Inverter vs Genset

I've never been able to justify a large inverter system on a boat, the cost of maintaining a large bank of batteries, chargers , and inverter vs running a generator don't make sense. Fix the main gen and look into installing a smaller night gen when your inverter system needs new batteries or major repairs.

I agree with bayoubud. I've considered an inverter numerous times. But with the electrical load requirements I just can't get enough run time from the batteries. Originally, my boat came with just a 20kw gen. It has has been modified to add a much smaller 9kw in addition to the 20kw. The 9kw runs 90+ % of the time considering I don't need A/C and heat is now from a diesel boiler vs. reverse cycle on the a/c chiller units. Even without A/C, the galley refrigeration, cockpit freezer, ice machines, etc. just draw too much load. The only way I would be able to use an inverter would be when the mains are running to keep batteries fed. That seems contrary to the point of an inverter.

Also need to consider that battery life will be greatly diminished with increased depth of discharge. Every time you draw a battery down a certain % and charge back up you have put the battery through a "cycle". Most batteries have a cycle time rating based on a very low % of discharge (yes, even deep cycle). So if you are going to consistantly draw a battery bank down by more than 20% (some even 10%), you will likely be very disappointed in the life span of your batteries.

That was PacBlue but I'll take credit ........

All good info. My point was in response to OP who said he was looking at an inverter in lieu of replacing his gen. So the question was about having an inverter without a generator. I believe this would be a mistake IMHO.

OP needs to fix the Gen with same setup as Pascal's, both have same size Hatteras. Your right Inverter only power source would not work well for size of boat and equipment.

There are actually all electric high end RV's being designed as we speak. (Not by hobbyists, by the big guys). And you charge it with a modern alternator while driving. Technology there too is developing. CAN bus controlled high output alternators (even at idle) without the cooling issues... etc. etc. You can stuff a LOT of LiFe under the kitchen floor of a Hatt galley. And they weigh a lot less than lead acid/AGM etc....

It's coming. That said, it's VERY expensive to do it right. The genny is, still, the most cost effective solution.

So to the OP, unless you're in it for the science and have an "open checkbook policy"...... just get a nice fresh genny.

ACTUALLY, the 53' Hatteras was designed to be run with the generator on always. The air horns are powered by a 120 volt air compressor in the engine room and the electronics battery is also the generator battery bank......so either the generator alternator OR it's battery charger charge it. Can't charge it with the engines because it's a 12 volt bank.

Sea Lion post #23 is interesting. Intergel Solutions, a generator system that mounts to the engine and can charge at idle. The video showed charging lithium ion batteries which are great but very expensive, 8D's cost about 2k to 3k depending on amperage. Did not see a cost for the system but said it will also charge AGM's.

Yes it works. Yes it's expensive to install. And I don't like their presentation in that it is trying (too) hard to sugarcoat the fact that main engine fuel consumption WILL go up. Every horsepower has a price. The laws of physics apply.....

These type gens would eliminate most of the maintenance required by conventional gens. Just think, no thru-hull, raw water strainer, impeller, HE, zincs, oil change! Sounds good to me! I doubt the fuel cost on the main engine would be any more than a regular gen. BUT, CaptJ says it will not work for the 53 Hat, would require electrical mods.

I think it is very plausible. However, if you are sitting at anchor for an extended period or even a dock or slip without shore power, do you really want to have to run a main engine to charge batteries once they get depleted? And how long and how often would you have to run that main to get batteries charged back up? Better yet, do you want somebody next to you running their m/e at idle for hours because they have no gen?

Plus AC and A/C underway at all times. And on the hook for a while with a big enough bank. Lithium batteries are getting better and cheaper and can be more deeply discharged and more quickly recharged for more cycles than FLA/AGM etc. Maybe cheaper than FLA/AGM in the mid-long run by now, but I haven't analyzed it that deeply, and the analysis is VERY application specific. It's safe to say that the best battery setup is as easy to agree on as the best anchor.

