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  • It is possible in terms of voltage -- The generator will deliver 120 Volts of alternating current at 60 Hz, exactly what the battery charger uses.
  • The generator's capacity may be inadequate; you'll need to check what current (the number of amps) the generator delivers and what current battery charger needs at max draw. This will be the 120V A/C current, not the 12V D/C current.
  • What is definitely true is that this setup will be inefficient. You burn gas in a motor, which turns an alternator, which creates 120V A/C, which is stepped down to just above charging voltage, rectified, and then regulated. You lose energy at each of those steps.
  • IMO, what is truly questionable is the use of a harbor freight generator. They are noisy and of dubious reliability. If you really insist on setting this up, pick a better generator. I'd look at the specs of a Honda EU2000i generator and see if it fills the bill. You can get that Honda model on sale for between $950 and $1000. Sure, they cost more but they last WAY longer! Here's a new EU2000i selling on E-bay for $970 (as of early April 2014).
 

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Yes you can, but your shore power cord won't plug into it...you will have to buy an adaptor that is 30 amp female to plug your shore power cord into and a 20 amp male to plug into the generator.

Not giving you a hard time, but why would you want such a large generator. Unless you have power hungry appliances like an electric stove and/or large AC unit, you don't need anything nearly that large. A Honda 2000 is the preferred unit on many boats. Much more expensive but way quieter and will take care of your needs unless you have the power hungry appliances.
 

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My situation is that I'm living aboard and using the power without putting any back. This would just be the temporary bandaid until I figure out what to do on the solar end. That's planning plus ship and install, and by that time my batteries will be pretty much toast. I thought a cheap Genny would be a good option as it would definitely be useful later and would keep my batteries in good shape for a week or two while I sort out a more permanent solution.

As far as the harbor freight genny goes, that was the only one with that particular type of plug that I could just run out and pick up locally. Definitely will go with something else if its as simple as buying an adapter.

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Generator is one of those dirty words to be avoided at all cost on sailnet. Don't talk about guns. Don't talk about politics. And don't anchor next to Jim. The answer to your question is yes.
 

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Until you tell us just what your 120v power requirements are besides the battery charger, a 4000 watt generator is definitely overkill and will be so noisy, you won't be able to stand it.

Just check out Marinco. THey have the adaptors you need to plug your shore power cord into a generator.

I don't think that Harbor Frt unit has the type of plug you need anyway so you will still need an adaptor to use that generator.
 

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Why would you jump to the conclusion I need it for anything other than what I asked?

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Yes you can, but your shore power cord won't plug into it...you will have to buy an adaptor that is 30 amp female to plug your shore power cord into and a 20 amp male to plug into the generator.

Not giving you a hard time, but why would you want such a large generator. Unless you have power hungry appliances like an electric stove and/or large AC unit, you don't need anything nearly that large. A Honda 2000 is the preferred unit on many boats. Much more expensive but way quieter and will take care of your needs unless you have the power hungry appliances.
Agreed. You will need to build a cord with the correct ends.
 

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Why would you jump to the conclusion I need it for anything other than what I asked?

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I'm not jumping to any conclusions. You haven't given any details about your boat and if all you need a generator for is to charge your batteries, a 4000 watt unit is overkill. You can't fit enough solar panels on the boat to generate anything remotely close to that much power.
 

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If you read before the post you would have seen that I already addressed this issue. Must have been when you said specifically that I should indicate my uses other than charging when it began to look like you were making assumptions. I thought you were reading the thread like everyone else. My mistake!

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Yes, you can, with one further consideration. First, get the right Marinco adapter, as mentioned, but they are not cheap. We use them when on the hard to plug into the nearby building to charge batts over the winter, so they could come in handy down the road.

The consideration is whether the generator will carry the amperage that your charger draws. It most likely will, as long as that is the only 120v system activated, but you might want to research this on your charger. If you did try to use other devices, this could get tricky. Some chargers are also adjustable for whatever shore power is available. In your case, whatever generator power is available.

When plugged in on the hard, the building receptacles are only rated to 20amps, not the 30/50 on the dock. We can adjust to only draw 20 amps, so we don't trip breakers.
 

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I use a Honda 2000 with a DIY cord from it to the shore power plug. I run it on the cockpit floor so there's additional sound buffering and during the time of day when there is dinghy traffic when around other boats. When I was at Marathon for 3 months on a mooring ball, I never had any complaints from any of the surrounding boats. It generally took 2-3 hrs to recharge my 255 ah.
 

