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Thread: Using Li-ion cells in LED flashlights safely

  1. #61

    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by DM51 View Post
    LeifUK, please do some reading on the subject before making such lofty pronouncements.

    Li-Ion cells are not sold to "the general public" in the way you suggest - you can't just walk off the street into a store and buy loose Li-Ion cells.

    They are only on sale to those who specifically look for them. It is completely unnecessary for people to be subjected to alarmist posts such as yours, claiming that they are dangerous. They are quite safe as long as you understand them and observe basic safety precautions.
    I'm sorry but my post is based on reading this thread. Are you telling me that the information here is wrong? If the information in this thread is correct, then it is my opinion that they are dangerous.

    As far as I know anyone can buy these cells online, whatever their age. Is that incorrect? If they go to a site that sells LED torches, chances are they will find that those using LiIon offer better performance. Hence they might want some.

    For example, in the first post it says "Don’t overcharge your cells, don’t charge ‘m too fast and don’t leave ‘m alone."

    And "After 15 minutes you need to check on your charging cells"

    So if I understand this correctly, this means that chargers do not come with safety mechanisms to prevent overcharging, or charging too fast. How many people would check them every 15 minutes? My guess would be no-one unless they had read this thread. And how many people would unknowingly charge too fast if they thought they could get cells charged more quickly? My guess is many people would unless they had read this thread. (Do the cells come with safety instructions? Do people read them? Usually not.) I suspect most people leave batteries charging overnight. I have LiIon cells for consumer goods such as cameras and iPods and as explained elsewhere, these are safe because the chargers are made properly with safety measures, as are the cells.

    The impression given by the first post is that these cells are unfit for sale to the general public. Of course you may disagree, but that is my opinion based on the information in this thread.
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  2. #62

    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by LeifUK View Post
    I'm sorry but my post is based on reading this thread. Are you telling me that the information here is wrong? If the information in this thread is correct, then it is my opinion that they are dangerous.

    As far as I know anyone can buy these cells online, whatever their age. Is that incorrect? If they go to a site that sells LED torches, chances are they will find that those using LiIon offer better performance. Hence they might want some.
    Yes. Anyone can buy second-rate Li-ion cells, along with many other dangerous items, online. The world's a big place, and many parts of it have little regulation of product quality. They can also buy known reliable ones, but that'll usually cost a bit more, so don't bet on them doing it.

    For example, in the first post it says "Donít overcharge your cells, donít charge Ďm too fast and donít leave Ďm alone."

    And "After 15 minutes you need to check on your charging cells"

    So if I understand this correctly, this means that chargers do not come with safety mechanisms to prevent overcharging, or charging too fast.
    Generally, they do have such mechanisms -- but do you feel comfortable with a SPOF like that and no safety check? Most of the chargers in use are cheap stuff from HK deal sites which have a history of occasionally shipping shoddy merchandise, including some completely non-Li-ion-related items, which cause electrical fires. Many of the Li-ion cells available also fall into this category. If you use name-brand cells and chargers, your risk goes way down, and you could probably leave them alone and be as safe as the guy with cheapos, checking them every 15 minutes (unless he forgets); even with off-brand ones, once I've satisfied myself of their quality, and closely monitored a number of charging cycles, I slack off the monitoring considerably. But given the scarcity of completely reputable chargers and cells, it hardly makes sense to give advice based on that scenario.

  3. #63

    Default Re: Using Li-ion cells in LED flashlights safely

    Benson, that is very informative, and answers a lot of my questions. Out of interest, what are the name brands that are generally considered good quality?

    Maybe this is a stupid question but would it not be preferable to have a certification process whereby chargers and cells that cannot be left unattended cannot be sold? (I suppose that assumes that the problems are design issues, rather than ones of quality control, since a certification test would not test the latter. It also assumes that the process could be enforced across borders.)

    By the way, what is 'SPOF'?
    Last edited by LeifUK; 12-27-2009 at 02:53 PM.
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  4. #64
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    Default Re: Using Li-ion cells in LED flashlights safely

    SPOF = Single Point Of Failure
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  5. #65
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    Default Re: Using Li-ion cells in LED flashlights safely

    Without wishing to be too infamatory, I walked into a high street store today (specifically Soni Electronics of North End, Portsmouth) and they had rechargable CR123 cells on sale, with a charger. It was the same Uniross unit I saw at RS. I didn't buy it - it was very overpriced. I asked and they said they could easily get me other Li-ion cells within a few days if I told them the types I wanted (I was careful to tell them I wanted cells, not battery packs).

