Troubleshoot problem/challenge for the Experts

I just received a light from DealExtreme. It is a two cell lithium-ion rechargeable dive light using Cree MC-E emitter. This is a hand held dive flashlight. The modes are accessed via a rotating magnetic switch.

It is bright (I think about 500 actual lumens) with 3 modes-100%,50%, and 20%.

It works fine out of the water. It doesn't overheat and all modes work as expected.

In the water after about 20 feet the pressure affects something and I'm not sure what or how but suddenly the light dims to almost off. I rotate the switch but it doesn't affect anything so I turn it off. After a few minutes I turn in back on and everything works for another 5 minutes or so and then the same thing happens.

How is pressure affecting the rotating magnetic switch and causing it to dim to this extent? Pressure isn't causing a leak and the batteries actually are at full power. It's something about the drivers or the magnetic switch at pressure and only at pressure that is causing this.

Any ideas as to what is actually happening and how to fix it?

I love this light and would rather not have to send it back to DealExtreme and wait another month or so for a replacement that might have this same problem.

At least one other person has had this problem. Other people have had different problems with this same light and many have had no problem.

Just in case some of the other problems are related I"ll mention them briefly. Someone couldn't turn the rotating switch if the head of the light was screwed in too tightly. Someone else suddenly has a problem with the light shinning dimly in standby mode where it shouldn't be on at all.

Any ideas would be greatly appreciated!

Where is the rotating magnetic switch? Is it on the tailcap or the head? From what you have written it sounds like it might be on the head. Can you post a link so we can see a picture and description of the exact model?

Is it made of plastic or aluminum?

Since you mention the problem has a time element, one guess is that it is related to temperature. 20 ft down the water is cold and does not have the insulating properties of air and a warm hand. It could be that the batteries or some other component are getting too cold to operate efficiently, though lithium ion is not normally sensitive to moderate cold.

You could test the temperature theory by putting the light in the fridge or in a jug full of iced water and see what happens.

Another guess is deformation. Magnetic switches usually work by bringing a magnet in proximity to a reed switch, causing the switch to close. It might be that the water pressure deforms the light somehow and moves the magnet out of position.

gcbryan said:

I just received a light from DealExtreme.

Click to expand...

There's your problem..

Now that piece of advise doesn't require any expertise now does it!

StarHalo said:

There's your problem..

Click to expand...

I don't know how to post pictures on here but here is a link :
http://www.dealextreme.com/details.dx/sku.26498

Look to the left and you can bring up all kinds of pictures included disassembled.

It is machined aluminum and there is a rotating magnetic switch on the main body just below the head. You don't rotate the head (or the tail). Just in case it's not clear from the pictures, there is no plastic in this light.

The thing is in our waters it's 50 degree right from the start. At 20 feet it's just as cold as at 100 feet.

Also, if it were temp it wouldn't work fine after turning it off for a few minutes and turning it back on as it would have been colder even longer.

I do think it has something to do with pressure and the switch and/or driver.

I hope these pictures help.
Thanks.

Mr Happy said:

Where is the rotating magnetic switch? Is it on the tailcap or the head? From what you have written it sounds like it might be on the head. Can you post a link so we can see a picture and description of the exact model?

Is it made of plastic or aluminum?

Since you mention the problem has a time element, one guess is that it is related to temperature. 20 ft down the water is cold and does not have the insulating properties of air and a warm hand. It could be that the batteries or some other component are getting too cold to operate efficiently, though lithium ion is not normally sensitive to moderate cold.

You could test the temperature theory by putting the light in the fridge or in a jug full of iced water and see what happens.

Another guess is deformation. Magnetic switches usually work by bringing a magnet in proximity to a reed switch, causing the switch to close. It might be that the water pressure deforms the light somehow and moves the magnet out of position.

Click to expand...

Are you following the review threads there?
I see one pointer to another review link at a scuba site, I didn't read that;
aside from that there's one dive report, one depth, no time or temp. given.
You should add yours with details.

