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05-27-2015, 01:49 PM
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#1
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1 Rivet Member
1987 31' Excella
Erin
, Ontario
Join Date: Apr 2009
Posts: 6
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How many watts/panels/batteries do we need?
Hello, we have a 31' Excella on some acreage near Owen Sound, Ontario. I have a Sunforce 4 panel , 80 watt solar package that I bought from Costco, hooked up to (2) 12 volt deep cell batteries ( parallel wired) . We would like to be able to run lights as required @ night and the Propane fridge electronics for 2-3 days max. We always run out of juice into day 2 @ best. How much more do we need & of what ? Thanks for any help.
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05-27-2015, 01:55 PM
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#2
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Rivet Monster
1975 31' Sovereign
1980 31' Excella II
Sprung Leak
, North Carolina
Join Date: Jun 2003
Posts: 7,172
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Depends on your solar exposure. Here in the Deep South I can get away with ~200 watts and live pretty large unless we have a run of cloudy weather. Typically I can recharge in 4-5 hours in the winter what I use overnight running the furnace and lights. That is with a 100 watt portable panel, that I can move for optimum gain.
Given how far north you are and the probability of cloud cover you may need more battery and a whole lot more solar. Eighty watts is obviously not enough. I would expect you are going to need in the 240 watt range just to break even.
Aaron
__________________
....so many Airstreams....so little time...
WBCCI #XXXX AIR #2495
Why are we in this basket...and where are we going
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05-27-2015, 02:11 PM
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#3
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Rivet Master
2005 39' Land Yacht 390 XL 396
Common Sense
, Texas
Join Date: Sep 2007
Posts: 5,319
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Quote:
Originally Posted by RJB54
Hello, we have a 31' Excella on some acreage near Owen Sound, Ontario. I have a Sunforce 4 panel , 80 watt solar package that I bought from Costco, hooked up to (2) 12 volt deep cell batteries ( parallel wired) . We would like to be able to run lights as required @ night and the Propane fridge electronics for 2-3 days max. We always run out of juice into day 2 @ best. How much more do we need & of what ? Thanks for any help.
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Don't know if you've done this or not, but you can reduce the amount of power you use for lighting by about 75-80% by switching to all LED bulbs.
__________________
Regards,
Steve
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05-27-2015, 02:31 PM
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#4
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Rivet Monster
1975 31' Sovereign
1980 31' Excella II
Sprung Leak
, North Carolina
Join Date: Jun 2003
Posts: 7,172
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Quote:
Originally Posted by SteveH
Don't know if you've done this or not, but you can reduce the amount of power you use for lighting by about 75-80% by switching to all LED bulbs.
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I forgot about LED... I have switched my house, RV's and barns over. I don't even think about non-LED stuff anymore.
LED's will definitely help reduce current draw if you use the lights much at all. On my RV's I have found the furnace, fridge control board and the smoke/CO and LP detectors to be the biggest draws. We use lights pretty sparingly and seldom watch television. I much prefer a good book.
Aaron
__________________
....so many Airstreams....so little time...
WBCCI #XXXX AIR #2495
Why are we in this basket...and where are we going
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05-27-2015, 04:15 PM
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#5
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Rivet Master
1978 25' Tradewind
Metro Phoenix
, Arizona
Join Date: Jun 2003
Posts: 1,524
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Is your solar package 80 Watts total? 80 watts into the batteries is going to give you on the order of 26 amp-hours a day - or roughly 4 hours of running your furnace.
I'm saying you need more than 80 watts of panels, but Lewster would be The Man to pitch in here.
__________________
"Between what matters and what seems to matter, how should the world we know judge wisely?" - E.C. Bentley, Trent's Last Case
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05-28-2015, 12:25 PM
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#6
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1 Rivet Member
1999 25' Safari
Palm Springs
, California
Join Date: Jan 2012
Posts: 17
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Have you considered using tow six volt batteries and running them in series? That is what I have and can do pretty well. I guess running the batteries in series gives you more amp hours.
