Can the LOD-CE blow up in my pocket?

[MarkKLC]

I'm thinking about buying the LOD-CE with 10440. I've read a posts here and there about it burning down your house etc.

I only use my lights occasionally, so I'm not worried about decreased lifespan, but am I actually risking bodily harm by over-driving the 10440?

Do you guys anticipate a 10440 compatible version being released in the near future?

 

[notoatmeal]

** Note, this information is my opinion only.

from what I've seen from RC use of unprotected lipo and lithion cells, I've never seen a cell fail during overdischarge.

I've only ever heard of people burning their garages, cars, carpets, gym floors and tables during the charging of damaged cells.

I would not worry about a cell blowing up in my pocket.

I WOULD worry that the cheap chargers people may be using could POSSIBLY allow a charge to start on a cell that had gone below critical voltage (~2 volts)

I WOULD worry that people leave their batteries charging unattended. Don't do this!

the 10440s are tiny cells, so there is not a lot of energy even if they "vent with flame". That said, I don't want one cooking off in my house!

So to wrap this up, I think the danger lies in people not understanding how fragile this cell chemistry is to overdischarging, coupled with failure during the charge cycle.

just watch the cell when you charge it, don't go shopping and leave it to charge. lithium cells should not get hot while charging, unlike nimh.

 

[MarkKLC]

Wow, that's a huge concern....I was planning to buy the $6 nano charger from Lighthound, but after your comments, I may not want to bet my life on it.

Does anyone have any suggestions on which charger/battery might have the lowest risk of burning down my house?

I don't use my light a lot, so I might not notice it get progressively dimmer and below the 2-2.5V range, so that's a potential problem.

 

[light_emitting_dude]

If your not comfortable with 10440's use some lithium AAA's. I use a 10440/nano charger with my LOD but I am very careful with it. I always top it off at least once a month and check the voltage periodically.

 

[TORCH_BOY]

I only use NIMH or Lithiun AAA cells when EDCing the Light, I want to keep my Jewels intact

 

[SoundMix]

The 10440 is not recommended by Fenix. I use Lithium cells.

 

[DM51]

There's nothing wrong with 10440s or the nano-charger, but as post #2 says, you need to treat the cell with respect and care.

There seems at the moment to be an epidemic of people putting 3.6v Li-Ion cells into lights designed for 3v Lithium primaries, and there have as a result been cases of overheating / LED degradation, but as yet (AFAIK) no unpleasant accidents.

Li-Ion cells become dangerous if overheated. These lights were not designed to take Li-Ions, and my advice would be to stick to using primaries if you want to avoid damaging your light (and, possibly, yourself too).

 

[2xTrinity]

Wow, that's a huge concern....I was planning to buy the $6 nano charger from Lighthound, but after your comments, I may not want to bet my life on it.

Does anyone have any suggestions on which charger/battery might have the lowest risk of burning down my house?

I don't use my light a lot, so I might not notice it get progressively dimmer and below the 2-2.5V range, so that's a potential problem.

Well, if you're not sure it's easy to check the voltage with a meter before throwing the batteries onto a charger. If one is low, I'd just discard it. If you buy them from Dealextreme, 10440s go for a little bit more than $2 -- this is similar to the price of Lithium Primaries, which you'd expect to go through anyway to have the next-highest option for brightness. Even after a handful of cycles, these will pay for themselves -- the difference is you essentially lose "low" and gain "ridiculously high"

What I do is I will periodically charge up several of the cells. Any day that I use the flashlight for more than just a quick burst, I swap the cell at the end of the day for one that's already charged. Every couple weeks I top off all my LiIon cells (10440, 16340, 18650 etc.)

 

[Vikas Sontakke]

As far as I can see, the Nano RCR123 charger seems to be very gentle and does not overcharge the cell even if the cell is left on it for overnight. It cuts off at 4.18 or somewhere around that range. I have heard that Ultrafire charger can lead to overcharged cells but I don't have personal experience with it.

- Vikas

 

[moon lander]

I only use NIMH or Lithiun AAA cells when EDCing the Light, I want to keep my Jewels intact

What do you call an explosive in a sealed metal pipe? it occurs to me that if my lithium ion cell fails in my "U2 style cree light" there would be nowhere for the pressure to escape and the whole thing would likely burst. maybe the tailcap would blow out, that would be better than shrapnel.

with that in mind, a couple of questions:

is there a cheap device or circuit one can buy/build that will turn off a light when the voltage goes below a threshold (say 2.8v). ive created cree under-cabinet lights (battery driven), and i cant leave them on unattended for fear of over-discharging the cells.

what voltage is too low to light a cree led? will it continue to light at 2v? also, if the led isnt recieving enough current to light, does it still consume current? example: i want to leave my light on and leave, once the cell drops to a voltage thats too low for the led to use/light, will it essentially turn off and stop drawing current, or will it keep drawing current without lighting the led and deplete the battery completely?

thank you to anyone with answers or a link to the answers, ive searched but havent found much info on li-ion safety etc.

 

[zipplet]

moon_lander, most lights have DC-DC regulators. Therefore, the regulator will keep providing a voltage that the cree LED needs, even when the battery voltage is quite low! Some regulators are designed to cut off before damaging the batteries whereas others will keep working until they can no longer suck enough current to light the LED.

Without a DC-DC regulator, LEDs will not consume any power once they can no longer light as they are diodes with a "forward breakdown" voltage, if the voltage is less than this they do not conduct. I don't happen to know the voltage for cree's off the top of my head.

