Advice on using an inverter and Amp usage - Page 2 - Fiberglass RV


Reply
 
Thread Tools Search this Thread Display Modes
 
Old 09-28-2012, 07:49 AM   #15
Member
 
Name: Ronnie
Trailer: 2000 Scamp 13, 72 Alpine Sprite
Alabama
Posts: 72
The battery I have now is in really good shape. It's less than a year old and has never been drained below 12 volts. I trickle charged it last night and it measured 12.9 volts this morning. I will measure it again this afternoon to see if it drops any after sitting all day. Then I will run the amp test with the appliances again.

I should have charged it all the way before I ran the test the first time but I was eager to try out the inverter!

Thank you again everyone for the advice!! I will report back after I hook everything back up this afternoon.
__________________

__________________
bicklebok is offline   Reply With Quote
Old 09-28-2012, 08:02 AM   #16
Senior Member
 
cpaharley2008's Avatar
 
Name: jim
Trailer: 2016 2ndGen Escape19 Prairie Schooner pulled by 2014 Dodge Ram Hemi Sport
Pennsylvania
Posts: 6,398
Registry
Just remember, with a 85 a/h battery you only have 34 a/h available to use, not 85. You maybe better off with a newer digital, led, 12v tv which would eliminate the inverter, box, and draw a lot less a/h.
__________________

__________________
cpaharley2008 is offline   Reply With Quote
Old 09-28-2012, 09:45 AM   #17
Member
 
Name: Ronnie
Trailer: 2000 Scamp 13, 72 Alpine Sprite
Alabama
Posts: 72
Quote:
Originally Posted by cpaharley2008 View Post
Just remember, with a 85 a/h battery you only have 34 a/h available to use, not 85. You maybe better off with a newer digital, led, 12v tv which would eliminate the inverter, box, and draw a lot less a/h.
Thanks. I will look into that. I think I saw another recent thread about 12v televisions.
__________________
bicklebok is offline   Reply With Quote
Old 09-28-2012, 09:47 AM   #18
Senior Member
 
Thomas G.'s Avatar
 
Name: Kinga DeRode
Trailer: For Sale Or Rent
Rooms to Let 50 Cents
Posts: 5,103
Quote:
Originally Posted by bicklebok View Post
Thanks. I will look into that. I think I saw another recent thread about 12v televisions.
Look for a TV that runs off a plug in wall transformer. If that transformer says -Output 12 volts DC - you are golden.
__________________
UHaul and Burro owners, join the UHaul Campers on Facebook. https://www.facebook.com/groups/529276933859491/
Thomas G. is offline   Reply With Quote
Old 09-28-2012, 09:50 AM   #19
Senior Member
 
cpaharley2008's Avatar
 
Name: jim
Trailer: 2016 2ndGen Escape19 Prairie Schooner pulled by 2014 Dodge Ram Hemi Sport
Pennsylvania
Posts: 6,398
Registry
Here is the one I have, it works great...
JE1512LED - JENSEN 15" 12 Volt LED LCD TV
It has front controls, front speakers and draws 2 amps
__________________
cpaharley2008 is offline   Reply With Quote
Old 09-28-2012, 11:25 AM   #20
Senior Member
 
David Tilston's Avatar
 
Name: Dave W
Trailer: Trillium 4500 - 1977, 1978 (2), 1300 - 1977, 1973, and a 1972
Alberta
Posts: 5,317
Registry
Quote:
Originally Posted by Byron Kinnaman View Post
Same thing with AC. The key is power (Watts) stays the same.
120 Volts x 1 Amp = 120 Watts.
12 Volts x 10 Amp = 120 Watts.
On AC you need to consider power factor as well. Power factor is the phase relationship between the voltage and the current. It is possible, with a purely capacitive load to have lots of voltage and current, but no power.

