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Thread: Honda generator, how big?

  1. #1
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    Honda generator, how big?

    Hello All,
    I borrowed a Honda "suitcase" style generator from another sailboater this afternoon to charge up my batteries. It was a 2000watt unit, pretty light, compact and extremely quiet. I was very impressed. I plugged it into my shore power hookup and ran the battery charger (Xantrex Truecharge 20amp) and the charger indicated it was putting 10 amps into the batteries initially. I also switched on some of the house lights and the refrigeration for a while to see if the Honda could take it. I had it set on "Eco throttle" which basically automatically adjusts the output based on load. I was pleasantly suprised that the Honda only ran a bit above idle to keep up. I am thinking that a 1000watt Honda would be an even better choice? All I am looking for is to charge batteries/augment while on the hook to keep from running the engine.

    So the question is: How do I figure how much juice I am drawing and do the conversion backwards from DC usage to AC needed? AFAIK, the Truecharge will keep up with the DC loads from the refigeration, lights, music, etc. when plugged in at the dock. I guess what I am asking is how much AC power will the Truecharge 20 consume at max output of 20 amps DC? I have checked the Xantrex website and I see plenty of specs listed but not that one....

    Thanks, RT
    Rob Thomas
    Wakefield, RI
    1983 Ericson E38 "Ruby"
    "I purchased a boat because setting fire to $100 bills was not an efficient enough way to dispose of them...."

  2. #2
    Interesting! I just used the 1000eu model last week. It was easily capable of running my 20 amp charger but had no chance against the inrush of my hot H2O tank. This thing sits in the garage all yr. with no care then starts on the first pull, Kewl.

  3. #3
    Contributing Member III Jim Mobley's Avatar
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    Elementary, Watts!

    In the boat world electrical draws are commonly given in amps. This is convenient as wire and circuit breakers are sized in amps and everything is 12 volts. But it's important to remember that amps aren't a measure of power. In order to compare 12 V and 120 V systems, it's easiest to convert everything into power--and electrical power = Watts. Horsepower is also a measure of power, one horsepower is 750 Watts (roughly). Power is the ability to perform work in a given amount of time.

    Again, amps are NOT power. Amps are current flow and you can have a lot of current flow and very little power and conversely you can have very little current flow and lots of power. Power in Watts is equal to amps x volts. Thus I can get my one horsepower with one volt and 750 amps or with 750 volts and one amp. The resulting power in both cases is the same--750 Watts--but I need much larger wire to carry all the current in the one volt system.

    For one horsepower in a 12 V system I need 750/12 = 62.5 amps; in a 120 V system I need 750/120 = 6.25 amps. This is why the power company delivers power over long distances at 500,000 volts. The wire size is manageable because the current is (relatively) low.

    On the battery side of your 20 amp charger you have 20 amps x 14.5 volts = 290 watts. If the charger was 100% efficient, then you would only need to supply 290 watts at the 120 V input, but nothing is free and Xantrex rates their charger as 85% efficient. (Pretty darn good, btw.) So at maximum output the charger will pull a bit more than 340 watts from the AC line. Well within the 1,000 Watt capabilities of the small Honda generator.

    The water heater on the other hand is not a 12 volt device, but a 120 volt device. So even though it may be a 10 amp device, (some small water heaters are only 10 amps) at 120 volts that's 1,200 watts (1.6 horsepower) and will trip the breakers on the small generator. And if the element is cold, the initial current flow may be higher. The little generator won't handle this load--and most water heaters use larger elements.
    Jim Mobley
    S/V Sea Myst
    1975 E-29

  4. #4
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    Thank you Jim Mobley!
    I knew someone would be able to clarify that. I had considered the hot water heater but I can't find a wattage spec on the 6 gallon Raritan I have. Likely even the 2000 watt model couldn't handle the load. I am thinking that eventually an inverter and larger batteries are the answer to using the hot water heater for brief periods and then letting the charger/generator play catchup. My waterheater seems to store hot water for quite some time. If I motor in the evening the water is still quite hot in the morning. I haven't tried to shower in the morning yet so I don't know if its hot enough but I hope so.

