inverter power useage? - SailNet Community
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inverter power useage?

1st off, electrical is not my cup o tea, so here goes.

I may put an inverter in my boat, to power of all things Christmas lights while doing a parade next year, along with other potential uses I am sure......figure this might be a better option than tying my Honda EB 3500 genset to the bow, listening to it along with diesel from boat!

I can figure out I need a minimum of 2000wt, and about 15-16amps in 110. I will assume either the 2500 or 4000W inverter HERE will supply enough power for my needs. Please note, this is an example of an inverter from a local supplier, not my first, nor maybe last choice, just seemed like a good brand/model to start with as an example!

How do I figure out how much AHr of battery I need?, I have an 80 ahr size 24. or will my 55amp rated alternator keep up with said inverter/battery draw while motoring along for 4-5 hrs at 3/4 throttle? I am assuming the Alternator is the one I need to be more worried about vs the battery. Other draws on battery/alternator while doing this will be a couple of house lights, running lights and basic depth/speed/wind ST60+ gauges. Nothing else at this time........

Marty

She drives me boat,
I drives me dinghy!
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Old 12-20-2010
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Marty
Your present battery doesn't stand a chance, and the engine doesn't produce enough amps to keep the battery from going flat if you expect to use the inverter to any serious level.

The easiest way to figure draw from an inverter is to divide by 10. In other words 1000 watts AC will cost you 100 amps @12 volts DC. 1000 watts AC for 1 hour will take a 200 AH bank to 50% state of charge. 2000 watts can do it in 1/2 hour.

Your present 80 AH battery with 1000 watts inverter output will be down to 50% state of charge in 24 minutes.

The small 100 to 400 watt inverters are common and will work well with most any system if used carefully but the large inverters are a different story.

Have you looked at LED Christmas lights?

Brian
Living aboard in Victoria Harbour

Last edited by mitiempo; 12-20-2010 at 10:36 PM.
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Brian,

that is with LED lights! about 1800-2000 of them. That is of course assuming I have done the how many watts/amps they use. I'm using about 9.6V/.08amps per 100 lights. I'm coming up with 2020 wts and 16 amps. Does this look correct to you?

maybe I will need to put the genset on the bow! yucko!

Marty

She drives me boat,
I drives me dinghy!
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Old 12-20-2010
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9.6 volts? Could you mean .08 amps @ 120 volts per 100?

Brian
Living aboard in Victoria Harbour
mitiempo is offline
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Rated capacity of the cords are 9.6V/.08amps ea. I'm assuming 20 light cords is 9.6 x 20 or 1920, made a mistake on total volt earlier, and about 16 amps of power use. I currently have about 1600 on the boat, and have not blown a 15a circut breaker.

Have I done the Volt useage wrong? so a smaller say 100-500 wt inverter might work?

as I said, electrical is not my forte!

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Old 12-20-2010
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Are these 120 volt or 9.6 volt lights?

Brian
Living aboard in Victoria Harbour
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They are 120's. I guess I need 16amps at 120

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Old 12-20-2010
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Marty,

I have a Honda EU2000. Would you like to borrow it? It will put out 15 amps no problemo. I can't imagine a Christmas light display needing more than that, unless you're doing the Chevy Chase thing on National Lampoons Christmas Vacation.

Ray
S.V. Nikko
1983 Fraser 41
La Conner, WA

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Boating for over 25 years, some of them successfully.

Last edited by erps; 12-20-2010 at 11:53 PM.
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Ray,

That might be an option too. a lot quieter than my EB3500! by 10 db or there abouts. I can do 240 with my generator. Along with 15, 20 and 25 amp circuit breakers! Just thinking an inverter might be a better way to go, for many reasons. Mostly quieter. The question becomes, is my current electric system capable of producing the 15-16amps of power for 4-5 hrs for the inverter.

That is the part I do not know how to figure or understand. Now if this was water for a sprinkler system in pipes. I know, same difference, different terms, but something I can do, blindfolded for that matter!

Time for bed!

marty

She drives me boat,
I drives me dinghy!
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Old 12-21-2010
the pointy end is the bow

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I have a big ass inverter on my boat powered by a 600 amp bank and a hundred amp alternator.

15 amps @ 120 volts equals 1800 watts.

From the 12 volt side, 1800 watts requires 150 amps. 12 volts x 150 amps = 1800 watts. I could not power that many amps for very long using my battery bank while running my alternator at full speed.

I have some time off this week. I could meet you part way to fix you up.

P.S., regarding the noise, I did not have a single person give me the finger when I ran the Honda during the day in Roscoe Bay a couple years ago. Of course I was flying an American flag off the transom and they may have figured I was armed, so that could have explained that too.

Ray
S.V. Nikko
1983 Fraser 41
La Conner, WA

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Last edited by erps; 12-21-2010 at 12:15 AM.
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