120 VAC x 1 A x 0.8 PF = 96 W
__________________
David Tilston is offline   Reply With Quote
Old 09-28-2012, 11:36 AM   #21
Senior Member
 
Thomas G.'s Avatar
 
Name: Kinga DeRode
Trailer: For Sale Or Rent
Rooms to Let 50 Cents
Posts: 5,103
Quote:
Originally Posted by David Tilston View Post
On AC you need to consider power factor as well. Power factor is the phase relationship between the voltage and the current. It is possible, with a purely capacitive load to have lots of voltage and current, but no power.

120 VAC x 1 A x 0.8 PF = 96 W
Interesting, Dave. What type of camper applications would this tend to apply to?
__________________
UHaul and Burro owners, join the UHaul Campers on Facebook. https://www.facebook.com/groups/529276933859491/
Thomas G. is offline   Reply With Quote
Old 09-28-2012, 11:42 AM   #22
Senior Member
 
Byron Kinnaman's Avatar
 
Name: Byron
Trailer: 2006 Scamp 13' towed with a 2005 Dodge Dakota 4.7l Magnum W/full tow package (over kill)
Oregon
Posts: 6,309
Registry
Quote:
Originally Posted by David Tilston View Post
On AC you need to consider power factor as well. Power factor is the phase relationship between the voltage and the current. It is possible, with a purely capacitive load to have lots of voltage and current, but no power.

120 VAC x 1 A x 0.8 PF = 96 W
In today's electronic and electrical stuff you're more likely to have an inductive load. Purely inductive or capacitive is NOT going to happen. The effect is very small, therefore for practical use can be ignored. If you wanted to get really picky you could through in power line wire IR loss, wire inductance, capacitance, Q, and etc., etc.
__________________
Byron & Anne enjoying the everyday Saturday thing.
Byron Kinnaman is offline   Reply With Quote
Old 09-28-2012, 12:48 PM   #23
Senior Member
 
Name: None
Trailer: None
None
Posts: 2,734
Capacitive loads have a leading power factor, inductive loads have a lagging power factor and resistive loads have the voltage and current in phase. For an example take the full load amperage x the voltage of a one horsepower AC single phase motor and you get the apparent power but when you compare that number to the true power to obtain one horsepower (746 watts) the numbers do not match That is because the voltage and current are out of phase. A normal home is assumed to be at 80% PF . I do not believe in a trailer the PF is a major concern because trailers do not have large inductive loads such as a well motor but if your worried about being absolutely accurate in your calculations you should consider it. Unity PF is hard to obtain
__________________
steve dunham is offline   Reply With Quote
Old 09-28-2012, 04:04 PM   #24
Senior Member
 
David Tilston's Avatar
 
Name: Dave W
Trailer: Trillium 4500 - 1977, 1978 (2), 1300 - 1977, 1973, and a 1972
Alberta
Posts: 5,317
Registry
On a trailer, all the DC loads are at unity PF. Just the nature of DC.

I did not mean to start a large discussion about power factor, I was just saying why, with AC, Volts x Amps is not always Power. Typically the largest inductive load on a trailer would likely be an old converter. Mine has a large transformer, (coil) in it.

I used to work for one of the power companies in Alberta. I was a lineman and a substation designer. We used large banks of capacitors, which are nearly pure capacitive loads, to provide power factor correction for large factories witch have lots of motors. Motors can have very low inductive, power factors, but since they also have resistance, they must have a large restive, (real) power element.

I am about to launch into some AC theory to tell what I thought was one of the strangest moments in my electrical education.

Reactive VARs, and Capacitive VARs cancel each other out. Resistance is what limits current flow in a typical DC circuit. It also limits it in an AC circuit, but there is additionally inductance, (coils) and capacitance, (capacitors). They are not referred to as resistance, but instead, impedance. These also limit current flow. Inductive impedance, and Capacitive impedance cancel each other out. That is part of the reason that you can use capacitors to correct the power factor of motors. It is also called a tuned tank circuit. Used in old radios for tuning in stations.

Our teacher in high school electricity was demonstrating this by putting a large coil in series with a large capacitor, which was selected to have the same impedance as the coil. This left just the resistance of the coil to limit current. After the demonstration, he unplugged the circuit and was discussing it while holding the plug in one hand and fiddling with the terminals on the bench with the other. I guess he touched the bench ground and just started swearing up a storm. Capacitors, it turns out have another property. They store a charge.