It may be this is a waterproof flashlight.
If a good sample of them were tested --depth/time/temperature -- it could be a dive light.

Ask yourself if you'd buy a regulator from the same source. Life-critical means that.

gcbryan said:

I don't know how to post pictures on here but here is a link :
http://www.dealextreme.com/details.dx/sku.26498

Look to the left and you can bring up all kinds of pictures included disassembled.

Click to expand...

Thanks, it's the link we need since it has the full info.

The thing is in our waters it's 50 degree right from the start. At 20 feet it's just as cold as at 100 feet.

Also, if it were temp it wouldn't work fine after turning it off for a few minutes and turning it back on as it would have been colder even longer.

Click to expand...

That's not necessarily true. Temperature is not eliminated until you do the cold water immersion test at home in your kitchen.

I do think it has something to do with pressure and the switch and/or driver.

Click to expand...

Yes, it might be pressure, but the pressure at 20 ft is not that great relative to an aluminum body. The most likely pressure issue would be leaks, but you are saying no leaks are observed.

What batteries are you using in it? 18650's are recommended, but quality on those is quite variable. Have you sourced good quality cells, or are you using crapfire ones from the same vendor as the light?

I just put it in the freezer for a few minutes and then into the refrigerator and no problems.

I'm using the best batteries available from that same site as recommended by those in the CPF diving lights forum. Trustfire 2500mA protected.

I have tested the voltage readings both before and after the dive and just off the charger is 4.2v for each battery and after a load 3.7v which should be fine I believe. I have a backup set and those tested the same. Others have been using these same batteries in this light.

I can burn this light for about 2 hours on high in the house and in cold water in my bathtub.

I just thought that perhaps the pressure was having an impact in some way on the rotating switch (not apparent however).

Mr Happy said:

Thanks, it's the link we need since it has the full info.


That's not necessarily true. Temperature is not eliminated until you do the cold water immersion test at home in your kitchen.


Yes, it might be pressure, but the pressure at 20 ft is not that great relative to an aluminum body. The most likely pressure issue would be leaks, but you are saying no leaks are observed.

What batteries are you using in it? 18650's are recommended, but quality on those is quite variable. Have you sourced good quality cells, or are you using crapfire ones from the same vendor as the light?

Click to expand...

I tried to leave a review at that site but it didn't post. I understand that's a common problem there with reviews. I have posted on all dive boards.

Give me a break regarding the life-critical remark. This is not comparable to a regulator, is not going into any penetration environment (cave or wreck) and I always have a backup light.

Dive equipment isn't better just because you pay $600 for a $100 light.

I wouldn't be much of a diver if my life was dependent on a light.

In any event we have to do this sort of experimenting since there isn't a dive light like this from a normal dive manufacturer. If I wanted a big clunky light, a small underpowered one, or a $2,000 cannister light I'd be in luck. Otherwise, I have to take things into my own hands. This light isn't leaking. The problem seems to be an artificial one in that if I made this a one mode light and took the magnetic switching out of the equation it would probably be fine. Either that or it's the driver.

hank said:

Are you following the review threads there?
I see one pointer to another review link at a scuba site, I didn't read that;
aside from that there's one dive report, one depth, no time or temp. given.
You should add yours with details.

It may be this is a waterproof flashlight.
If a good sample of them were tested --depth/time/temperature -- it could be a dive light.

Ask yourself if you'd buy a regulator from the same source. Life-critical means that.

Click to expand...

The only problem I have with the pressure theory is the apparent delayed reaction. If I understand you correctly the light works for a while at depth before cutting out, but if you switch it off (while remaining at depth), it works again after a few minutes wait, and then cuts out again?

Mr Happy said:

The only problem I have with the pressure theory is the apparent delayed reaction. If I understand you correctly the light works for a while at depth before cutting out, but if you switch it off (while remaining at depth), it works again after a few minutes wait, and then cuts out again?

Click to expand...

