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I got it fast (as always thanks Amazon) on a lightening deal. I saw it was a 500W for the price of 300W units. Got it and hooked up the clamps to a charged large battery (large SUV / Truck battery) and started applying load through a volt/watt monitor to watch quality. Handled up to 300 W well. Past 300W it started dropping voltage. 0-250 W: 115V, 60Hz 250-350ish: 113V 350-450W: down to 105V!
I only loaded up to 450W with a work flood light and the voltage was down to 105V! That is very questionable...I am concerned of loading up sensitive things on it.
So, probably will keep for the money up to 300W but not sure I'll trust it for the "rated" 500W
The unit is is very compact and is only for light duty, however, with a USB voltage of only 4.8V many devices will probably complain/reboot. It did hold at 4.8V even under a 1amp load so it is regulating nicely and the usb spec does allow voltages that low...but many devices "want" 5V in today's world. If you plan on running DC sensitive devices, double check your USB voltage minimums!
The product was intended to be used for traveling. It arrived and already had a flaw because a part was bent. Since it did not inhibit the actuall function and instead only prevented the item from being mounted to something, I chose not to complain. It has then been used for travel right away and after one week it already has trouble remaining in power mode. As soon as the device or cable gets moved a little, the power is off. This is particulary annoying as it is used in a moving car without a mounting option. After returning home now, I tried to return the product, but missed the deadline by one day. Based on my experience, I cannot recommend this product as I will need to replace it after one month of owning it.
I am not enchanted by this unit. The aluminum casing is just that: thin aluminum - with a few ripples to suggest an actual heat sink surrounding a transformer. Sorry, there is no heat sink. Earlier iterations of similar products from other manufacturers (or perhaps just re-branded) did actually provide thickish-aluminum finned sinks as a cover with this category of transformers.
The supply cables with large alligator clamps is first rate, however, the accessory plug cable's eyelets are far too thin. I am using a spare pair that won't bend at the slightest tug.
One other difference between this and my old example: the one/off switch is now a much smaller rocker switch. You can operate it with a small finger's tip and nothing much bigger than that. I hope its tiny internal spring is good quality. The fuses have covers - which require a phillips screwdriver to remove, which seems unnecessarily fussy.
The "wording" in the printed instructions have been translated back a forth a few too many times. And these products might actually be required to keep your devices functioning and communications open to those that are important to you.
I need to highlight a particular ludicrous attempt at relevance. I noted that this model has a bracket for presumably mounting it on a sheet of plywood, metal or something equally industrial. The current web-site splash page for the latest BESTEK automotive power accessory product, however, appears to display this same unit (minus the bracket), but renamed, and shown positioned on a mid-market sedan's center console, with all manner of devices plugged-in and charging themselves from its various ports. It's nice to know that a console lid was spared from the pointy end of a wood screw. But a weighty metal-cased inverter, simply resting on a console near your torso in a moving car, sounds like a bad idea.
Beef it up physically. Give the marketing group a reality check.
Otherwise, it worked as advertised and also knows to *not* run the cooling fan when no current draw is present. That *was* one area where the older units were not as smart.