This product works great, especially when you consider the price point.My unit started making a loud whirring noise on startup, so I contacted their customer service and explained the issue. They asked me to send them a video of the problem then shipped me a brand new one within the same week. Excellent customer service!

Inverter technology has come a long way in 30 years, and true sine wave technology has become more affordable. I use solar power for charging computers, phones, and other portable devices that require power. This inverter works great for me. Charges a laptop with a 45 watt hour battery in under an hour, with no issues. The phones take a little longer, but they’re limited by the charger itself. The inverter puts out slightly more heat than the modified sine wave inverters, but it’s not much more, and the devices charge much faster.

I am so happy I purchased this inverter. My husband had another one and my laptop wouldn't work with it. I need it for when I'm teleworking as he's driving. The inverter works well with MSI Cyborg 15 A12V gaming laptop. I was able to use my wireless hotspot and play some Steam games with mixed results while riding (I almost wrote "driving" but I was never driving while using my laptop with this inverter). This was able to plug into my husband's truck and my car, and I assume would work in pretty much any car. It has a fan which makes a slight noise, but not any more than normal road noise while traveling in a vehicle. I hardly noticed the fan. What I did notice that I was playing some pretty intense games and I found that I never really went down in power which was impressive to me. I have a game pad, wireless mouse, USB hub type thing with a few more USBs and sometimes a second monitor attached and this brick takes care of power for me just like I'm sitting on my couch.

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.

Output is quite clean (no audible whine or noise in audio equipment; I've not stuck a 'scope on it yet), runs cool and works well. Note that 300 watts is well beyond what you can pull out of a lighter socket as those are typically fused at 10 Amps, so if you try it you're going to pop the fuse. If you need the actual 300W then you need to either put in a power point that's rated for 30A (with wiring and fusing to match) or hard-wire it similarly. For what you get this is a nicely-priced option.

The nature of my job requires I travel and, on rare occasion, I need to power up the laptop and do something for a customer mid-trip. My laptop battery is losing its ability to hold a charge, so I need something that will help to keep it running. Enter this 300 watt inverter. More than enough power to keep the laptop running. Aside from this specialized need, it is handy to have for small appliance on the go. It brings alternating current into the car when needed. Portable and easy to set up. Also has a USB socket if you have to power your phone on the go and charge it while driving. It is also a pure sinewave output, which beats the "modified sine wave" units any day. Modified sine wave does not play nice with some devices. This unit does the job.

On l utilise avec notre panneau solaire qui est a notre camping. Fonctionne très bien en plus non bruyant!

I have an older MacBook and had no issues powering it with this inverter. Paid a little more for this BESTEK sine wave version for safer power conversion and other older legacy devices that do not have a USB-C port for power.Keeping this in my vehicle as a backup when I need power conversion. Even though the instructions specify a 40 amp fuse is built in to prevent overheating/overloading, keep in mind how much wattage your 12 volt vehicle port can handle just in case. Too bad it does not have any clamps so that I can connect it directly to my battery.

Clean sinusoidal wave.

Fonctionne bien et assez silencieux !

I have just received my unit about 2 days ago and started testing. Unit works exactly as per the specifications. Low voltage shutdown is 10.6vdc. (Manual says 10.5vdc – close enough!). The tests were done in my vehicle with a small 250watt Kaz (Honeywell) heater, running on half setting. (Tried full setting but that immediately popped the cigarette lighter fuse in the vehicle’s fuse box – NB: There is definitely NO fuse in the unit’s plug itself!). The inverter powered the heater with no issues while the engine is running but gets to the low voltage shutdown within minutes when the engine is shut off. This is due to quite a voltage drop at the cigarette lighter plug. Probably due to thin gauge wiring used by GM to wire the vehicle. The fan noise can be lower if better fan is used but is not too bad. One get used to it very quickly. The wires and the unit stayed cool, no heat detected except at cigarette plug itself. (but it doesn’t overheat). I think that is about as much (125 watts) as one can expect from the cigarette socket in a typical vehicle.To get to the full 300 watts, one must use a Female Cigarette Lighter Socket extension cable (at least 12AWG) directly to the battery. (Not included in the box – pity).Haven’t tested the direct connection to the battery yet since my extension cable is still on its way.