Review on 🔌 Premium Quality BESTEK 300W Pure Sine Wave Power Inverter Car Adapter DC 12V to AC 110V with 4 by Chris Lemm

Most inverters output a "modified sine wave", which is essentially a stepwise square wave approximation of a sine wave. This is quite satisfactory for many purposes such as lighting, electronics with switching power supplies (laptops, phone chargers, etc.) but can cause problems for devices that are very sensitive to the quality of the power received, such as motors, some medical devices. Appliances, etc. Such appliances require a "pure sine wave" inverter that provides a smoothly varying sine wave very similar to that provided by electrical current. sinusoidal (see attached photos). This is a fairly typical 59.5 Hz sine wave (North American electricity is 60 Hz, and 59.5 Hz is perfectly acceptable). My device peaked at 158V, which is 111V RMS. This is within the 110 - 120v nominal range in North America and should be universally compatible with any device. If you zoom in on the waveform you can see the 24.3kHz switching steps around 10V that the device produces. This is an inevitable consequence of DC-AC conversion and happens at such a high frequency that it shouldn't affect connected devices. Ideally I'd like to apply some sort of low pass filter to the output of the inverter to filter out that 24.3kHz noise, but then I remembered that this is a $40 thing and that kind of noise doesn't affect anything . .The 12V wire is thick and looks like the 11AWG (4mm^2) wire Bestek uses for its battery terminals and cigarette lighter sockets. This is normal for this power level. The 12V plug is spring loaded and fits snugly into the outlet. The small fan turns on when needed and is not very loud. In idle mode without a connected load, however, it lights up from time to time, for which I deduct a star for the "volume". The quality of the PCB on my unit looked good, no assembly issues, bad soldering. etc. There are two small downsides that I noticed: 1. The fuses are inside the block, require disassembly (remove the rubber feet, unscrew the four screws there, then unscrew the board inside from the support posts ab), and the fuses (two car fuses of the standard size "Mini" of 25 A connected in parallel) are soldered on the circuit board. Again, I realized it was built for the price, but it's incredibly inconvenient that fuses are soldered to the board rather than in sockets and preferably accessible from the outside of the unit. A built in fuse in the 12v cigarette lighter cable or plug would have been nice too, but the fact that they were internal and soldered on is annoying.2. The cable does not come off. While Bestek offers a good set of cigarette lighter battery clips, it would be convenient to simply unplug the cigarette lighter cable and replace it with a cable with battery clips that plugs directly into the device. It would also make the device more compact for storage. In short, my first impression is that the inverter is a perfectly maintained pure sine wave inverter that far outperforms modified sine wave inverters with only a small price premium. Although larger than some other inverters for its power, it is not overly large. Its output power is quite acceptable and goes well with my home UPSs (which are usually very sensitive to power quality). The lack of easily replaceable fuses is annoying enough to warrant a star deduction; it would not be a problem for them to have a higher rated internal fuse to prevent a fire in the event of a major fault and a current rated fuse in series with the cord or in the plug to prevent the mains from overheating. with normal overload. Aside from the security issue, I am completely satisfied with the device so far.