Review: KD 2 x Cree XML-U2 4+10-Mode 2200 Lumens Bicycle Light (picture heavy)

Thanks ledoman for your review. As I said over at MTBR, I may ditch my exact looking model from KD (though 4.2v with different driver) and get this one instead. I think I will practice the potting method on my old one though. My unit (without coil) has 6.3mm of empty space between the driver and PCB for potting. The thread on modding my light's driver (with pics of light) is here.

siata94, I have this headlamp at FastTech on my wishlist for its 2 cell battery case (buy a battery case and get a free headlamp! :) ).

-Garry

Thanks Garry. Would love to see how your modding turns out also all about potting stuff.

Battery case from Fasttech you pointed out is 2P1S (4.2V) while with this "KD2" you would need 2S1P ie. 8.4V, so no go. But it could be good for your KD version.

Sorry, forgot to point that out. It's likely moddable though to 1P2S.

-Garry

Nice review, thanks for taking the time.

Re heat sinking - it needs more. Most of these lights need more heat sinking.

I contacted KD about buying this lights driver (this "10-step user programmable" one). They will sell the driver for $8. They also reminded me that for my 4.2v version light the LEDs would need rewired to series (I appreciated hearing this from them as it showed me they had some knowledge on what they were telling me about driver replacement). If interested, you would just have to contact them and say you wish to purchase the driver used in bike light sku#S023788.

-Garry

This "10-step programmable driver is now available for purchase here: http://www.kaidomain.com/product/details.S023801 .

-Garry

^ Thanks garrybunk for getting that driver available. I just bought one.

ledoman,

Thank for this very informative review. Nice work. Although the thermal path to the housing appears limited, it might do the job fine at moderate currents. Depends on if that copper trace covers the whole MCPCB and how thick it is. Also, there appears to be some room for upgrading behind the MCPCB.

EDIT: Guess I didn't look at the pictures close enough. I just noticed this post by ledoman:

There is not much space left. Coil is almost touching the PCB. Then there are the wires, too. There is only some small space left on the both sides. PCB could be cut away on sides since on the other side there are TIR lenses leaving some space. Using artic alumina bond it is possible to stick there some small chunk of copper. I might just do something in this direction in the future.

I recall reading elsewhere that the original Gemini Duo and the earliest clones under the Yinding name had a solid aluminum wall across the middle of the housing as a thermal path, ’til early in 2014 somewhere — but those have disappeared, because people copied the outside appearance while cutting material and build time, gutting the insides. Somewhere I saw someone had just weighed the good ones vs. the recent ones — lots of material gone away.

Has anyone tracked down the early design anywhere?

This is like the ‘solid pill, hollow pill’ thing, I guess.

It's the same as the SolarStorm X2's; all the good ones appear to be gone.

-Garry

Hopefuly this Yinding is a good http://www.gearbest.com/led-flashlights/pp_124468.html.

I was talking to them to get one to test. Will see in a few days if I'm going to get one. Also I think we can get some coupon afterwards. It is just light head no other shitty accessories. If it's really good one price is not so high. Combining with this battery case can make really good light setup for helmet use.

>> all the good ones appear to be gone….

> Hopefuly this Yinding is a good

Did you decide to get that one? Any idea if it’s got heatsinking?

and

has this one come to anyone’s attention?
http://www.gearbest.com/led-flashlights/pp_71062.html
UltraFire HD-16 Cree XM-L L2 2400lm LED White Bicycle Headlight Flashlight 4 x 18650 with Head Strap Battery Charger

“Uniquefire” in the pictures

Yes I've decided to get Yinding. I'm just waiting to be sent out. It should have good heatsinking and XM-L2 U2 1A leds.

If you want to buy it including battery pack then use coupon "Yinding" for $38.04 shipped. It is currently the most wanted light there over at MTBR.

> Yinding
OK, we need something, I’ll go with that one.
I don’t see anything specific about the included battery pack — I know those are iffy — any idea how good that part of the deal is?
Well, I’ll know in a while.

Unfortunately I don't know the battery. We think we have found original manufacturer of Yindings and the first batches, before clones came out, and even my 2nd gen. have had quite good batteries. Not the best, but reasonably good. At least I can speak for mine sample. I can ask over at MTBR if the manufacturer can give some figures about real capacity.

Thanks, I figure on supplying my own good batteries, but I’m wondering about the battery box — does it have a protection circuit built in, so I can use unprotected cells?
And of course is the included charger a threat to life, or acceptable, since so many cheap chargers fail HKJ’s tests I don’t trust them much.
I’ll comment when mine gets here, but it’ll be next year sometime.

About battery box you should read this thread and yes it has protection built in. It is safe to use unprotected but brand cells. Can't tell anything about charger. I've found reasonable good ones at ebay. Search for "8.4V charger P7". Still would test each if it is CC/CV.

> Battery box
Thank you! that’s a good one. I’ll have two, because I’d ordered one of those weeks ago that’s en route.
Oh well, never hurts to have a spare.

> test if it is CC/CV
If you have a pointer to how to test that, I’d like to know. I’ve never known how to test chargers

See post #12 in this thread. Perfect cheap solution. (They are cheaper from China, but I linked a good fast US Seller.) To look for CC/CV just watch that the current is constant during the beginning up to somewhere around 8.0v (I'm totally guessing on the 8.0v part) and then see that it switches to maintaining constant voltage with current slowly dropping down from where it was. You may not see the constant voltage on the display (because I'm guessing you'll be seeing the battery voltage rising), but you will see the current dropping. The only two chargers I've tested this way just maintained CC right up to full charge / termination voltage.

Ledoman (or others), please correct me if I'm wrong.

-Garry

More or less correctly, yes. This dual led device can be used to measure power to the light or from charger to the battery. It is just the matter how you set the connectors (male/female) - you should follow the current flow. It is not highly accurate, but good enough to get the feeling what's going on. I'm using 30V/10A device expecting it being more accurate than 100V /50A for example. You can see the pictures in the first post of this thread where the power to the light is measured. Of course you can use 2 multimeters instead.

When want to test the charger you are watching voltage and the current flow to the battery pack. Voltage should gradualy raise up to 8.4+/- 0.05V (it is OK a bit more because of the voltage drop in wires and connectors down to battery). The current at some point (at 8-8.2V is a guess) should start to decrease slowly towards the 0A. Until 8V the current should be constant, but some cheaper chargers are starting to drop the current even before. Nothing wrong with that except the charging time will be longer

You should also watch the status led on the charger when it turns green. If it doesn't turn green or/and the current stays relatively high (> 50-200mA) for longer period even when the green turns on then you have an issue. It should follow CC/CV type of charging fo Li-Ion batteries. Read more at batteryuniversity.com.

First to test - without load charger shouldn't put out more than 8.4-8.5V, lesser is better.

Ledoman, can you tell me how the Kd2 programmable driver behaves at low voltage. I know it flashes red for low voltage warning, but does it ever cut off the light?

Reason I ask, the Kd2 mcu used in my custom hd-016 doesn't seem to ever cut off the light. It just continues to flash for low voltage.

Thanks,

-Garry