Unusual Boat

DIY
,
1

Here is the puzzle. I am in the process of mapping out my Trawler’s electrical system so that I can best modify it using Victron components but don’t have a diagram yet so please excuse the textual explanation. I have combed the interwebs for an answer but, being a novice, still do not have a concrete solution. I have a 42’ trawler with a professionally installed electrical system that is very unusual. It is comprised of 50a Shore power, 2 Northern Lights diesel generators, feeding a 120v breaker panel via a 3 way distribution switch. It has a 12v system comprised of 4x12v starter batteries, one each for the two propulsion diesel engines and the two generators. There is a 120v marine charger that can charge the 12v batteries from the 120v pannel as well as each engine has an alternator. There is NO INVERTER! Therefore, I have to run one of the generators in order to power the 120v loads while underway or even worse, at anchor. This will not do, specially since I have the following 120v loads that must be on at all times:

Fridge, 24" Under Counter
Freezer, 24" Under Counter
Refrigerated Ice Maker
9’ Chest Fridge/Freezer on Fly bridge

Clearly I need to add an inverter charger as well as a LifePo4 house bank of batteries with enough storage to run those 4 systems as well as the other loads common to a boat at anchor. I will do the math asap but for now, I don’t even know what Victron to even think about.

Like I said, I have 50a shore power so as far as I understand that is 2x120v coming into the boat, through a breaker, through a galvanic isolator, and then to the three way distributor switch (two gensets) on to the breaker panel. I am not entirely sure how that is split but I’m guessing (novice) that each 120v goes to a separate bus on the panel. I guess this means that the gensets are also putting out 2x120v but I will confirm this soon.

Bottom line, I don’t know if I should get a Multiplus II 2x120, A Quatro II 2x120, or some other of the myriad of inverter chargers that Victron offers. I greatly appreciate any guidance on this matter as I’m a software engineer and not an electrical one.

Some notes:

  1. I will add solar later but it is not mission critical for now
  2. I will add dc to dc charging so I can charge the house bank later but not important yet
  3. I am not looking for someone to design the entire system for me just some guidance on what inverter charger is the best fit.
2

Seems that the electrical installation is not so unusual for a commercial boat.
Looks like you have a main generator and a back up, during normal fishing operations, one would be running together with the main engines.
You could probably think about removing one of the generators.
I would look at a Quatro 2x120 for the inverter, as this can take both shore power or generator input with no additional (external) switching. Also use an isolation transformer on the shore power input. As a design concept consider replacing one of the generators with the inverter battery combination, this should minimise changes to the wiring.

3

Interesting assertion. The funny part is it’s a pleasure trawler, a Grand Banks to be exact. Furthermore, the generators are nice Northern Lights units and I love having the back up, specially since I have the room in the massive engine room. That said, I like your idea of replacing the input into the distribution switch from one of the generators to the inverter. I understand this but how would the batteries then be charged if the inverter has no 120 line going to it?

4

Since you’re considering LiFEPO4 I would strongly advise just getting a Multiplus II and using the Lynx BMS, and a Cerbo GX for control/monitoring.

You can get rid of a lot of other complication by just using DC-DC converters to charge the starting batteries and run everything on board with Li except that starting of generators/engines.

The isolation transformer suggestion from the other post is VERY good advice.

We’ve got essentially this same on our Hinckley and it’s been bulletproof running DX 250 Balmar alternators and Wakespeed Regulators. You’re going to need to up-rate your main cabling to the battery banks and the chargers though, as your old wiring will not handle the loads with Li, as the acceptance and discharge rates can be much higher than your old system, and you don’t want a fire on that nice boat.