Small Sun T012
I did a search and didn't find any posts about this light.
Anyone have one?
Manafont.com | $74.5 SMALL SUN T012 2 X Cree XM-L T6 LED 4-Mode Bicycle Light/Headlampw/Remote Pressure Switch (Battery Pack Included)
Things I like:
1. Threaded cable connectors
2. Battery case
3. Looks, it's a sharp looking light
4. Mount looks interesting
5. Battery level indicator. Doesn't look overly bright/distracting (in the photo anyway)
6. Pressure switch option
Things I wish were different:
1. I wish the reflectors were OP textured.
2. Price could be a little lower
I have it, it's an almost complete clone of Niteye B20. Battery is chinese crap with 3100mAh capacity, light itself is good.
Do you have any specific questions about it?
Oh I see. I wasn't familiar with the Niteye. I tend to only hang out in this forum during fall/winter, so I get out of the loop the rest of the year, lol.
Thanks, I'll do a search under Niteye B20. But I do see that it has the OP textured reflectors which I like. I just don't like the price.
I like the removable remote. I wish more lights had that option.
I was looking to purchase online a bike lamp and I found a chinese importer of LED based stuff (flash lights, auto bulbs, etc), so I did not have to wait 3-4 weeks for shipping, plus the price was the same as the online one. Of course the quality is so-so, but reading some reviews I realized it might not be so bad. So, I found this light, a clone of the Niteye B20. I bought it and immediately I disassembled it and took measurements. Here is some pictures and data.
The construction is solid, good finish, nice quick holder. Battery is waterproof in silicon, has a velcro strap bag, I don't know yet the capacity, but it took quite a long time to charge from completely empty. Comes with a pressure remote. You have the official pictures, so I will post only the pictures taken when disassembled, to understand what's inside.
So here we go:
Mechanical construction is not bad, but not brilliant either. The two XML-T6s (I presume) are soldered on 15-16mm pads.
They have ALU pills underneath:
The finish of both the pills and pads was bad, the pads were not flat on the back from the stamping, so the thermal transfer should have been very bad. I just flattened the pills and the pads by rubbing them on sand paper (800) and used Arctic Silver for a good contact.
Here is the light case seen from the back, where the driver sits:
The two longitudinal grooves are for the driver board to slide inside. Although the case is solid, the wall in the middle has two large holes, about 12mm diameter, so the pills sit in contact with the case only on an outer ring of 1.5mm. What is worse than this is the fact that the LEDs are pressed against the wall behind by the front covers screwed in. I am thinking to find a solution to screw in the leds to the back wall and have a fixed pressure to the heat-sink that the case is.
Another view from the front side:
Between the two leds there is still a solid wall. Here is another view that shows the longitudinal groove that guides and holds the board inside the case:
The driver is a two driver design, one for each led, because the sequence of operation is:
1) Max output -> two leds full current Iled=1.55A
2) Middle output -> two leds half current Iled=0.78A
3) Min output -> one led half current Iled=0.78A.
The two drivers are cycled through on the minimum setting, so you get left or right LED ON alternatively each cycle MAX->MID->LOW->MAX
The driver on this picture is in the lower right corner:
In the next picture (the other side), the driver is on the upper right corner. It's not bad, since the drivers are on opposite corners (the other driver in this picture is on lower left now, but the other side of the board).
So, all in all is a better design than other cheap lights. The remote is quite useful, since you can keep your hands on the handle bar without moving you center weight left of right to activate the light.
Also, worth mentioning, from OFF mode you get an instant full ON of the RIGHT led (only this one) by pressing HALF WAY the button on the case, or either UP/DOWN buttons on the remote. It stays ON as long as you press it, so it's good as a manual flash during the day for incoming traffic.
I had to replace the wires, since they were quite thin for 1.5A, and why not have as small as possible the losses on them? The Schottky is an odd type, not sure if it's SS54, since the case does not match the 5A rating of the SS54 datasheet. I will check them to see if the losses can be lowered by replacing them with real 3-5A diodes.
The power consumption and efficiency need some characterization in the lab, I only did brief measurement with the meter at home to get an idea where this light is. The current through the leds is 1.55A and 0.78A, while the voltage on the led is 3V at 1.5A (which is good, the datasheet specifies 3.1V at this current), so basically it's:
1) 100% with two leds
2) 50% with two leds half power and
3) 25% with one led at half power.
I will check with the scope the details. At 1.5A through an XML we have 4.65 Watt of power and should expect about 100 lumen/watt, so 465 lumens per led at full, max 930 lumens total.
The electrical efficiency of the driver, measured with a hand meter (by inserting in series with the unit the meter leads at about 0.5 ohm), is about 86% at full, measured briefly, since the leds were hanging in the air and could not take more than 2-3 seconds of full power.
Iin=0.72A, Vin=7.5V (batt pack was not fully charged)
This is Pin=0.72*7.5=5.4 Watt in
Pout=1.55*3=4.65 Watt out to the led
Taking into consideration the dissipation on the meter wires: Pwire=Iin^2*Rwire=0.72^2*0.5=0.259 watt
we get the real power consummed by the driver as:
Pcorr=Pin-Pwire=5.4-0.259=5.14 Watt, so the efficiency must be Eff=4.65/5.14=0.9
That is quite high, but needs checking with a digital supply that shows both voltage and current delivered to the load and not do calculations. I am surprised a bit. With a better diode and mosfet, it's possible to get a real 90-92% efficiency at full power and increase the power to the leds, if the thermal resistance allows it.
Running the unit full power for few minutes standing still at 25C ambient heats up the case to about 60C.
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