 

[notoatmeal]

What do you call an explosive in a sealed metal pipe? it occurs to me that if my lithium ion cell fails in my "U2 style cree light" there would be nowhere for the pressure to escape and the whole thing would likely burst. maybe the tailcap would blow out, that would be better than shrapnel.

with that in mind, a couple of questions:

is there a cheap device or circuit one can buy/build that will turn off a light when the voltage goes below a threshold (say 2.8v). ive created cree under-cabinet lights (battery driven), and i cant leave them on unattended for fear of over-discharging the cells.

what voltage is too low to light a cree led? will it continue to light at 2v? also, if the led isnt recieving enough current to light, does it still consume current? example: i want to leave my light on and leave, once the cell drops to a voltage thats too low for the led to use/light, will it essentially turn off and stop drawing current, or will it keep drawing current without lighting the led and deplete the battery completely?

thank you to anyone with answers or a link to the answers, ive searched but havent found much info on li-ion safety etc.

I'm much too lazy, but all the answers can be found on RC sites like ezonemag and rcuniverse.

the chances of a lithium cell failing in your pocket are zero, unless you charge batteries in your pockets...?

all the guys who have had damage to property did two things wrong:

1. left cells unattended during charging.

2. left cells charging near things that can burn.

it's the charge cycle that causes these cells to fail. From what I can remember, going under a certain voltage causes small 'hairs' of chemicals to form. when they get big enough or whatever, the cell shorts out with impressive results.

a protected lithium cell has under/overvoltage protection, and overamperage protection, too. The 10440s don't have any such protection, it's built into the charger.

don't forget, overdischarging NiMH cells is also bad for the cells, but usually the voltage drops so low that we stop using them long before serious damage occurs.

 

[notoatmeal]

As far as I can see, the Nano RCR123 charger seems to be very gentle and does not overcharge the cell even if the cell is left on it for overnight. It cuts off at 4.18 or somewhere around that range. I have heard that Ultrafire charger can lead to overcharged cells but I don't have personal experience with it.

- Vikas

and another FYI, lithium chargers fill the cells about 80% within the first hour of charge. it takes another hour or so to get that last 20% in.

there is some variation in how high the final voltage gets on a resting lithium. 4.22, 4.25, 4.17... etc. Some of the crazies turn a pot to increase their chargers final voltage readings, but it seems like a very risky move for a tiny amount of power.

all lithium chargers (when working correctly) will taper the charge to about .05A for last few %, and will never "overcharge" a cell, even if you leave it on overnight.

(of course, you're home, and the cells are away from anything flammable, right!?)


lithium cells are an incredible mix of great low-temp performance, low self-discharge, high energy.

however, they take a couple hours to charge, and can be damaged by discharging too deeply, and fail in a way that most people would consider dangerous.

be safe, go and read some sites on unprotected lith-ion safety.

 

[Patriot]

MarkKLC, I have 4 Nano chargers and never had any problems. They are easy on lithium ions and automatically stop charging at 4.16 volts. They're about as fool proof as it gets, which is perfect for me.

 

[moon lander]

moon_lander, most lights have DC-DC regulators. Therefore, the regulator will keep providing a voltage that the cree LED needs, even when the battery voltage is quite low! Some regulators are designed to cut off before damaging the batteries whereas others will keep working until they can no longer suck enough current to light the LED.

Without a DC-DC regulator, LEDs will not consume any power once they can no longer light as they are diodes with a "forward breakdown" voltage, if the voltage is less than this they do not conduct. I don't happen to know the voltage for cree's off the top of my head.

thanks for the info!
i should have been more specific, i was refering to a direct drive setup. so if the "forward breakdown voltage" of a Cree led is greater than 2 volts, than theoretically it should be safe to leave that led hooked directly to a li-ion 18650 or 14500 etc. since it will stop drawing current before it depletes the cell to below 2v. ill try to to find the cree spec on this, hopefully it is greater than 2v.

 

[moon lander]

how long would a cell take to blow when short circuited? i know the internal resistance is very low. hopefully its not instantaneous, when fiddling around checking currents/voltages etc it is easy to cross 2 wires and short them out accidentally for a moment...

 

[2xTrinity]

how long would a cell take to blow when short circuited? i know the internal resistance is very low. hopefully its not instantaneous, when fiddling around checking currents/voltages etc it is easy to cross 2 wires and short them out accidentally for a moment...

I have accidentally shorted out some LiIon cells before (putting them into a light with a short) but noticed it almost immediately when the light didn't turn on, I pulled the cell out. It felt slightly warm after a few seconds, that's about all. This would actualy be an interesting experiment to try, perhaps outside in a fire pit or something -- short out a LiIon cell, watch, and wait.

 

[Alin10123]

I only use NIMH or Lithiun AAA cells when EDCing the Light, I want to keep my Jewels intact

When you say Lithium AAA cells are you referring to these?

http://www.batteries.com/images/256x256/16706.jpg

Is there a difference in runtime between those and Nimh?

 

[TigerhawkT3]

Yeah, there's a difference. The L92s provide more output for more time, are just as expensive as NiMHs, and can't be recharged. Check flashlightreviews or chevrofreak's work for runtime charts showing the differences between NiMH curves and L91/L92 curves. This review, for example, has a great runtime chart with curves for 1AA and 2AA on alk, NiMH, and L91 (the AA-sized lithium), plus 1xCR123A.


I use a 10440 in my L0D-CE, and I haven't had any problems so far.

 

[Handlobraesing]

If you want to check for thermal runaway limiter, you can wrap it in fiber glass insulator, put it in a metal pail and leave it on where explosion won't harm you. Attach a thermometer to the light itself.

If the light is designed well, it would limit temperature rise at a reasonable level.

If it's crappy like my RiverRock 3W headlamp, it might reach over 300F.