Harbor Freight's 45 watt solar panel - Page 2 - Fiberglass RV


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Old 08-06-2015, 09:15 PM   #15
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Don't know what fridge you have, but if it is 120V or 12V electric only, you'll need more like 350 watts, or ten panels and two or more batteries.
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Old 08-06-2015, 09:21 PM   #16
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Glenn
The fridge was on propane and the 2amps was for the fans and electronic controller.


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Old 08-06-2015, 09:27 PM   #17
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I was referring to Ellpea's fridge and question about running it on a 35 watt panel.
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Old 08-06-2015, 09:39 PM   #18
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All a solar panel does is charge your battery. A 35 watt panel puts out 3 amps, about the same as a trickle charger, that's under optimum conditions. It will help extend you battery usage. Converting to LED lights is a big battery saver over conventional lights, and most early 3-way refrigerators don't require any power when running on gas.
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Old 08-06-2015, 10:03 PM   #19
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Ellpea -

Yes. That appears to be the same panel that Northern Tool carries.
http://www.northerntool.com/shop/too...2420_200512420

Northern Tool sent me a sale flyer and coupons. I used a $20 off of a $100+ dollar purchase coupon to bring the cost down to $109 plus tax.

It would be hard for me to know exactly what your current draw would be and, as has been mentioned, panel wattages are usually stated for full sun and good directional conditions.
Keeping that caveat in mind, I think that the 35 watt panel and a good battery should last for somewhere between several days to more than a week. But that is just my guess.

I have a Group 27 battery on my Scamp 13 trailer. My LED lights and my refrigerator (running on propane) didn't draw much current. Using the Fantastic Fan on the lowest speed (just long enough to pull in some of the cool Wisconsin night air) took some current out of the battery and then the solar panel replaced at least part of that current draw the next day (sitting at a fairly flat angle in full sun).

With careful to moderate current usage, I think that a 35 watt panel and sunny days should make a Group 27 battery last long enough for many folks needs. ???

As always, YMMV. ��

Good luck! ��

Ray




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Old 08-07-2015, 12:37 AM   #20
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I think Bob hit the nail on the head. If dry camping is what you like, then don't use large power consumers. I have no water pump, my old Dometic RM24 uses no electricity and I changed all the lights to LEDs. Now when I turn everything on (5 Light fixtures), I draw 90ma. That means a 100AHr battery will last 41 days with everything on constantly. I had a 56 Watt solar panel, but I stopped taking it. The largest electrical consumption when we camp now is charging our IPads that we use as E-readers, and I charge them in the tow vehicle.



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Old 08-07-2015, 10:05 AM   #21
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Originally Posted by Ellpea in CA View Post
Ray, is this the one?
http://www.amazon.com/NPower-Crystal...+35+watt+panel

Would this give me enough power to run the fridge, occasional lights, a fan, and charge computer?

LP
Fridge is the sticking point. A typical 3 way fridge that can use propane uses heating element so the answer to solar running that type of appliance is an emphatic not going to happen.

Some of the 12 volt compressor type refrigerators can live off of solar but that panel strikes me as undersized. I believe Doug outlined that one might pick up an extra day from a small panel (3 days vs. 2 days without) I think the people running that type of appliance off of solar are in the 100 watt solar or possibly even over that.

One can add more panels later. Say a 35-40 watt with stand today and maybe a 100 watt flexible on the roof or a 100 watt suitcase later. If you want to go that route buy a charge controller with the higher capacity up front so you don't have to replace that component to upgrade. Just add the panel(s) to the existing system.
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Old 08-07-2015, 11:49 AM   #22
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Hey LP, can you tell us the make and model of your fridge?


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Old 08-07-2015, 01:35 PM   #23
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Originally Posted by dleverton View Post
Hey LP, can you tell us the make and model of your fridge?


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Figuring out how much solar or battery you need is simple. You have amp hours storage your battery is rated at. Solar panel puts out a certain amount of amps each hour to put into the battery. You have amps draw from appliances and devices times the duration each one draws those amps.

You only get to use 1/2 of the amp hours in the battery without stressing the battery and decreasing its usable life span.

100 amp battery = 50 amps you can use.
2 amp output solar panel x 8 hrs. = 16 amps you can put back into battery.

Real world that would probably be more like 12 than 16 from a days worth of sun and a 2 amp panel. 2 hrs. morning and evening are at enough angle output goes down.

What do your electrical devices use in amps per day? Less than 16 you can go almost indefinitely. 31 amps and you are out of juice after 3 days.

Thus the need to know what your fridge model is and what it needs for power and what else you have that uses power from the 12 volt system.

Fridge runs a lot and tends to draw a lot of amps. Some items may use a lot of amps but not run much, say the water pump. Others use very little such as LED lights but you might have them on 3 hrs. each day. Coffee pot might use massive amps but only for 25 minutes. You have to add all that up to determine what you need to balance that usage.
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Old 08-07-2015, 02:27 PM   #24
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Ellpea -

As mentioned, knowing a fair approximation of your appliances current
draw is an important consideration. I have a Scamp 13. I'm not sure
what the appliances in your Bigfoot might actually consume. Perhaps
you could call Bigfoot and they could tell you?

If you know how many amp/hours are in your fully charged battery,
the number of amp/hours consumed by your appliances, and the number
of amp/hours replaced by your solar cell(s), you will be able to calculate
how long your battery might last.

As mentioned, we dry camped for 8 days using a Group 27 battery and
that crystalline 12 watt solar panel. At the end of that time, my battery
voltage was still over 13 volts.