Ohms law states that current = voltage / resistance

This can be transposed to: voltage = current x resistance

This is also true for: voltage = current x reactance

The reactance was around 1000 ohms, and at slightly less then one amp, the capacitor was seeing voltages of nearly 1000 VAC. Pretty impressive for something plugged into the wall. ~1000V is what was discharged across my teacher, to ground. He said he nearly dropped.
__________________
David Tilston is offline   Reply With Quote
Old 09-28-2012, 04:18 PM   #25
Senior Member
 
Thomas G.'s Avatar
 
Name: Kinga DeRode
Trailer: For Sale Or Rent
Rooms to Let 50 Cents
Posts: 5,103
Quote:
Originally Posted by David Tilston View Post
..........I did not mean to start a large discussion about power factor, I was just saying why, with AC, Volts x Amps is not always Power. .........

So, is this why a hard start capacitor is useful to allow a small generator to start an air conditioner?
__________________
UHaul and Burro owners, join the UHaul Campers on Facebook. https://www.facebook.com/groups/529276933859491/
Thomas G. is offline   Reply With Quote
Old 09-28-2012, 04:31 PM   #26
Senior Member
 
David Tilston's Avatar
 
Name: Dave W
Trailer: Trillium 4500 - 1977, 1978 (2), 1300 - 1977, 1973, and a 1972
Alberta
Posts: 5,317
Registry
Quote:
Originally Posted by Thomas G. View Post
So, is this why a hard start capacitor is useful to allow a small generator to start an air conditioner?
This is just a guess, but the capacitor would help overcome the inductive reactance, in the air conditioner motor. This leaves the generator to overcome the resistance. If the motor has a power factor of .8, then the generator is relived of 20% of the burden.
__________________
David Tilston is offline   Reply With Quote
Old 09-29-2012, 06:39 AM   #27
Member
 
Name: Ronnie
Trailer: 2000 Scamp 13, 72 Alpine Sprite
Alabama
Posts: 72
After sitting all day, the battery measured 12.8 v. I will run another test today with the appliances and report back the results. Thanks for all the advice. Lots of things I never considered.
__________________
bicklebok is offline   Reply With Quote
Old 09-29-2012, 07:40 AM   #28
Senior Member
 
Bob Miller's Avatar
 
Name: Bob
Trailer: 1973 Hunter Compact II
California
Posts: 7,912
FWIW: I think you need to go back to the original readings and find out what your true current draw is. CRT TV's typically draw more like 60+ watts, that's about 5 times what you were measuring and, in itself, would explain why your battery went down so quickly. In addition, you need to know if your battery was fully charged in the first place.
How are you measuring the 1 amp draw?
How are you measuring battery voltage?
Do you have a second meter to verify any of the above?
What does it say on the back of your 13" TV for current/wattage requirements?
__________________

__________________
Bob Miller is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off


Similar Threads
Thread Thread Starter Forum Replies Last Post
fantastic fan battery usage kayleigh0302 Problem Solving | Owners Helping Owners 15 07-19-2017 01:16 PM
Getting repairs done - advice & comments welcome KarenH Care and Feeding of Molded Fiberglass Trailers 10 09-19-2010 08:38 AM
Need advice on visiting Utah Nat'l Parks & Grand Canyon peterh General Chat 14 02-16-2010 12:06 AM
Fiberglass RV Pricing - Holding Value vs. Usage Depreciation Mitchell Money Matters 54 08-11-2009 09:30 PM
Propane usage khoa l General Chat 13 11-03-2008 10:07 PM

» Upcoming Events
No events scheduled in
the next 465 days.
» Virginia Campgrounds

Reviews provided by


Copyright 2002- Social Knowledge, LLC All Rights Reserved.

All times are GMT -6. The time now is 04:13 AM.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2017, vBulletin Solutions, Inc.