
There is probably room for one flexable solar panel on the T Top. The boat has a dometic fridge, hot water heater, tv, elec cooktop, we would need to charge phones and computers, operate sm hand tools, all boat 12v systems ie. lights, pumps, electronics, etc. It also has AC, but it would only needed while at the marina on shore power. Need batteries that are safe from fire.
My questions: Can I charge the batteries from the engine alternator ? Would it be better to use both engine alternators or one ?
Inverter and battery bank size? I see pricing is coming down. I'd rather oversize than under size the system. I would also like a system monitoring station in the cabin where the old gen set panel was located.
To summarize we need a system with multiple charging inputs that can run everything for 3-4 days. We have plenty of room now that the gen set is gone. I included a photo of the boat and a photo of a different boat with an unknown battery system.
Any help would be greatly appreciated. Love to find an all in one system with more batteries than I need. I'm open to a 12v, 24v or 48v system whichever would be best for my situation.
Thanks in advance.
Russ

 

[SailorHarry]

Rusty,

I am looking into designing a similar system for my 42’ houseboat. Have you made any progress on it? There do not seem to be any off the shelf systems for doing this, you can design your own ($ = as much as you want to pay) or pay someone to design / install it ($ = as much as they want you to pay).

I am a marine /industrial electrician so I plan to design my own. There are some affordable all-in-one systems that I am looking at, such as SunGold Power who makes a 5kw 48v. You will want 48v inverters for the power density, unless you decide you can downsize the system to 3kw by doing without the AC. For 3kw you can do 24v or 48v depending on which batteries you pick. I am looking at metal case LiFePo4 batteries in the 24v 300ah class. They are also available in 12v 600ah. Either way you will want as much battery and solar capacity as you can fit.

With the all-in-one inverter you hook the shore power up as a generator feed and it will charge the batteries off that when power is available. Adding alternator charging would be done with a DC-DC charger such as Victron makes, the details will depend very much on the details of your existing electrical system.

Sounds like a fun project.

 

[paulgrenga]

Rusty,
Hope you were able to accomplish your set up.

I'm in the process of "attempting" a similar replacement of a Westerbeke 12.5KW gen-set. It's in a 52' Bluewater Millenium. I'd like to use a new 48v "all in one" solar inverter charger set up. I'm hopelessly lost and am on a budget.

That said, I think I made my first mistake yesterday by "being too cheap". I purchased 2 LiTime 48v 100ah "rack batteries" and LiTime's new 5000w solar pure sine wave inverter charger that supposedly has 10kw surge or "peak" performance. After it shipped, I realized that the inverter is single 120v rather than a 120/240 system. I assume, and SailorHarry would likely know, that the westerbeke was 120/240 with G1 and G2 outputs to the transfer switch (and then to an old Ball Products load center). The load center has two columns of breakers with ammeters above, each that can read to 50amps. The shore power cord is 50amp with 4 "lugs", i.e., ground, neutral and two power (L1 & L2).

All that said, now I'm wondering if I need a 100 amp Autotransformer or if I should just buy another $800 LiTime all-in-one inverter. (For the present, I'm pretending that the neutral-ground bonding issues aren't urgent). I too am considering 2 DC-DC chargers (one off each engine) to supplement off grid charging of my 2 new LifePO4's. I'll add solar panels this summer.

There's 3 8000Btu HVAC units that rarely run (being in upstate NY), a full-size house fridge, a microwave and stove top unit. No oven. I'm mostly concerned with running the house battery chargers and on occasion 1 of the HVAC units for heat. The LED TV is always on as is the coffee pot.

I'd really appreciate any advice on how to fix this (well, other than to return the LiTime inverter - I know I won't and it'll just set somewhere wasted).

Finally, I'm sorry if I'm high-jacking your post. I'm as inexperienced with forums as I am with electricity. If I should post this as a new thread, please tel me.

In any case, good luck Rusty! If I sort this all out, I'll let you know what we finally did and how well it works.

PS: That's a beautiful boat!!!!

Paul