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Check out the Honda 2000 companion model. A friend bought one and it has the typical 30 amp plug built in already for not much more than the standard model. I borrowed it a couple weeks ago and in regular mode was able to start my 12kbtu air conditioning, refrigeration and 50 A battery charger. Due to starting impulse I couldn't run all at once but could run two out of three and then put it on eco mode which was nice and fairly quiet.
 

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I would say something like this:

2500 Peak/2200 Running Watts, 4.7 HP (125cc) Portable Inverter Generator

Ryobi 2200-Watt Gasoline Powered Digital Inverter Generator-RYI2200 at The Home Depot

or even:

900 Peak/800 Running Watts, 2 HP (63cc) Gas Generator

Would be more than sufficient unless you are using an inordinate amount of electricity. though the 800 watt unit might not be big enough. Remember the bigger the unit the more fuel you will use, and where will you keep the big unit? Harbor Freight make great inexpensive generators, but I can't imagine they would last long in a marine environment. They tend to use cheap metal, that will start corroding quite quickly. The compact units also tend to be much quieter.

One other issue is that some chargers do not like the power put out even from a high quality generator. I believe Xantrex often will not work off the Honda 2000, let alone some cheap Harbor Freight unit. I would imagine it depends on the amounts of electronic controls on the unit.

You do need to analyze the amount of electricity you are going to use so you know how big a generator you might need. Do you plan on running A/C? Do you use electric to cook with? Do you have LED lighting? Much more info would help give a more accurate answer. Solar is great, but unless you live on the equator, where it is never cloudy, never rains and you have huge panels you may need a generator to top off the batteries occasionally so I would not think of it as a "temporary" solution. Look for something you will be able to store out of the weather long term, no need to throw away money only to decide to get a compact one later. The compact ones will store in a lazarette that full sized one will not.
 

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The Honda EU2000i Companion model will very likely fit the bill. It can handle battery chargers up to about 75 amps output. If your battery charger is 75 amps or less, you'll find no better solution.

BTW, get those batteries charged quick. Any time batteries sit at less than full charge condition, they begin to sulfate and lose capacity, thereby shortening their useful life.

Bill
 

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Wow, thanks for all the great replies. Manual for my truecharge says 120v 12amp max. Not sure if its going to regulate the amperage coming in, but since 30 amp shore power is the type of shore plug installed on the boat it seems like it should. For you guys who made your own plug, are there any special considerations, or would I just be splicing the 30 amp plug with a 20 amp plug? Just pos to pos, neg to neg and ground to ground? Or will I need something else to do it correctly?

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Wow, thanks for all the great replies. Manual for my truecharge says 120v 12amp max. Not sure if its going to regulate the amperage coming in, but since 30 amp shore power is the type of shore plug installed on the boat it seems like it should. For you guys who made your own plug, are there any special considerations, or would I just be splicing the 30 amp plug with a 20 amp plug? Just pos to pos, neg to neg and ground to ground? Or will I need something else to do it correctly?

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Let's get this absolutely crystal clear.

1. You have a Trucharge battery charger installed in the boat which says it draws a maximum of 12 amps @ 120 VAC. Is that correct?

2. You plan to alter your boat's 30A shorepower male plug, and install a 15A or 20A three-prong household-type plug so you can plug that into a generator such as the Honda EU2000i. Is that correct?

3. You plan to turn off all other AC boat loads (hot water heater, frig, etc.) when you use the generator so as not to exceed the generator's maximum sustained power output. Is that correct?

Bill
 

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Wow, thanks for all the great replies. Manual for my truecharge says 120v 12amp max. Not sure if its going to regulate the amperage coming in, but since 30 amp shore power is the type of shore plug installed on the boat it seems like it should. For you guys who made your own plug, are there any special considerations, or would I just be splicing the 30 amp plug with a 20 amp plug? Just pos to pos, neg to neg and ground to ground? Or will I need something else to do it correctly?

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Why have 2 power cords, 1 to plug into a standard shore power receptacle and one to plug into your generator when a Marinco adaptor will allow you to use the one cord either way.
 

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Manual for my truecharge says 120v 12amp max.
I'm wondering if that is the max charge amperage it will provide to the battery, rather than the max amperage it will draw from shore/generator. The 30 amp cabling in your boat is just a limit and should not be a concern to your generator at all. The cabling is theoretically already able to handle your charger, among other systems, already. You want to be sure the output from the generator is sufficient to handle the input to the charger. Both are going to be below the 30 amp cable circuitry, as they should be. The 4kw generator is oversized, unless you plan to run other 120v systems from it at the same time.
 
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