Product Review, Bestek 300W Pure Sine 12V Inverter

bestek300wps_325x250As 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.

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Extracting Potash

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).

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Freezer False Alarm

Last week, we took our two Duracell 29HM deep cycle marine batteries and the MicroSolar 24v inverter from our hurricane ground solar experiments and added an AC charger, essentially building an oversized UPS for our freezer. We’ll talk about that system more in detail once we’ve run it for a while, but this morning it appeared that this system had failed. Although this turned out to be a false alarm, the steps we went through to verify the continued operation of the freezer and its power system are good to know.

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Ground Solar, Part VI, Wiring, Connectors and Tools

We’re ready to finally wrap up our series on the ground solar installation we used during Hurricane Matthew to keep our freezer and refrigerators cold. We’ll provide links to all the previous articles at the end of this post as a convenient reference. In this post, we talk about the wiring, connectors and tools used for connecting all the components. We’re not done talking about solar, though; future articles will address lead-acid battery alternatives and other solar power options beyond our hurricane experience.

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Ground Solar, Part V, The Batteries

We’ve been discussing our Hurricane Matthew ground solar installation (overview, combiner, charger and inverter), as well as fundamental solar panel principles and off-grid lead acid battery principles. This time, we will discuss the battery array used for this exercise, as well as the automotive DC safety breaker. Refer again to the photo of our inside components below:

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Ground Solar, Part IV, The Inverter

In previous articles here, here, and here, we’ve been discussing our off-grid solar power system we used during Hurricane Matthew. We also gave an overview of solar panel and lead-acid battery principles. While there is much more to discuss regarding batteries, including alternative battery technologies, let’s skip ahead to the inverter, which is the tip of the off-grid power spear. However, some features of inverters are often misunderstood, or obscured by clever marketing claims.

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Introducing Caveman Chemistry

cavemanchemistrycoverIt’s the holiday season at the Old School, and this means it is finally cool enough for those chemistry projects we’ve been looking forward to all year long, including those best done over a nice fire in the wood stove. Our favorite book to guide these experiments is Caveman Chemistry, by Dr. Kevin Dunn. Dr. Dunn is a chemistry professor, and a lot of other material is available at his site, You may have also seen him on The History Channel’s Modern Marvels program.

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Off-Grid Lead Acid Battery Principles

We’ve been dedicating several posts to building an off-grid energy system with solar panels. Any off-grid energy system, especially solar, is best operated with batteries to store energy, unless you plan on making a generator available 24/7 to fill in the gaps. There are many available battery technologies, and eventually we’ll review many of these. For this post, we are going to focus on lead acid batteries, which are the standard by which all others are compared, good or bad. In later posts we’ll cover nickel-iron (or Edison) batteries, lithium iron phosphate, and other options.

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Offers 7 Nov 2016

Saturday’s post about chargers mentioned that our sponsor SoftBaugh might be able to get pricing that would beat Amazon pricing for some items. Here are the latest quotes SoftBaugh is able to provide (in all cases, ground shipping to US locations is included):

Midnite Solar Classic Lite 150 MPPT Charge Controller: SoftBaugh can offer this item for $689. Note that this item has been discontinued by the manufacturer.

Outback, SmartHarvest MPPT Charge Controller, 10A, 100VDC SCCM10-100: SoftBaugh can offer this item for $99.

Outback, SmartHarvest MPPT Charge Controller, 20A, 100VDC, SCCM20-100: SoftBaugh can offer this item for $149.

More from SoftBaugh about these offers:

The distributor has a limited number of these items available, and orders will be processed on a first-come, first-served basis. Click this link for contact information for SoftBaugh. We are working on the ability to handle custom orders online, but for now these special orders will have to be processed manually. Although a reasonable effort will be made to verify stock exists before a card is charged, if a credit card is charged and inventory is depleted, the credit card will be refunded and we’ll give you a 5% coupon toward the purchase of any of our normal catalog items.