[Dominik]

Rayovac / River Rock / Headstream / Cabela's - K2 headlamp.

It is well know headlamp branded with many names and with many different prices from 25 do 49$ - Rayovac, River Rock, Headstream, Cabela's.... Choose your favorite
Sometimes you have to spend half an hour looking for the same lamp under other name but with the better price.

After some time it comes to the old world too - this time branded as a Mactronic HLS-K2SL.

• Super-bright LED emits up to 85 lumens for up to 5 hours (up to is very important phrase here)
• Uses AA batteries
• Four light modes including strobe
• Red safety lights on battery pack provide visibility from behind (constant or strobe).

There is also green safety light version, and in some cases they are claiming only 60 lumens output that is more consistent with the reality.

Mactronic from the front side :

from the rear side :


After disassembling a back plate, the lamp shows its guts :

The heatsink is small but is a bit bigger than in Petzl’s MYO XP.

After unscrewing the heatsink from collimator holder, you can remove the led and driver board from the case easily.

Yet it’s genuine (it looks like ;-) Luxeon K2 not some Chinese 5mm high power invention.
Two chips glued with epoxy – producer does not like to reveal his secrets.

On the other side of the board there is more parts, it looks like the producer left some space for additional resistors .


Now, some measurements, I decide to test both typical power supplies alkalines & NiMH’s

with Luxeon K2 led, powered from alkalines 4,68V without load

V-in   I-In     P-In    V-led  I-led  P-led    Eff. 
4,45V  104mA   0,46W    3,14V  106mA  0,33W   72,35%
4,32V  204mA   0,88W    3,32V  206mA  0,68W   77,71%
3,94V  506mA   1,99W    3,60V  506mA  1,82W   91,37%

on NiMH’s 3,78V without load

V-in   I-In    P-In    V-led   I-led  P-led    Eff. 
3,74V   41mA   0,15W   2,95V   41mA   0,12W   80,63% 
3,69V   83mA   0,31W   3,10V   82mA   0,25W   82,00% 
3,55V  206mA   0,73W   3,40V  204mA   0,69W   94,77%

After replacing K2 led by SSC P4 Bin U - USX0H
on alkalines 4,63V without load

V-in    I-In    P-In    V-led  I-led  P-led    Eff. 
4,40V  129mA   0,57W    3,06V  131mA  0,40W   70,03%
4,27V  255mA   1,09W    3,24V  258mA  0,83W   76,68%
3,84V  621mA   2,38W    3,31V  635mA  2,10W   88,09%

on NiMH’s 3,76V without load

V-in    I-In    P-In    V-led  I-led  P-led    Eff. 
3,67V   71mA   0,26W    2,93V   74mA  0,21W    83,39%
3,58V  138mA   0,49W    3,10V  146mA  0,45W    92,36%
3,34V  317mA   1,06W    3,13V  317mA  0,99W    93,46%

After mod it works much better when it's powered from 3 NiMH’s – rest of the measurements are meeting expectations.

Now some beamshots :
Before and after led replacement
LOW

MID

HIGH


Comparison between Myo XP ‘08 and Mactronic HLS-K2SL after mod (it should be called HLS-SSCSL ;-) ). Both headlamps powered from alkalines High/Mid/Low :




MOD
It wasn’t hard, the only problem was cutting in the heatsink for the K2 emitter - it is hexagon shaped and SSC is round- I have to use a hammer and level it with the rest of the heatsink. Then using AA (or other thermal epoxy) glue the new emitter, center it with the optics, solder wires and voila!

Summary:
For 25-30$ you can get good quality headlamp that isn’t worse than old MYO XP – you can also say that it is even better because it have K2 on board and rear blinkie. For some people the biggest disadvantage of this lamp will be lack of the wide-angle lens or color filters - others won’t need them.

Lamp is well sealed In opposition to MYO XP, every possible joint is sealed with rubber seal : joint of the head with the back plate, cable connection with the head, lens with the head, and battery holder lock.

After modd it is working much Belter when powering from NiMH’s than MYO.

So, much cheaper and after mod even better than New MYO XP . What a shame that there is no Belt version - there is no problem to replace the power cord and add some external battery pack, but some people don’t like to change too many things in the brand new headlamp ;-).