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06-17-2015, 11:19 AM
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#1
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3 Rivet Member
2018 19' Flying Cloud
Eugene
, Oregon
Join Date: Mar 2015
Posts: 220
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12v direct vs Inverter
My 2015 Bambi Sport 16 has a Samsung LED TV (35watts). It is a 14v TV that has a converter that one plugs into the 110 socket when connected to shore power. I was wondering how I could use the TV when boondocking. I could (A) buy a 50 watt inverter or (B) Use a direct cigar lighter plug to TV unit. The complication is that the TV is 14v not 12v and I have to find the correct connector that plugs into the 14v TV. If I went the inverter route, I know it is less efficient, but at that small wattage would it make that much of a difference in terms of battery drain vs the 12v connector?
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06-17-2015, 11:43 AM
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#2
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4 Rivet Member
Vintage Kin Owner
Superior
, Colorado
Join Date: May 2014
Posts: 442
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06-17-2015, 12:14 PM
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#3
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3 Rivet Member
2018 19' Flying Cloud
Eugene
, Oregon
Join Date: Mar 2015
Posts: 220
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I thought I read somewhere that the car charger plug only draws 100w - to get 500 you have to connect it directly to the battery via the alligator clips.
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06-17-2015, 12:40 PM
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#4
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4 Rivet Member
Vintage Kin Owner
Superior
, Colorado
Join Date: May 2014
Posts: 442
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Quote:
Originally Posted by tjwoods1
I thought I read somewhere that the car charger plug only draws 100w - to get 500 you have to connect it directly to the battery via the alligator clips.
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I have heard the same. I suspect that the cig socket on most cars is connected to a 15 amp fuse, and 12v x 15amps is just 180 watts.
But my suggestion of the 500 watt inverter is because it has capacity to spare. I had an inverter rated at 150 watts and it was pathetic. It made weepy beepy sounds all the time, and the fan was annoying.
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06-17-2015, 12:50 PM
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#5
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Moderator
2017 26' Flying Cloud
Alamo Heights
, Texas
Join Date: Aug 2006
Posts: 8,493
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You could get a DC boost converter, but I've never seen a packaged one. There's DIY stuff like this you can buy and hook a few wires to, but you'll still have to find the right connector for the 14V into the TV.
It's too back the USB output they're putting on new trailers instead of 12V sockets is current-limited (because of the USB standards) or you could use that, but you could still get behind it and use the 12V wiring that supplies it.
A good inverter is a useful thing, though. I bought one to run my CPAP, and I'm going install it in a fixed position in the 28' trailer we're working on. I've ended up using it to run my laptop when boondocking and I had to do some work, to charge the phone when I didn't otherwise need to start the generator that day, etc.
__________________
— David
Zero Gravitas — 2017 Flying Cloud 26U | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill
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06-18-2015, 11:19 AM
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#6
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Rivet Master
2008 22' Safari
Oracle
, Arizona
Join Date: Oct 2007
Posts: 1,174
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Been running my LED TV on 12vdc for several years now without complaint. My laptop and phone charger run off it too.
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06-18-2015, 05:49 PM
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#7
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Rivet Master
2006 23' Safari SE
I'm In
, Kentucky
Join Date: Dec 2012
Posts: 4,251
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I purchased a 12vdc to 19.5vdc adapter for my laptop at Amazon ($22). It puts out 4.62 amps (90 watts). I'm sure there's an adapter for your TV. Have you checked Amazon for one?
__________________
-Rich
Rich & Yvonne
2006 Safari SE -Dora-
2004 4Runner SE 4.7L V8
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06-18-2015, 09:48 PM
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#8
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3 Rivet Member
Currently Looking...
Currently Looking...
Madison
, Alabama
Join Date: Feb 2015
Posts: 172
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"A good inverter is a useful thing, though. I bought one to run my CPAP, and I'm going install it in a fixed position in the 28' trailer we're working on. "
Many CPAP machines run on 12 VDC & do fine on battery voltage. Same for the LED TV.
VERY wasteful to convert battery chemical energy to 120 VAC & then right back to DC. Loss is about 20% @ each change.
Shore Power 120 VAC to 14VDC to charge battery = 20% loss
14 V recharges battery = 20%
chemical action to 12VDC = 20%
12VDC to 120 VAC by inverter = 20%
120VAC back to 12VDC by appliance brick = 20% loss
This kind of inefficiency can really pull down a battery bank.
Let's think these things through. Flat batteries spoil the fun.
Let's Roll !
Wolf
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06-18-2015, 10:12 PM
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#9
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Rivet Master
2006 25' Safari
St. Augustine
, Florida
Join Date: Oct 2011
Posts: 2,670
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The energizer model shared sounds like a good option and it is flexible. You NEED right now a cig lighter 100 watt inverter. Consider if that is all you would want to run boondocking.
__________________
WBCCI 8653/AIR 60240
2022 Ford F150 PowerBoost Platinum w/7.2KW
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06-18-2015, 11:03 PM
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#10
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Moderator
2017 26' Flying Cloud
Alamo Heights
, Texas
Join Date: Aug 2006
Posts: 8,493
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Quote:
Originally Posted by Wolf Alaska
"A good inverter is a useful thing, though. I bought one to run my CPAP, and I'm going install it in a fixed position in the 28' trailer we're working on. "
Many CPAP machines run on 12 VDC & do fine on battery voltage. Same for the LED TV.