    Soni Electronics typically sell various houshold stuff (bedside lights, spare plugs, fuses, TV aerials, watch batteries etc. etc.) and I would not class them as specialist.
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  6. #66
    Flashaholic Midnight Oil's Avatar
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    Help Re: Using Li-ion cells in LED flashlights safely

    Do some P60 drop-ins have a low-voltage protection mechanism that turns off the light to prevent the Li-Ion battery or batteries from over-discharging, while others that don't simply fall out of regulation, go into direct drive, and allow the battery or batteries to continue powering the light with dimming output?

    Is getting a drop-in that has a low-voltage protection mechanism and using protected Li-Ion cells a substitute for monitoring the cell voltage with a multimeter, or should one always monitor the voltage, which means a lot of unscrewing the light, removing the batteries, and testing them?

    Thanks.

  7. #67
    Flashaholic* Black Rose's Avatar
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    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by Midnight Oil View Post
    Do some P60 drop-ins have a low-voltage protection mechanism that turns off the light to prevent the Li-Ion battery or batteries from over-discharging,
    I've read that some drop-ins will blink when the battery voltage gets low.

    The ones I have purchased or received with lights did not.
    I modified most of those with a driver that does have low-voltage protection built in.

    Is getting a drop-in that has a low-voltage protection mechanism and using protected Li-Ion cells a substitute for monitoring the cell voltage with a multimeter, or should one always monitor the voltage, which means a lot of unscrewing the light, removing the batteries, and testing them?
    Using a drop-in that has low-voltage protection is a way to save the battery from being damaged, but no matter what, you should still monitor the cell voltages.

    By doing so you will learn how your various drop-ins work with your batteries and you'll know when to charge your cells instead of ending up with no light and a possibly damaged battery.

    In the end, these protection circuits (baattery and driver circuit) are simply electronic devices that could fail.
    Should the protection circuit fail, you are left to your own devices to determine when the light will go dark.

    Li-Ion cells prefer to be topped up (unless being stored for a long period of time) so it's not going to hurt to pop them in the charger to top them up after they've been used.

  8. #68
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    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by JBorneu View Post
    Ahoy there

    I created this guide because I felt we lacked one single comprehensive guide which tells newbies how to use Li-ion cells in a safe manner in their LED flashlights. Now I know why: At least the "comprehensive" part is impossible.

    ...
    Hello,

    If it's OK I'd like to transfer this post to the CPFWiki.
    Reasons are

    • other people can extend the text (now only sysadmins or the original writer can do that) - especially with comments that pop up later in the thread: it is extremely tiring to having to read a whole thread to distill information...
    • the text can be shortened a bit

    As a side issue, I think that a lot of knowledge that can be found on CPF is currently hidden in thick layers of thread comments. IMO it would be good to condense posts into wiki articles - but I'm aware this is too much asked from most CPF users.
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  9. #69
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    Default Re: Using Li-ion cells in LED flashlights safely

    Hello Axd,

    I think it would be OK.

    If there are any objections from JBorneu, we will address those at a later time.

    Tom
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  10. #70

    Default Re: Using Li-ion cells in LED flashlights safely

    Thanks JBorneu for an extremely informative post.

  11. #71
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    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by Black Rose View Post
    In the end, these protection circuits (baattery and driver circuit) are simply electronic devices that could fail.
    Should the protection circuit fail, you are left to your own devices to determine when the light will go dark.
    The general idea behind multiple safety layers is to decrease the possibility that failure of a single layer will cause the entire system to fail. My car has 3-point seat belts, front & side airbags, anti-lock brakes, vehicle stability control, and multiple crumple zones. Is it death-proof? No, of course not. But the failure of any one safety component in a potential collision won't mean certain death under most circumstances. Especially if the operator takes care and pays attention to what he is doing (the most important part).
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  12. #72

    Default Re: Using Li-ion cells in LED flashlights safely

    Thank you for this easy to read and understand primer on lithium cells. It helped this newbie out.

