Generators needed on boat with solar and lithium.?

[Statistical]

Generator isn't needed with a lot of solar and good high output externally regulated alternator. Keep in mind due to engine sizing vs alternator output plus low efficiency of alternators (no permanent magnet) they tend to be a bit less efficient (gallons per amp hours or kWh) than a generator. So a lot comes down to how much you need to use it. If solar covers most your needs and you rarely need the alternator then that lower efficiency doesn't really matter. The $15K+ cost of a generator buys a lot of diesel. The more you need the alternator the more a dedicated generator might make sense.

[sailorboy1]

Originally Posted by The Yacht Rigger

Yes exactly. Fire up the engine, instead of the generator - 300A going in to a Lithium bank gets the juice put back in real quick. If you're on a cat, make that 600A with both engines running. Bump the batteries back up to 50-75% first thing in the morning and then let solar take over.

Wow, how many boats have a 300a alternator??????????? Running a main engine to charge batteries is the worst!

[motion30]

The only time I use my generator is in the winter when the days are short and often Gray. After March my generator rarely gets started

[Takitimu]

We switched to Lifepo batterys 600 amp hours 24v, added 1100 watts solar power. We have a DC Fischer Panda with 58 hours on it. It passed away after the warranty expired when we went to try it out. Something about a voltage management board or something expensive, not fixing it. Pulling it out and adding another 600amp hours worth of lifepos is cheaper than fixing the generator. I also have a 180 amp alternator on my engine if I have a dire need. Just keeping an extra diode for the alternator Incase of issue there. We installed a DC water maker and DC USB ports and converted the starlink to DC. We only use the inverter for the microwave and the coffee pot. Everything else is DC. Working out with what we already have so the extra battery will soak in the extra sun. Our solar fills the batterys by 2-3 pm so the extra will let us be a bit less careful with our consumption.

[Kd9truck]

Originally Posted by Sailingnomad

Why do boaters need generators with adequate solar panels and lithium batteries?

Why does the sun not shine all day everyday? Why does the wind not blow all day every day? Renewable energy is not reliable energy all day every day as much as we all want it to be.

[rslifkin]

Originally Posted by Kd9truck

Why does the sun not shine all day everyday? Why does the wind not blow all day every day? Renewable energy is not reliable energy all day every day as much as we all want it to be.

Whether or not you need something else to supplement for those poor power production days will depend on how much battery capacity you have (how long you can go with no input power) and how much surplus capacity you have to catch up when the weather improves.

[Simi 60]

Originally Posted by The Yacht Rigger

Yes exactly. Fire up the engine, instead of the generator - 300A going in to a Lithium bank gets the juice put back in real quick. If you're on a cat, make that 600A with both engines running. Bump the batteries back up to 50-75% first thing in the morning and then let solar take over.

Not even sure if a 24v 300amp large frame J180 mount alternator is a thing
Would be insanely expensive if it was

But a good time to drag this possible alternative out again.

Some boats used to have Cruise Gens
Essentially a small belt driven generator head on engine activated when running in a set RPM range - at cruise, we do a set RPM for hours at a time

I toyed with the idea of a Mecc Alte 5 kVA wired into the inverter charger
I got a quote from a supplier in Australia and they are about $500.

Like this
https://www.ebay.com/itm/Belt-Driven...edirect=mobile

Some mention of them here on this site
https://www.google.com/search?q=%22c...e-gws-wiz-serp

[The Yacht Rigger]

Originally Posted by sailorboy1

Wow, how many boats have a 300a alternator??????????? Running a main engine to charge batteries is the worst!

More and more, now that the tech is available. I have 28V 185A alternators on my cat engines.
I much prefer charging at 300A (24v system) running my engines briefly, while I make some hot water, than running and maintaining a generator that can only charge at my on board charging systems capacity (120A).
The rest of the time... silence.

[The Yacht Rigger]

Originally Posted by Simi 60

Not even sure if a 24v 300amp large frame J180 mount alternator is a thing
Would be insanely expensive if it was

But a good time to drag this possible alternative out again.

Some boats used to have Cruise Gens
Essentially a small belt driven generator head on engine activated when running in a set RPM range - at cruise, we do a set RPM for hours at a time

I toyed with the idea of a Mecc Alte 5 kVA wired into the inverter charger
I got a quote from a supplier in Australia and they are about $500.

Like this
https://www.ebay.com/itm/Belt-Driven...edirect=mobile

Some mention of them here on this site
https://www.google.com/search?q=%22c...e-gws-wiz-serp

Yeah not sure if a 300A 24V alternator exists. But my 185A units (APS) are producing at a consistent 150A each at 28V.

