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05-04-2018, 12:10
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#16
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Registered User
Join Date: Nov 2013
Location: Edmonton/PNW
Boat: Hunter 386
Posts: 1,745
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Re: Inverter myths?
Quote:
Originally Posted by sailorboy1
30 watts divided by 12.5V DC is 2.4 amps. So if at 0 amps 120 volt AC uses 30w of power you are losing 2.4 amps DC to do nothing but be in standby waiting for an AC load. If you left that on all day that’s 57.6 amp-hours. That’s a lot of wasted power !!!!
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So it isn't 30W / 120V = .25A? That's what the spec seemed to imply? I am ok if I am wrong but i'd like to know how to read these things.
__________________
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Gaudeamus igitur iuvenes dum sumus...
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05-04-2018, 12:22
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#17
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Registered User
Join Date: Oct 2016
Location: Vancouver Island
Boat: Hullmaster 27
Posts: 1,043
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Re: Inverter myths?
Quote:
Originally Posted by Macblaze
So it isn't 30W / 120V = .25A? That's what the spec seemed to imply? I am ok if I am wrong but i'd like to know how to read these things.
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What you are missing is that the load is on the OUTPUT 120V side of the inverter. By definition, with no AC load there is no current on the 120V side of the inverter = 0.0A. That is true for both the big and small inverter.
What you are asking about is the current on the INPUT 12V side of the inverter ... you are consuming 12V current to make that 30W of waste heat. What the spec is saying is that it will need 2.4A of 12V just to give you 0.0A of 120V.
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05-04-2018, 12:23
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#18
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Registered User
Join Date: Nov 2013
Location: Edmonton/PNW
Boat: Hunter 386
Posts: 1,745
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Re: Inverter myths?
Quote:
Originally Posted by Kelkara
What you are missing is that the load is on the OUTPUT 120V side of the inverter. By definition, with no AC load there is no current on the 120V side of the inverter = 0.0A. That is true for both the big and small inverter.
What you are asking about is the current on the INPUT 12V side of the inverter ... you are consuming 12V current to make that 30W of waste heat. What the spec is saying is that it will need 2.4A of 12V just to give you 0.0A of 120V.
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Thanks.
__________________
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Gaudeamus igitur iuvenes dum sumus...
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05-04-2018, 12:49
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#19
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cruiser
Join Date: Jan 2017
Boat: Retired from CF
Posts: 13,317
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Re: Inverter myths?
Quote:
Originally Posted by sailorboy1
The problem with plugging DC devices that use AC and then convert them to DC is that lots of times they don’t like the way boats DC varies. On my boat the voltage of house battery varies between 12.1-14.9V. So don’t just think you can cut off the plug “brick” and connect directly to the batteries.
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No of course not. dcdc converters, if nominal 12V 13.8V is normal.
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05-04-2018, 13:43
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#20
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CLOD
Join Date: Jul 2007
Location: being planted in Jacksonville Fl
Boat: none
Posts: 20,415
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Re: Inverter myths?
Do whatever you want it’s ok with me
__________________
Don't ask a bunch of unknown forum people if it is OK to do something on YOUR boat. It is your boat, do what you want!
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05-04-2018, 14:06
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#21
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Registered User
Join Date: Jun 2007
Location: SW Florida
Boat: FP Belize, 43' - Dot Dun
Posts: 3,823
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Re: Inverter myths?
30W sounded high to me, so looked at the Magnum 2812 manual, with the search feature enabled, if the AC load is less than 5W, the unit goes into search mode and pulls <8W from the battery. When an AC load greater than 5W is discovered, the inverter turns on and that is when the battery load is minimum 30W. Search mode enablement can be adjusted from 5W to 50W. Search mode disabled and inverter on pulls minimum 30W.
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05-04-2018, 14:14
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#22
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Registered User
Join Date: Nov 2013
Location: Edmonton/PNW
Boat: Hunter 386
Posts: 1,745
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Re: Inverter myths?
Quote:
Originally Posted by DotDun
30W sounded high to me, so looked at the Magnum 2812 manual, with the search feature enabled, if the AC load is less than 5W, the unit goes into search mode and pulls <8W from the battery. When an AC load greater than 5W is discovered, the inverter turns on and that is when the battery load is minimum 30W. Search mode enablement can be adjusted from 5W to 50W. Search mode disabled and inverter on pulls minimum 30W.
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I'll have to check that. I do no if there is no load, the remote reads "Searching" so I am going to guess that means Search Mode is enabled.
Reading the manual...who knew.
__________________
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Gaudeamus igitur iuvenes dum sumus...
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05-04-2018, 15:59
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#23
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Registered User
Join Date: Nov 2013
Location: Port Moresby,Papua New Guinea
Boat: FP Belize Maestro 43 and OPBs
Posts: 12,891
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Re: Inverter myths?
Quote:
Originally Posted by Macblaze
I'll have to check that. I do no if there is no load, the remote reads "Searching" so I am going to guess that means Search Mode is enabled.
Reading the manual...who knew.
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But note that search mode still draws up to 8W, compared to the small inverters "(at 12V) <0.3 A" which is < 4W.
And as soon as you are drawing any real load (5W is very little), you have that parasitic 30W kicking in.
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05-04-2018, 17:26
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#24
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Registered User
Join Date: Nov 2013
Location: Edmonton/PNW
Boat: Hunter 386
Posts: 1,745
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Re: Inverter myths?
Quote:
Originally Posted by StuM
But note that search mode still draws up to 8W, compared to the small inverters "(at 12V) <0.3 A" which is < 4W.
And as soon as you are drawing any real load (5W is very little), you have that parasitic 30W kicking in.
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Noted.
__________________
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Gaudeamus igitur iuvenes dum sumus...
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05-04-2018, 20:26
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#25
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Registered User
Join Date: Jun 2013
Location: canada
Posts: 4,659
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Re: Inverter myths?
the magnum draws 2-3 amps just being on.
so it'll be 3a + .89% of your load.
vs like 0.2a + 85% of your load.
the load needs to be pretty big before the magnum starts to win
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05-04-2018, 20:33
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#26
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Registered User
Join Date: Jun 2013
Location: canada
Posts: 4,659
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Re: Inverter myths?
Quote:
Originally Posted by DotDun
30W sounded high to me,
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the xantrax 2000 draws 4-5a on. the magnum is actually a pretty low one.
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