  13. #73
    Flashaholic Midnight Oil's Avatar
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    Default Re: Using Li-ion cells in LED flashlights safely

    I have a regulated Nailbender XRE-R2 with a 1.2-4.2V buck/boost driver in a Solarforce L2. It pumps out approximately 225 OTF lumens on high according to its sticker.

    Last night, I let the light run on high off of a new AW 18650 2600mAh @ 4.16V fresh off of my Shekor charger.

    The light ran for almost exactly 2 hours, then flickered and turned off---the over-discharge protection of the battery had kicked in.

    I let the cell sit and rest for about 20 minutes and its resting voltage slowly climbed back to 3.17V, at which point I popped it back into the charger. I measured its resting voltage this morning and it was again at 4.16V.

    A bit of context for my question below --- member Vidpro in another thread mentions that the voltage corresponding to a given remaining cell capacity is a function of the discharge rate. In other words, two cells with identical remaining capacity will register different resting voltages if they have been discharged at different rates: the one discharged at a higher rate will register a lower resting voltage.

    Given that my light was on high for the entire duration of the 2 hours, hence the draw was high, did I really overdischarge the cell? Have I done any harm to it?
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  14. #74
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    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by Midnight Oil View Post
    A bit of context for my question below --- member Vidpro in another thread mentions that the voltage corresponding to a given remaining cell capacity is a function of the discharge rate. In other words, two cells with identical remaining capacity will register different resting voltages if they have been discharged at different rates: the one discharged at a higher rate will register a lower resting voltage.
    I don't think this is so. If you measure the voltage of a cell under load, the observed voltage will be lower under higher loads due to the effect of internal resistance. This means the protection circuit will cut in sooner, before the cell has been drained as much. If you then look at the resting voltages after the discharge has been stopped the cell discharged at the higher load will have a higher resting voltage and a higher remaining capacity than the cell discharged at a lower load.

    The resting voltage is the stable voltage recovered after the load has been removed. In every case a higher resting voltage on the same cell indicates a greater remaining capacity.

  15. #75
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    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by Midnight Oil View Post
    ......The light ran for almost exactly 2 hours, then flickered and turned off---the over-discharge protection of the battery had kicked in.

    I let the cell sit and rest for about 20 minutes and its resting voltage slowly climbed back to 3.17V......
    I just thought I'd mention that if the protection circuit in the 18650 tripped, you would not be able to read any voltage but zero, from the cell, until it was placed in a charger to reset the PCB. I'm not familiar with your light setup, but I rather imagine that the light shut down, and not the 18650.

    As for Mr H's excellent explanation, I think that is likely what Vidpro actually meant. Most protection circuits in the cells we use work best at medium to high current loads. Using protected cells at very low current levels, runs the risk of over discharging the cell.

    Dave

  16. #76
    Flashaholic Midnight Oil's Avatar
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    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by 45/70 View Post
    I just thought I'd mention that if the protection circuit in the 18650 tripped, you would not be able to read any voltage but zero, from the cell, until it was placed in a charger to reset the PCB. I'm not familiar with your light setup, but I rather imagine that the light shut down, and not the 18650.

    As for Mr H's excellent explanation, I think that is likely what Vidpro actually meant. Most protection circuits in the cells we use work best at medium to high current loads. Using protected cells at very low current levels, runs the risk of over discharging the cell.

    Dave
    Thank you, Dave and Mr Happy for clearing this up.

    VidPro, if you read this thread, sorry for misinterpreting your explanations.

    Much to learn I have.

    Dave, about whether it was the light or the battery that decided to quit... My NB drop-in has a buck/boost driver and can run off of a single AA. That's why I think it was the battery, because the voltage didn't go so low that the boost circuit could not be powered to light the light. Isn't the protection threashhold of the AW cells set around 3.2-3.5V or so? Or it could have been that there was no way to stay in the high mode, but the cell could have continued to power the medium and low modes with the help of the boost driver?

    So the consensus sounds like I did over-discharge the cell. Shame shame. Well that's the only time and the last time. The cell seems to have fully-recovered, as far as my DMM tells me. In light of this, I have to say runtime for this drop-in is a bit disappointing. I was expecting a solid 2 hours on high without over-discharging the cell. Unless my expectations were totally unrealistic to begin with. I hope my XPG-R4 with identical drivers will do better.

