43DC - 6kW Generator enough?

[oscarvan]

I have a 7.5 and it supplies just a bit more than the shore power cords ( 3 x 30 amp)

How do you figure that?

3 x 30A at (I assume) 120V = 10,800W


To the OP.... there's a few trade offs. Bigger generator is more $$, more weight, more space, more noise and more fuel.

And yes, more watts.

I run a 6000W Onan so 50A total in my motorhome. Depending on season I juggle 2 AC's (one is a heat pump), Inverter/Charger, electric water heater, residential fridge, microwave, coffee maker, block heater, electric fire place and 134 TV's, computers, phone chargers, X-boxes and what have you.

Yes, I have to "manage the loads" but I have not had the feeling that I needed a bigger generator.

I did install two ammeters to keep an eye on things. (Most Hatties seem to have them) Really helps.

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

[Boatsb]

Fat fingers

2 x 30 amps.

[krush]

Yeah but if you lower the charge rate you spend a lot more time running the genny. Not worth it

One must look at the entire system to properly analyze. Depending on the size of the battery bank, and the chemistry, the batteries may be limited on how many amps they can accept.

I'll put this in perspective: A 2kw portable gas Honda or Harbor Freight inverter generator easily will start and run my 12,000 or 18,500 BTU unit (I'd estimate they are 80-85%, based on the RPM drop when eco-throttle is on). Using this data-point, a 4kW should easily run both.

I would not put any larger than a 6kW in the original posters boat. I'd also consider using a hybrid inverter that can supplement the generator when needed.

[Boatsb]

7.5 kw means I don't have to shut things down to run others. That would be the minimum I'd use. The inverter could be set to take up to 50 amps in and pass through what's needed and charge with the rest available. If I were to be starting from scratch that's the way I'd design it.

[Pascal]

Well you can camp like a bloboater or you can be comfortable. 25 years using generators on boats Have taught me that having to juggle loads is a PITA.

Sure it sounds easy on paper: turn off the water heater while cooking then you run out of hot water because you forgot to turn it back on. Forget to turn off the water maker as you fire up you oven while someone is using a blow dryer and it s another trip to the ER to reset the breaker on the genset while the boat has gone dark

Not worth it if you have a choice. Instal coats are the same anyway...

Hondas belong on small sailboats and cabin cuddles

[oscarvan]

A 2kw portable gas Honda or Harbor Freight inverter generator easily will start and run my 12,000 or 18,500 BTU unit (I'd estimate they are 80-85%, based on the RPM drop when eco-throttle is on)

You must have the latest and greatest in "soft start" technology and a rotary versus piston compressor.

The EU2000 is 2000 PEAK and 1600W continuous. That's 1600/120=13.3A

I have used a 2000EU with a travel trailer and it BARELY pushed a 12,000 BTU latest and greatest AC. It was pulling 11.1A when running. Peak load during start was 15-17A and it JUST got over the hump. If it was cold and the oil was thick it would quit. There is no way in hell it will push an 18,500 BTU unit.

I'm with Pascal. The Honda's are not suitable for extended marine use, especially in a salt environment. Plus.....You paid all that money to have diesels, and now you have to schlepp gas cans. That said..... Having one hidden somewhere for when the you know what hits the air accelerator....

I pretty much run the genny 24/7 when not plugged in in the Moho. I disagree with him that a little load management is a deterrent. Some gauges and switches in logical places and life flows around it just nicely. I would need twice the generator (12,000W) if I wanted to be able to turn everything on at the same time.

[Mike36c]

The issue on my 36 with the 9kw was underloading, especially at night when the a/c’s were cycling. I found significant coking in the elbow when I swapped it out due to this. And although a fan of NL gennys I went with Phasor this year to replace my 12.5kw. Already past 500hrs trouble free and parts/filters etc can be bought at Napa. Phasor makes a compact 8kw which might fit your needs perfectly.

[krush]

You must have the latest and greatest in "soft start" technology and a rotary versus piston compressor.
.....There is no way in hell it will push an 18,500 BTU unit.

I'm with Pascal. The Honda's are not suitable for extended marine use, especially in a salt environment. Plus.....You paid all that money to have diesels, and now you have to schlepp gas cans. That said..... Having one hidden somewhere for when the you know what hits the air accelerator....

My units have soft-starts built in. But I can assure you the 18.5 runs nicely on the honda 2000. The purpose of my comment was not to say use a honda, it was to put the typical 40foot boat electrical load in context.

The issue on my 36 with the 9kw was underloading, especially at night when the a/c’s were cycling. I found significant coking in the elbow when I swapped it out due to this.

Few people think like you! I agree. and most generators are likely underloaded, not overloaded. Oversizing a generator for the 5% of the time when "all the stuff is on" is kind of silly...especially with new hyrbrid inverter tech (assuming an inverter is going to be installed).

My boat has a massive 12kw genset. My RV has an oversized 8kw genset. Both are 3cyl Isuzu engines. I doubt I'll ever load either at 50%.

The water heaters both have heat exchangers to allow engines to heat the water...plumb it to the genset and you'll rarely need the electric element on. I hate the noise of genset running if not needed. In the RV, the only time I need to run the genset is when running the A/C units. The rest of the time it's 12v loads or inverters (and charge the battery every few days). My boat doesn't have an inverter, yet.

MicroAirs EasyStart makes A/C compressor start up surge a non-issue. No need to oversize anymore. But everybody has different needs and desires.

[oscarvan]

The issue on my 36 with the 9kw was underloading, especially at night when the a/c’s were cycling. I found significant coking in the elbow when I swapped it out due to this. And although a fan of NL gennys I went with Phasor this year to replace my 12.5kw. Already past 500hrs trouble free and parts/filters etc can be bought at Napa. Phasor makes a compact 8kw which might fit your needs perfectly.

That's a VERY good point. Under loading a diesel for most of it's life is not the best thing. In fact, I make it a point to load mine up, if not already happening, on a regular basis.

[34Hatt]

I have that loading problem also I have a 8K but the panel is 2 30 amp sides 7200 total, so you can never load it 100%. I think Scotts boat is also (2) 30 amp plugs which if it is a 9K is a total waste how is the panel setup?