BESTEK 500W Pure Sine Wave Power Inverter DC 12V to 110V AC Car Plug Inverter Adapter Power Converter with 4.2A Dual USB Charging Ports and 2 AC Outlets Car Charger, ETL Listed, Grey

Took it camping to inflate a large mattress and it worked perfectly. No hesitation and the motor ran at full speed with no extra humming or noises you'd get on a modified sine wave inverter. There's a photo attached hooked up to the car battery to do this job. This load is about 190 watts, with whatever spike that happens when the motor starts up.When it first arrived, I tested it with an oscilloscope because I was skeptical of the "pure sine wave" claim on an inverter at this price point. There's two photos attached- the one that looks perfect is this inverter running an LED 110v lamp. The one that looks a little rough around the peaks/valleys is from a 4000W inverter meant to run a house off the grid (costs several thousand dollars)- but it's running an air conditioner, refrigerator, and all the other junk people plug in at home. Still, it goes to show that this little inverter makes a really nice sine wave. This is good because many types of electrical devices don't function well (or they make weird humming noises) with a poorly shaped sine wave (or a square wave like the cheaper ones make).Other tests I tried:- Charging my Macbook worked fine with normal power plug- Connected it to a 50 watt power source to see what it does under overload. When you try to draw more power than your source can supply, it resets until you turn it off and on again then it happily tries again. This is nice because if you run it from a weak battery it won't sit there trying to make 110v and failing miserably, possibly damaging whatever you're trying to run.- Used USB port to charge the Macbook as it can accept power from a normal USB source (obviously it'll charge a lot slower because there's less power available, but still it gets some juice). Worked fine.- Charged a phone from USB, worked fineI read the bad reviews before I bought this inverter. Some of the bad reviews maybe they got a defective unit, but others are almost certainly from improper use (especially the blown fuse ones). Some things to watch out for:- The cigarette lighter or power port on your car will NOT supply 500 watts, I guarantee it unless you've got an electric car or something and even then probably not. My truck has a 20 amp fuse on that circuit and the car in the photo attached has a 15 amp fuse. At 12 volts, that means they can supply 240/180 watts respectively. And that's at the point the fuse blows, not the point you can safely draw power- the car port says "125 watts max" when its fuse blows at 180. So the people mad because this inverter "doesn't work in my car" or "blew a fuse in my car" were simply trying to draw more power from the inverter than the fuse in their car would allow.- Note in the photo above that I connected directly to the battery. If I had plugged this into the 15 amp power port inside the car with the cigarette lighter adapter, it most likely would have blown the fuse.- The power adapter on my laptop says 140 watts, so even plugging that into the inverter using the car's power port *might* blow the fuse if there's a spike on startup. You REALLY need to look at what you're plugging into this thing if you're using it inside the car and see how many watts it uses- then pad that for safety and because the inverter is not 100% efficient at converting DC watts from your battery to AC watts that it outputs.- Like any electronic device, solder joints can break if you drop it so be careful with it. Treat it like a laptop or something else you don't want broken. Broken solder joints will result in intermittent failure or complete failure. Maybe keep it in the box when you're not using it.Things I haven't tried:- drawing a 500W load to see if it really is 500W. I can only verify it supplies about 200W well.- checking how much power it draws when off with no load, or on with no load. I'd like to get around to this because would be nice to know if it needs to be unplugged when not in use.

The two fuses in mine are 40 amp. They make a point that you do not want to hook something up to it that is more than 150 watts if you're using the cigarette lighter in your car. I decided to be on the safe side and replace the 40 amp fuses with 15 amp fuses. I could even go down to 10 amp if I want to make real sure that I have overload protection on a sensitive piece of equipment that I connect up to it. The math on this is very straightforward. A 12 volt battery times a 15 amp fuse is equal to 180 watts. This will keep you within the range of 150 watts of the car. If you want to go lower than that then you could put in a 10 amp fuse and that would end up triggering if something exceeds roughly 120 watts. The point needs to be made that if you really want to take advantage of the full full power of this then you want to use the clips directly on your car battery or on a 12-volt off-grid battery. In this way whatever you're running up to 500 watts will simply drain the battery down to the low warning cutoff. You can always put the 40 amp fuses back in there. You use the fuses in the same way you would use a circuit breaker in your house. if you want to make sure to really protect your equipment then simply go with a lower fuse whether you're using a cigarette lighter on the car or you're using a separate off-grid battery sitting in your tent or in the corner of your house when the power goes out. This would apply to situations where you're running your computer or a CPAP machine and you want to make sure that there is no overload. And, you can see that by using fuses you can buy a 500 watt inverter like this and simply tone it down to where it's going to act more like a 120 to 180 watt inverter. // The inverter that I would love to buy is the one that would come with a tiny little LED screen that reads the voltage on the battery when an off-grid mode and not connected to the vehicle. I charge my batteries to around 13.5 to 14.4 volts. It would be lovely to have an inverter that automatically reads the voltage of the battery so that I could keep an eye on things and make sure that I'm prepared to recharge the battery when it gets down around 11.5 volts. As it is I purchased a inline DC voltmeter so that I can do that, but it's terribly cumbersome and annoying so I took the thing off. IT IS EQUALLY ANNOYING TO HAVE TO USE MY CLAMP VOLTMETER to determine where my battery is at.I highly recommend this for people that live in apartments and are willing to go out and spend the money to buy a 35 amp hour to 100 amp hour battery for emergency purposes. If you find yourself trapped in a city with no power for a couple of days this inverter will prove to be worth its weight in gold or maybe five times its weight in gold because it's a very light inverter. So if you have this and you have a well charged battery you can be guaranteed that your CPAP equipment may run, you can charge your cell phones, and I'm sure there will be other uses.I highly recommend this one because each AC outlet has its own fuse holder.___________I took it out of the box, hooked it up to a 35Ah battery, and attached a coffee heater. It works. I still have some equipment tests to run should I need it for an emergency. My voltmeter at the plugs said 116V ac. Being pure sine wave I am very happy to get this. It will likely prove useful in my car for charging batteries for tools on trips. The 500 watts at a price point of $70 is fine with me. My next test will be the drain on my battery for certain items.My need is mostly emergency when we have NO power and I might want to run some lights. This is not the sort of thing you want for running fridges and microwaves. This is excellent for running particular pieces of medical equipment due to low load requirements.Could be very useful in some foreign countries where you might need to siphon energy off of a car battery.

Works great

The inverter came well packaged and protected. My only complaint is that the USB ports on the side of it were arched and very hard to plug a USB charging cord into it. I figured maybe I needed to slightly shift the side cover to better align the USB ports with the cutout on the side cover but that wasn't the case.I pulled the side cover completely off the body and found the entire circuit board inside the inverter was bent with a huge arch in it. It was in the grooves that secure the circuit board from flapping around inside but was not good to see a circuit board that looked to be a bit over the width of the case and was just crammed in there. I had some spare rubber bumpers and placed them down the center of the circuit board as a wedge against the case to straighten out the circuit board. I hope that makes it have a longer life to operate in but time will tell.The only suggestion that would be nice is if the built in fan could operate in a power power mode to stay off and then increase it's speed when it's getting warmer or power draw is increased. From the factory the fan will always run at low but if you increase your load or it get warmer it will ramp up the fan speed. If the fan could be setup to remain off unless it needs to cool down the heatsink then it can help squeeze just a bit more battery life I would imagine.Otherwise the problem of the bent circuit board, it worked amazing! The sinewave output is pretty clean, only a little bit of distortion in the middle of the waveform but nothing that electronic devices can't handle.