Double inverter question

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Jared20459

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Jun 6, 2007
20
-Hunter 34 Saba Rocks II
If I have an inverter on the boat to convert 12v to 120v and plug in my kids' DVD player that has an inverter to convert from 120v back to 12v, will I use the same amps (more or less) as I would if I just plugged the DVD directly to 12v DC?

We seem to have lost the 12v plug but still have the 120v plug with the DVD... I want to make sure I am not doing something crazy that will burn 10x the amps from the boat batteries and it has been a long time since I had any kind of circuits class.

Thanks!
 
Maine Sail

Maine Sail

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Feb 6, 1998
11,760
Canadian Sailcraft 36T Casco Bay, ME
Jared20459 said:
If I have an inverter on the boat to convert 12v to 120v and plug in my kids' DVD player that has an inverter to convert from 120v back to 12v, will I use the same amps (more or less) as I would if I just plugged the DVD directly to 12v DC?

We seem to have lost the 12v plug but still have the 120v plug with the DVD... I want to make sure I am not doing something crazy that will burn 10x the amps from the boat batteries and it has been a long time since I had any kind of circuits class.

Thanks!
Click to expand
Your efficiency loss will be upwards of 25-35% going 12V - 120V - 12V vs. straight to 12V...
 
J

Jared20459

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Jun 6, 2007
20
-Hunter 34 Saba Rocks II
Great. Thanks. That won't kill he battery and is worth it to have occupied kiddies at bedtime. Thanks!
 
B

Bob McL

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Oct 16, 2008
512
MacGregor/Venture 25 Mesa AZ
All you need to do is get the correct adapter for the DVD and go 12-volts only. You won't need the converter(s).
 
B

Benny17441

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May 24, 2004
7,215
CC 30 South Florida
Yes there will be roughly a 30% loss in efficiency but when considering those DVD players use very little power it will not be a significant loss. As a matter of fact we do it all the time with our LED TV which has an internal step down transformer from 120V to 12V. We have considered hardwiring it into the 12V but decided not to as the TV is mostly used at the dock when tied to shorepower and the unit could also be sensitive to voltage variations which would be common on the 12V side.
 
Bill Roosa

Bill Roosa

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Jun 6, 2006
6,990
currently boatless wishing Harrington Harbor North, MD
AND you will not have the "DVD motor don't like the inverter waveform and runs slow/fast" problem when going straight to 12 v
 
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