Automotive inverter
Bestek MRI1511AU Automotive Power Inverter. Image credit: Nicholas Brown/Kompulsa.

The Bestek MRI1511AU 150W power inverter is a 12VDC to 120VAC inverter (it takes 12 Volts DC from a battery and outputs 120 Volts AC for devices that require that) for cars (cigarette lighter inverter). It also provides 5V USB outputs to charge phones, tablets, cameras, and similar devices.

Accuracy Of Claims: Is This Inverter Really 150 Watts?

There are inverters that may not be able to handle their stated wattage (especially if they found a way to skirt around regulations), or they may instead put their peak wattage on the packaging instead of their continuous power handling capacity. This is a rampant issue among many electronic devices and it serves as a reminder that you get what you pay for.

The Bestek MRI1511AU inverter was able to power a 120 Watt lamp I plugged into it without shutting off. However, I didn’t plug in anything that draws 150 Watts. Nevertheless, this is a good sign as the sketchy inverters I mentioned above shut off if you try to draw even half of their advertised wattage.

Voltage Regulation And Brownout Protection

Proper voltage regulation is crucial in a power inverter because abnormally high or low voltages can cause appliances to malfunction or shorten their lifespan. If your battery’s voltage falls below a certain level, the inverter should disconnect the appliance to prevent damage to the battery, and to prevent a brownout from occurring. The Bestek MRI1511AU did so successfully.

It also shut down properly (i.e. shut off once and stayed off) when I tried to draw more from it than the battery could safely provide. With regards to regulation of the output voltage, the inverter did a great job of sustaining the 115-120V output voltage instead of dipping to unacceptably low voltage levels like some units do.

This Is A Modified Sine Wave Inverter

The Bestek MRI1511AU is a modified sine wave inverter, meaning that it does not generate the smooth, gently curved pure sine wave that an alternator or pure sine wave inverter would.It absolutely matters if an inverter is modified sine wave or pure sine wave because some appliances need a pure sine wave (for example: vapour compression refrigeration and air conditioning systems, washing machines, AC fans, among other things). In general, pure sine wave inverters are superior to modified sine wave models. Although they are significantly more expensive.

I’m not saying that using it to power those types of appliances will surely destroy them, however it is not ideal and may cause problems. Stay on the safe side and seek one of the pure sine wave models if you want to power one of those expensive appliances. If you’re curious, a modified sine wave has sharp voltage transitions (swings between high and low voltages instead of gradually transitioning between them like a pure sine wave inverter does). This causes an unpleasant buzzing noise in some transformers and alternating current (AC) electric motors.

Noise Levels And User Experience

Believe it or not, one of the first things to impress me about this inverter is that it wasn’t very noisy, considering the size of the fan. Inverters typically have tiny axial fans that whir horribly loudly and they don’t generate much airflow. This one is reasonably quiet most of the time, but will become audible if the unit gets warm (due to drawing large amounts of current from it, or exposing it to high temperatures inside a car (for example: a hot day).

This is why you shouldn’t leave your inverter in the car, and you should also wait until your car’s AC cools off before you start using the inverter. I’m not saying you have to, but I wouldn’t want to expose an inverter to the temperatures of a car without the AC running. The Bestek MRI1511AU inverter also has a nice aluminium chassis with a plastic bezel on the back and front, which look fairly polished (it doesn’t look or feel cheap). It includes one 120 Volt power outlet (which is all that can fit in such a compact design), and two 2.4A USB ports.