Community Forums

elkhornsun · 03-26-2013, 11:54 AM

I am surprised at how many people assumed a problem with the solar or wiring without any idea of the capacity of the battery bank and the Watts drawn by the TV system (TV, satellite receiver, antenna signal booster, etc.) in the RV.

Three batteries means 300 AH of capacity at 12v. A 50" plasma TV can eat up 160 to 535 Watts. The average 50" LCD TV will consume over 200 Watts. A bare bones satellite receiver will draw 50-60 Watts and a DVR will pull more than 200 Watts. It can easily add up to a total load of 500 Watts and with an inverter there is a power loss with the DC to AC conversion as well.

It is easy to understand why 3 batteries is not able to handle the load. Easiest fix would be to fire up the generator when using the TV. Best fix would be to not bother with the TV when "boondocking".

Groovy · 03-27-2013, 08:47 AM

elkhornsun - We've found that 4 6-volt golf cart batteries is a good solution (440 ah of capacity).

A 50" TV would dwarf our 36' fifth wheel because of the placement of our recliners and our TV. We have a 26" TV on a telescoping arm and it's plenty big enough for the distance from where we sit. It draws less than 100 watts.

We watch a few hours of TV or watch a movie on our DVD player most nights, and we boondock all the time.

WheelingIt · 03-27-2013, 08:58 AM

Quote:

Originally Posted by Groovy

elkhornsun - We've found that 4 6-volt golf cart batteries is a good solution (440 ah of capacity).

A 50" TV would dwarf our 36' fifth wheel because of the placement of our recliners and our TV. We have a 26" TV on a telescoping arm and it's plenty big enough for the distance from where we sit. It draws less than 100 watts.

We watch a few hours of TV or watch a movie on our DVD player most nights, and we boondock all the time.

We're with Groovy on this one. We have exactly the same battery capacity as them (440 ah) and usually watch a few hours of TV or a movie nightly. Our TV is an 27" LED... doesn't use much power at all and anything bigger would be way too big for the coach. We also have LED lighting throughout the rig.

Nina

YC1 · 03-27-2013, 09:19 AM

Panels mounted flat rarely reach peak output. Dirty panels will not reach peak. Shade will diminish as well. Oh, and snow is a problem.

So, how much power are you really getting to the batteries. You need an ammeter or at least put a voltmeter across the batteries as they are charging.

Simple formula. Marbles in the bucket, marbles out of the bucket. Amps that is. If your bucket is 200amps/marbles. How many are you putting in and how many are you taking out. Even with decent solar I have to run my generator a couple of hours each day to keep up.

WheelingIt · 03-27-2013, 12:26 PM

Quote:

Originally Posted by YC1

Even with decent solar I have to run my generator a couple of hours each day to keep up.

I have to admit we don't have that problem at all. In our 4 years on the road and with quite alot of dry-camping in that time we rarely ever run the generator (in fact, I usually have to force a run just to exercise it).

Alot of solar problems come down to incorrect wiring & losses. We have 600 watts of solar and thick, short wiring runs. Usually our 440 ah batteries are fully charged by ~mid-day each day. In winter we tilt the panels for an extra boost, but in summer we never bother.

As an example last night we watched 3 hours of TV (it was re-run of Game Of Thrones) and we've been on the internet since early AM. We're in the last throwes of absorb right now at 11:30AM and I expect we'll be in float in about an hour. Life in the boonies is good

Mike_Harriet · 03-27-2013, 01:48 PM

Wheelingit, what do you use as a tilting mechanism? Can you tilt the on top of the roof, or is this on a ground mount? I'm trying to engineer a system like what's on my boat, for a motor home. Any pics?

WheelingIt · 03-27-2013, 02:04 PM

Quote:

Originally Posted by Mike_Harriet

Wheelingit, what do you use as a tilting mechanism? Can you tilt the on top of the roof, or is this on a ground mount? I'm trying to engineer a system like what's on my boat, for a motor home. Any pics?

Our panels are roof-mounted so it's basically get up on the roof and tilt up there. Doesn't take too long, but just means you gotta climb up there. It's usually a good excuse to clean the panels too

We made our own tilting bars from Aluminium stock and used the AM Solar Panel mounts which make it super-easy. Just unscrew, tilt and re-screw. I've got pics of the whole process here:
RV Solar Part IV – Panel Tilting & Winter Solar Optimization

We get a very nice boost from tilting in winter.

