REXLIGHT 2.0 AMPERAGE DRAW?

[big beam]

Has anyone done a test to see how much the rex draws on nimh or primary lithium AA's at the battery?

1 member tested a 14500 and it ran for 2 hrs but only 1 hr with a nimh 2700

:thinking: DON

 

[HarveyRich]

Originally Posted by big beam: 1 member tested a 14500 and it ran for 2 hrs but only 1 hr with a nimh 2700

Very strange. A 14500 typically has 900mah capacity. So, especially with greater brightness because of the voltage, one would expect a considerably shorter run time than on those NiMH?

 

[NetKidz]

Yes, That's strange.

I didn't measure the current draw yet. On high, my 750mAh AW protected 14500 only run about 1 hour and about 45min for 2000mAh Eneloop NiMH.

 

[big beam]

He did the test twice with the nimh(1-2000 and 1-2700)and both times it ran for a little over an hour.It was longer with the 2700 but not like the 14500.maybe it has something to do with the driver being MUCH more efficient @ 3.7 volts.

DON

 

[big beam]

WHC did a test in the review section post#58 with AW's 14500(750mah).
2 hrs and 5 mins :thinking:

DON

So does that mean it's sucking about 2.5 A at the battery with nimh on high?
My C-LE draws .92 on high with primary lithium.

 

[bridgman]

Maybe the NiMH cell voltage drops below some regulator input voltage threshold before all the battery capacity has been used, while the 14500 started at a much higher voltage and was able to use all its capacity before dipping below the threshold ?

The above is a wild-*** guess.

Can I say "***" on CPF ?

 

[nerdgineer]

...maybe it has something to do with the driver being MUCH more efficient @ 3.7 volts...

Too bad if true. I'd happily give up 3.7 V capability if I could get top notch efficiency for the batteries I normally use (1.2V-1.7V).

 

[2xTrinity]

Maybe the NiMH cell voltage drops below some regulator input voltage threshold before all the battery capacity has been used, while the 14500 started at a much higher voltage and was able to use all its capacity before dipping below the threshold ?

The above is a wild-*** guess.

Can I say "***" on CPF ?

That sounds very reasonable. I know this was an issue with running a couple of the Elly lights, though there the problem is that the light wont turn on above a certain voltage. But if the light is left on, it will drain the batteries almost completely. I'd suspect that their circuit doesn't even operate at all below some cutoff voltage that is unreasonably high for a AA light.

 

[NetKidz]

Just done the runtime test of the medium output. (Please refer to #3 above)

The current draws are:
NiMH: High=2.3A, Medium=0.38A, Low=0.09A
14500: High=0.83A, Medium=0.23A, Low=0.08A

Seems reasonable with my runtime charts.

 

[dardar]

from KD website.

"and a regulator circuit that takes (UPDATE: 1.0V - 4.2V)"

I think the jetbeam mxiix accept 0.7v-4.2v

Does that mean the rex stops working when the cell falls below 1v? Way tooo soon

 

[big beam]

It seems that 2.3 A on high is a little out of proportion (with nimh) than the rest of the settings.But meters don't lie.Does anyone have primary lithium to test.

DON

 

[big beam]

Well now that I did the math in my head 2.3 isn't that far off.1/3 of 2.3 is about .800A then figure 70 or 80% efficient driver(maybe)now your at .600A maybe less to the LED.Still seems like a lot but maybe the driver is more like 50 or 60% efficent?

BTW NETKIDZ did your light get hot on high with nimh?WHC said his did.

 

[NetKidz]

BTW NETKIDZ did your light get hot on high with nimh?WHC said his did.

How hot is hot?

The temp raises faster but I still could hold it over 3 minutes. I did the runtime test with a fan blowing, thus I'm not sure how hot it'll be.

 

[big beam]

Well I guess what I meen is did it get hotter with nimh than it did with 14500 on high?

DON

 

[big beam]

Here's a little trick I learned to do when doing runtime tests on smaller lights like L4 and nuwai 301-5 type lights.Wrap them in a damp paper towel and run a fan on it .Evaporation is a cooling process.Works great

DON

 

[NYLYTE]

I bought several. The first I have tested with 2000mah eneloop and 2500mah energizer NiMH cells. I am afraid the thing may be dangerous.

I left the light standing on its tailcap on high for an informal runtime test. After about 10-15 minutes the LED cut out. About 15 minutes after that I went to check on the light and nearly burned myself picking it up.

I do not mean that the light was hot and uncomfortable to touch. I mean the light was so hot I could not touch it. Not hot enough to sizzle water, but well on its way. I do not have a thermocouple equipped multimeter, but I may be able to borrow on later this week.

Despite no light being emitted by the LED the converter/ driver board was still sucking power from the battery and converting it directly to heat. Were I to have mistakenly placed the light in a pocket, bag, drawer, or other insulated confined space, believing it to be off, I worry what might have happened.

I picked up the light by the lanyard I had attached and performed an impromptu "dunk test". After the light was cool I was able to switch it back on again. The failure is reproducible.

I am eager to hear if anyone else can replicate this behavior with an uncooled Rexlight 2.0. This looks like a pretty bad failure mode IMHO.

All that and, the SOS mode is not Morse code SOS ( ... --- ... ), rather, it is merely a slow flash @ ~1 sec

I am still working on a detailed email to Kai.

//NYLYTE

 

[al2k]

Thanks for the report NYLYTE, I just canceled my order for four Rexlights and will order Dexlights instead (more proven thanks to them being based off Jetbeam MkIIx's board).

 

[HarveyRich]

These are serious failures. I am very interested in hearing more testing before cancelling my order.

 

[Nake]

All that and, the SOS mode is not SOS it is merely a slow flash @ ~1 sec

Mine does the same thing, acts like a beacon mode. Perhaps Kai didn't translate correctly. This is from the Rexlight write up on his site.

"Strobe mode flashes about ten times per second, and the SOS mode cycles through on and off every half a second."

 

[jsr]

On a 14500, the driver is likely bypassed and it is running in DD, so the internal resistance of the pass elements of the driver are able to limit the current to ~830mA (per Netkidz).

On a NiMH, input voltage is 1.2V (assuming no voltage droop, which is unrealistic). At 2.3A and 1.2V, that's 2.76W. Most boost converters are not very efficient at such a high input voltage to output differential (assume Vo needs to be about 3.5V, Vin is only 1.2V), so assume 70% efficiency (if even that). 2.76W x .7 = 1.93W. 1.93W at 3.5V is only 550mA, so the LED is seeing about 550mA. Sounds right to me.

I'm disappointed on the SOS mode not being SOS. Kind of wondering if I should cancel my order. It still shows "collecting from suppliers"...I'm 47xx though...pretty late order number I believe.

I like the look of the Dexlight, but WAAAAY too many modes for a flashlight. I wonder if a Hexlight will come out with AI that will sense your environment and adjust output accordingly and will interface via bluetooth to other equipment and has a built in 5GB flash drive and....blah blah...it's just a flashlight.