Generator, replace or not

Mako · Feb 26, 2019

Riverguy that's a good call-out of the claims being made. Digital inverter motors however ramp up in speed, they don't rely on huge capacitors to reduce startup draw.

Reference to the laws of thermodynamics, more efficient aircons do reduce power use of course. On another thread it was discussed mini splits with air cooled condensers. A good unit can use 25% less than a typical marine water cooled package unit.

Granted however, most boats don't want to fit mini-splits.

wjstults · Feb 26, 2019

captDJ said:
My northern lights 5kw has died, I like to hear thoughts on replacement vs using the space for battery bank and sizable inverter? If I go the battery option where can I find information on what to buy and install?

I remover our old Onan generator 5 years ago and installed a Efoy Power Cell. We’ve been very happy with this but we have done a lot to reduce our power usage. Our trawler is about 95% DC and has LED lights throughout. We don’t need AC when at anchor so rarely turn on our inventor. For example, we must have coffee in the morning but use a coffee press so just boil water on out propane stove.
We do have 2 DC freezers and found that we had to shut down one for this to work. We could spend 2 to 3 days at anchor without the need to charge with a high output alternator.
2 years ago we added four 160 watt solar panels. We can now run both freezers and if there is good sun stay at anchor for several days.
This setup may not be ideal for everyone but we love the quiet of not running a generator every day.

ranger58sb · Feb 27, 2019

bostew said:
What would determine if it could be rebuilt. I’m in the same situation I just bought a mainship with a 6.5KW NL genset. Only 120 hours on it and a big sell point. 2015 installed. Ran great twice for ten minutes during the survey. I didn’t need it for about a month and it wouldn’t turn over. First we thought bad battery. Replaced, no luck. Called in Norther lights rep. He said it was locked up. They let it set with marvel mystery oil thru the injectors, still locked up. 1k to tell me it’s locked they want another 1k to take the heads off and tell me if it can be rebuilt. They also said it was installed by an unqualified person.
Specifically:
1. the exhaust is too low vs the exhaust riser outlet.
2. there is no loop coming out of the waterlift
3. The clamshell covering the exhaust outlet points down rather than aft.
All this contributes to water easily finding its way into the cylinders.

I feel like if I put another 1k in this unit I’m throwing it in the trash. Am I wrong? Any advice.

I think that's a new genset in an "elderly" boat? If so, aftermarket install. If so, experienced installer.... or not. NL's diagnosis of faults could well be correct...

But to decide how to proceed, first you need to know whether you actually need a genset or not. Must you have A/C and battery charging on the hook, or not. Et cetera.

IF you decide you need the genset, then it's just a question of cost to rebuild compared to cost to buy new.

And then buying new might get back to those same possible installer issues, so installer selection is likely still something to pay serious attention to.

-Chris

Mrwesson · Feb 27, 2019

If you're on a thin budget or need a right now solution you could look into a inverter generator paired with a significant inverter/battery setup.

You open yourself up to potential issues with CO poisoning and having to keep gasoline on board but there are ways to mitigate that risk. I'm not posting any specific recommendations or taking a stance one way or another but we'll just say they aren't uncommon on boats.

If I were you i'd simply shop for a used genset, do every bit of maintenance I could while it was out of the boat, keep the old genset, i'd attempt a diy rebuild, and then sell it. If I got in over my head on the rebuild i'd sell it for parts. 3-5k is a good enough budget to buy a nice used genset. A quick search on craigslist turned up 10 results all under $3,500 ranging from 3-7kw.

captDJ · Mar 3, 2019

Update, I remove the generator this weekend and can confirm it took a solid 10 hours to remove, and that was with removing everything that was bolted on, would not be surprised with a large bill to remove. After all that work, no way I’d rebuild a 10 year old genny and reinstall. I want smaller and better which is what I can find today for 5-6K new.
Thanks again for all the advice and perspectives.
Duane

Ostriman · Mar 28, 2019

OK, I am sure to be stoned for this, but can a portable generator be obtained from your hardware/tool store,and exhaust piped out? Fuel lines plumbed in and installing output wire. I am sure there are lots of reasons not to do this, but just asking as a relative new comer. Whole bunch cheaper, but labor will be hard.
Just spitballing.

captDJ · Mar 28, 2019

I would guess many reasons not to do this, too many to list. I have thought long about a way but considering the safety issues with having a portable generator on deck, fuel/ exhaust, I imagine a 10x unsafe to install underfloor.

FoxtrotCharlie · Mar 28, 2019

"Update, I remove the generator this weekend and can confirm it took a solid 10 hours to remove, and that was with removing everything that was bolted on, would not be surprised with a large bill to remove."

