Replace the genset with an inverter

H

Happy Feet

New Member
Jun 29, 2022
4
Boat Info
2007 Sea Ray Sundancer 340
Engines
Mercruiser 8.1 vdrives
Got a 2007 340sda and considering replacing the dead generator with an inverter and lithium batteries. Anybody done this? Currently need up to six hours of run time. Would like enough power to run the AC. Would charge from shore power.
 
There are a number of threads on here concerning inverters, and batteries to do this, but its a long discussion, and a major engineering project. If you have the technical expertise and budget, most certainly can be done.

http://www.clubsearay.com/index.php?threads/inverters.89680/#post-1013207

I have just installed 2x 304 LiFePo4 batteries connected to a Magnum 2800W inverter. More designed to power kitchen appliances, but a couple more will run the Front AC for a night.

http://www.clubsearay.com/index.php?threads/lifepo4-battery-build.106858/

Charging them in a reasonable time frame then becomes the issue.
 
Search on @ttmott, he's in the process of converting to Lithium, and you can get an idea of the complexity issues and cost.
 
Hoplite808 said:
Better to get a generator to replace a generator with. The size lithium batteries and inverter you’d need to run the AC would be ridiculous.
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Nah, he can just get a Honda 3000 portable and run it to charge the batteries. LOL
 
Consider the impact on resale as you make these decisions. Future prospective buyers would likely need to be one percenter nerds (like many of us here) to ever consider buying a boat with that kind of battery/inverter setup.
 
Just spit balling here.

On a 340 with a single 16K BTU AC unit and a pump to feed it cooling water, your drawing about 1700 Watts x 8 hrs of run time = 13600 W Hrs on the AC Side. Your Inverter is probably about 85% efficient and realistically you can only use about 80% of the capacity in a LiFePO4 battery bank, so youll need about 20000 WHr battery bank. That works out to about 8 200AH batteries just to run the AC. At current pricing, your battery bank is about $8K-$9k, and the inverter system another $3-$4K

Assuming you can charge the battery bank back at 100A (using generator or shore power) it would take about 12 hours to recharge the used energy. If you want to charge it faster, you'll need to look into some high output alternators

It adds up fast cost wise and finding the space for the batteries is probably unrealistic on a 340.

My guess is, rebuilding the genny would be much much cheaper, and also improve your resale value. You dont say if the issue is on the motor end, or on the electrical end, but both can be rebuilt (fairly inexpensively) and are fairly common MX items on all Sea Rays.

And for the record, DO NOT put a Honda generator on your deck or swim platform.
 
OP, you are getting some good advice here. Repair that genset. It will be money well spent. When you go to sell your boat, the price you get will be higher if you have a running generator. Augment with an inverter/battery bank if you want. They are handy for non-AC uses while anchored if you don't want to run the generator. (and DON'T use a portable generator - that was a joke)
 
Hoplite808 said:
Better to get a generator to replace a generator with. The size lithium batteries and inverter you’d need to run the AC would be ridiculous.
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Size per size. You could overnight with a bank of lithium batteries the size of the generator. Maybe even a couple of nights.
 
jmauld said:
Size per size. You could overnight with a bank of lithium batteries the size of the generator. Maybe even a couple of nights.
Click to expand...

This isn’t realistic unless you have unlimited funds. Cheap batteries would be big and take up more space than might be available after the removal of the old generator and probably would be less safe. As Dtfeld pointed out the cost of the batteries would be around $10,000 and the inverter another $3000-4000. The best batteries out there will still only have a life expectancy of 5-7 years and that’s only if they are exercised properly. $10,000 every 5-7 years to keep the system working is not cost effective. The other consideration is that you’ll have to hire a professional electrician, probably another $5,000-10,000, to wire the whole thing, otherwise I can guarantee your insurance won’t cove jack diddly on your boat which is now a giant fire/explosion hazard if wired at all incorrectly. The fire on the Conception that killed all those people was a lithium battery fire if memory serves. You would neither be saving money or the environment with this setup. If you were just worried about fumes from the generator you could always switch it to one that is powered off of propane.

https://www.ntsb.gov/investigations/AccidentReports/Reports/MAR2003.pdf
 
Outcome of the conception fire investigation: “The National Transportation Safety Board determines that the probable cause of the accident on board the small passenger vessel Conception was the failure of Truth Aquatics, Inc., to provide effective oversight of its vessel and crewmember operations, including requirements to ensure that a roving patrol was maintained, which allowed a fire of unknown cause to grow, undetected, in the vicinity of the aft salon on the main deck.”

