What is the Best Battery to use and Solar Charger

[bdosborn]

I did some extensive metering of my 12V fridges, using the Morningstar Sunsaver MPPT hooked up to a laptop. Here's what I found:

I have a Waeco 40 and it uses around 1/2 amp-hrs with a 40F interior Temperature.

I replaced the propane fridge in the camper with a 12V Tundra TJ22 and it uses 1 amp-hrs at 40F interior temp.
Click on the links to go to my web page for more details.

To estimate what your panel will harvest per hour you can use NREL's PV Watts 2. It's a little cumbersome at first to figure out the website but here's what you get when you run it. I circled the hours per day at full output using a fixed tilt panel:



The harvest goes down around 20% for a flat panel. This is where a folding panel helps, you can increase your harvest by 40% over a flat panel by moving the panel during the day to track the sun. This is for a zip code close to you (I think). PV watts only deals with kW size arrays so divide all the energy values by 1000 for your 125 watt panel.

Bruce

[Esteban]

Bruce, thanks again for your information. SC thanks for yours about camping in less than full sun too. I'll mess around with PV Watts some more. Santa Maria is 30 miles south and is similar for climate calculations. It would not represent the solar radiation available where I may travel which could be greater, or less.

If a chest style (top opening) fridge/freezer like Bruce's Waeco 40, or a similar sized Truck Fridge TF41, or ARB 37, uses on average 12 amp hours daily that is much lower than 20 AH or so daily I estimated one would use. Very, very good if usually true to life.

I am considering using a computer fan to draw (cooler) fresh air into the cabin from under the floor. It would be on a switch, and maybe a thermostat too. That could reduce power used by a Fantastic Fan. The Fantastic Fan, a 5000rbt, I will use has a thermostat to turn it on or off as needed. So it (FF) will only use power intermittently. (I like the lower power used by a 14 speed 6600r/417 http://www.fantasticvent.com/products/products.html or http://www.rvvent.com/6600r.htm but they are too costly for me to justify)

All cabin interior, galley and porch lights will be LED so they should not use much power per day.

I do not plan to install or use an inverter which hogs power. Nor an air conditioner, heater, TV, any electrical cooking, warming, or coffee brewing devices, water heater or water pump.

A fridge/freezer is the one "luxury" big user of power.

I may use 12 volt bed warmer pads if I winter camp. I don't contemplate any other high power usages.

All this is to say it seems that a 12 volt 125 watt solar collector, with a 100 amp or so deep cycle battery for power storage, a PD 4045 for AC/DC power and battery charging when hookups are available, and charging from the tow vehicles alternator when traveling may be adequate, or more than adequate for my teardrop. I estimated using between 20 and 30 amp hours daily. Most of it used by a fridge/freezer.

The choice of whether to use a pwm or a mttp (my preference) controller may not be one of absolute necessity but one of wanting to utilize an extra edge that takes no extra ongoing effort to harvest the maximum amount of power possible each day...treating myself to a nicer luxury, maybe a little bit of glamping.

Portable solar collectors could be an option if the roof top solar panel is sometimes, or often, inadequate to keep the battery higher than 50% discharged (SOC?) after about 3-4 days of camping. I would most likely get on the road again after that time and charge from towing, or may have access to AC power to recharge the battery.

If I can boondock off grid for a week or so beginning with a full battery and collecting the weeks solar harvest, so as to not run the battery down any lower than 50% that would be golden. Even more golden would be to keep the battery fully charged from solar power while boondocking.

Getting a bit goofy, I don't plan to use an electric blender to make pitchers of icy margaritas (though that could be mighty nice) or to make big bags of pop corn in a microwave nor to watch TV or play loud music while camping in a teardrop. Will not air condition a side tent either.

Sorry for my long windedness

[bdosborn]

If a chest style (top opening) fridge/freezer like Bruce's Waeco 40, or a similar sized Truck Fridge TF41, or ARB 37, uses on average 12 amp hours daily that is much lower than 20 AH or so daily I estimated one would use. Very, very good if usually true to life.

12 amp-hrs daily is probably the best case scenario, I would plan on anything from 12 to 20 amp-hrs per day. Usage is completely dependent on the interior temperature as well as the ambient temperature. Crank the fridge down to 32 for that really cold beer will drive your usage way up. You'll use more on a 100F day than a 68F day, no matter what you set the fridge at. As always, YMMV. I'll turn my fridge down during the day when I have plenty of power and turn it up at dusk so I ride through the night using less energy.

Bruce

[Shadow Catcher]

The one recommendation I would make, don't bother with the Fantastic Fan and forget thermostatically controlling. We have two 80MM Antec case fans a large volume 400 cubic feet interior space and only a few times have both fans been on high.
We do have AC that can be left home and the case fans are use to help circulate the air. The fan housing is a Fantastic Fan, minus the fan.

[Esteban]

The one recommendation I would make, don't bother with the Fantastic Fan and forget thermostatically controlling.

SC, thanks again for sharing your ideas. I have a Fantastic Fan already. I want it for ventilation and for a skylight to help the cabin feel "roomier."