You are lucky - took my guys over 30 hours to dismantle a 30 yr old 15k 4 cyl Westerbeke (in soundshield), remove it from boat, and replace with new Kohler 9k. Includes replacing the entire exhaust hose 25' to the stern. They did a beautiful OCD worthy job, so I can't complain too much. :blush:

Next they are installing our new 3000W inverter - but I will be there to assist - my presence will probably cost me more :banghead:

Need the inverter for our 110v refrig and ice-maker during days when gennie is not required for air conditioning or washer/dryer. Getting ready for the Loop

DavidM · Mar 28, 2019

Ostriman said:
OK, I am sure to be stoned for this, but can a portable generator be obtained from your hardware/tool store,and exhaust piped out? Fuel lines plumbed in and installing output wire. I am sure there are lots of reasons not to do this, but just asking as a relative new comer. Whole bunch cheaper, but labor will be hard.
Just spitballing.[/QUO

No stoning, but it won't work. Portable generators are air cooled. Sitting in the bilge, cranking away and recirculating all of that air cooling heat, it will heat the engine compartment to high temperatures and overheat the engine. 75% of the gas burned to make power goes out as heat, some in the exhaust but at least half in the air cooling.

So of your genset is making 1,500 watts, at least an equal amount of heat is being rejected in the cooling air. That is equivalent to a 1,500 watt space heater running in your engine compartment.

David

Comodave · Mar 28, 2019

Ostriman said:
OK, I am sure to be stoned for this, but can a portable generator be obtained from your hardware/tool store,and exhaust piped out? Fuel lines plumbed in and installing output wire. I am sure there are lots of reasons not to do this, but just asking as a relative new comer. Whole bunch cheaper, but labor will be hard.
Just spitballing.

To say nothing about voiding your insurance if they find out. We bought a boat that someone had installed a non marine A/C in the geas powered engine room. Our insurance company demanded we remove it before they would cover us. We were obviously going to remove it asap anyway because of the danger. Same with a non marine genset belowdecks. Probably even more dangerous.

Ski in NC · Mar 28, 2019

Dave, way more heat than that. A gas genny making 1.5kW of elec power might make 3-4 times that in waste heat.

Absolutely a no-go below deck. Still sketchy above deck.

DavidM · Mar 28, 2019

Ski in NC said:
Dave, way more heat than that. A gas genny making 1.5kW of elec power might make 3-4 times that in waste heat.

Absolutely a no-go below deck. Still sketchy above deck.

Yeah, I was basing my numbers on diesels: 1/3 power/1/3 exhaust/1/3 cooling and a little for engine block radiant/convective heat losses. I knew gassers, particularly small genset gassers were worse, but I didn't know they were that bad.

David

bostew · Mar 28, 2019

ranger42c said:
I think that's a new genset in an "elderly" boat? If so, aftermarket install. If so, experienced installer.... or not. NL's diagnosis of faults could well be correct...

But to decide how to proceed, first you need to know whether you actually need a genset or not. Must you have A/C and battery charging on the hook, or not. Et cetera.

IF you decide you need the genset, then it's just a question of cost to rebuild compared to cost to buy new.

And then buying new might get back to those same possible installer issues, so installer selection is likely still something to pay serious attention to.

-Chris

Well your right it’s an old boat. The PO did the install in 2015 he put a total of 120hrs on it. I spent a day at the boat looking it over the genset I mean. I was surprised to find while they were looking at it they just took a saw and cut the water hoses away instead of removing them. Took the injector lines off and cover plates. Diesel and antifreeze in the bilge stinks to high heaven. Did see that the exhaust comes out just Above the water line with a cam shell facing down. When the exhaust on the engine blew out it’s possible it could have been under water but with certainty I can say we never ran the genset from the time I bought the boat until maybe a month after we had brought it to Solomon’s and that was just an attempt to start which it never did it so water never got sucked up. But at this point I’m probably going to disassemble it lift it out and take it home to rebuild. I’m tired of being upset with it. Frankly we don’t need it at least for now.

Ostriman · Mar 29, 2019

I have a very happy diesel generator in ER, but bud has problems and set a nice unit on back deck. Quiet. Ran cords below. Has to add gas on deck, which is a bit iffy. What is famous quote on here? What some guy says he got away with?

FF · Mar 30, 2019

If you have a davit for the dink , or a lift post to bring the anchor aboard simply hanging the Honda solves most fears.

In the Carib some charter folks would place their noisemaker in the dink trailing aft.

Montenido · Mar 30, 2019

I just returned from a trip to the boat down in the Sea of Cortez. I've been having generator issues (won't stay running), have replaced the fuel solenoid with no love, and had a guru look at it. The guru told me to order a specific part, available only in the USA, and it turned out to be the wrong part. :banghead:

So rather than being stuck in the marina for two weeks, I bought a Honda 3000 genny. I ran it in my cockpit, exhaust pointing out the open transom door, to charge my batteries. It was a pain to keep fueling it, due to the small gas tank, but it definitely solved my charging problem. Now I have a back up generator if needed.

I don't recommend it as a permanent solution, but it does work in a pinch.

Cheers, Bill

FF · Mar 31, 2019

"It was a pain to keep fueling it, due to the small gas tank,"

Modify it so it can use a 6 gal outboard tank , switch them as needed.

