Review of Ultrafire WF-502B XM-L T6 3-modes

LED Flashlights – General Info 18650 Flashlights
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INTRO

This is my first post so I will probably violate some rules… Feel free to comment below.
I don’t consider myself as a flashalcoolic. I own a simple 10USD AA LED flash light for 2 years and I’m happy with it. I received today my second flash light.

Presentation


Ultrafire WF-502B with an XM-L T6 supposedly 800lm (2.2A)
Bought on DX (sku.160509) for 12.54USD

Pros
-Feels solid
-Nice finish, doesn’t scratch easily
-Almost watertight, there is a small leak through the clip screws
-This is a flood light (I like it) but there is a good hot spot in the middle
-Switch feels really nice

Switch assembly:

Cons
-Bigger than I thought (way bigger than my AA flash light)
-DX claims memory mode but it doesn’t. It goes to high each time you switch it off. (then a slight press does High,Low,Strobe)
-DX claims 2.2A but this is not true unless the battery is full. See results below.
-Bad heat management as all P60 dropins. I ran some temp tests with the P60 dropin out of the host. the temp increased from 30°C to 80°C in 2 minutes (video here with 4.1V using a power supply). I can’t imagine the temp it reaches after 5 minutes on high. Enclosed in the host the heat can’t go away. Must do the aluminium foil trick.
-No Low voltage Warning/Cutoff. Will discharge your battery below 2.5V

Driver:

There is a 0.2ohms resistor that “regulates” the current. Efficiency has to be poor because of that.

Others

Here is the current measurements:
Low:
3.6V -> 100mA
4.2V -> 200mA

High:
3.6V -> 1.2A
4.1V -> 2.1A

Here is the stabilized temperature (dropin alone - 18°C ambiant) at low mode:

Here is how I measured temperature (you can see the thermocouple stuck on the P60 dropin):

OVERALL
I like that light except for the driver.
I got 18650 LG 2600mAh cells out of a laptop battery so for 13USD I got a great flashlight.
I will probably change the driver with a 7135 based driver with group modes.
I don’t recommend that light if you don’t want to tinker it in order to improve heat sinking.

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Pretty great first post. Congrats on the solid new light. :beer:

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Nice review, and welcome to BLF!

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Thanks. I tried to keep things short but still showing the important points not described on DX (heat, driver,…)
I’m quite angry that DX says it has mode memory…

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Welcome to BLF :beer: :beer: entering BLF with first review … you’re the Man! :bigsmile:
the driver looked different than I have… and looks like you could add R100 parallel to that R200 to bump it to 3+.A :smiley:
Correct me if I’m wrong? :~

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Thanks for the review and welcome to BLF.

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I like your signature DayLighter!

Adding R100 in parallel would reduce the resistance value to about 67mohms. So the current would be multiplied by 3 right? Would be better to add R400 in parallel to get about 3A. No?
Anyway I don’t like this driver as the output lumen drops with the voltage. I will probably order a 7135 based driver at some point.

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Where do you get them r100 and r200 resisters from?

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Nice review. I actually like this type of driver because of the easy mod to get more current, (as long as the pwm-frequency is high enough).

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So there are worse drivers? :open_mouth:

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Absolutely! How about the "Next-Mode-Memory" meaning that every time you turn in off, it comes on in the next mode: Turn it on with "High", next time it comes on in Low, next time in strobe.

You have to cycle through all the modes every time you turn it off if you want to make sure it will start with high next time you click the switch...

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Faaaaaaaaaaaaaar worse. Haha.

As with a lot of budget lights the odds of getting one with the dreaded next-mode memory is pretty high. We have a simple fix for that though, thankfully. :slight_smile:

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I just did a quick calculation about that R200 (0.2ohms) resistor:
Power = Resistance*Current^2
=> Power=0.2*2.2^2=1W
There goes a watt just in that resistor…

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Howdy and welcome aboard. Nice review. I have tons of lights and you can do a whole lot worse than the 502b, well the 501B comes to mind actually. Starting on High is pretty nice and some places consider that to be mode memory. As others have said it’s better than next mode which is horrible.

A couple of things you can do for the light. Instead of tinfoil you can use copper. Go to the hardware store and have them cut you a one inch section of copper pipe. They might not even charge you for it because it’s so small. Depends how much you shop there I guess. LOL Take a hacksaw to that and cut it down the middle. Then open it up and place it around the reflector. It will just barely jam into the body and it will make heat transfer much better. Also instead of buying a resistor you can simply solder a wire across the existing one making it a Zero resistor and you will have a direct drive. Your resistance will then depend on your wires, springs, battery and whatever internal resistance is built into the driver, there usually is some other than just that resistor.

Next make sure there is some kind of thermal paste under the star. If you don’t have anything to put under there then find anything really. The idea is to replace the air with something else. Even toothpaste is better than nothing. Just use a very thin layer. You just want the air gone not another layer that will act as insulation. The more heat you can draw away from the emitter the longer your lumens will stay on high. (Thermal sag is bad, it lowers lumens and turns battery power into heat)

Next, if you want better throw and a neutral tint to the light you can de-dome the emitter. Simply take it out and soak it in gas after a few hours the dome will fall off. Be very careful after than because the bond wires will be exposed. They are TINY and FRAGILE. So don’t bump them. This should almost double your throw and give you a better tint.

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Thanks a lot for your explanations, that’s very informative.
I already made an error report on DX about that memory mode… To me it was clear that memory means it restarts in the same mode you left it… I’ll see what they say but I’m sure they don’t care.
I stuck some aluminium foil around the reflector a few hours ago. It improved the temperature a lot. before it would be at 80°C in 2 min (18°C ambient). Now after 4-5 minutes it’s at about 75°C. I don’t think I’ll go to the trouble of buying copper pipes…
I didn’t remove the LED to verify that there is thermal paste because I saw some white paste that got pressed out around the LED board. So it looks like they added enough thermal paste.
I was afraid of de-doming but I didn’t know it can make it more neutral. Now that is interesting as I don’t like cool white! I’ll think about doing it.

Thanks again everybody for your wise advices! :slight_smile:

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Welcome aboard, good review

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Nice review! I think you should have bought this 502B instead. Just add another $0.88 to upgrade to a 2.8A driver (with 8*7135) or just order it as is because 3*7135 is enough and doesn’t heat much. It does have mode memory after leave it on for 2-3s.

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That does look like a very good deal! I never tried Aliexpress however. The reviews all seem to be typed by robots who never touched the light… These reviews are not as informative as DX ones.

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Aliexpress doesn’t accept paypal?? I don’t feel comfortable giving my credit card to a Chinese store… Even a big one.

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They are not really reviews mostly feedback just like eBay. I’ve bought a few times from him before and you can just send the money directly through Paypal. Chat with him in Ali and he’ll give you his PP address. The store owner is Simon and he’s a member here.