IOW. They don’t know. And you should know that there are several different lithium battery types on the market. Some are ”claimed” to be as safe as AGM batteries. While others are many times more hazardous.

What are you basing your 5-7yr battery lifespan on? This is something that will be dependent on many factors just like the fire hazard.

The battery option isn’t a cheap option. I’m not arguing that. Charging is also a significant hurdle for a large bank. But if OP has the coin and isn’t trying to operate away from the dock for more than a weekend, it is an option they can pursue.
 
Hoplite808 said:
This isn’t realistic unless you have unlimited funds. Cheap batteries would be big and take up more space than might be available after the removal of the old generator and probably would be less safe. As Dtfeld pointed out the cost of the batteries would be around $10,000 and the inverter another $3000-4000. The best batteries out there will still only have a life expectancy of 5-7 years and that’s only if they are exercised properly. $10,000 every 5-7 years to keep the system working is not cost effective. The other consideration is that you’ll have to hire a professional electrician, probably another $5,000-10,000, to wire the whole thing, otherwise I can guarantee your insurance won’t cove jack diddly on your boat which is now a giant fire/explosion hazard if wired at all incorrectly. The fire on the Conception that killed all those people was a lithium battery fire if memory serves. You would neither be saving money or the environment with this setup. If you were just worried about fumes from the generator you could always switch it to one that is powered off of propane.

https://www.ntsb.gov/investigations/AccidentReports/Reports/MAR2003.pdf
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Let's not overreact.
Today's LiFePo batteries are as safe as any SLA battery. Also lithium FePo have a life expectancy of 15 years with an amazing 70% useability remaining. Some replacement warrantees are even 10 years.
It appears to me that you will need upwards of 2000Ah of energy to do what you want. So that is around 2500 rated capacity. Right there in commercial batteries you are at about $25K invested just in batteries. Then the Inverter(s), control and monitor system, wiring, circuit breakers, buss bars, fuses, etc etc, add another $8K. You will need the system engineered and installed so let's plan another $6K. Right there we are around $39K. Then you still need a means to charge the system so a generator is needed anyway (albeit a much smaller generator)...
Unless this is a project you want to do because it's a cool project and fun to implement, it's absolutely not cost effective.
I completely disagree with the loss of insurability and loss of value; If the system is implemented in a professional manner, well-engineered, and meets the ABYC requirements, I suspect your boat is as marketable as any other.
 
I just did a LiFePo install on our 500DA. I put in three, 200aH LiFePo batteries, and a Xantrex 3000W inverter. I sized the batteries to handle all expected 120V loads, which for us would be, currently, the salon fridge (120v only), icemaker, lights, microwave/convection oven, coffee maker, etc. When this boat gets to Florida, it will have a watermaker installed as well. This was designed to augment the generator, not replace. A/C units are 240V, as is the hot water heater and the stove, so the genny is still needed. The biggest reason for this upgrade was the Admiral (aka, the Spousal Unit) didn't want to have to run the genset 20 hrs a day to keep the fridge alive, and wasn't willing to give up cubic feet of fridge space to go to a AC/DC fridge.
 
Wow, a first post and a bunch of answers. Thanks to all, even to the ones that were done in jest.
Bottom line for me I still have a decision to make. I have a professional generator company quoting $15,000 +/- for the inverter and 2 batteries although 3 batteries seems to be a better fit for my intended use. That’s another $3300. New genny $20,000 and a 3 to 4 month lead time; inverter and lithium battery system with three batteries $18,000 done in a month.
 
Can you post the specs on the inverter / battery system?
 
Happy Feet said:
Wow, a first post and a bunch of answers. Thanks to all, even to the ones that were done in jest.
Bottom line for me I still have a decision to make. I have a professional generator company quoting $15,000 +/- for the inverter and 2 batteries although 3 batteries seems to be a better fit for my intended use. That’s another $3300. New genny $20,000 and a 3 to 4 month lead time; inverter and lithium battery system with three batteries $18,000 done in a month.
Click to expand...

How would you recharge the batteries? Not poking fun, genuinely interested.
 
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