Yes, and I know it's weird. It actually doesn't turn off, it just gets very dim, much less than the 20% low power setting. Even when this is going on if you play around with the rotating switch sometimes it goes to 100% brightness for a second and then dims. I turn it off at that point.

So, the power is there it just isn't getting where it needs to go. Theres are protected batteries but that can't be a factor because once they shut down due to low voltage they don't reset until you recharge them again.

So what else controls the current...the drivers. How they can be effected by pressure outside of the housing I can't see. Therefore I can't think of any possible variable other than the magnetic switch. I don't know a whole lot regarding magnetic reed type switches and there operation.

I just went and bought some flat magnets the size of a nickel (6 of them) and played around with my light. If I get the polarity in a certain direction I can move the magnets of the rotating magnetic switch in the area that say "standby".

I can turn the light on and off this way. I'm doing a test dive tomorrow night and will take the magnets with me. If/when the light suddenly dims I'll see if I can get the bright light back with the magnets.

If so, it's a problem with the magnet switch.

Under Pressure the dive light malfunctions and dims to almost
zero output. Then after the internal components cool for
awhile the dive light will turn on again to full power but soon
suffers the same malfunction.

My theory is that there is a cold solder joint or cracked
trace in the electronic circuit that only manifests
when the light is hot (internally) and being squeezed under pressure.

Suggest you take the head apart and touch up (re-solder) all
the likely components and use a magnifier to look
for broken circuit traces.

I once dropped a radio and the volume control stopped working.
It was stuck at full blast although the dial still turned and felt normal.
Opened it up and after looking at the solder connections for minutes
I wiggled the pot and saw all 3 solder pads had lifted on the circuit
board breaking the traces. It was completely invisible and easy to fix.

hopkins said:

Under Pressure the dive light malfunctions and dims to almost
zero output. Then after the internal components cool for
awhile the dive light will turn on again to full power but soon
suffers the same malfunction.

My theory is that there is a cold solder joint or cracked
trace in the electronic circuit that only manifests
when the light is hot (internally) and being squeezed under pressure.

Suggest you take the head apart and touch up (re-solder) all
the likely components and use a magnifier to look
for broken circuit traces.

I once dropped a radio and the volume control stopped working.
It was stuck at full blast although the dial still turned and felt normal.
Opened it up and after looking at the solder connections for minutes
I wiggled the pot and saw all 3 solder pads had lifted on the circuit
board breaking the traces. It was completely invisible and easy to fix.

Click to expand...

Thanks. I'll try that after the dive tomorrow!

> life-critical

No offense to you intended. I'm thinking of my caving days, recalling one particular climb out of a deep pit using homemade ascenders on a muddy rope with water trickling down it and one light left out of the six we started with. Stuff happens.

Problem solved. I went on a test dive tonight with a set of magnets intending to see if I could switch the light to bright after a dimming episode.

In my house I was able to turn the light on and off with the magnets.

The only thing I did differently for this dive was to switch to another set of Trustfire batteries that I purchased at the same time as the light. I'm not sure of the brand included with the light. They are blue just like the Trustfire's but are not branded.

No problems. I went all the way down to 100 feet and slowly came up for a dive lasting a total of 45 minutes.

I'll keep in mind Hopkins advice regarding cold solder joints and broken traces if it happens again as I thought for sure this would be what I would have to end up checking. I may switch back to the other batteries at some point as a test as well.

This is a great light if that problem is truly eliminated. Thanks for the help everyone.

Ah, so it was "CrapFire" batteries then. You might want to check out the cells available from AW in the CPF MarketPlace. Everyone here highly recommends them for quality and consistency.

Mr Happy said:

Ah, so it was "CrapFire" batteries then. You might want to check out the cells available from AW in the CPF MarketPlace. Everyone here highly recommends them for quality and consistency.

Click to expand...

Well, the ones that worked were Trustfire 2500 mA. The ones that didn't were unmarked 2200mA.

The AW cells with button top at 2200mA. Why don't the 2600mA AW cells come with button top? I'm not really into soldering batteries or using magnetic spacers.