In the previous article, we discussed the background behind our experiment in heirloom blueberry cuttings. In this article, we expand the series by describing the cuttings. As you will recall, we accidentally cut a 7-foot shoot from a bush while we were clearing it of vines and saplings back in February. Having had a successful round of cuttings from the same bushes years ago (despite having those cuttings all die later from unrelated neglect), we decided to turn this shoot into cuttings. Only about a foot or two of this shoot had significant bark, the rest being mostly green growth.
Here at the old school, a dozen or so giant heirloom blueberry bushes line one edge of the property. These bushes produce amazing blueberries each year. We know there are at least two varieties growing here, but we are unsure of the specifics. One variety produces large, plump sweet berries, while the other is a little smaller, but not by much, and produces a sharper blueberry taste. The combination in muffins or waffles is amazing.
Most of the bushes themselves are about six to seven feet high and about as round. Some shoots are as high as eight feet. Fortunately, when the bushes are heavy with berries even these taller shoots are easy to pick.
In the first article in this series, we described a small double-conversion UPS consisting of a 600 watt AC charger, two deep cycle batteries, and a 1000 watt pure sine wave inverter. In this article, we present test results obtained for a load well above, and a load well below, the applicable 20-amp-hour rating for the batteries. As we will see below, there is a significant difference in the available amp-hours between these two extremes. This result was predicted (along with a description of what the 20-amp-hour rate means), in a previous article on lead acid battery principles.
Three decades ago, we bought some glass food storage jars, and really enjoyed them. For the last decade or so, though, they’ve sat in the corner of the kitchen as little more than a decoration because the seals have dried up, cracked and allowed the food to spoil. We recently decided to 3D print some new seals for these.
The first step was to remove the old seals. After plucking off some of the worst portions of the seals, a good amount still remained stuck to the glass, as shown below:
Most people are familiar with the idea of an Uninterruptible Power Supply (UPS), such as used to help keep a computer running throughout power outages. Intended for only seconds to minutes of use, long enough to get past a short power glitch, or to give the user time to save files and shut down before power fails completely, a home or office UPS is typically small and inexpensive. Plus, a typical UPS will be a square wave or modified sine wave (essentially the same thing with gaps), which is fine for a computer, but we would prefer a pure sine wave output. See our previous ground solar inverter article for more details about these different waveforms.
In previous articles, we have been describing the use of LED Christmas lights as emergency off-grid lighting powered directly from a 24 volt battery array. The first article described using strings of cool white lights. Subsequent articles described building a test fixture for these and warm white lights to overcome problems with untested lights, and then constructing arrays with red LED lights, including the use of an external resistor. In this article, we finish the series by describing the use of multi-color lights, some of which are manufactured with a separate resistor embedded in the string. We’ll also describe a useful design procedure for creating off-grid LED strings using any color combination you wish.
In two previous articles, we discussed using LED Christmas lights as emergency lighting powered straight from an off-grid battery array, as well as a test fixture to sort individual lights for making a reliable DC-powered string from the random sampling of LEDs in a typical 110 volt string. Both of those articles focused on cool white and warm white LEDs. In this article, we’ll discuss the use of red LED lights. For some applications, red light is a better choice, and a few red strings sprinkled in with cool white strings can even out the spectrum a little bit if warm whites are not available.
In a previous article, we described the adaptation of LED Christmas lights as emergency solar lighting powered directly from an off-grid battery array. This approach provides many advantages versus running them from an inverter, including useful lighting while trying to fix your inverter. In that article we made some recommendations about string lengths, current and light levels. Immediately after publishing that article, we discovered that some strings burned out although they should not have, and some strings did not burn out when they should.
To figure out what is really going on, we built a test fixture using materials accessible to most people, and tested batches of cool white, warm white and red LED lights. The results are enlightening, and the whole project makes a great homeschool science lesson. Plus, by using this test fixture with your own lights, you can create light strings, emergency or otherwise, which are more reliable, consistent and long-lasting.
As part of our off-grid solar series, we’re looking for bare-bones options for the charger and inverter components to meet the minimum requirements of driving a 70 watt freezer, 24/7 if possible. We recently tested a Bestek 300W Pure Sine 12V Inverter, shown to the right. Although this unit failed to drive the freezer, it is still worth reviewing in detail. Also, review our previous inverter article in the off-grid solar series for important background information regarding inverters in general.
The unit is small, light and fairly rugged, so we wouldn’t think twice about tossing it in the trunk or the tire well and forgetting about it until it is needed. While we wouldn’t chock the wheels with it, it isn’t a glass slipper, either, but rugged enough to be comforting. The small size and light weight caused us to suspect that it wouldn’t be able to handle the promised surges, though. This turned out to be the case.
After a sweltering hiatus due to warm weather on and after Thanksgiving, winter is finally back to the old school, so this means that we can continue our winter chemistry experiments over the wood stove. We like extracting chemicals from things around us, so we’ll start with potash, which is derived from wood ashes (1).