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.
Make it a bundle
We found 2 bundles with this item:
BESTEK 300Watt Pure Sine Wave Power Inverter Car Adapter DC 12V to AC 110V with 4.2A Dual Smart USB Ports
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BESTEK 300Watt Pure Sine Wave Power Inverter with 150W Modified Power Inverter Car 12V to 110V Adapter with Dual 4.2A USB Ports$55.99 $69.93This bundle contains 2 items -
BESTEK 300Watt Pure Sine Wave Power Inverter Dual 4.2A USB Ports with 12.1ft / 3.7m 12AWG 12V 24V Cigarette Lighter Extension Cord$59.38 $68.98This bundle contains 2 items
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Product Description
Designed for your devices that require careful protection
BESTEK Advantage
America's leading power inverter brand. Provides 300 watts continuous DC to AC power and 700 watts of peak power.
- Pure Sine Wave Power Inverter
- 2 AC Outlets
- 2 Smart USB Charging Ports
- Smart Cooling Fan
- Built-in 40 Amps Fuse
- High-quality Plastic Housing
BESTEK 300W Pure Sine Wave Power Inverter
[Pure Sine Wave] BESTEK Power Inverter with 2 USB ports and 2 AC outlet.For charging your iPad, please use the 2.1A USB port and keep the other USB port free. It's normal for the inverter to become warm to the touch while you are using it, avoid placing the inverter in direct sunlight or next to heat-sensitive materials. Do not use to power high power electric devices such as hair dryers, electric heaters, which might blow a fuse.
- Designed for your devices that require careful protection
- Detects your devices automatically
- Top Speed Charging
- Built-in fuse, Full protection
- Easier to dissipate heat
- Isolation Voltage Protection
- Durable Cigarette Lighter
- Ultra Compact
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Pure Sine WaveDesigned for your devices that require careful protection.Provides sine wave output which is more stable and can be applied to the curling iron,hair straightener and the electric toothbrush within 300W designed for your devices. |
2 AC Outlets And 2 USB Charging PortsEquipped with 2 Smart USB charging ports, which detects your devices automatically to deliver its fastest charge speed up to 2.4 amps per port/4.8 amps max, and you can charge most phones and tablets simultaneously. |
Smart Cooling FanSmart cooling fan system makes the car power inverter very silent when operating,and the fan runs faster when the device gets warmer or output power exceeds 70W. |
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Durable Cigarette LighterDouble durable springs each side for tight mount stable and electrical safety.The lighter socket is resistant to up to 5000 times of insertion and extraction, can plug into almost all vehicles. |
Isolation Voltage ProtectionSafe charging design provides protection against, overheating, under and over voltage charging, short circuiting, overloads, and overcharging. |
Car Becomes RVWith our car power inverter, you can use most of home appliances in your car in the open air, such a watching TV, playing games, give you the experience like being in an RV. |
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| BESTEK 300W power inverter(red) | BESTEK 200W power inverter(white) | BESTEK 200W power inverter(black) | BESTEK power strip(white and gray) | BESTEK 75W power inverter(black and silver) | |
| Color | Red | White | Black | White and Gray | Black and silver |
| Power | 300W | 200W | 200W | --- | 75W |
| Feature | Smart cooling fan | ETC and Smart cooling fan | ETC and Smart cooling fan | FCC | Silent Cooling Fan |
| isolation voltage protection | ✓ | ✓ | ✓ | ✓ | ✓ |
| USB Port | 4.2A Dual USB | 4.2A 4 USB | 4.2A 4 USB | 2.4A 3 USB | 3.1A Dual USB |
| Dimension | 4.8 x 3.1 x 1.9 inches | 6.2 x 3.3 x 1.4 inches | 6.2 x 3.3 x 1.4 inches | 3.4 x 3.1 x 3.4 inches | 5.5 x 2.4 x 1.6 inches |
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BESTEK 300W Power Inverter DC 12V to 110V AC Car Inverter with 4.2A Dual USB Car Adapter
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Cobra Power 500W Power Inverter, Portable – 500-Watt Car Charger, 2 Grounded AC Outlets, 2 Fast Charge USB Ports and Remote Controller (CPIALCDG1) Compatible
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Ampeak 1000W Inverter with Dual AC Outlets 2.1A USB Inverter 12v to 110v Digital Display 12v Power Inverter
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Go Power! GP-SW300-12 300-Watt Pure Sine Wave Inverter , Yellow
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| Customer Rating | (3474) | (22415) | (161) | (596) | (111) |
| Price | $49.99 | $35.99 | $49.95 | $72.99 | $168.55 |
| Shipping | FREE Shipping. Details | FREE Shipping. Details | FREE Shipping. Details | FREE Shipping. Details | FREE Shipping. Details |
| Sold By | BESTEK. | BESTEK. | Amazon.com | AMPEAK-US | Amazon.com |
| Color | Black | Red | Black | — | Yellow |
| Item Dimensions | 8.1 x 5.3 x 2.6 inches | 4.8 x 3.1 x 1.9 inches | 7.01 x 5.39 x 2.83 inches | 8.19 x 5.91 x 2.76 inches | 11.75 x 8 x 5 inches |
Customer Questions & Answers
Customer reviews
Top reviews from the United States
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Reviewed in the United States on May 16, 2019
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.
