Category Archives: solar

A Solar Upgrade for the Teardrop Trailer

Teardrop Trail: June 4, 2017

In the last few months, I’ve been working on a larger solar system to pump water at the ranch. We live out in the Texas Hill Country and occasionally experience power interruptions, and I wanted to use solar power to improve our emergency preparedness. The experience of designing and building that system led me to rethinking the teardrop solar system.

A New Battery

Cutting a hole for the data display

Two 100-watt solar panels provide enough power to meet our modest camping needs, but I felt the battery could be improved. We were using a marine battery, but it was a compromise between high starter current (which we would never use) and deep-cycle power for camping use. An Absorbed Glass Mat (AGM) deep-cycle seemed a better match. I ordered an Optima D34M Blue Top that could supply up to 55 Amp/hours of power and fit into the modest available space.

And a way to measure it

The new data display

Of course, fully discharging any lead-acid battery will shorten its life and normally one leaves at least a 50% charge. How do you know when you’ve reached 50% remaining power? You can estimate from the battery voltage, but measuring power directly would be best. That led to the second upgrade; a digital energy meter. It shows voltage, current and power, as well as the total power in watt/hours consumed since the last reset. Using the Optima battery as an example, I could use up to 330 watt/hours of power ((55 amp/hours / 2) * 12 volts = 330 watt hours) before it was wise to recharge.

Electric Kettles for Camping?

Finally, we enjoy electric kettles for heating water, and they’re perfect for camping. In many campgrounds, shore power is available and we can heat water for tea, coffee and washing up with ease. Would it be possible to use an electric kettle on solar power?

With 1000 watt inverter installed

Researching electric kettles and hot pots I found one model that only used about 1000 watts. A lot of power, but within reach of a not-too-expensive 12-volt to 120-volt inverter. It looked like fun to see if I could make it work, and I ordered an inverter and the necessary wiring to hook it up. Besides; the same inverter could be used to power a Crockpot or Slow-cooker — something we’ve already shown is practical.

The picture tells the story. The new battery, inverter and hot pot were connected and did indeed heat 12 ounces of water to boiling. It used 164 watt/hours of energy as measured by the new digital meter — about half of the available battery storage. Not too practical, but a fun experiment!

: Boiling water with solar energy

: Boiled water energy consumption

Antenna (or Fishing Pole) Storage on a Teardrop

Ten Tec Triton II with digital frequency readout

I knew from the beginning there would be amateur radio aboard our teardrop trailer. I’ve been interested in radio since junior high, and it’s great to be out in the woods with a battery (or solar) powered radio, talking to hams around the world. I will never forget making my first overseas contact while driving through Wyoming in a thunderstorm. Or skiing down a mountain with a handheld radio while talking with another ham stuck in the city. Magic!

Radios have gotten smaller and more capable, and can be powered with modest solar-power systems, so ham radio from a teardrop trailer is a natural. Antennas, on the other hand, are about the same size. You can’t change physics or the laws of nature. Mobile antennas, while smaller than their fixed base comrades are still several feet long, and storing them is a challenge in our tiny teardrop. What about storing them in a long tube mounted to the rear frame of the trailer?

3-inch PVC with plastic strap hangers

I’ve worked with PVC pipe alot through the years, and the solution was obvious. A 5-foot length of 3-inch inside diameter pipe would easily store several antennas and their resonators (after disassembling them into sections) without taking up space inside the trailer. Each end was sealed with a screw-on “clean out” and voilà! Secure storage for my skyhook treasures. Several plumber’s straps would attach the pipe to the trailer frame. It’s cheap, strong and easy to work with. The job was done in no time and we set off.

Repairing the antenna tube

It wasn’t long before there was a problem. The trailer transmits substantial vibration and shaking to the tube, and the constant motion tends to break the plumber’s straps. Fortunately they don’t all break at once, but I was replacing straps often. I needed a better solution.

Improved steel strap hanger

Cruising around the home store one day, I found it. Zinc Plated, punched-steel bar. 1 3/8-inches wide and made of 1/16-Inch steel, it’s plumber’s strap on steroids.

