Mtbr's 2016 Winter Biking GearReviews and Roundups

FAT BIKES

WINTER APPAREL

TRAINERS

1. Originally Posted by Vancbiker
Keep in mind that the lead bike has the light pointed away from the camera, while the nice bright one is likely pointed at the camera.
Originally Posted by steelhmr
Independent of beam shot, lamp comparison, etc., that pic is beautiful.
Of course, actual difference between lights is not as big as picture shows it (hence I've noted it as "advertising"), but in any case the light is quite bright. Our local bike club's members are using various powerful lights for long time, so they're familiar with most setups consisting several single- and dual-XMLs, but this one caused many jokes like calling me "landing aircraft" and "approaching locomotive"...

2. ahahah nice nicknames XD

By the way a friend just told me to buy 3 of these that should give me the value of 0.050ohm Resistori SMD Resistenza basso ohm, 1206,0,33W,1%,R15 Panasonic ERJ8BSFR15V consegna in 24 ore , I guess I'll be even safer with the heat

3. How do you mean. Correct dimension, but putting three of those .15, corresponding to 0.05, will give you a much higher current than stock and a small-sized frying-pan

Original
1/(1/.25+1/.1+1/.33) = 0.906 and 16W

The mod discussed above

1/(1/.25+1/.1+1/.33+1/0.1) = 0.476 and 31W

Yours?

1/(1/.25+1/.1+1/.33+1/0.15+1/.15+1/.15)=0.032 and I guess ~45W!

Originally Posted by purifier82
ahahah nice nicknames XD

By the way a friend just told me to buy 3 of these that should give me the value of 0.050ohm Resistori SMD Resistenza basso ohm, 1206,0,33W,1%,R15 Panasonic ERJ8BSFR15V consegna in 24 ore , I guess I'll be even safer with the heat

4. Ouch some calculations errors I guess then
Can you point me to the correct model on that website?

5. BTW, I misunderstood you. You are replacing the old resistors, all with a R15. All good then.

6. Originally Posted by lofberg
BTW, I misunderstood you. You are replacing the old resistors, all with a R15. All good then.
Yes, remove all the old ones and install 3 of these, proceeding to order them now

7. Awesome light after the mod. Unfortunately, it said bzzz after a couple of minutes (a couple of degrees above freezing outside, not moving just checking the light). Hadn't had the time to do any thermal management mods.

The diod (marked ss34) popped off, and one leg of the coil hangs loose :-)

To the lights defense, I was running it on a 12.5V LiPo battery. I've always run my lights on 3-cell LiPo and directly from motorcycle battery and never had any problems with this. I thought higher voltage simply meant lower current (within limits), but maybe that is not the case?

8. mmm sorry to hear that
I've done (or rather, my friend has done) the mod and tested it only for a few seconds,
now I gotta find a new battery for my old 35w HID spotlight to take a beamshot photo
for comparison (that should be 3'500 lumens while this should output a little less), as for
the bike ride I'll let you know if it lasts for a 40 minutes test lap...

9. Trying to learn these things from scratch (even installed spice to simulate boost drivers. yes I am an engineer...), so could someone correct me if I am wrong anywhere.

1. The board uses a boost driver in order to increase incoming input voltage to ~25V for the 7 LEDs in series.

2. The MOSFET switching is controlled by the QX5241. Datasheet here

3. Since the 5241 lists Vin as 5V-36V in its datasheet, a 12V (effectively 13.5V) battery should be no problems

4. In the datasheet, it says I = 0.2/Rsense, so theoretically the LEDs should see 2.2A at nominal 0.0907Ohm. However, that makes no sense as the current goes over 7 LEDs in series, and that would be 50W. So, by guessing from the schematic in the datasheet and thinking CSN = current sense, the 5241 actually controls the *input* current on this lamp?

5. The HT7133 simply supplies a constant 3.3V for auxilliary power on the board (the battery indicator led for example). I.e, it is not really involved in the boost process.

What really confuses me is that I saw 2A when I ran the lamp on the 12V battery, i.e., what Archie noted on presumably original 8V battery since he stated 16W. Wouldn't the boost driver account for the higher voltage and thus require lower current? Or is my hunch above correct, the 5241 controls the input current, so a simple mod here is to simply run the lamp using a higher voltage battery (since the 5241 can accept that). Lines up with the fact that I saw 2A .

10. 1,2 - Correct.
3 - The power range of particular IC and working voltage limits of whole assembled light head are different things. Connecting the battery of significantly higher voltage is dangerous action in most cases, and this one is no exception.
4 - Regulation circuit normally controls the power applied to the load, in turn, by adjusting power consumed from the energy source.
5 - Correct.

It's difficult to make "theoretical model" of what exactly happened to the light when you've simultaneously overvolted it and increased the current (especially without thermal management), but putting it simple, it's somewhat like plugging American 110v soldering iron into European 220v outlet. It surely will increase the temperature, but not for long...