Ski in NC · Mar 31, 2019

Riverguy said:
Re: "A gas genny making 1.5kW of elec power might make 3-4 times that in waste heat."

Absolutely no. Wrong. Off by an order of magnitude. Since I've already debunked this (common) myth above, I won't go through it again here...other than to re-post the link to the physics...

https://www.e-education.psu.edu/egee102/node/1942

Wrong. You got some bits right, but still way off.

A gasoline engine does not run on the Carnot cycle, but the Otto cycle. Math is quite different there.

A typical gasoline engine runs about 20-25% thermal efficiency at best load, even worse at light load. Thermal efficiency is defined as useful power out compared to the energy content of the fuel burned. Cheap emergency gennies are not made for efficiency and who know how much worse they are.

Theoretical efficiency of the Otto cycle can be quite a bit higher than 25%, but that is theoretical. Get a new gennie out of the box, crank it up and measure burn rate compared to actual kW produced and compare the numbers. Shocking poor efficiency.

Say you have a decent one that is 25% efficient. It is making 1.5kW of elec power. Every bit of energy consumed that is not converted into elec power comes out as heat (well, maybe some as noise). That is 4.5kW of heat rejected, some in engine air cooling, some in exhaust heat. But the total of heat rejected will be around 4.5kW.

If running at 20% efficiency, heat rejected is 6kW.

Run one at no-load, all the fuel consumed goes into heat (and noise)!

Riverguy · Mar 31, 2019

Ski in NC said:
Wrong. You got some bits right, but still way off.

A gasoline engine does not run on the Carnot cycle, but the Otto cycle. Math is quite different there.

A typical gasoline engine runs about 20-25% thermal efficiency at best load, even worse at light load. Thermal efficiency is defined as useful power out compared to the energy content of the fuel burned. Cheap emergency gennies are not made for efficiency and who know how much worse they are.

Theoretical efficiency of the Otto cycle can be quite a bit higher than 25%, but that is theoretical. Get a new gennie out of the box, crank it up and measure burn rate compared to actual kW produced and compare the numbers. Shocking poor efficiency.

Say you have a decent one that is 25% efficient. It is making 1.5kW of elec power. Every bit of energy consumed that is not converted into elec power comes out as heat (well, maybe some as noise). That is 4.5kW of heat rejected, some in engine air cooling, some in exhaust heat. But the total of heat rejected will be around 4.5kW.

If running at 20% efficiency, heat rejected is 6kW.

Run one at no-load, all the fuel consumed goes into heat (and noise)!

Thank you, I stand well corrected. The math on the Honda 2000i is 7.4 kWh from a gallon of gas (from my owner's manual) and a gallon of gas is worth about 33 kWh, so 22% efficiency.

High Wire · Mar 31, 2019

Montenido said:
I just returned from a trip to the boat down in the Sea of Cortez. I've been having generator issues (won't stay running), have replaced the fuel solenoid with no love, and had a guru look at it. The guru told me to order a specific part, available only in the USA, and it turned out to be the wrong part. So rather than being stuck in the marina for two weeks, I bought a Honda 3000 genny. I ran it in my cockpit, exhaust pointing out the open transom door, to charge my batteries. It was a pain to keep fueling it, due to the small gas tank, but it definitely solved my charging problem. Now I have a back up generator if needed.

I don't recommend it as a permanent solution, but it does work in a pinch.

Cheers, Bill

Make sure you are running ECO THROTTLE ON! Makes a huge difference in fuel consumption.

Ski in NC · Mar 31, 2019

Riverguy said:
Thank you, I stand well corrected. The math on the Honda 2000i is 7.4 kWh from a gallon of gas (from my owner's manual) and a gallon of gas is worth about 33 kWh, so 22% efficiency.

While you typed, I did a little checking on the 2000i

0.95gal capacity, run time 3.4hr at full load, 8.2hr at 1/4 load

The thing is rated at 2kW at full load, but 1.6kW continuous. Not sure if the burn rates are referring to 2 or 1.6kW. I'll assume 2kW.

So at full load 3.4hr at 2kW is 6.8kWh. Using 33kWh/gal for gas and 0.95gal tank, efficiency is 21.6%.

At 1/4 load, 8.2hr at 0.5kW is 4.1kWh. Tank has 31.35kWh (0.95x33) so efficiency is 13.1%.

Shows how gas engine efficiency really drops off at light load. Diesels drop off too at light load, but not that much.

CapnCrunch · Mar 31, 2019

Montenido said:
It was a pain to keep fueling it, due to the small gas tank, but it definitely solved my charging problem. .

Since the Honda 2000i is fueled by a pump rather than gravity, you can buy a cap for the tank that lets you hook it up to any size external tank - like the one used for your outboard.

DavidM · Mar 31, 2019

I never argue with Ski, except maybe chemistry stuff. He is a degreed ME and a great engine mechanic. Can’t beat that combo.

David

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