Inverter Question

[Notniuq21]

Hello Trojan Forum,
Well, I’m about to pull the trigger on a 1985 10 Meter Sedan Convertible. I and the surveyor are just trying to figure out a good time for both of us to do the survey/sea trial. Anyway, during the period when I was looking at the boat until a few weeks later when I made an offer and the owner accepted there was a kohler generator. A few days ago he calls me and says he had to pull the generator out because it wasn’t working. He tells me that he spent close to 4K installing a 6500 W Inverter with a 12000W startup capacity with a 9 bank battery system. He said this would power all my needs. I was a little surprised at the moment, especially since he just spent 4K. He stated that he would make this money back when he fixed the genny and sold it later. Right now he just wanted me to have power for the boat. So far, he has been very honest showing everything he has fixed/replaced/updated…..for which I’m very grateful. My question is will this inverter be able to supply power for the reverse cycle air/heat system if I’m on the hook. And what about the other electrical items? Appreciate any info, help, or critiques about this .
Thanks in advance,

Ed
South Jersey, Delaware Bay

[ready123]

Short answer is yes as it equates to approx: 100 Amp service..... What is key though is the rating of the batteries to say how long you can draw 120V at what amps and then how do you charge them back up.... no genny means shore power. Size of charger gives an idea of how long to get them fully charged.
Personally had it been mine I would want the genny...... I'm not a big fan of Inverters for large loads as the whole idea of starting with AC going to DC and back to AC is just inefficient.

You need to decide on the risk of loosing your AC power while out on the hook early and it's effect on your day or w/e???

For me if I have to come back to a marina in the middle of my trip because my Inverter is dead just does not attract me..... generator all the way is my style. My inverter barely makes coffee, my genny runs the whole boat including A/C, stove & hot WATER!

[The Dog House]

+1. A generator is what you want. Inverters may be good for small loads, but if you plan on being on the hook for any length of time you will want a generator.

I question why the current owner would remove the generator and spend $4K on an inverter setup without consulting the prospective buyer. He just changed the makeup of the boat considerably (and spent $4K doing it) without knowing if this is a change you want. I personally would back out of the deal and look for a boat with a generator.

[prowlersfish]

+1. A generator is what you want. Inverters may be good for small loads, but if you plan on being on the hook for any length of time you will want a generator.

I question why the current owner would remove the generator and spend $4K on an inverter setup without consulting the prospective buyer. He just changed the makeup of the boat considerably (and spent $4K doing it) without knowing if this is a change you want. I personally would back out of the deal and look for a boat with a generator.

I agree ( with ready too )

Something sounds very wrong . Why spend 4k on a inverter system ? He could find a used generator for that I would think or fix the old one .
My thoughts is the gen set was shot and he put in a inverter for less the 4k ( a lot less ) or sold the get for $$$$$ ( or saving it for his new boat )

I would walk or knock off 8k , and see what else ha been swapped or striped .

Be careful his this seller

[yorklyn]

Agree with Prowlerfish. somethings odd. he could have just told you the gen was not working and lowered the price? if it was the original 6.5 onan they are very hard to get parts for and the parts are $$$$$ if you can find them. Do you know what type of genny it was? any chance of him including the old broken gen with the boat?

[Notniuq21]

Hello….
I want to thank you all for excellent input and advice! I was basically thinking the same thing, but I guess I just wanted to hear it from the Trojan forum. Yorklyn….you are correct, it is an Onan 6.5, my mistake. It really perturbs me because it took almost 2 years to find this boat. It has everything I wanted and was looking for. I know that he did a lot of work on it because we kept in touch for about a year and he would tell me every detail when he did something! But taking out the genny really threw me for a loop…especially since I was ready to do a survey and all. I sent him an e-mail asking for more detail. I definitely think this will be a deal killer. I will keep you updated when I hear more.
Once again ….thanks again for all your help!
Ed

[prowlersfish]

A few questions Did you have a contract and a deposit ? If not its possible he did not know how serious you are as you been talking for a year and had not pulled the trigger yet . when you said a Kohler I assumed it was a newer set then the old Onan . how will you use use the boat will be a factor on who important the gen is to you .

[Notniuq21]

UPDATE: Received e-mail from owner. Thanks again for all your help.

