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01-25-2014, 09:11 AM
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#1
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Senior Member
Fleetwood Owners Club
Join Date: Jul 2012
Posts: 332
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Voltage drop
I picked up a 300 watt psw inverter for my front led tv and DVD player. My kill o watt meter shows 113volts output from voltage drop, I suspect. My question is, is that low enough to damage my tv over time? I tried to find the answer on the net with no success. The set is a 40" Toshiba.
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01-25-2014, 09:14 AM
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#2
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Senior Member
Newmar Owners Club
Join Date: May 2007
Location: Somewhere....
Posts: 4,054
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Nominal AC voltage is 120V with allowable variance of +/- 10%, so anything from 108V to 132V is within spec. You're fine at 113V.
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2008 King Aire 4562, Spartan K3(GT) w/ Cummins ISX 600
2014 Jeep Grand Cherokee Overland 5.7L V8 Hemi w/ Blue Ox Aventa LX Tow Bar and baseplate, SMI Air Force One brake
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01-25-2014, 09:20 AM
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#3
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Senior Member
Fleetwood Owners Club
Join Date: Jul 2012
Posts: 332
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Thank you very much. Gotta love this forum!
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01-25-2014, 09:23 AM
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#4
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Senior Member
Join Date: Jul 2012
Location: DeLand, Florida
Posts: 464
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Utilization voltages are about 104 on the low side to 127 on the high side. The supply for the power company should be less than this but the utilization allows for more loss. See link below for more explanation.
http://www.pge.com/includes/docs/pdf..._tolerance.pdf
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The only thing that always works on a RV is it’s Owner…
2012 Thor Outlaw
2014 Harley Limited
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01-25-2014, 09:32 AM
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#5
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Senior Member
Join Date: Apr 2012
Posts: 1,526
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Quote:
Originally Posted by so47
I picked up a 300 watt psw inverter for my front led tv and DVD player. My kill o watt meter shows 113volts output from voltage drop, I suspect. My question is, is that low enough to damage my tv over time? I tried to find the answer on the net with no success. The set is a 40" Toshiba.
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As noted in the previous post you are fine with 113V, however your statement about "output from voltage drop". Just curious about this statement. What did you mean?
Your inverter converts the DC input to an AC output. Did you measure the voltage output with different DC input voltages?
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01-25-2014, 10:51 AM
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#6
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Senior Member
Fleetwood Owners Club
Join Date: Jul 2012
Posts: 332
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Measured the output from the same outlet while on shore power and it read 120v. I made the leap that my whole house inverter ( 2000w msw ) being more powerful made the difference and overcame the long wire run. Am I looking at this correctly?
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01-25-2014, 11:04 AM
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#7
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Senior Member
Newmar Owners Club
Join Date: May 2007
Location: Somewhere....
Posts: 4,054
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Quote:
Originally Posted by so47
Measured the output from the same outlet while on shore power and it read 120v. I made the leap that my whole house inverter ( 2000w msw ) being more powerful made the difference and overcame the long wire run. Am I looking at this correctly?
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If you got 120V when on shore power and 113V when not, it means the output from your inverter is low. But an MSW inverter doesn't put out the waveform your meter is looking for, so it's not surprising that it's getting a low reading.
I'd be more worried about whether your TV and DVD player will handle the MSW power from the inverter than I would be about the voltage your meter is showing.
joe <- not a big fan of MSW inverters
__________________
2008 King Aire 4562, Spartan K3(GT) w/ Cummins ISX 600
2014 Jeep Grand Cherokee Overland 5.7L V8 Hemi w/ Blue Ox Aventa LX Tow Bar and baseplate, SMI Air Force One brake
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01-25-2014, 11:37 AM
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#8
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Senior Member
Join Date: Apr 2012
Posts: 1,526
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Quote:
Originally Posted by so47
Measured the output from the same outlet while on shore power and it read 120v. I made the leap that my whole house inverter ( 2000w msw ) being more powerful made the difference and overcame the long wire run. Am I looking at this correctly?
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Thanks, but now I really don't understand. An Inverter has DC in and AC out. Cannot figure the relationship to your main inverter (2000W) or any 120Vac power source in relation to the 300W inverter you are using for your TV etc. Logic tells me that a lower DC voltage in would likely produce a lower AC out.
Line power loss is contingent upon the line resistance and the current flow through that line. Smaller wire = higher resistance = more power loss. And if power is being dissapated in the line, there will be a voltage drop in that circuit. Voltage applied to a load is directly related to the current flow through that load, It has nothing to do with the supply being capable to supply more current.
But how does your main inverter come into play here or even the shore power voltage for that matter? Does your 300W inverter not get its power from the batteries?
Just one thing to consider re "line loss": It is better to have a long line at higher voltage, hence less power loss in the line. Power = I (squared)R so it is best to have an Inverter as close as you can to the 12VDC source and leave the longer distance to the 120Vac side.
Sorry, I must be missing something, but in the end, 113Vac would be fine for the TV in any case.
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01-25-2014, 12:24 PM
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#9
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Senior Member
Fleetwood Owners Club Ford Super Duty Owner
Join Date: Jun 2012
Location: SoCal
Posts: 15,749
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The lower voltage is ok.
To minimize voltage drop, have the inverter close to the batteries with large wire and have the longer run the AC line to the TV. AC is less affected by wire loss than DC.
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Vince and Susan
2011 Tiffin Phaeton 40QTH (Cummins ISC/Freightliner)
Flat towing a modified 2005 Jeep (Rubicon Wrangler)
Previously a 2002 Fleetwood Pace Arrow 37A and a 1995 Safari Trek 2830.
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01-25-2014, 10:20 PM
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#10
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Senior Member
Join Date: Sep 2013
Posts: 596
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Quote:
Originally Posted by so47
I picked up a 300 watt psw inverter for my front led tv and DVD player.
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How much power is your equipment drawing from the inverter? A 300 Watt inverter would draw about 26Amps DC... Is your coach DC wiring up to the task?
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01-26-2014, 08:34 AM
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#11
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Senior Member
Join Date: Jul 2011
Posts: 2,303
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This was mentioned earlier but I'll note it again because it is important: measuring voltage all by itself (meaning without considering the load) tells you nothing about voltage drop. Voltage drop is dependent on the resistance of the path and the amount of current being drawn... no current draw, no voltage drop.
Most inverter designs either work or they don't, meaning they don't show output voltage fluctuations based on input voltage, they just stop working if it gets too low. But it would be a worthwhile test for you to measure the DC voltage at the input of the inverter with no load connected to the inverter, and then a high load. Ideally you should see no more than a few tenths of a volt difference, but in any event it should be less than 0.5 volt. If it is high you need larger-gauge wiring between the DC power source and the inverter.
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01-26-2014, 03:25 PM
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#12
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Senior Member
Damon Owners Club Workhorse Chassis Owner
Join Date: Mar 2009
Posts: 24,024
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It is very hard to damage a TV with low voltage.. now an air conditioner, that's a whole nutter horse power..
But it is very hard to damage a TV with low power... And they should work well down to 105 by design, and likely down to 100 or perhaps even lower.
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