11. Thank you for the answers.

4 is what really confuses me, as the current draw on the source was the same regardless of input voltage, and increased proportionally when modding it. On my other lights, which work well under both 8V and 14V, the current drops proportionally when increasing the voltage. Could be that the control algorithm simply saturates somehow when running the light beyond the spec on input voltage.

Anyhow, I liked the light, so I have a new on order (could not salvage the board, new schottky and resoldering the inductor did not help)

12. Yes, probably control circuit was already damaged by overvolting: otherwise, it should adjust input current according to the voltage. At least, all the bike lights I have are doing that, more or less successfully.

Good luck modding the second unit, and don't forget to improve thermal sinking first!

13. I bought one based on this thread. It puts out about 1500 lumens out of the box comparing it w my Dinotte XML. I did the mod w 100 mohm and it then put out like a beast drowning out the dinotte. So far, so good. I then thermal pasted the led slug to the case, etc. You want the outer case to get hot. And it does get hot. I turned it on but got distracted for about 15 minutes. Oops. The light was off as well as the status light. There is no thermal shutdown on this. The clamp diode on the boost converter desoldered itself. The 100uf cap was blown. Inductor lead desoldered itself. Smell of burnt electronics, probably the cap. I'll repair what I can at work, but if the switch or controller are blown, I may need to get creative and design my own w/ thermal protection. LEDs looked ok.
I don't know if the REAL lights are protected, but I won't be testing my dinotte in likewise fashion.
Note to myself, these things need air flow

14. One more thing. I was worried about the case prior to blowing it up. It is handsome but is heavy and does not have much heatsink area. This may be why they keep the power down for the general masses?

15. I don't think so. Cooling is adequate if you're moving - I've tested that. IMHO, underpowering is implemented because of marginal batteries typically included with such lights: running on full power will exhaust them almost instantly...

16. A thermocam would be handy to get a visual of the driver components temperature. But the cheapest I found is about 200 EUR

17. That's a carbon copy of my melt-down

Originally Posted by dnitake
I bought one based on this thread. It puts out about 1500 lumens out of the box comparing it w my Dinotte XML. I did the mod w 100 mohm and it then put out like a beast drowning out the dinotte. So far, so good. I then thermal pasted the led slug to the case, etc. You want the outer case to get hot. And it does get hot. I turned it on but got distracted for about 15 minutes. Oops. The light was off as well as the status light. There is no thermal shutdown on this. The clamp diode on the boost converter desoldered itself. The 100uf cap was blown. Inductor lead desoldered itself. Smell of burnt electronics, probably the cap. I'll repair what I can at work, but if the switch or controller are blown, I may need to get creative and design my own w/ thermal protection. LEDs looked ok.
I don't know if the REAL lights are protected, but I won't be testing my dinotte in likewise fashion.
Note to myself, these things need air flow

18. Sorry lofberg,
I missed the irony of your prior post. I'll try the repair a bit later.
Anyways, DC/DC converters are power in/power out less efficiency usually 90% if the coil and switch are in their zones. So agree a higher voltage would be less current.

19. What irony? Anyway, just noting that our lamps went down exactly the same route when going up in smoke (cap, and desoldered diod+inductor).

Originally Posted by dnitake
Sorry lofberg,
I missed the irony of your prior post. I'll try the repair a bit later.
Anyways, DC/DC converters are power in/power out less efficiency usually 90% if the coil and switch are in their zones. So agree a higher voltage would be less current.

20. Archie,
That was a good mod you did and I bet if I was moving it would be fine. Very informative. It makes having 7 LED's worth while, otherwise why bother.
I wonder how Lupine does it at full tilt. For \$1100 they can do a LOT of things.
Bet it self protects.

21. Yes, Lupine actively adjust the current according to the temperature: it was mentioned many times. Many inexpensive lights also have thermal monitoring circuitry, but this one unfortunately does not: just be careful. Or add protection yourself, if you think it's absolutely necessary.

As for the light, I'd say I really like it. After modding, I extensively use it on offroad rides: no problems so far, and very impressive output.

22. Quick question, I have the same light but with a different driver, could anyone tell me how to figure out which resistors need the mod, I have 9 resistors on the board. Values 102 to222. Don't see any in parallel. 2 feed indicator LEDs (102)and 2 are across legs of mosfet
(103 and 153) 2 are in series(103+222). A 124 is in series with a cap from input voltage
Board is a yytd84-04c.

23. Originally Posted by -Archie-
Recently, Eastern web shops started to sell new bike light with seven XM-L LEDs, in various sets, with 4- to 8-cell battery or as stand-alone head:

As its quality seems to be higher than "average Chinese light", I'd like to share my opinion about it: perhaps, it will be useful for some of you. I've ordered this particular one:
Super Bright 7T6 BIke Light / 7*Cree XM-L T6 Bicycle Light ( Lamp Cap Only )

Honestly, I'm very impressed. The quality of parts and assembling is surprizingly high, especially if compared to my previous five-LED light.