VERY wasteful to convert battery chemical energy to 120 VAC & then right back to DC. Loss is about 20% @ each change.
Shore Power 120 VAC to 14VDC to charge battery = 20% loss
14 V recharges battery = 20%
chemical action to 12VDC = 20%
12VDC to 120 VAC by inverter = 20%
120VAC back to 12VDC by appliance brick = 20% loss
This kind of inefficiency can really pull down a battery bank.
Let's think these things through. Flat batteries spoil the fun.
Let's Roll !
Wolf
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It is true that many CPAP machines run on DC voltage. Mine, however, does not and in fact the manufacturer specifies a pure-sine inverter where an inverter is used. I would have chosen a different one had I been camping at the time I got it, but that wasn't a consideration and my health insurance provider doesn't really care that it's less efficient on my Airstream's batteries and hasn't offered to help me pay for a new one.
You should perhaps consider a better inverter for your comparisons, mine is 90% efficient and is not an esoteric or expensive model. The efficiency of the converter-charger is essentially a non-issue unless you have some tiny 500w generator, in my case the inefficiency is that my generator is ridiculous overkill for just charging the batteries, but I haven't gotten to the point where I'm ready to invest in solar just yet. The chemical efficiency of the battery is also a wash, because you're dealing with that whether you're using 12V DC directly or using 12V DC to power an inverter.
There'll also be some degree of inefficiency inherent in stepping up 12v DC to 14v DC with a booster.
By all means, let's think these things through.
__________________
— David
Zero Gravitas — 2017 Flying Cloud 26U | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill
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06-19-2015, 01:22 PM
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#11
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3 Rivet Member
2014 25' FB Flying Cloud
Fitchburg
, Wisconsin
Join Date: Jul 2014
Posts: 226
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Powerstream.com PST-DC2171
I have what is probably the same TV in the bedroom of my 25FC. I had exactly the same question as you. It made no sense to me to invert and then convert so I looked around and found this:
Car DC converter: 12 volt to 12V, 15V, 18V, 21V, or 24V DC/DC converter with 2.5 amp output.
This boost converter has selectable outputs of 12, 15, 18, 21, and 24 volts, all at 2.5 amps or 37.5 watts at 15 volts. It also comes with various output adaptors, one of which fits the TV. It has a standard "cigarette" 12 v input. I assumed that 15 volts would be close enough to 14 that the TV wouldn't notice. It's been fine. Others with more knowledge or experience may find this unacceptable but it's been working for me.
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06-19-2015, 01:57 PM
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#12
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Moderator
2017 26' Flying Cloud
Alamo Heights
, Texas
Join Date: Aug 2006
Posts: 8,493
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Quote:
Originally Posted by BillfromWI
I have what is probably the same TV in the bedroom of my 25FC. I had exactly the same question as you. It made no sense to me to invert and then convert so I looked around and found this:
Car DC converter: 12 volt to 12V, 15V, 18V, 21V, or 24V DC/DC converter with 2.5 amp output.
This boost converter has selectable outputs of 12, 15, 18, 21, and 24 volts, all at 2.5 amps or 37.5 watts at 15 volts. It also comes with various output adaptors, one of which fits the TV. It has a standard "cigarette" 12 v input. I assumed that 15 volts would be close enough to 14 that the TV wouldn't notice. It's been fine. Others with more knowledge or experience may find this unacceptable but it's been working for me.
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THAT is the sort of thing I hadn't stumbled across as a commercially-packaged product. A variable-output DC booster. It seems like a good solution, though in a 2015+ you may need to add a 12V socket for it, all the 2015s I've seen just have USB charging ports.
__________________
— David
Zero Gravitas — 2017 Flying Cloud 26U | WBCCI# 15566
He has all of the virtues I dislike and none of the vices I admire. — Sir Winston Churchill
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06-19-2015, 11:24 PM
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#13
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3 Rivet Member
2018 19' Flying Cloud
Eugene
, Oregon
Join Date: Mar 2015
Posts: 220
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I converted one of my USB ports to a 12v in my 2015 Bambi Sport. I guess the question now is, since the TV is 14V, is there less harm to the TV using less voltage (12v) or more (15v)?
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08-09-2015, 09:35 AM
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#14
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3 Rivet Member
2016 16' Sport
Port Angeles
, Washington
Join Date: Jul 2015
Posts: 195
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Hey TJ any issues with converting the sub plug? Is it fused? Did you power up an inverter and run the TV? I have a 2015 16 as well. Thanks
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08-09-2015, 11:40 PM
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#15
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3 Rivet Member
2018 19' Flying Cloud
Eugene
, Oregon
Join Date: Mar 2015
Posts: 220
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The converted USB plug works great. Just switched out the plug. ( don't know about the fuse). Haven't had the need yet to run the TV via the inverter so I can't say. I've had power at all the campsite so far. Don't know why it wouldn't work though.
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