Generator pros / cons - seeking advice

[tpd]

Hello Forum members

We are taking delivery of an SO 440 in July and are trying to decide if we should install a generator.

The installer recommends the Next Gen ultra compact marine 9.5kw generator. link Given the all in install cost (~USD20,000), we really aren't sure we should do it.

The installer has also recommended upgrading the stock alternator to a GenMaxx super high output 250 amp unit, which has been pitched to us as a 'generator eliminator'. link 

So we're seriously questioning if we want both. We're basic coastal cruisers around the north east US, and will keep the boat at mooring in Long Island Sound.

We went for the lithium battery bank and have the boat wired for the generator. We did not go for the solar. Thinking about that for an aftermarket job once we've had the boat for awhile.

Appreciate any thoughts and recommendations.

best
Tom

[Zanshin]

Before making a decision on the alternator upgrade or the generator, think about how you are going to use the boat when aboard.

Add up your power usage per day in Amp-Hours (add in fridge, freezer, instruments/autopilot while sailing, lights, stereo, ice-maker, phone chargers, etc.)

Once you have that number, calculate how long you would need to run your engine to replace those amps. With lithium batteries the number is a lot lower than with traditional lead-acid batteries, since the charge profile is linear.

I have a 10kW generator and I use it for charging and for high-drain things like my dive compressor. But I'm a full-time liveaboard for 6 months of the year. And I have other high-drain items like a washer/drier and a watermaker.

[puravida35]

2016 SO439: We had a NextGen 5.5kw installed during commissioning. We have been very happy with the generator with only one issue due to the on/off switch failing. Replaced it and all is good. The unit is able to drive all 3 hvac units plus all other house circuits. Our boat is on the Texas coast (very warm summers), I think the 9.5kw might be a bit oversized for a SO440.

[NZL50505]

Zandhin is right in his approach to making this decision.

Bottom line, if you think your normal engine usage (for moving the boat around) plus solar / wind would deliver 75%+ of you power reqs then no need to invest in Genset - just add the high output alternator and run the engine a bit more at anchor.

But if normal engine + supplementary power is much less than that, go for Genset.

Another consideration - if you’re at a marina plugged into shorepower your batts will always be perfectly conditioned when you arrive at the boat. But on a mooring there’s a chance they are less than well-conditioned unless you have ample solar and / or wind. If not, that would swing the argument in favour of Genset because after a few hours running over a weekend that would help recondition the batts.

[loredo]

My advice, coming from my personal experience using my boat similar to you would be :

Skip the generator. In place of the generator install the largest battery bank possible and a very powerful inverter.

On my SO49 there was the factory installed 4.5KW generator and at 15 years old had 120 hours on it.  95% of these hours was running the genny to keep it exercised. For coastal cruising I would only install the largest externally regulated alternator possible.  Then I'd install as much Lifepo batteries as possible. That and a big inverter should do the trick.  Should you later then want to do "more", then you can always add solar to keep the batteries topped up.

My still relatively new to me J57 has also a 9.5KW generator installed. In three years I've NEVER used it for it's intended use but only to keep it exercised. During the winter I installed a 1680AH @ 24V DIY LPO house battery bank (That's roughly 45KW energy stored.). Since the install I've used the shore power charger only once.  And that was more to see if everything works. I also have a high output externally regulated alternator and he is enough (in MY use case) to keep the batteries happy.  Now, if I would get rid of the genny and use that space also for LPO batteries I think I'd need to charge them maybe once every couple months. That I can do on shore power in a marina...

The only exception to the above is HVAC.  While running an air conditioner on batteries is possible, they're very power hungry. Yet, I've never felt the need to use the HVAC while on the hook but only in a marina.  In a marina there's shore power...

[moonshadow]

I have a 7.5kw Onan generator factory installed on my 2014 SO469. My use pattern is 6 months each winter cruising in the Bahamas and occasional week long trips in the hot, humid Chesapeake Bay during the rest of the year. I usually don’t spend night at marinas when traveling. Large battery bank and solar are adequate for my needs except in the few winter months with short daylight hours. 9 months of the year my solar keeps up with my daily electrical needs with occasional motor use when leaving anchorage etc. I find the generator a great addition to the boat.
I know that the generator is an expensive option. But the factory installation is very quiet and fuel efficient. The gen gives me the option of a good way to charge batteries when needed. Also I have a 120v Watermaker that produced about 35-40 gal/hour. And it’s nice to use air conditioning when I want to dry out the humidity in the boat. When cruising I run the generator once or twice a week for these purposes. So I like having it on the boat. I am sensitive to noise and try to avoid annoying others when I am anchored near them. I have never had another boat say they heard my generator running. It’s a lot quieter that running the engine to charge batteries.
I really can’t say whether it is more efficient to run engine or the gen to charge batteries. My engine has a 120 amp alternator, well regulated with temp probes etc and I haven’t measured fuel burn at lower rpm’s. But maintenance is based on engine hours and is sometimes difficult when cruising. Using the generator likely reduces total engine hours enough to make a difference. The Onan generator has been very reliable and maintenance is a once a year chore. I don’t know if the newer generators that Jeanneau is installing are performing the same.
Overall I think it is an important item for my style of using my boat. Is it worth $20,000? Probably yes for me. If I took shorter trips and did more marina stops or motored more when traveling, maybe not.
I hope this is helpful. Paul

[shenandoah]

We opted for lithium batteries and an inverter and no generator and have no regrets. One additional benefit to not having the generator is that we now have a very large storage locker. We have the three cabin layout and the added storage is a huge benefit. 

The only thing we would ever need a generator for would be air conditioning, but for us if it is that hot then we are not anchoring out. Twenty thousand dollars will buy a lot of nights in a marina plugged in to run the AC.  In the Northeast I can't imagine needing to run the AC very often. 

Having said that. The options you listed are not the factory options. They would be installed aftermarket, so why not wait and see? 

Warm regards,

Chuck

[tpd]

Hi all;

I'd like to close out this thread and reflect on what we actually did.

In the end, we installed a Cummins Onan 7.5Kw generator. We did not add the GenMaxx super high output alternator.

For the benefit of others, I feel the need to share our experience.

We ordered the SO440 with the lithium house battery option. It came with 2 x 90Ah Super-B Lithium batteries. Based on the demands we put on the house battery system, this is woefully inadequate. I want to expand capacity, but cannot simply add more Super-B 90Ah batteries because they are no longer for sale! So, my new off-season project will be to replace the battery bank.

I'm glad to have the generator so we can charge the house batteries. More importantly, it is necessary to run the air conditioner when not connected to shore power. Since we moor our boat, having the option to run the AC, even for a bit, is awesome. I'm aware it is possible to wire the AC so it runs off the battery bank, but the SO440 comes with 3 AC units, and running all would drain the house bank pretty darn quick.

Lastly, it's worth noting that when we ordered our boat, Jeanneau was NOT able to offer it with the generator installed. It does come pre-wired for the Cummins Onan unit. We got incredibly lucky and were able to secure one on our own. However, it's a bit frustrating to invest in a beautiful boat and then have to figure out the generator ourselves.

Many thanks to those offering feedback. 

best
td

[shenandoah]

Glad it worked out for you. Just curious. Did you confirm directly with Jeanneau that they would not install a generator in the factory? I know they did so when we had ours built and that seems very strange. Sounds like something a dealer might make up because they would make more by selling and installing the generator themselves. 

just curious. 

[moonshadow]

For a while last year Jeanneau resorted to shipping boats without generators to the USA since shipping the boat takes a month and lots could get done while waiting for the generators to arrive. The plan was to airfreight the generators when available.