The most important thing - thermal management - is excellent here. All the LEDs are soldered on common baseplate, mounted onto massive aluminium base. Instead of thermal paste, thermal compound is used, but it's used quite properly. Layer is very thin, and it was applied immediately before mounting (excessive compound squeezed in holes), so overall thermal path is undoubtedly good. Big contact surfaces also assure that. The reflector is securely mounted with two M3 screws. Moreover, massive aluminium reflector not only used to provide mounting pressure to the LED plate (via separate plastic insulators), but also participate in thermal sinking - as it's very tightly contacted with both aluminium base and the outer case.

Positioning of each LED in the cells is perfect. Assembled LED module and outer case both have wide and well machined contact surfaces. It's quite uncommon for Chinese light to be completely watertight, but it's the case here! Silicone button cap is not just inserted into hole, as it's usually done in other lights, but fixed by separate screw-in metal ring. And even power cord's hole is equipped with rubber boot. Obviously, glass bezel is also sealed with rubber rings. The handlebar mounting is typical, but is done more stable: shape of case's mounting surface have protruding edges preventing the mounting from rotation.

Electrical scheme is not bad either. All the LEDs are connected in series, and powered by boost driver made of QX5241a IC, H35N03 mosfet transistor and SS34 Schottky diode. Power to the circuit is stabilized by Holtek 7133-1 regulator. Indication of battery state is tri-colour (green-blue-red-flashing red). Wires connecting the LED module have high-temperature silicone insulation. All the soldering is fine and clean.

As the light is relatively heavy (225 g), I've replaced the mounting with self-made one:

Power consumption seems artifically lowered. In the default condition, current in the High mode was only 2,07А (16,2 Watt), and brightness at 1m - 13800 Lux. In former lights, underpowering was probably used to compensate inferior assembling quality, but in this case, I see no reasons for that. The only thing I can suppose of, is the absence of good batteries: for year or two, Asian web-shops are selling absolute crap instead, so probably reduction of power is implemented to maintain at least marginal runtime. Enough to say, in the "6*18650 included" variant, amount of money left for the battery is around \$15, so go figure...

Anyway, I've modified the driver to increase the power to the reasonable level by changing current sense resistor's value to 0.0475 Ohm. Power component's parameters, according to their datasheets, allow for that without problems. The only thing in question is the inductor: it now works in the near to the magnetic saturation regime, and to prevent overheating I've added thermal paste and heatsink to it (simple piece of thick aluminium). Also, I've added thermal paste in all the fittings between LED base, reflector, and outer case, and replaced power cord with MagicShine one (for compatibility with my set of batteries, and because of its better quality).

Now at full beam it eats 3,78A (power is 31 Watt), providing 21500 Lux at 1m. Further increase is possible, but at the cost of replacing some of electronic components and inductor. Most likely, it will cause problems with common cables and extensions (due to high current and voltage drop), and will require replacement of battery protection circuits with ones that can sustain such load without triggering overcurrent protection.

As for now, heating is quite great. In the room test (25°C), after 10 minutes at full beam temperature reached 64°C. With household cooling fan, the temperature after the same time was just 42°C, and after 15 minutes stabilized at 45°C. During actual night ride, it remains barely warm - the cooling seems to be sufficient. But do not forget to switch it off at long stops!

Beam is similar in shape to the famous MagicShine MJ-808, but have some imperfections due to the multiple smooth reflectors used. I believe, it would be great if manufacturer will ever implement version with slightly deflected optical axes of reflectors, so that individual beams will be shifted a bit around centre - that way, effective cone of light will be wider. But even in current state, it's sufficient for most offroad landscapes IMHO.

Conclusion: the light is quite well made, and after minor modding is really powerful one.
Archie,

I recently purchased one of these, and am interested in doing the resistor mod you mention in this thread. Unfortunately all your photos seem to have disappeared. I was wondering if you still had any of those so I can make sure I understand adding the resistor properly.

24. Originally Posted by mtrain
Archie,

I recently purchased one of these, and am interested in doing the resistor mod you mention in this thread. Unfortunately all your photos seem to have disappeared. I was wondering if you still had any of those so I can make sure I understand adding the resistor properly.
I'm sure I still have the pictures on my HDD: will check later. The problem mentioned above is caused by ImageShack site: they tried to earn some money by converting formerly free hosting to the commercial service and deleting old content. Quite wise move nowadays, isn't it?

25. Originally Posted by Hobie21
Quick question, I have the same light but with a different driver, could anyone tell me how to figure out which resistors need the mod, I have 9 resistors on the board. Values 102 to222. Don't see any in parallel. 2 feed indicator LEDs (102)and 2 are across legs of mosfet
(103 and 153) 2 are in series(103+222). A 124 is in series with a cap from input voltage
Board is a yytd84-04c.
Can you post up a clear legible closeup pic of the driver (both sides if possible)?

-Garry

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