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05-28-2015, 12:56 PM
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#7
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Rivet Master
Commercial Member
Vintage Kin Owner
Naples
, Florida
Join Date: Dec 2005
Posts: 7,508
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Quote:
Originally Posted by RMichler
Have you considered using tow six volt batteries and running them in series? That is what I have and can do pretty well. I guess running the batteries in series gives you more amp hours.
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You have to connect 6 VDC batteries in series to get to the required 12 VDC. The amp/hour rating stays the same. Series connections increase voltage. Parallel connections increase amperage.
Lew Farber
RVIA/RVDA Nationally Certified Master Tech
Master Tech Energy Systems, Inc.
AM Solar Certified Installation Center
Lifeline Batteries**Magnum Inverters
541-490-6357
__________________
lewster
Solar Tech Energy Systems, Inc.
Victron Solar Components and Inverters, Zamp Solar Panels, LiFeBlue and Battle Born Lithium Batteries, Lifeline AGM Batteries
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05-28-2015, 02:31 PM
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#8
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Rivet Master
2013 31' Classic
billings
, Montana
Join Date: Feb 2010
Posts: 3,577
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Looks to like it would be easier to start the 2000 watt honda generator......
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05-28-2015, 03:43 PM
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#9
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2 Rivet Member
2013 16' Sport
Boulder
, Colorado
Join Date: Dec 2012
Posts: 83
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nice little calculator here:
Solar Sizing Calculator
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05-28-2015, 04:22 PM
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#10
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Rivet Master
2006 25' Safari
St. Augustine
, Florida
Join Date: Oct 2011
Posts: 2,670
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Quote:
We would like to be able to run lights as required @ night and the Propane fridge electronics for 2-3 days max. We always run out of juice into day 2 @ best.
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You must be using incandescent lights. First, get LED replacements. If I run every light in my AS except inside cabinets I use 29.2 watts. Your fridge electronics should not be too much a draw. Two nights would be 10 hours as I run the lights for about 5 hours each night. One of those OEM light bulbs is I believe 14-28 watts depending on type, I had two types in mine - a 1141 and another one. That is a huge difference. My 48 hour light use at max would be 292 watt-hours DC. Your 80 watt panel should be able to add around 64 watts per hour avg. into the system for around five hours, then less as daylight weakens. That is 320+ watts DC. This example is how they figure it and tell you how much you need. They told me that I would need a 300 watt system to boon dock indefinitely as I used 226 watt-hours each day and needed the other wattage to charge the battery plus the low draw times, etc. I plan more off and on use like you so I am looking at 150-200 watts. I use two group 24 batts with a total of 184 amp hours or 1764 watts that needs charged to keep topped. The simplified calculation is 1 watt for every amp hour.
__________________
WBCCI 8653/AIR 60240
2022 Ford F150 PowerBoost Platinum w/7.2KW
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05-28-2015, 11:32 PM
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#11
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Rivet Master
Commercial Member
Vintage Kin Owner
Naples
, Florida
Join Date: Dec 2005
Posts: 7,508
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Quote:
Originally Posted by RJB54
Hello, we have a 31' Excella on some acreage near Owen Sound, Ontario. I have a Sunforce 4 panel , 80 watt solar package that I bought from Costco, hooked up to (2) 12 volt deep cell batteries ( parallel wired) . We would like to be able to run lights as required @ night and the Propane fridge electronics for 2-3 days max. We always run out of juice into day 2 @ best. How much more do we need & of what ? Thanks for any help.
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To start, you should have LED lighting as mentioned above as incandescent lights are real power hogs. Next, you have to determine your approx. amperage use for each day you wish to be off grid. This is done by listing every appliance you desire to operate, the estimated amount of time for each and their amp draw. The total will give you the amount of amperage (or wattage, depending on which measure you use) you can reasonable expect to draw from your batteries each day.