Mounting Bracket

A 48-inch piece is only about $7, and with some 1/4-20 bolts, washers and nuts, I was in business. I took a scrap of 3-inch PVC, and wrapped it using a vice and hammer to form the steel. It is stiff enough to be challenging, but has a comforting level of strength. Drilling the frame for the 1/2-20 hardware isn’t hard, and two brackets are perfectly adequate. No more strap repairs for this teardrop!

By the way, for those of you who like to dangle a worm or two while camping — the tube could store fishing poles as well. I’m just sayin’ . . .

Antenna storage tube secured

Solar Chili

Making good food with limited resources has always been appealing to me, and camping presents a perfect challenge. I still enjoy cooking over an open campfire, but solar power presents a new opportunity to make great food with simple tools.

Solar-powered system in the galley

With the addition of a slow-cooker to our galley and the upgrade of the teardrop’s solar power system, I began thinking about combining the two. Marilyn’s recipe for “Teardrop Pork Chops” proved we could have dinner ready when we got back to camp in the evening. I wondered if the solar system could effectively power the slow-cooker. Some quick measurements with the “Kill-a-watt” meter showed power usage for the 1 1/2 quart cooker to be well under 100 watts — even on the “high” setting. The “low” setting only consumed about 65 watts. With our 200-watts of solar panels and adequate sun, it should work fine. What to cook for an experiment?

Slow-cookers have always worked well with bean dishes, in fact, they were invented for cooking beans. The combination of low temperatures and long cooking times guarantee tender beans that retain their shape and texture. Chili is an iconic bean dish, and what could be better after a day of camping fun?

Solar Chili

Cooker: 1 1/2 quart oval, powered by a 300-watt Bestek Inverter plugged into a 12-volt, 200-watt solar system
Settings and Cook times: HIGH for 2 to 2 1/2 hours, then LOW for 8 to 9 hours

1/2 pound dried pinto beans, cleaned and soaked overnight and drained
2 cloves of garlic, peeled
1/2 pound of course-ground lean meat, beef, pork or turkey
1 medium onion, chopped
3 ounces of tomato paste or puree
1 1/2 tablespoons of Dixon medium hot (or other high quality) chili powder
1 tablespoon ground cumin
1 teaspoon salt (or to taste)

For serving:
Shredded sharp cheddar cheese
Chopped fresh tomatoes
Chopped green onions
Warm cornbread or saltine crackers

Starting the beans and garlic

Put the soaked and drained beans and whole garlic cloves in the slow cooker, adding enough water to cover. Cover and cook on HIGH until tender but not mushy, 2 to 2 1/2 hours. Drain and discard the garlic.

All ingredients cooking

Meanwhile, brown the ground meat and onions in a large skillet and drain off the fat. Mix the meat, onions, partially-cooked beans, tomato paste, chili powder and cumin in the slow-cooker. Add enough water to cover and stir. Cover and cook on LOW for 8 to 9 hours, stirring occasionally. During the last hour, season with salt. Serve with toppings and warm cornbread.

A solar dining experience

How did we do? Using the measured slow-cooker wattage on high and low settings, a little quick math showed a total power consumption of about 750 watt-hours — within the production capacity of our 200-watt solar system on a sunny day. With the skillet-baked cornbread, all the fixins’ and a glass or two of wine — delicious.

The Teardrop Gets a Solar Power Upgrade

Teardrop Trail Log: September 20, 2016

MC4 solar branch connectors

After the unfortunate incident with the solar panel on our way to the Red Power Roundup, we were able to use shore power for the remainder of the trip. Disappointing, but not a show stopper. We had already determined that a single 100-watt panel was not enough for our needs, so I was planning an upgrade anyway. With a trip planned in late September, it was time to act. I ordered two new 100-watt panels, MC4 combiner connectors and additional MC4 crimp-on connectors. This would double our previous power capacity and allow for daytime use of a couple of small appliances including a crock-pot and solid-state cooler.

