|"Harvest Host" camping at the Kepler micro-farm
"A little knowledge can be dangerous," so the saying goes. What I've found with my first true experience of using my travel trailer with a solar suitcase is that a little knowledge just left me with the desire to know more. Before I explain any further--yes, the Zamp suitcase/Airstream Basecamp configuration worked, keeping the trailer up and running for my two-and-a-half-day trial. Luckily, posting my original version of this article a couple of days ago prompted some useful reader feedback--so useful that I've decided to revise and update this article. No read on for the new and improved version!
Because I was working on some deferred home maintenance with my son, I had put off a camping trip; however, I still wanted to try out my Zamp 230-watt suitcase with my AS Basecamp. My solution was to camp "off-grid" for two days in the driveway. If I couldn't get to the campground, the campground could come to me!
I had hooked up the Zamp once when it had first arrived by mail just to make sure it was in good working order--and it was. Since the Basecamp comes with an exterior Zamp plug-in, even that initial set-up was easy, consisting of opening up the suitcase, connecting the array cord with a Zamp solar extension cord I had also bought, and then plugging the unit into the Zamp receiver on the trailer. The array controller was even default matched with an AGM battery, so I didn't even have to choose the battery type. The unit worked, and after an hour I packed the suitcase up and put it in the garage.
Fast forward to a fine spring day, three days of sunshine forecast, and then a string of ten days of rain and thunderstorms predicted. I decided to combine my house spring spiff-up with two days of driveway camping, relying solely on the Zamp solar suitcase. My wife wisely suggested that I keep notes.
The result of my three days and two nights on solar was that the suitcase kept me in electricity--lights at night and 24-hours 12v refrigeration. However, especially after reading my notes after completing my "experiment", I realized that I didn't fully understand what all the numbers and figures I wrote down meant. My notes coameme from two monitors, the Basecamp battery monitor and the Zamp controller monitor. After posting the original article to some travel trailer camping groups on Facebook, one kind and helpful member of the Airstream Basecamp group explained "what all the numbers and figures" meant.
One clear result was that the Zamp 230-watt solar suitcase fully charged the batteries every day, drawing from the full spring sunshine ample power. Each day by around noon to two P.M., both monitoring stations would indicate 13.6 amps, with the Zamp controller also including "FUL" on the monitor. As one FB comment state, "Your central observation is correct: [your solar suitcase] is sufficient to keep the lights on and the beer cold!"
I'd read the manuals and so understood that the Zamp charges the batteries and then goes into "float" mode, which means it just adds more charge with necessary, once the batteries are fully charged. What I didn't understand was why the monitor numbers kept changing. I knew that I was just going to have to continue reading and researching in order to better understand the significance of the data the monitors provide. In the earlier iteration of this article, I provided a list of five aspects of the solar charging and monitoring that I didn't understand. I had even confused readings as amps instead of volts. My list of confusions did generate some good information, though, so I've deleted the list of what I didn't understand and have replaced it with what my further research and FB advice from one fellow camper revealed.
- The Zamp solar control panel provides three display numbers: Battery Voltage, Charging Current, and Charged Capacity (in Amp-hours). The Basecamp "SeeLevel II Monitor Panel" displays the battery voltage.
- Regarding what is the safe battery level, the FB advice was as follows: "In short, your Basecamp should never consistently go below 12.0V. That is the 50% point of an AGM battery. For maximum battery life, AGMs should not drop below 50%. There’s a proper way to measure this that most do not realize. When you have loads, such as your DC powered refrigerator running, the vent fan, or the water pump, you will get a “worse than actual” reading. To accurately verify your battery voltage, turn off these three devices, wait about 30 seconds, then take a reading. If you’re 12.0V or higher, you’re fine. If 11.9V, no need to worry, just make sure you charge soon and remove all but critical loads, for example, the vent fan. At 11.5V, you should charge IMMEDIATELY to prevent long term damage to the battery. At 11.0V, damage may have happened. However, if you charge immediately, “damage” likely means your battery is only 95% of its rated value." (I assume this last sentence that the damage would be a permanent loss of five percent of the battery's capacity.)
- Regarding the Zamp's "Charging Current" reading, useful explanation was also provided. Essentially (as I understand it, anyway), this reading can be used while positioning the panels to ensure the highest charging, both in terms of direction and time of day. Amp input will vary because of time of day and cloud coverage. "It is not uncommon for amps to float +/- 5 amps on a partly cloudy day and even more so if there are more clouds. You can generally ignore all readings on your controller but amps. Use amps as your 'peaking meter' to achieve the highest rating so that you know you are peaked at the sun. For maximum efficiency, you can 'track' the sun throughout the day."