[rslifkin]

Originally Posted by The Yacht Rigger

More and more, now that the tech is available. I have 28V 185A alternators on my cat engines.
I much prefer charging at 300A (24v system) running my engines briefly, while I make some hot water, than running and maintaining a generator that can only charge at my on board charging systems capacity (120A).
The rest of the time... silence.

Size of the main engines in question is a big factor. There's a big difference between running a small sailboat diesel at high idle for an hour with a decent load from a massive alternator and running something like Simi's Cummins 855 or my gas big blocks where even with a huge alternator, you'll still be presenting a very light load at high idle. And with bigger engines, running a generator will almost certainly be more fuel efficient than running the main(s) to produce power.

150A at 28V is 4200 watts. Assuming 80% alternator efficiency, that'll present a 7 hp load to the engine. If you're talking about 30 - 40hp diesel (which has a lower max output at the RPM you'd be running for charging), that may be a reasonable load. For something like Simi's boat or mine, that's almost an irrelevantly small load to the engine, especially once you get any bit above idle, as we're talking about 300+ hp engines.

For comparison, my 6.5kw generator has a 13hp engine, and that's well powered to handle motor starting loads, etc. I'd much rather put in a bigger charger setup than put huge alternators on the mains and run them just for charging. The generator burns about 1 gal/hr at full load, less with a lighter load. My mains burn a bit over 1 gal/hr each just at idle, more if you raise the RPM a bit.

[The Yacht Rigger]

Originally Posted by rslifkin

Size of the main engines in question is a big factor. There's a big difference between running a small sailboat diesel at high idle for an hour with a decent load from a massive alternator and running something like Simi's Cummins 855 or my gas big blocks where even with a huge alternator, you'll still be presenting a very light load at high idle. And with bigger engines, running a generator will almost certainly be more fuel efficient than running the main(s) to produce power.

150A at 28V is 4200 watts. Assuming 80% alternator efficiency, that'll present a 7 hp load to the engine. If you're talking about 30 - 40hp diesel (which has a lower max output at the RPM you'd be running for charging), that may be a reasonable load. For something like Simi's boat or mine, that's almost an irrelevantly small load to the engine, especially once you get any bit above idle, as we're talking about 300+ hp engines.

For comparison, my 6.5kw generator has a 13hp engine, and that's well powered to handle motor starting loads, etc. I'd much rather put in a bigger charger setup than put huge alternators on the mains and run them just for charging. The generator burns about 1 gal/hr at full load, less with a lighter load. My mains burn a bit over 1 gal/hr each just at idle, more if you raise the RPM a bit.

Totally agree. With bigger engines it certainly starts to make less sense. Also with that size engine, you're likely on a bigger boat, with more storage, more room for additional chargers and a generator.

On my cat, space and weight are a primary concern. So getting rid of the gen, and more than tripling my charge rate, felt like a no-brainer.

[rslifkin]

Originally Posted by The Yacht Rigger

Totally agree. With bigger engines it certainly starts to make less sense. Also with that size engine, you're likely on a bigger boat, with more storage, more room for additional chargers and a generator.

On my cat, space and weight are a primary concern. So getting rid of the gen, and more than tripling my charge rate, felt like a no-brainer.

It's also a question of how often you need it. If you only need supplemental charging every once in a rare while, it's not worth carrying extra equipment around. But if you're using it a couple times a week, then a generator starts to look more attractive.

[team karst]

We cant live without the gen. Continuous blend nitrox with a 3hp motor for 6 tanks in series becomes possible. Even as we transition to CCR, the gen is needed for air con and some 50 gal of water daily. I pulled out a 75 gal water tank, which weighed more than the gen, its diesel tank when full, and the WM. [emoji1362]
Surface seawater temperature is now 87 deg F. Fans dont do the job.
We survived a season with the honda2.2kw. I am very much over the 3am gas fills into a hot motor during rainstorms.

[smj]

Originally Posted by team karst

We cant live without the gen. Continuous blend nitrox with a 3hp motor for 6 tanks in series becomes possible. Even as we transition to CCR, the gen is needed for air con and some 50 gal of water daily. I pulled out a 75 gal water tank, which weighed more than the gen, its diesel tank when full, and the WM. [emoji1362]
Surface seawater temperature is now 87 deg F. Fans dont do the job.
We survived a season with the honda2.2kw. I am very much over the 3am gas fills into a hot motor during rainstorms.

Takes us 2 weeks to go through 50 gallons of water.[emoji4] Just shows, different strokes for different folks.

[Simi 60]

Originally Posted by smj

Takes us 2 weeks to go through 50 gallons of water.[emoji4] Just shows, different strokes for different folks.

Same with us, and we have 2500 litres of water tankage and a 150 litre/h watermaker
Tanks never get below 50%

And no air con.