Agree, idle hrs. not good on hi-performance marine engines. Might work on small mains.

As Sea Lion just posted, very application specific. Probably worked well on that Catamaran in the video. Most likely small mains. System as designed probably works best for moderate loads. Still a good concept, on the right boat would be a good system.

True. All the Li family require a BMS and smart charging to monitor for overheating, etc.

I reviewed the Integrel site and watched the video - I offer these comments. The Integrel system includes additional and updated components that represent performance improvements, but the idea is the same as the system I have on my trawler - I could say, in jest, that they adapted my idea.

FYI, I have a 340 Ah 48 VDC battery bank and a 3kW inverter/charger, no generator (yet). I have identified 2 vendors who can provide a 48 VDC engine driven alternator/regulator/charge controller, but I have not yet moved on that.

Based on the research I did, the Integrel claim of 9 kW from their engine driven unit is optimistic. Both my vendors say they can provide a 100 A maximum 48 VDC alternator on a conventional high output alternator frame - a separate drive belt would be required, and the pulley would be sized to operate the alternator at about 2500 - 3000 RPM when my Cummins 6BT -5.9 is at 1950 RPM cruise. This would be 4.8 kW, a conservative match for the 3kW inverter/charger, and I will have ac underway, and the 48 VDC bank will be topped off when I'm finished with the engine - I don't plan to run the engine when not underway, and won't have ac off of shore power. The load on my 210 HP engine would be about 6.5 HP (4800 watts divided by 746 watts/HP = 6.43 HP. Integrel's 9 kW alternator (don't care what they call it) would be 12 HP. I don't doubt they can provide a 9kW alternator, but I need to be enlightened about how a 30-40 HP sailboat auxiliary diesel can output 12 HP just idling along. Their advertising is true though - you can do without the generator, you just have to accept a bit of sacrifice of comfort.

As we have discussed earlier, the 48 VDC lithium technology battery bank shown in the video is latest technology, and, IMHO, the correct choice for their system. The many advantages of a 48 VDC bus, in addition to the 12 VDC system retained, is a topic for another thread. I don't know about 48 VDC appliances, but these folks are not US based.... Also, it would take a big 48 VDC bank to provide much ac overnight .... But you can't please everybody.

Dream system ( or nightmare based on your view). Separate 12 VDC or 24 VDC system for navigation electronics, running lights, engine power and starting, bilge pumps, etc. Inverter based 230/115 VAC system. Primary and secondary high quality inverter/chargers, switch selected, correctly sized for worst case loads. 48 VDC input, 230/115 VAC output. 48 VDC lithium technology battery bank, sized per your wallet, charged from 2 sources. Source 1 = shore power via inverter/chargers. Source 2 = Onboard new diesel generator (this is technically an alternator) - product of established marine rated equipment manufacturer. 48 VDC output, sized for worst case loads. Although not typically marinized, these units are often used for backup power for long line telephony equipment stations, and marine rated units will be available soon if not already.

In my opinion, this configuration would be very robust, and expensive, but practical up to about 12kW. Because of the control capabilities built in to the modern inverter/chargers, there would not be a need for much by way of interfacing components - only primary/secondary inverter switching. Larger boats, larger systems, multiple generators, another discussion.

Briefly, the advantages: Clean power, at proper/consistent voltage, for all onboard equipment, no sags or switching of power under normal circumstances - the inverter (virtually no moving parts) operates 100% of the time, even shore power quality issues are eliminated. Generator (alternator) run time is minimized to reduce maintenance and fuel cost. Automatic operation. 12/24 VDC batteries charge whenever there is a need, without engine run. No need to over-size the generator to provide for starting motors.

Thanks. I especially appreciate those posters who have provided their descriptions of inverter issues.

Joe

Yep, did not consider that. Still a good system with AGM's on the right boat.

What is so wrong with running a generator? They burn next to nothing in fuel and they do the job.