- I was concerned (and still am) about the capacity of the batteries to keep their charge and maintain the trailer's capabilities, especially 12V refrigeration, while traveling. If I travel for three days, for instance, and stop at night where I can't plug in or set up the solar panels, will the batteries be excessively drained and damaged? More practical advice: "Real damage is done to AGM batteries when they sit at these low voltages for long periods of time, such as days or weeks. If you drop to 11.5V and you charge the next morning, you’re fine. If you drop to 11.5V and park your camper for a month, that can cause real damage. Those on this thread who have bought a used Basecamps and your batteries struggle to make it through the night likely have batteries that have suffered from this practice." What this means for me is that over time and use, I will become more familiar with the Basecamp's 12V battery capacity. I will know when I need to stop and plug in, or if I can keep rolling down the road.
- More information was provided about how battery charging works. "A quick word about how charging works. In simple terms, there are 3 stages: Bulk, Absorption, and Float. You can Google more about it, but it’s important to know about these three stages when charging. Unlike lithium batteries, which charge similar to your smart phone, it isn’t a 50% charge to 100% and you’re done proposition. AGM and 'wet' batteries require an absorption period. During this absorption period, your batteries will typically be at around 13.8-14.2V or so, with emphasis on the 'or so.' Don’t get nervous if it floats around a bit. This absorption period can take 3-4 hours, depending on the battery. If you cannot meet the absorption period criteria due to lack of sun or enough amps, no big deal, but your batteries will lose charge a little bit faster than a battery that has met the absorption period. Think of the absorption as the time when AGMs go from 90 to 100%. Finally, the float voltage is just that. Float is usually 13.3-13.4V or so, but once you unplug or the sun goes down, it will slowly drop to 12.7V. 12.7V is 100% charge. The biggest advantage to Lithiums are twofold. 1) You can drop to about 10% power without any damage. The battery will 'shut off' before any damage is done. 2) There is no absorption period for Lithiums. They charge from 10 to 100% during the 'bulk charge,' similar to your cell phone. The end result is one Lithium is nearly the equivalent of two AGMs, and they charge faster since there is no absorption period. If you buy two Lithiums, you get nearly double the power of two AGMs."
|Trojan 24-AGM 12V battery
I intend to research more, including learning more about my AGM batteries, which are Trojan 24-AGM 12V batteries. I spent a bit on an afternoon getting to the batteries in the Basecamp, which are in the front of the trailer below the storage cabinets. It was a bit of work getting to the batteries, which are stored in a steel box (which had a broken latch). I was surprised at what I thought was a pretty shabby job with the cabinetry access, which required some shimming by me to keep the cabinet floor level after accessing the batteries.
My first experience with solar power has been a success, though. The solar panels do provide power. Even though the Zamp solar suitcase weighs about fifty pounds, I can manage tit. I can go boondocking now at Iowa's primitive campgrounds and "keep the beer cold."
My next experiment will be to go off-grid for a while without the solar panels to see how long the batteries will last just by themselves, say if my wife and I were traveling for two or three days and not plugging in with shore power or solar power. (I realize there will be some battery charging while towing.) Will the batteries be up to such a task, even with us being careful with power usage? I also understand from my reading that outside temperature plays a big role in battery capacity, so "How long will the batteries hold?" is a moving target. I want to establish a rough baseline, though. I want to know that, yes, during mild spring weather I will be able to run the refrigerator and a few lights for so many days and nights--for instance, three days and two nights, and then I will need to connect to 30-amp shore power the third night--something like that.
I had a lot of fun experimenting with our new trailer. I've learned a lot from the advice shared with me from readers of the first iteration of this article. I now have confidence in trying boondocking, even though there's not much "wild" in Iowa's wilderness. The state is mostly farmland with pockets of land set aside for recreation and conservation. However, some of those pockets of land are pretty nice, and I have a few in mind, a couple pretty close by home, where the campground consists of an outhouse, a fire ring and maybe a table, campgrounds where you pack in your water and pack out your trash. This isn't like camping on BLM land or in national forests, but it's what's available. I probably won't be sighting Sasquatch, but I might see a friendly neighborhood groundhog or maybe a raccoon. I'll be off the grid while camping in my Airstream Basecamp glamper. Nice!
Any further comments, suggestions, or advice from readers of this revised article will be appreciated. Thanks, all!