Aluminum bar seals leading edge to teardrop

Analysis of the incident and the remaining parts of the old panel made it clear that wind entering the leading edge had repeatedly flexed the panel causing it to fatigue and ultimately fail. It seemed to me that sealing the leading edge to the teardrop roof with a rigid mount would prevent this type of failure in the future. A trip to Home Depot secured an aluminum strip, and by drilling holes that matched the existing screw mounts, I could seal the leading panel to the teardrop skin. The leading panel then overlapped the other panel so it was also sealed to the wind.

The new panels began working immediately

Once installed, the panels began producing power immediately. Although we currently only have about 80 Amp-hours of storage, the two panels can easily replace the day’s power use with 10 to 12 amp output in full sun. Also, by adding a 300-watt inverter, we are able to run a 1 1/2 quart crock pot during the day with power to spare. The next upgrade will be a larger battery.

The Ambassador was ready for a trip to Bob Sandlin State Park.

photo of solar panels on teardrop trailer

The panels overlap like shingles

You Want the Good News or the Bad News?

Teardrop Trail Log: June 15, 2016

After leaving Perry, Missouri, we settled into an afternoon of travel. After a couple of hot and humid nights in Missouri parks, populated with marauding raccoons, we decided a night in a “clean, comfortable room for the lowest price of any national chain” would be a welcome change. Marilyn had the room booked, and all was right with the world.

This was my first time on an Illinois road trip in about 30 years, and that had been on a January night in an ancient International Harvester school bus (but that’s another story), so I didn’t have a visual memory of the state. The day was sunny, and the farmland was lush. Small towns marked our progress, and we pulled into Peoria in the late afternoon. Being a larger city, I had hopes of a Mocha, and as usual, Marilyn was already on it. She turned on The Girl, and in no time, we were pulling into a Starbucks. Finally a day without incident.

All that’s left

Hot drinks in hand, I noticed something amiss on the Ambassador. Where was the solar panel? The two feed cables and wing nuts with the torn corners of the fiberglass panel were all that remained. What had happened? No idea. Disappointing, but I had already decided a single 100 watt panel wasn’t enough, so this was an opportunity for improvement. Stay tuned for the Solar Ambassador Revision 2!

Tomorrow was another day. Besides, Tom Bodett was leaving a light on for us.

Marine-Style 12 Volt Outlets in Our Teardrop

Jim, July 23:

One thing we learned on our trip to Big Bend, we needed more power outlets! With two smart phones, an iPad, a laptop, two cameras and other low-voltage doodads and geegaws, the two 12-volt and two 120-volt outlets that came with the trailer were simply not enough. Multi-outlet USB chargers helped, but added to the clutter in the cabin — especially at night. Also, the existing outlets were located on the aft interior and galley walls. Not convenient for charging while reading in bed.

Galley outlets

We had been working on a friend’s tiny house, and learned that the universe of 12-volt equipment has greatly expanded in the last couple of years. The tiny house was equipped with a marine power center, and offered 120/240-volt and 12-volt service. Just what was needed while at shore or underway. We equipped the tiny house entirely with 12-volt lighting, and easily found fixtures, light bulbs and other 12-volt outlets. With all the interest in solar power the number and quality of such devices is rapidly improving, and a trip to the Amazon store yielded several marine-style USB, cigar lighter and battery monitor fixtures.

USB power outlet detail

Fortunately, the Ambassador has hollow wood-paneled walls, so expanding the existing 12-volt wiring wasn’t too difficult. I simply replaced the two 12-volt cigar outlets with double and triple-gang devices on the back wall of the cabin and galley, while adding a pair of USB outlets on the forward wall under the cabin light. The marine system is nice because the 2 or 3 position panels can accept any combination of outlets and monitoring.

Now we can read in bed while charging our iPhones and other USB and cigar-lighter-based devices. Perfect!

: Interior — looking aft

: Interior — looking forward

: Cabin light and USB power outlet

A Trip to Krause Springs

Marilyn

Jim, July 22:

Marilyn was eager to connect with teardrop trailer enthusiasts and looked for groups we might join. The Southwest Teardrop & Vintage Trailers had a scheduled meetup in May and we decided to go. The three-day event was more than our time allowed, so we drove up for the day on Saturday. That way, we could make some new friends and check out Krause Springs at the same time.