My Dometic 2193 refrigerator running on propane doesn't consume
any battery. My LED lights consume only milliamps of current and are hardly any consideration at all. The water pump was run only infrequently
and probably consumes between 4 and 5 amps for only a minute at a time
until we shut off the switch. We did charge 2 cell phones every other day (and sometimes a tablet) in the trailer at maybe 1 to 2 amp/hours per charge? The ceiling-controlled Fantastic Fan (Fantastic Vent MDL 1250?) was probably our biggest amp/hour consumer? We probably ran it on low
speed for a couple of hours per evening/day (sometimes up to 3 hours???).
The company told me that the Mdl 1250 draws 1.86 amps on low speed, 2.29 amps on medium speed, and 3.0 amps on high speed.

I'm guessing that my 12 watt panel probably replenished somewhere
between 5.2 and 6.5+ amp/hours each fairly sunny day.

You can do the math.

In the other thread, Bob suggested: "Here's what I had measured once upon a time.
Item Ahr
LP + Radio 0.18
Refrigerator 0.32
Bath Fan low 1.49
Night
Lights 0.03
Range
Light 0.62
Ceiling
Light (single Bulb) 1.37
Converter 0.20
Water Pump 4.52
Furnace 2.82"


How long will battery last...
How long will battery last...

At Northern Tool, the same little $17 solar charge controller would be
adequate for either the 12 watt panel or the 35 watt panel. They do
have another solar controller for ~$25 that would handle a little more
wattage. Depending on how your calculations work out, it might be
wise to buy more controller than you need so that you could add more
solar panels/wattage later?

Because our needs were small and we were careful, the 12 watt panel
was adequate (maybe barely?) for that 8 day dry camping trip. For future
trips, I might add a second small 12 watt panel or just go ahead and
buy the 35 watt panel? Still TBD.

I'm afraid that is about all the advice/information that I can offer and
it might be worth about what you paid for it.

As always, YMMV.

Good luck!

Ray
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Old 08-07-2015, 02:59 PM   #25
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Quote:
Originally Posted by rdickens View Post
Ellpea -
I'm afraid that is about all the advice/information that I can offer and
it might be worth about what you paid for it.
As always, YMMV.
Good luck!
Ray


LOL! Actually, the advice and assistance has been of such great value here, I'd almost be willing to pay for it!

Truly, without information and encouragement, this Lil Bigfoot out there would only be a pipe dream, not a reality. It's hard to take steps when there are so many unknowns.

That said, I was pretty determined to bring this one home, even if some systems were not there or not working correctly. Will still post photos of interior as Bob and some others have requested, but with some pretty determined testing over the past few days I'm pretty sure the fridge is not up to snuff. It does fire up on propane and get cool. I haven't taken it to the point of trying to freeze. But under shore power, it cools, but will not freeze. I gave it about 6 hours.

I guess when I was querying about battery usage and appliances we could use, I should have clarified that the fridge is propane and would use that for long-term. The battery would only be used when traveling (so charged by auto), and while we're waiting to set up and getting ready to go. So fridge was not so much of an issue (and now less so). Something will have to be done about that, either repair or replace, but it is lower on the list of priorities than installing fan and solar.

So I think the main drag on battery would be lights (not LED yet but will be), fan, computer charge, phone charge, and sound system of some sort (still to be determined). I wouldn't be running a television, but might fire up a movie on the laptop of an evening.

I appreciate the math lesson on amps. It does make perfect sense. Will confess without shame to having a Masters in English but needing tutoring through math requirements. I can do it. It just gives me a big headache and causes an uncontrollable desire for strong drink.

I keep a binder/journal of camping info and will add these figures for later laborious perusal.

Now for strong drink.
Cheers!
LP
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Old 08-07-2015, 03:39 PM   #26
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If you have a propane fridge, it may still use some 12 VDC for controls. Unless it is an older fridge. An RM211, RM36 or RM24 use no electrical power when running on propane.

Another thing to consider for your hitch install is the 12 VDC supply wire. It should be #10, or larger. This will allow it to supply enough power from the tow vehicle. Many people find that after a day of travel, they arrive at their destination with a warm fridge, and a dead battery in their trailer. This is because the fridge is pulling more power then their tow vehicle connection can supply. Propane fridges use a heater, in place of the propane flame. This heater is on the order of 200 watts. This would be close to 17 amps.
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Old 08-07-2015, 04:07 PM   #27
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About the refrigerator... What is the Make and Model number and did you have a manual for it with the trailer.


Is the trailer level, that's very important for that kind of refrigerator.


Next, 6 hours isn't even a starting point for the first cool down after a long period on non-use. Take and freeze up about 6-10 1 liter bottles of of water and put those in the bottom of the refrigerator to help pre-cool it. Next put a glass of tap water on the top shelf and record it's temp. Then leave it on 120VAC for 24 hours and see how its doing. These refrigerators don't get cold inside like a home unit, they absorb heat out of what's in the refrigerator. Also there is a thermostat for 120 volt operation, be sure that's at maximum. Monitor the temp of the water in the glass. It should stay at least 30-40 degrees below outside temp.


As long as it works OK on electric the LP part can be fixed. We'll get to that next.
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Old 08-07-2015, 04:10 PM   #28
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LP, your refer on shore power will take a lot longer than 6 hrs to freeze. Most folks run them at least 24 hrs before a trip to get them to temp. Put a cup of water in the freezer to check it.
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