My idea to also use a computer fan for ventilation. I'd have a vent pipe, maybe 3" pvc, to draw outside air into the the cabin area. The vent pipe would be open (with a bug screen) under the trailer floor then go upward into the galley near the bulkhead. It then makes a 90 degree turn toward the cabin through a (3"?) hole in the galley/cabin bulkhead. The fan would be mounted to the cabin side of the vent. The fan would have a closeable cover to close the vent if outside air is too hot or cold for comfort and to keep dust or moisture out when traveling.

It would pull cooler outside air from under the trailer into the foot of the cabin. Good anytime, it could be very useful if rain threatened and open windows could let water in. Exhaust air could go out the side windows and/or out the Fantastic Fan in the roof...which could be turned on or off as needed. The computer fan would have a on/off switch. Maybe a thermostat too...partly to help save power.

Newegg http://www.newegg.com/Case-Fans/SubCategory/ID-573 has many computer fans to choose from. I'd most likely pick an 80 mm fan with multiple speeds, a quiet rating, and no LED.

The Fantastic Fan I have is the 5000rbt http://www.rvvent.com/5000rbt.htm with reverse and a thermostat.

Looking at your picture, thank you for sharing it, a simpler version could have a vent and fan in the front side wall(s) near where your head rests. An outside vent cover would be needed. Maybe something from a marine or boat supplier. Or maybe a porthole that opens. There are too many choices sometimes making it hard to KISS. (keep it simple #####)

Time to go buy some local See Canyon apples.

[Shadow Catcher]

The head of our bed is at the rear and we have two windows that open wide. We like the central vent location and I can reach up and either increase or decrease fan speeds or turn one off. There was a thread a couple of years ago on how to slow down a FF and the out come was, you can use resistors (wasteful) or a PMW, less wasteful. Our first tear only had one door and that meant the hatch had to be an escape hatch and so had no fan which is when I came up with the case fan idea. I researched the CFM and noise, Antec won rated at 100CFM (a bit optimistic) and one of the lowest sound levels.

[OverTheTopCargoTrailer]

Now I know why your called Shadow Catcher , you like shaded parking

[GuitarPhotog]

Now I know why your called Shadow Catcher , you like shaded parking

There is no sunny parking/camping in Big Basin Redwoods State Park. Lots of tall redwood trees everywhere.

<Chas>

[bdosborn]

That's why I like portable panels, you can camp in the shade:



Bruce

[Shadow Catcher]

Bruce, wouldn't have helped to have a portable at Big Basin Redwoods
There were some shafts of light that did make it down, briefly, but with most panels my understanding is that this gives you nothing in the way of usable current.

[bdosborn]

Some panels are better than others in low light, the thin film is supposed to be the best. Unfortunately, they're big and have largely been replaced by silicone panels so they're hard to find. However, all panels do poorly in the shade. In the picture the rooftop panels were putting out about 10 watts out of 400. The portable panel was putting out a little over 60 out of 80. I had it paralleled with the roof panels, I probably would have done better if it was the only panel connected to the controller.

Bruce

[Esteban]

Thought I'd update with some information on solar panels and MPPT controllers that are more affordable and likely to fit on a teardrop.

Grape Solar sells a 12 volt 160 watt panel that is 58" long and 26" wide which may fit on a five foot wide teardrop's roof. It's $229.99 from Home Depot. With one of these you can have power for a luxury like an ac/dc fridge/freezer, lights, a fantastic fan, outlets, and other electrical goodies.

If you need a shorter solar panel UL-Solar sells a 12 volt 125 watt panel that is 48.5" long and 26" wide. It costs $239.00 from ul-solar.

The physically smaller Grape Solar 12 volt 100 watt panel is 40.8" long and 20.7" wide. Home Depot sells one for $139.99. It should be able to fit on just about any teardrop trailer's roof.

There are many more choices for solar panels.

I like the glue-on solar panel mounts from Instapark Instapark® ZJ-34W Universal Drill-free Solar Panel Rooftop Mount, Color White They add an aerodynamic look, do not need screws to penetrate the roof so there is less opportunity for a water leak, and if used with theft resistant bolts your solar panels are less ikely to "walk away."

Amazon.com now sells two lower cost MPPT solar controllers: MPPT Tracer1210RN Solar Charge Controller Regulator 12/24V INPUT 10A for $72.00 or a MPPT Tracer 2210RN Solar Charge Controller Regulator 12/24V INPUT 20A for $135.00. MPPT controllers can harvest more power than PWM solar controllers. The reviews on each of them are good.

Less efficient PWM solar controllers cost considerably less, as little as $22.00 from Amazon.com.

Solar power is becoming much more affordable to use on a teardrop trailer. It can allow you to camp in comfort when shore power is not available.

[Shadow Catcher]

Again, part of the success with ours is that it is a 66 cell panel with an open circuit voltage around 70V and I have seen 17V from a full moon.

[Esteban]

[OverTheTopCargoTrailer]

After you watch this , he's got one on how to make $50k making you tube video's
he has 7 solar video's in all 3.5 hours approx.

great find