Color: BlackVerified Purchase
Solidly built, very nearly perfect sine wave, needs external fuse
By Pete S. on May 16, 2019
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.By Pete S. on May 16, 2019
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.
Images in this review
Reviewed in the United States on March 28, 2019
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.
Color: BlackVerified Purchase
Bigger than non-sine version - Works Great
By Rodolfo Zanzibar on March 28, 2019
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.By Rodolfo Zanzibar on March 28, 2019
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.
Images in this review
Reviewed in the United States on April 14, 2019
Color: BlackVerified Purchase
Reviewed in the United States on April 30, 2019
Extremely poor quality solder joints, dirty connections, some random wire hand-soldered to a trace connecting to the heat sink of a transistor THROUGH the high voltage/ low voltage isolation cutouts?? The design looks solid, but assembly shoddy & QC non-existing on this particular unit. We ordered a second unit to compare and the quality of build is night and day - but which one do you have in your hands?? If quality was there, this would be an amazing unit, but I can't advise anyone plug a $2000 computer or even $200 speaker into this unless you've checked under the cover.
I want to like this thing. It has well placed thermal protection sensors, solid heat sink, good amounts of adhesive used to fix heavy components to the board to keep everything together if it gets dropped. --just someone's putting really sorry excuses for these units on the market and you won't know until yours blows... hopefully, only a few fuses and the unit.
Color: BlackVerified Purchase
DO NOT plug your sensitive electronics into this!!!
By Daniel on April 30, 2019
I purchased this as a clean power source or an AC motor, laptops, and sound system to use while out camping this summer. It worked great the first time we tested it, then the first time we'd actually need it, failed. It pulled a WHOLE lot of power - and blew several fuses in our setup. It even burned the cigarette lighter from the current draw. Since it's been in our possession under a week, I wanted to figure out what happened & opened it up. SCARY!By Daniel on April 30, 2019
Extremely poor quality solder joints, dirty connections, some random wire hand-soldered to a trace connecting to the heat sink of a transistor THROUGH the high voltage/ low voltage isolation cutouts?? The design looks solid, but assembly shoddy & QC non-existing on this particular unit. We ordered a second unit to compare and the quality of build is night and day - but which one do you have in your hands?? If quality was there, this would be an amazing unit, but I can't advise anyone plug a $2000 computer or even $200 speaker into this unless you've checked under the cover.
I want to like this thing. It has well placed thermal protection sensors, solid heat sink, good amounts of adhesive used to fix heavy components to the board to keep everything together if it gets dropped. --just someone's putting really sorry excuses for these units on the market and you won't know until yours blows... hopefully, only a few fuses and the unit.
Images in this review
Reviewed in the United States on April 7, 2019
Color: BlackVerified Purchase
Reviewed in the United States on April 6, 2019
Color: BlackVerified Purchase
This is a pure sine wave.
By Amazon Customer on April 6, 2019
Bestek products are always good. Fast shipping and great quality!
By Amazon Customer on April 6, 2019
Images in this review
Reviewed in the United States on April 9, 2019
Color: BlackVerified Purchase
Reviewed in the United States on April 27, 2019
Verified Purchase
Well Designed and Functional
By Egger on April 27, 2019
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.
By Egger on April 27, 2019
Images in this review
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