Happy Prospector · 03-27-2013, 07:31 PM

Quote:

Originally Posted by elkhornsun

Three batteries means 300 AH of capacity at 12v. A 50" plasma TV can eat up 160 to 535 Watts. The average 50" LCD TV will consume over 200 Watts. A bare bones satellite receiver will draw 50-60 Watts and a DVR will pull more than 200 Watts. It can easily add up to a total load of 500 Watts and with an inverter there is a power loss with the DC to AC conversion as well.

I bought one of the "Kill-A-Watt" meters and found out my 32" LCD TV was drawing 153 watts and when I upgraded to a 32" LED TV the wattage dropped to 29 watts, I have a Direct TV DVR and the wattage draw is 35 Watts.

Life is great with solar!!

Groovy · 03-27-2013, 11:22 PM

Our record for TV watching while boondocking was 15 hours one day during the 2008 summer Olympics. Our 26" TV is an LED.

Last summer we had two 13" laptops going for 12-15 hours in one day on quite a few occasions.

With good wiring and at lesat 500 watts of solar power there should be no reason to run a generator in the summer except for air conditioning.

We found 500 watts a little skinny from December 15 to Feb 1.

We don't tilt our panels. If I were to set up another rig I'd have tilting brackets and probably another 200 watts of panels.

Solar panels now cost less than 50% of what they did when we installed them on our first rig in 2007, and about 65% of what they did when we installed them on our second rig in 2008...

okmunky · 03-28-2013, 07:23 AM

Thanks for the info, Kevin. I just ordered a VuQube and a new 32"LED 12volt TV. I knew the power draw is low, but it's good to have more exact numbers.

On the subject of panel tilting -- I have 4 Uni-solar panels that are stuck to my roof. I have been told that tilting is unnecessary because the panels are thin and there is no air space or glass to refract the sun's rays. I get decent charging even on partly cloudy days. My 272 watts is enough to keep us charged, but I do use LED lights and an iPad.

Mike_Harriet · 03-28-2013, 07:49 AM

WheelingIT. Like your solar setup! Mine is different in that it is mounted on a round SS tube and pivots a on the centerline. However, I can't get as much tilt as you, and swinging on an anchor means frequent adjustments. Also don't do 60mph+, down the highway. But I will be copying your design on my MH. Thanks for sharing.

terry735001 · 03-28-2013, 04:38 PM

yes you have a lot of power there my roof was just made for the over 2000 lbs i dont think you can add more to yours

Happy Prospector · 03-28-2013, 05:26 PM

Quote:

Originally Posted by okmunky

Thanks for the info, Kevin. I just ordered a VuQube and a new 32"LED 12volt TV. I knew the power draw is low, but it's good to have more exact numbers.

My LED TV and Direct TV DVR are both 120 volts and I run them as well as my MotoSat Internet equipment off a 600 Inverter.

elkhornsun · 03-29-2013, 02:06 PM

My point was missed. The OP stated a problem and many folks jumped to the conclusion that the installation was done improperly or that more panels were needed or a 60 amp controller, and without thinking to ask what the total load was and what the total battery capacity was for the RV. Hard to offer sound advice without these two pieces of information.

Mentioned was a 440 AH with 6 volt batteries. Is this providing 440 AH at 6 volts to the charge controller and 12v devices in the RV or is it 440 AH at 12V as there is a big difference in comparing load to capacity.

A neighbor kept tripping his 15 AMP @110V breaker and when I started adding up the loads from his TV, DVR, satellite receiver, power chair, room lights plugged into the wall outlets, and then a small space heater, it became obvious why this was happening.

Our new Dish DVR pulls a lot more power than our old bare bones Dish receiver but then our old Hughes Satellite modems were pulling a lot more power than our EVDO mifi device. Our 52" LED LCD draws a third as much power as the DLP set it replaced and a plasma used more power than the DLP set. Point is to do the math and allow for inverter loss and then problems with the batteries are easier to troubleshoot.

We have a 22" LED LCD combo unit for use on the road and it pulls twice as much as the 15" Combo TV that it replaced. It was offset in part when I replaced most of the tungsten interior lamps with LED ones.

During freezing temperatures with the heater fan going a good deal we still only draw the batteries (220 AH @ 12v) down by 10% or less overnight and on a sunny day that is replaced by the two 100 Watt solar panels providing 11-12 amps at 17 volts, in less than 3 hours during the winter months (panels are not tilted).

After four days of heavy rain and little sun and high TV usage our batteries were down 22% and it took 5 hours to recharge the batteries. This confirmed that our system was not undersized in any respect for our needs while off the grid.

I looked at many sites on the Web while putting in our system and none were anywhere near as useful as Bill Moeller's book "The Complete Book of Boondock RVing" or the Solar Electricity book by Michael Boxwell. Both are current and provide great information and advice that I could find nowhere else.