Krause Springs

Located in the Texas Hill Country off Highway 71 on the way to Llano, the privately-owned, 115 acre park has been in operation since 1955. It’s on the National Registry of Historic Sites and has been owned by the Krause family for over 50 years. We happen to be on the right side of Austin, so it’s very close to our home, Roy Creek Ranch, northwest of Dripping Springs. We were there in less than an hour. It’s a beautiful park with camping, hiking trails, a butterfly garden and or course, the springs! One of the best swimmin’ holes in Texas, the springs ultimately empties into Lake Travis. With both natural and man-made pools, it’s easy to cool off on a hot summer day.

A tour of Teardrops

Marilyn had already contacted the group, and they were expecting us. They quickly found us a spot in the impressive line of teardrop trailers, and we spent the next couple of hours visiting with our new friends. Most of the trailers are custom crafted, and The Ambassador fit right in. There were a wide range of sizes an looks, and it was clear that everyone took teardrop camping very seriously. Our solar-powered beer cooler was a hit, and I was glad we had a special feature to show off.

: Rodger’s Teardrop

: Diane’s Teardrop

: Shelley’s Teardrop

Hiking the Springs

The initial flurry of introductions and tours completed, we had bite of lunch and decided to look around the park. We spent the next couple of hours exploring.

: Down to the swimmin’ hole

: A knotty problem

: Dragonflies

: House and Butterfly Garden

: Hangin’ out

: A butterfly feast

An Evening Potluck

Hikes, swims, naps and other afternoon activities completed, it was time for cocktails and a potluck. Marilyn had prepared some potato salad, and the overachievers in the group insured no-one left hungry. It was amazing to see what was produced in the tiny teardrop galleys: chips and dips, casseroles, slow-cooked pulled pork and a variety of desserts and more. An amazing day — lots of unique trailers and new friends!

Krause Springs Pool

A Solar-Powered Beer Cooler

Jim, May 31:

Tiny, Solid-state cooler

We were recently invited to the Southwest Teardrop & Vintage Trailer meet-up at Krause Springs and knowing there would be some cool trailers there, I wanted to add something unique to ours. Solar power is that not that common on teardrops yet, so it seemed a possibility. A couple of years ago, we purchased a little solid-state cooler from The Home Depot. It cost less than $30, and was shaped like an old Coca-Cola Machine. A similar product is available from Amazon, but without the Coke branding. Best of all, it could run on 120-volt or 12-volt power. Would our solar panel power it for a day?

Photo of the interior of a beer cooler with bottles and cans

Cools a 6-pack

We’ve traveled with the little cooler several times, and I routinely use it in my shop. It will hold a 6-pack in cans, or 4 short glass bottles. I’ve always got it filled with “cool ones”. I had never tried it on 12-volt power though. We also have a solid-state ice chest from Igloo, and it’s always in the car — perfect for keeping groceries cool during the hour-long trip out to the ranch. It draws about 6 amps at 13 to 14 volts (car running), so it’s not super power efficient. We once drained the car battery by forgetting to unplug it while the car sat in a parking lot for several hours. I guess that’s why I hadn’t ever tried the beer cooler on solar. Didn’t want to drain the battery.

Solar panel is removable

This was a different situation. Although the rig would be sitting idle for several hours during the meet-up, we would have sun available, and that might make it practical. I designed the solar panel to be removable, so it can be located in full sun while connected to the trailer electrical system (sitting in the shade) via a 20-foot cable. That should be sufficient to power the cooler and a a few other accessories during the day.

Well, long story short, it worked. Since we weren’t staying for the night, the Lady and the Ambassador stayed hitched and I located the solar panel on her windshield. The extension cable just made it to the normal panel connection on the trailer, and the cooler was plugged into the galley. By the afternoon, I had cold beer. The solar panel kept up just fine in spite of the partially cloudy day and occasional rain. Hmmm, now what else might we be able to power?

