Cross post from Lights and Night riding.

I know there is plenty out there that dont want to spend $100s on a commuting light. BUt want decent output, usb charging, self contained light. I got this one in for review, been using it for over a month and works awesome. Not a single issue with it even in light rain or snow (heavy rains/storms are beyond dangerous to ride in for my commute so have coworkers with trucks in that case lol)

SANGUAN SG - BU20 LED Headlamp-39.81 and Free Shipping|

Im actually kind of impressed. Taking into consideration the price (get what you pay for) its actually pretty decent. And makes an AWESOME budget commuter or just self contained bike light. Something we havent seen yet that has been worth the time to bother with.

-Rating is 800 lumens
-Run time of 2 hours on high
-4 modes
-Usb Charging
-Uses XP-G2 R5 Emitters in Cool White.

First Impressions:
Simple light, lots of plastic, but didnt feel overly cheap. Expected heavier but still feels solid. This is one of the "the beauty is in its simplicity" type products. For $40 its built well enough, usb chargeable, a lot smaller and LIGHTER than my Fenix BC30R (though lower output of course and no fancy LCD screen). Its not high end, but this is one that "will do the job plenty well enough"

The handlebar mount itself works well, the quick release type feature is a bit difficult as the button to release the light is under the head and kind of small. BUT FUNCTIONS.

Most of the case is plastic, with the exception of the top panel. Had me worried regarding heat dissipation till I took the light apart (get to the in a minute). Button is silicone seal around a metal core. Look nice. The silicone ring around the core acts as the battery level indicator as well (typical leds inside). But its much less annoying than the standard silicone buttons we're used to. Rubber cover over the USB port, obvious rubber seals around the optics.

Decided to do a "Cat's shower test" Cause we got ONE rain storm early in the day for like the last month or so. No water internally.

More Technical:

As for output, I put it up next to my Fenix BC3R, 800 lumens without a doubt. This isnt as bright. Not bad, but not 800 lumens worth. Id say more like at or a bit above 600.

Modes are a bit odd. They claim better mode spacing but its NOT. They are rather close together. Not all bad being the light isnt overly bright. The 4 modes not having big jumps makes a bit more sense to me. Between low and max is a obvious difference, but each step is minor.

Run times, dont know yet, havent managed to run the thing out and I didnt get a chance to charge it up fully. Been using it for commuting. Was green for first 5 minutes I used it, been in blue ever since. So run times are pretty good, at least matching claimed.

Here it is opened up:

First thing you notice, Lipo battery pack. That explains both the size and weight being what it is. Says its rated at 4400mah. About right for 2 hours run time vs emitter output.

Full orings on all layers. The Seals for the optics are actually quite large, not just simple orings. The upper plate fits into upper case half, this upper plate is aluminum and screws directly to the back of the emitter PCB. This is sealed with a large oring as well. And explains the thermal path for the emitters. BUT AS USUAL, NO THERMAL PASTE. But ive yet to even feel this thing get warm. Temps here havent gone above 75 anymore so not a great judge but left on high while commuting, stopping and talking etc, never even got beyond warm to the touch.

Optics are the same as the ones from LEDDNA for the XP series emitters. I have the exact same ones, 10 deg is what these are. My camera is sucking at fully showing the tint or the hot spot (time for a new phone) but its a tight spot with some spill, VERY OBVIOUS BLUE TINT AND WASHING OUT COLORS. So tint is known.

-And before anyone asks, yes Im going to mess with it, but only an emitter change, you all know may hatred towards cool white emitters. This is a cool little light though, so I have Nichia 219C's on the way for it (thnx garry for getting me started on those now :P ) Im going to use it for commuting for a while, give my fenix a break.