Strange behavior from Nuwai ALX-233C

I have a Nuwai ALX-233C (3 Watt, 3 power level, 3-C cell). It's a pretty nice light for the price ($35), but I'm having a weird problem with it.

When I first got it, I loaded 3 fully charged NiMH batteries and turned it on. It worked fine. I used it for a few more minutes, turned it off, then set it down on my desk. 3 days later, I grabbed the light to use it but it wouldn't turn on. I checked the batteries and the voltage across all 3 batteries was 0.9V!

I thought the batteries might have been defective and somehow discharged themselves. I loaded in a different set of fully charged NiMH batteries. The light turned on and worked fine. After using it, I again set it down on my desk. 2 days later I went to use it and again it wouldn't turn on. This time, the battery voltage was 1V.

I was (and still am) baffled by this :huh2:. Each time I set the light face down on my desk. There was nothing around it and it didn't get bumped/accidentally turned on. No one else used the light either.

I loaded in another set of batteries. This time, I loosened the tail cap about ¼ turn before storing it. 3 days later, I picked it up and it worked. I always loosen the tail cap before I put the light away now.

One other strange thing I noticed is that if I load some batteries, put on the tail cap and tighten fully, take the tail cap off, and then push the power button, the light actually flashes on momentarily. This would seem to indicate there's a capacitor inside that gets charged when the tail cap is tightened enough to complete a circuit.

I'm grasping at straws, but if there really is a capacitor inside, could it somehow be getting charged and discharged (through what I have no idea) whenever the tail cap is on? This could be why my batteries got drained even though the light wasn't on.

Anyone else have the same light and observe similar behavior?

Anyone have any other ideas as to what might be causing this strange behavior?[font=&quot]

Thanks.
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I have the same light.

I have left Alkalines in the light for 2 years. I store the light face down.

No problems with the batteries discharging.

maybe something is connecting the batteries to the light's body....

shine a light inside to see

ernsanada: How about the other strange behavior I noted- load batteries, put tail cap on, take it off, then press power button. Does yours flash on momentarily?

chesterqw: I've looked inside the light, but I don't see anything obvious that could be causing a short. I guess I'll try putting in some regular alkalines and see if that makes any difference (though I doubt it will).

Anyone else have any ideas?

Thanks.

Putting a multimeter across the battery and case gives a reading of 0.045mA. This is pretty much next to nothing. The current starts out high then drops to this level. You're right, after removing the circuit and pressing the button there is a flash from the LED. So the cpacitor guess is a good one.

The off current is negligible and your batteries would not be affected over any length of time.

If you have a multimeter check the off current. I only have one 233C so perhaps a helpful soul could confirm for you? You might have a duff regulation circuit.

Since its all three batteries that are depleted and the case and cap make a simple connection the problem can only be in the switch and regulator circuit. If it was the tailcap causing the problem then that may explain a problem with the last battery in the chain but not the other two.

The spring is pretty aggressive and perhaps the pressure pushing the first cell into the contact in the head is causing some other problem. Do the multimeter test pressing the batteries hard into the body.

Cheers

CoolLEDs said:

ernsanada: How about the other strange behavior I noted- load batteries, put tail cap on, take it off, then press power button. Does yours flash on momentarily?

Thanks.

Click to expand...

Sorry I took so long. I just remembered about what you asked.

My light does exactly like yours. Load the batteries, put the tail cap on, take it off, then press the power button. My light does flash momentarily.

How long have you had your light?

Maybe you can see if you can return the light.

leduk: Thanks for the current measurements. I've tried to use my multimeter to measure the current as well, but for some reason I'm not able to get any reading. I think you're right that there might be something weird with the regulator, though I don't know what would cause it to drain a battery with the power switch off.

ernsanada: Thanks for confirming the behavior of your light. As for returning it, unfortunately I think I've passed the return period .

Oh, and I tried some alkalines- they get drained too.

I have two of those lights, one not yet opened. I haven't had any problems with battery drain in the one I've had loaded for about 4 months now. I'll have to open the other and test it as well as compare tint. I hope you can find a fix or get yours taken care of.

In case anyone else ever has this problem, I figured out why my batteries were draining. I opened up the light to take a look at the circuit board inside and discovered a damaged diode. It's a bit hard to see in the picture, but it's the component in the upper right hand corner of the board.

http://img204.imageshack.us/my.php?image=img18964er.jpg

I used my DMM to measure resistance across it and got 100 ohm. I'm not sure why it started to act as a resistor when it got damaged, but it explains why my batteries would drain. One end of the diode is connected to the positive terminal of the batteries. The other end of the diode is connected to the body of the light (which connects to the negative terminal of the batteries). Whenever batteries were installed, they would just drain through the "resistor".

So how did the diode get damaged? Well, a buddy of mine thinks I'm crazy because I'm always playing with my lights (I don't have many, but that will probably change over time). He thought it would be funny to take out my batteries and install them backwards so that when I went to use the light it wouldn't work. I think that putting the batteries in backwards damaged the diode, which I'm guessing was put in the circuit for reverse voltage protection. The diode probably wasn't able to handle the large current of the rechargeable batteries and got damaged.

Fortunately, the LED didn't get fried when he did this. If it had, I would have been pretty mad. I've fixed the problem by removing the damaged diode. I don't have a replacement part, so I'll just leave it like this for now. As long as no one else decides to put the batteries in backwards, it should be fine.

Just thought I'd share.

Coolleds I have the same light alx-233C and checking inside there is a piece of plastic for reverse protection on the positive contacts behind the head. Could your problem been caused by using rechargeable nimh battery? Just wondering for I want to buy some nimh myself, for this lights. Are you still using nimh with no problems? Please let me know.