Most inverters output "modified sine wave", which is essentially a stepped square wave approximation of a sine wave. This is perfectly satisfactory for many purposes, like lighting, electronics that use switching power supplies (laptops, phone chargers, etc.), but may cause problems for devices that are quite sensitive to the quality of power they get such as motors, some medical devices, etc. Such devices need a "pure sine wave" inverter, which delivers a smoothly-varying sine wave much like that provided by the electric utility.
This inverter is just such a "pure sine wave" model, and outputs a rather nice sine wave (see attached photos). It's a pretty typical sinusoidal wave with a frequency of 59.5 Hz (utility power in North America is 60 Hz, and 59.5 Hz is perfectly acceptable). The peak-to-peak voltage of my unit was 158 V, which corresponds to an RMS voltage of 111 V. This is within the nominal range of 110-120V found in North America, and should be universally compatible with any device.
If one zooms in on the waveform, one can see the 24.3 kHz switching steps of about 10 V that the device produces. This is an unavoidable consequence of converting DC to AC, and it's at such a high frequency that it should have no effect whatsoever on any device connected to it. Ideally, I'd like to see some sort of low-pass filter applied to the output of the inverter to filter that 24.3 kHz noise, but then I remembered that this is a $40 item and that such noise isn't going to affect anything.
The 12V cord is thick and looks to be the 11 AWG (4mm^2) cable Bestek uses for their battery clamps-to-lighter-socket set. This is perfectly fine for this power level. The 12V plug is spring-loaded and fits snugly into the receptacle.
A small fan comes on as needed and isn't terribly loud. Still, it comes on periodically when the unit is idle with no load attached, for which I'm deducting one star from "noise level".
The quality of the circuit board on my unit looked fine, with no assembly problems, bad solder joints, etc.
There's two small downsides that I've noticed: 1. The fuses are inside the unit, require its disassembly (pop off the rubber feet, unscrew the four screws there, then unscrew the circuit board inside from the supporting posts), and the fuses (two 25A automotive "Mini" size fuses wired in parallel) are soldered to the board. Again, I realized it's built to a price point, but having the fuses soldered to the board rather than being in sockets and preferably accessible from the outside of the unit is incredibly inconvenient. Having an in-line fuse in the cord or 12V lighter plug would be fine as well, but having them be internal and soldered down is annoying.
2. The cord is not detachable. While Bestek offers a nice battery clamps-to-lighter-socket set, it sure would be handy to simply be able to unplug the lighter cord and replace it with a cord with battery clamps that's connected directly to the unit. It'd also make the unit more compact for storage.
In short, my initial impression is that the inverter is a perfectly serviceable pure sine wave inverter that is far superior to modified sine wave inverters at only a slight price premium. While it's bulkier than some other inverters for its power level, it's not excessively large. The power it outputs is quite acceptable and makes my home UPSs (which are normally very sensitive to power quality) happy. The lack of easily-replaceable fuses is annoying enough to warrant the deduction of a star; it wouldn't be hard for them to have a higher-rated internal fuse that's there to prevent fires in the event of a major fault and a fuse for the rated current in-line with the cable or in the plug to prevent overheating in the event of a normal overload. Other than the fuse issue, I'm perfectly happy with the unit so far.
This was about 40% less than other brands so I gave it a shot. I also have the non-sine Bestek 300w inverter which you can see in the pictures. I'm using it to charge my wife's car battery with a CTEK 7002 (I like -Tek stuff I guess) battery tender and a 35AH SLA battery. There are no outlets near where she parks so I needed a solution to charge her car and this fits the bill. I'm using a fuse tap rated at 15A and the charger does 7 so I should be good.
The non-sine inverter does work for this application but if you're going to leave something plugged into your car for a few hours unattended you probably want to spring for the pure-sine version, just in case.
I bought this to run my 70 watt TV and 20 watt blueray/dvd player off of batteries in my RV. It does the job and makes no noise whatsoever. I was concerned that it might run loud but when inverting 90 watts it is completely silent.
Got this for my wife's car since I have one each for our other cars. These devices are handy and provide power to devices that require AC power via a standard AC plug. This one is really well designed and attractive-very sleek and quiet. We mainly use it for my grandchildren's devices that don't have USB plugs but only AC power blocks. Because of that, I had to add a three-outlet adapter to allow for the size of the power blocks-the outlets on the device are too close. I got this inverter because I heard that it is recommended that you use one that provides a pure sine wave output to protect your computer from uneven power. I'm no electrical engineer, so I have to take that one on faith. Anyway, I really like the way this one looks and for the additional USB outlets it provides too.
The instruction "manual" that came with this is a joke...contains nothing...not even a hint on how to change the fuse. I had to guess at it. But the unit itself works well and seems to be high quality. Come on, Bestek, you can do better.
I use this for the USB and a lap top but mostly for charging 24V Li-Ion batteries used in power tools I use when off roading. I wanted something small and it had to be a Pure Sine Wave. This inverter is well made, very solid. I use a Anderson connector to attach directly to truck battery.
Allow me to apologize for the other Vine reviewer that simply copy and pasted the description for their review. Some of us actually make the effort to test and write reviews that are useful.
I have a few different versions of inverters like this, since I have a Jeep and we often do camping, or even tailgating at football games. So things like this can be very helpful.
My only real complaint, and why I took a star off, is that I wish the cord were longer. Depending on your vehicle, and the placement of the plugs, this may or may not be as easy to use. My SUV's have all had an outlet in the back, so for me this isn't a critical issue but for someone in a car, that may only have one of them up front, a longer cable would allow for easier use for some items.
I also like that the USB ports are angled and not on the same flat surface as the regular outlets, so it makes it easier to fit things.
There are four little rubberish feet on the bottom, but they don't do much for keeping it from sliding around.
The red and black looks great though. Far more visually appealing than the most recent one I used.
I'm a pro photographer and I've been looking for a pure sine wave inverter for a while now. I use this to charge my MacBook Pro 15 retina, drone batteries and camera batteries. So far no issues and i'm quite impressed. The fan noise isn't loud in my opinion, its barely noticeable when your car's ac is on. I've heard other inverters with way louder fans.
Works great! Use this to power a PS4 and a tv in my travel trailer. Silent fan, never overheated, runs off of cigarette lighter which is tied in to the same circuit as the Trailer’s stereo and tv antenna with no problem. Very happy.