"Ed, Let me explain a little something to you about myself, I am an electrical engineer and my main business is building generator and alternative energy systems. In the past 40 years I highly doubt anyone in this country has had more experience in this area than myself. I designed the system for the fenceless border protection system for Lockheed. These boats are a hobby and a small extension of my other business. I did not change the system for your benefit,I did it for my self in the event I would keep this boat as most of the potential buyers have been pretty flaky. One thing to keep in mind is the fact that the reverse cycle system for air only works one ac unit when not on shore power. The Onan unit was, as most were, a 120 volt unit supplying the primary 120 volt system. --The Onan suffered a direct shot of water from a hose leak and shorted itself. This is the most common problem with all marine gensets as small as this one. By your description this is a (big boat) which it is really not. The designed system for 120 volts at sea is based on a 30 amp feed. It would be sufficient to feed this system with a 4 kw unit. The Onan was a 6Kw.--I installed a 6KW inverter with a 9 battery storage bank of deep reserve marine batteries which is charged either dockside or by the two 150 amp alternators on the engines. This system at rest would give you 900 minutes of reserve at full draw of 6,000 watts.That translates to 15 hrs.---The likelihood you could draw 6000 watts is for all intent and purpose very remote.--The AC system is the most efficient style for power consumption as its merely taking its cooling from the differential temperature of the water to air much the same as modern geo thermal systems in homes.---The unit when running draws about 7amps or 840 watts per hr. --At maximum the Microwave would draw 1000 watts/hr.---The stove would draw 1840 watts max /hr.--Hot water heater rated at 1840 watts.---lights and refrigeration might draw another 600 watts combined .--------That's a total of 6,120 watts/Hr.-----
Now by common sense you will understand that you will never have this wattage combination running all at the same time or continuous for any 1hr period or anything close to it. At the most you may run at a 20% capacity draw under normal conditions. Translating that would equate to nearly 75 hrs . of operation prior to drawing down the reserve. ---- The other factor you may not have taken into consideration is the fact that the main engine alternators will recharge the batteries fully in about 3 hrs. ---That's a lot less fuel than running the generator for 75 hrs .at 1.3 gallons per hr. and certainly one hell of a lot more quiet than the generator plus nothing to maintain.---
In so far as advice from other boaters----most know just about enough to turn the key and that's it. Most inverter systems you would see on boats this size are only there to provide a minimum of electric without the use of a generator. Not for live aboards .This system would run most standard homes and through out the Caribbean and islands they do!
Money was not my concern here as much as reliability and performance, I will rebuild the genset and get my investment back .Owning a boat can be one problem after another in mechanicals and everything you can do to reduce that makes ownership more pleasant.I would rather drive it than fix it!
One last tidbit of info to keep in mind is that this is an intelligent system which monitors battery voltage and usage. Should the system draw the batteries down to an unsafe level it will self monitor and shut down the inverter to leave sufficient engine starting capability.. "

[prowlersfish]

Sounds great on paper . But I can poke a lot of holes in this . And I will when I have time as I am on a short break , But lets start with the 150 amp alternators that's great if the upgrade from 55 amp to 150 was done right . better brackets , dual belts the alt should be larger not a bumped up small frame alt . 150 amp alt is not made to put out 150 amps constantly , it won't last . It also needs rpm to put out max output can't just sit and idle to get it . Love to see photos of this alt up grade .

[gitchisum]

Wow!

I wonder what else this "expert" changed? I for one, would run, not walk, away from this!

There are many boats on the market!!!

[bjanakos]

The bottom line is he accepted your offer on the boat with a particular configuration. Then he made a change after the fact. That contract is nullified.

[captainmaniac]

I haven't seen any comments in any of the posts (or the seller's letter) to state where the inverter in question or batteries are located on the boat, is there proper ventilation for when the batteries are charging (to disperse the hydrogen gas that will be produced), whether the upgraded alternators and inverter are marine versions (ie ignition protected), and if marine grade wiring was used for everything. Since he decided to bash boaters it would appear that he is not one, but considers boats to be a hobby. He might be an electrical genius (or not), but does he know enough about his hobby to not build the most awesome electrical death trap?

See this page : http://www.pcmarinesurveys.com/Stoopid% ... tricks.htm Specifically about 8 rows up from the bottom, where someone has a bank of batteries in the bilge under the lower cabin floor.

If you are going to stick with it, verify how much your surveyor knows about inverter systems like this. I would make sure you have the survey done by someone who can look at what the seller has done and give you a clear statement re good vs bad.

[prowlersfish]

Capt M you bring up great points . One area you hit on was the marine rating of these "upgrades" Even is some of these maybe marine are the rate for use with gas ? I can get 150 amp alternators for marine us on diesels But have not seen any ones rated for use on gas boats .


He said something about flaky buyers , well there can be flaky sellers too .

[Big D]

Interesting thread. I'd like to know a few things;
- to what voltage are his capacity numbers based on; bringing the bank down to 12 volts, 11, 10, 5 or are they while still maintaining a charged bank during use? I can make capacities look really good but deplete batteries too low and you'll kill them for good really quick.
- What type and gage of battery cable did he use?
- what is the cable length from bank to inverter and back?
- what type/brand of batteries were used?
- what type of battery post fasteners were used?
- what type of battery cable lugs were used?
- what type of fuse on the DC side and rating?
- what type of AC wire and gage?
- What type of battery/DC line switch and rating?
- What make and model of inverter so that ignition proof rating can be checked
- is the inverter pure/true sine wave or modified wave?
- Where is inverter mounted in relation to batteries?
- What is the type, age, and rating of the battery charger?
- How is the inverter output tied into the ship's AC system?
- does the inverter automatically switch on when shore power is disconnected?
- Does the vessel have a bonding system and is the inverter chassis ground tied into it?
- IS THERE A WARNING LABLE AT YOUR PANEL STATING THAT THERE IS AN INVERTER WIRED TO THE AC PANEL??

I can go on and on but the answers to just a few key items above would be a pretty good indication of how good and safe a system this is. Anyone can throw in even a $10K system, the question is; was it done right and safe for a MARINE application. 9 batteries is a lot of power and can do a heck of a lot of damage if something isn't done right, heck, one battery can do serious damage.

Personally I am not a big fan of inverters for large continuous loads. They do have their place but not for me in this type of application. There is no way I would prefer that setup to a generator but that's me - a boater who spends time on the hook! Wonder how much all that weighs? Probably as much as the generator but a much larger footprint.

PS; It's encouraging that he is an electrical engineer however AC wiring on a boat is NOT the same as in a house!

[Big D]

Just saw the link CM. Gotta love it, see that Sh%T all the time.