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Dthoreson81 · Apr 11, 2017

I've got an LED rated to accept three lithium ion cells. Using three cells, it gets EXTREMELY hot, and has shut off a couple times I'm assuming due to this.

Can anybody recommend a way to improve the heat sink for the led?

Thanks

Marfenix · Apr 11, 2017

http://www.candlepowerforums.com/vb/search.php?searchid=39684

Use this link or login to candlepowerforums and do an advanced search. That will give you the info you are looking for.

Dthoreson81 · Apr 11, 2017

Well, it turns out that heat is not a factor. With two cells, the same exact thing happens minus excessive heat.

Sigh

Advanced search here I come.

StarHalo · Apr 11, 2017

Heat is good, heat means the LED is sinking properly to the body and it's all bleeding heat properly. Most contemporary LED lights are designed to run hotter than the whole setup can actually withstand, it's assumed you will turn it down when holding the body gets uncomfortable (and if you don't it'll just burn out the LED.)

The first step in abrupt turning off is to check the charge of the cells, please be sure all cells are as close as possible in voltage and are between 3.6-4.2 volts.

Ozythemandias · Apr 11, 2017

What LED and what are the spec? What cells? Are they protected? Serial or parallel? Is this a flashlight? How hot is hot?

More info needed.

Dthoreson81 · Apr 11, 2017

StarHalo said:
Heat is good, heat means the LED is sinking properly to the body and it's all bleeding heat properly. Most contemporary LED lights are designed to run hotter than the whole setup can actually withstand, it's assumed you will turn it down when holding the body gets uncomfortable (and if you don't it'll just burn out the LED.)

The first step in abrupt turning off is to check the charge of the cells, please be sure all cells are as close as possible in voltage and are between 3.6-4.2 volts.

This is the case. I only use cells that have come off of the charger together or as close as possible. All of the cells end up at 4.3-4.5 v on my nitecore d2 charger.

Thanks for the info about the heat. The led still works thank goodness.

Ozythemandias said:
What LED and what are the spec? What cells? Are they protected? Serial or parallel? Is this a flashlight? How hot is hot?

More info needed.

The LED I'm using is a Malkoff MDM4 M91T. The website says that it is rated for three lithium ion cells. The cells that I'm using are Nitecore RCR123 lithium ion cells in series, in a flashlight.
They have only been through one cycle of charge and use and charge in a 9p equivalent with yet another Malkoff drop in.

The flashlight in question is a Lego configuration consisting of a m961 adapter connected to a 65mm extender and an SW01 tailcap.

"Hot" to me is "Woah, that's hot, but not hot enough to worry about burning myself"... Hot enough though to feel that the light is hot before even touching it.

Thanks for the help everybody.

Bullzeyebill · Apr 12, 2017

What brand, model number, Li-Ions are you using?. 4.5 volts is a pretty serious over . voltage.

Bill

Chicken Drumstick · Apr 12, 2017

I'm not really familiar with Surefire or Malkoff stuff, but just Google'd the item you list. Seems it's just a drop in running an XP-L HI LED to moderate levels of output.

And uses a high voltage driver.

Just for the record and info, the LED itself will work perfectly fine on 1 x Li-ion (but this driver may not support that voltage). It only needs 3.x volts to operate normally. The multi battery setup is really only to promote longer runtimes and likely the fact the hosts simply hold more batteries, probably as a hangover from incandescent bulb days.

Heat really shouldn't be an issue. And shouldn't be causing it to shut off unless it's faulty.

I suspect what might be happening is the protection circuit on one of the batteries is tripping under load, effectively breaking the connection of the batteries to the rest of the light.

When it shuts off, does it turn back on again?

Have you tested the voltage of each cell when this happens? If the protection circuit has tripped it will read 0 volts. Putting it in your charger should reset the protection circuit.

Dthoreson81 · Apr 12, 2017

Chicken Drumstick said:
I'm not really familiar with Surefire or Malkoff stuff, but just Google'd the item you list. Seems it's just a drop in running an XP-L HI LED to moderate levels of output.