Next, multiply this amount by a factor of 4. Say you calculate a 38 amp draw each day. This would be a total of 152 amps per day. I would then suggest a battery bank with a capacity of 300 amp/hours minimum which would allow your batteries to be discharged to the 50% level each day.
Next, depending on your latitude, the type of batteries you have and seasons that you will be using the trailer off-grid, you then plan the size of your solar array. Liquid cell batteries take more amperage and more time to re-charge due to their higher rate of internal resistance. AGM batteries are far better and quicker to re-charge, and lithiums are lightning fast for recharging.
Based on where you are and starting with liquid cells, I would use a 600 watt array, AGMs; 400-500 watt array and lithiums; 300-400 watt array, all with an MPPT charge controller of sufficient capacity to handle the array.
Over capacity will allow you to have full batteries each day, even in overcast conditions and as I have been told by clients, battery charging from their solar array even in the rain!
Any of these configurations will allow you to stay off-grid far beyond the 2-3 days you are experiencing now.....but be forwarned! You don't get systems like these for Costco prices!!!
__________________
lewster
Solar Tech Energy Systems, Inc.
Victron Solar Components and Inverters, Zamp Solar Panels, LiFeBlue and Battle Born Lithium Batteries, Lifeline AGM Batteries
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05-29-2015, 09:59 AM
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#12
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1 Rivet Member
1987 31' Excella
Erin
, Ontario
Join Date: Apr 2009
Posts: 6
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Quote:
Originally Posted by SteveH
Don't know if you've done this or not, but you can reduce the amount of power you use for lighting by about 75-80% by switching to all LED bulbs.
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Thanks, we are already switching our house over, makes good sense to do the same with the trailer.
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05-29-2015, 10:24 AM
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#13
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Rivet Master
1974 Argosy 20
2014 20' Flying Cloud
Kooskia
, Idaho
Join Date: Jul 2009
Posts: 4,591
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Quote:
Originally Posted by RJB54
Thanks, we are already switching our house over, makes good sense to do the same with the trailer.
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And you can even consider using 120 volt LED bulbs powered by a small inverter in your Airstream as an inexpensive way to do the conversion.
See my post on the subject:
http://www.airforums.com/forums/f447...am-126542.html
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05-29-2015, 10:52 AM
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#14
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4 Rivet Member
2012 28' International
Prince Edward County
, Ontario
Join Date: Nov 2013
Posts: 338
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We have a basic system installed by Can-Am when we picked up our trailer two years ago. We have a 160 watt GO Power panel mounted on the roof (with no inverter) used to the power the lights, fridge electronics, furnace, etc. We upgraded the batteries to Lifeline AGM Group 24 six months later. We have no problem in the U.S. south west running lights, furnace (at night), etc. when we have a reliable source of sunlight. With cloudy, cold weather (i.e. Grand Canyon this past April), we can last at most two days being careful. During a one month period (April to May) from Grand Canyon to Moab, we dry camped about 15 days with no problems keeping the batteries at full charge. In Newfoundland last summer, we were OK after two days of cloudy weather in Terra Nova National Park; then again we didn't require the furnace in summer.
That said, we are considering a generator for periods of cool, cloudy weather which we may encounter on Vancouver Island this fall.
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05-29-2015, 05:08 PM
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#15
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Rivet Master
1978 25' Tradewind
Metro Phoenix
, Arizona
Join Date: Jun 2003
Posts: 1,524
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We had a period of three days over Memorial Day when our camping spot was shaded, plus it was pretty much overcast about 90% of the time. I ran our little sixty-four dollar 800 Watt Hazard Fraught generator two hours a day to feed the PD9245 converter (750 Watts) and it kept the batteries up perfectly. Lot of 5.5 Amp furnace blower, plus two CPAP machines and various night lights.
__________________
"Between what matters and what seems to matter, how should the world we know judge wisely?" - E.C. Bentley, Trent's Last Case
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