    Either way the little 1000watt Honda seems just the ticket to keeping the batteries topped off while on the hook, entertaining, maintaining, etc. I can always sell it if I want more.....

    Thanks, RT
    Rob Thomas
    Wakefield, RI
    1983 Ericson E38 "Ruby"
    "I purchased a boat because setting fire to $100 bills was not an efficient enough way to dispose of them...."

  5. #5
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    Generator

    Pick up the 2000 watt unit, it will run your hot water heater. The element is only a 1500 watt element. Try not to run much else while the hot water heater is on though. Good luck. Ryan

  6. #6
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    how much do these little cuties go for?

  7. #7
    Accelerant CaptnNero's Avatar
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    The EU1000 is about $500 and the EU2000 is about $900. I think the 3000 is closer to $2000 it is much heavier and bulky too. I just got an EU2000. I found out that the aftermarket people sell a propane conversion kit for it. I might do that for summer trips of a week or two to recharge the batteries after some heavy loads. I'd much rather deal with propane on board than gasoline.

    I've also got a 2hp 4 stroke Honda out board that I want to convert to propane also but it looks like I will need to call the conversion people directly on that one.

    Quote Originally Posted by NateHanson
    how much do these little cuties go for?
    -- neal
    S/V KOKOMO
    '88 E34 #253
    Get there fast and take it slow

  8. #8
    Moderator Guy Stevens's Avatar
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    Be careful with the valves

    The valves on these little units are very very suceptable to damage from salt air. I have seen more than one destroyed because the owners left the intake valve open when storing it, and as little as two weeks later found it wouldn't work. The key is to make sure that you put it away with the valves closed the cylender in the compression stroke, and take a moment to fog the intake side of the unit with a good fogging agent before putting it away.

    Guy
    :-)

  9. #9
    Accelerant CaptnNero's Avatar
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    Guy, thanks for the heads-up on the valves. I haven't used mine yet but I saw the instructions about storing it properly. This is another reason to not leave it on the boat. For regular weekend use I don't need it anyway.

    Quote Originally Posted by Guy Stevens
    The valves on these little units are very very suceptable to damage from salt air. I have seen more than one destroyed because the owners left the intake valve open when storing it, and as little as two weeks later found it wouldn't work. The key is to make sure that you put it away with the valves closed the cylender in the compression stroke, and take a moment to fog the intake side of the unit with a good fogging agent before putting it away.

    Guy
    :-)
    -- neal
    S/V KOKOMO
    '88 E34 #253
    Get there fast and take it slow

  10. #10
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    Quote Originally Posted by Guy Stevens
    The valves on these little units are very very suceptable to damage from salt air. I have seen more than one destroyed because the owners left the intake valve open when storing it, and as little as two weeks later found it wouldn't work. The key is to make sure that you put it away with the valves closed the cylender in the compression stroke, and take a moment to fog the intake side of the unit with a good fogging agent before putting it away.

    Guy
    :-)
    This is interesting. There are 4 of these Hondas in use at my club all are at least a year old and all are stored on the boats. No issues yet.... Still, it makes sense to do a bit of preventive before it is stored. The really interesting thing is how fume-free these units are. Now I'm not recommending this but the owners I know store them on the boats sometimes in living space. There is no detectable gasoline fumes. I have never seen any other gas powered thing do this. Go figure. RT
    Rob Thomas
    Wakefield, RI
    1983 Ericson E38 "Ruby"
    "I purchased a boat because setting fire to $100 bills was not an efficient enough way to dispose of them...."

  11. #11
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    Ordered a 2000watt Honda from www.mayberrys.com today. $899.00 shipped to my door. Best price I could find. Thanks all, RT
    Rob Thomas
    Wakefield, RI
    1983 Ericson E38 "Ruby"
    "I purchased a boat because setting fire to $100 bills was not an efficient enough way to dispose of them...."

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