And uses a high voltage driver.

Just for the record and info, the LED itself will work perfectly fine on 1 x Li-ion (but this driver may not support that voltage). It only needs 3.x volts to operate normally. The multi battery setup is really only to promote longer runtimes and likely the fact the hosts simply hold more batteries, probably as a hangover from incandescent bulb days.

Heat really shouldn't be an issue. And shouldn't be causing it to shut off unless it's faulty.

I suspect what might be happening is the protection circuit on one of the batteries is tripping under load, effectively breaking the connection of the batteries to the rest of the light.

When it shuts off, does it turn back on again?

Have you tested the voltage of each cell when this happens? If the protection circuit has tripped it will read 0 volts. Putting it in your charger should reset the protection circuit.

It does not turn back on again with the same batteries. The voltage readings are in the mid 3.x and I get a reading of 0 mAh on one of the three if that makes a difference.

Ozythemandias · Apr 12, 2017

Chicken Drumstick said:
I suspect what might be happening is the protection circuit on one of the batteries is tripping under load, effectively breaking the connection of the batteries to the rest of the light.

I agree with this. I suggest trying other, unprotected cells.

When dealing with multi cell lights, it's always best to start off with brand new cells and "marry" them, only use or charge them at the same time to ensure they're all equal. If you have one or two slowing down then the third one will bear the brunt of the draw and trip its protection circuit.

Dthoreson81 · Apr 12, 2017

Ozythemandias said:
I agree with this. I suggest trying other, unprotected cells.

When dealing with multi cell lights, it's always best to start off with brand new cells and "marry" them, only use or charge them at the same time to ensure they're all equal. If you have one or two slowing down then the third one will bear the brunt of the draw and trip its protection circuit.

Any "oh snap! Turn that thing off! NOW!" Signs to look for should I find unprotected cells to put in the light?

staticx57 · Apr 12, 2017

No. Running cells without shutoff circuits in series is always recommended against. In any case, a single rcr123 even with a circuit should be enough to power that. The fact that it gets extremely hot tells me there is something else amiss. Perhaps even a short somewhere. Are the wrappings on all the cells completely intact?

Chicken Drumstick · Apr 12, 2017

staticx57 said:
No. Running cells without shutoff circuits in series is always recommended against. In any case, a single rcr123 even with a circuit should be enough to power that. The fact that it gets extremely hot tells me there is something else amiss. Perhaps even a short somewhere. Are the wrappings on all the cells completely intact?

I don't think there is a right or wrong answer for running cells in series. But ICR chemistry cells, the ones with the protection circuits are typically ones that can have thermal runaway if they short out.

IMR chemistry, while still containing huge amounts of power, does not tend to suffer thermal runaway. Most of batteries of this type do not have protection circuits and are normally higher performance batteries.

As that is a high voltage driver in that drop in, it may well not work with a single battery, as it is buck driver and likely requires 6v to operate. But the op would need to check the specs.

The LED itself, if it had no driver will happily work on a single Li-ion cell.

Personally I don't mind running multi Li-ion, but I prefer to run 2x in series over 3x.

It'd be trial and error, but the op might be able to run 2 x 16500 batteries instead of 3 x 16340, should work out to a similar length. But no guaranteed.

Op - as far as batteries go, I like the Efest IMR/INR batteries. Lots of info here on batteries:
http://lygte-info.dk/review/batteries2012/CommonSmallcomparator.php

Dthoreson81 · Apr 12, 2017

staticx57 said:
No. Running cells without shutoff circuits in series is always recommended against. In any case, a single rcr123 even with a circuit should be enough to power that. The fact that it gets extremely hot tells me there is something else amiss. Perhaps even a short somewhere. Are the wrappings on all the cells completely intact?

Well, I can check. Not sure why that would matter. Also, how would I go about fixing such an issue should it arise?

THANK YOU EVERYONE! THANK YOU THANK YOU!

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