Current Galley

Solar Power on the Teardrop Trail

In an earlier post, we described a simple solar system for the our teardrop. With only a 15-watt capacity, we needed to upgrade and did so last year. We’ve gotten some questions about our solar power installation on the teardrop, and I wanted to share what we’ve done. This a work in progress, but during our recent Big Bend trip, we never hooked the trailer up to shore power (aka 120 volt hookups) and used solar power almost exclusively. It’s important to state our goals however, we didn’t intend to replace shore power. Instead, we wanted to extend the practical range of our trailer, making it possible to use primitive campsites for days at a time. This is where solar power can really shine (pun intended) on a small trailer.

There are several elements to a solar system. At minimum, a solar panel, a storage battery and some kind of charge controller are needed. Additions include 120/240-volt capabilities like battery chargers and inverters. Our system is almost exclusively 12-volt. With it we run lighting and have the ability to charge multiple devices such as smart phones, tablets, a laptop and digital cameras. We even have the ability to run a few high current 12-volt appliances like an electric tea kettle intermittently. Our trailer has a 7500 BTU air conditioner (this is Texas after all), but that must be run on shore power.

photo of battery, charger and charge controller

Charge controller in place

Broadly speaking, there are two types of charge controllers: Maximum Power Point Transfer (MPPT) and Pulse Width Modulation (PWM). Both have their advantages, but a PWM controller won in cost and efficiency for our particular application: hot, sunny climates and systems of 170 watts or less. An article with a more complete comparison may help with your decision.

Here’s what we ended up with:

Renogy® 100-Watt Monocrystalline Bendable Solar Panel (update: no longer available, but this panel is similar)
Renogy® 10-Amp PWM Solar Charge Controller (update: no longer available, but this controller is similar)
Interstate Group 27 Marine Deep Cycle/Starting Battery (available from Costco)
Jensen JMP-800 75-Watt Power Inverter (plugs into a 12 volt outlet for occasional use)

Fortunately, our trailer was built with dual wiring: 12 and 120-volt. There is 120-volt power in both the galley and interior, and a 12-volt outlet is available in the interior. I added a 12-volt feed into the interior cabinets to power a Ten-Tec Triton II amateur radio. Most of the installation work involved mounting the solar panel on the trailer’s roof. The charge controller was mounted in the galley storage adjacent to the battery. The trailer was already equipped with a small charger, and it charges the battery when we’re hooked up to shore power. The solar panel can be removed from the roof and located away from the trailer using an extension cord. This way, we can park the trailer in a shady spot while the panel is located in the sun. The photos show the mounting screw installation process.

: Tapping into the aluminum skin with a double-ended screw

: Re-mounting the screw with marine epoxy

Incandescent Bulb

The trailer came with 12-volt automotive light fixtures and incandescent bulbs.

LED “corn” lamp

These were replaced with LEDs resulting in a 75% power savings. As I mentioned, it is a work in progress, and I would like to add a second panel. There’s room on the roof, and that would double our capacity.

Mounting the panel

Jim, June 7 – June 21:

I wanted to add my ham radio and a solar power system and we were about 2 weeks from departure. The TenTec Triton II radio was mounted in an interior cabinet and connected to the antenna ball mount. A piece of 3″ PVC tubing, mounted outside in the rear, provided storage for the whip antennas and their coils. A weekend shopping trip to Costco yielded a 15 watt solar panel and charge controller that I connected to the existing trailer 12 volt system. Although we were likely to have 120 volt “shore power” when camping, the solar panel could provide power if we decided to set up camp in a remote area. Time to pack!

Ranch foreman, P.T., supervises

Galley view of teardrop trailer

Door/side view of teardrop trailer

Ham radio mounted in teardrop trailer

Solar panel for teardrop trailer

Teardrop electrical system with solar charge controller

A New Battery

And a way to measure it

Electric Kettles for Camping?

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Solar Chili

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Krause Springs

A tour of Teardrops

Hiking the Springs

An Evening Potluck

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