    BTW, Dave, what is 45/70, because there is also a member old4570? You're not the same guy, right?
    Last edited by Midnight Oil; 06-19-2010 at 10:45 AM.
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  17. #77
    Flashaholic* 45/70's Avatar
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    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by Midnight Oil View Post
    Isn't the protection threashhold of the AW cells set around 3.2-3.5V or so? Or it could have been that there was no way to stay in the high mode, but the cell could have continued to power the medium and low modes with the help of the boost driver?
    Protection circuits vary, but I think usually they trip around 2.50-2.75 Volts. This is somewhat dependent on the amount of current load the cell is under. If the current is low enough, there is a point where most protection circuits won't trip at all!

    Yes, I think your suggested scenario is likely. You might check and see if the light does, in fact work at the lower levels the next time this happens. Also, I don't think you necessarily over discharged the cell. Keep in mind though, that Li-Ion cells prefer shallow discharges over deep discharges. The cells last a lot longer with the former. Personally, I wouldn't discharge LiCo cells beyond where, when rested a minute, they recover to 3.6 Volts. Normally, I aim for ~3.8 Volts.

    BTW, Dave, what is 45/70, because there is also a member old4570? You're not the same guy, right?
    The "45/70" comes from the rifle caliber of the same name. I can't actually speak for old, but I think he's referring to it also. And yes, we are two different Guys. It's really pretty easy to tell us apart. Being on the other side of the Planet from me and all, he's the one, along with his neighbors in N.Z. that walk around upside down all day. At least that's how it looks from my perspective.

    Dave

  18. #78

    Default Re: Using Li-ion cells in LED flashlights safely

    +1, this is really do for me as a newbie! thank you, JBorneu !
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  19. #79

    Default Re: Using Li-ion cells in LED flashlights safely

    Glad I read this, it answered a lot of questions. Thank you for taking the time to post a wealth of knowledge.

    Looks like last time the original post was updated was in 2010, maybe an update with the latest and greatest recommended batteries and changers available would be beneficial for 2012?

    Cheers and thanks again!
    Hawk

  20. #80
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    Default Re: Using Li-ion cells in LED flashlights safely

    As I've gone through the threads I've seen some real good tips on this subject. I recall reading one post that had a real good summary of charging and hadling tips, and I cannot find it again. I thought there may be a sticky on it as well, but perhaps I missed it? So my thought was a thread that summarized just safe handling practices for these cells, my apologies if I've missed one that exists already. Here's my contribution to that subject that I don't recall seeing before:

    One tip in the forum is to not leave the room while you are charging Li Ion cells. Someone else mentioned doing it outside. Well outside may not work so well if you live in an apartment or in winter, but if you have a barbecue on your deck or balcony or back yard perhaps it could. Just run an extension cord over to the BBQ and charge it in there, close the lid if there is precipitation or curious ravens about. In summer, if you have a fireplace, you could place your charger in there as well and if the charger vents or catches on fire the smoke and toxic fumes go up the chimney.
    Last edited by Norm; 01-22-2013 at 06:54 PM.

  21. #81
    Flashaholic* LEDninja's Avatar
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    Default Re: Summary of 18650 charging and handling tips


  22. #82
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    Default Re: Using Li-ion cells in LED flashlights safely

    Yes that's the one. Thanks you very much for taking the time to get me pointed back to that. I must be pretty dense to have not noticed the give away forum title "Smoke and Fire, Hot Cells and Close Calls - The dangerous side of batteries"

    Sometimes I groan when I see people asking obvious questions that have been answered numerous times, now I'm one of them. I guess I better learn some humility from it then.

    My only thought now is as that thread was originated in 2008, would an updated version be warranted now?

    Thanks again.
    Last edited by Norm; 01-22-2013 at 06:54 PM. Reason: Update

  23. #83
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    Default Re: Using Li-ion cells in LED flashlights safely

    I have another question to clarify. I've noted that it is accepted that you should never use an unprotected 18650 cell in a 'multi cell' light. But I'm wondering if that actually means, 'a light that has cells in series'. If I read it right, the danger comes from cells in series going into a state of reverse polarity due to dichotomous internal resistance. However if you have a battery pack with 4 cells in parallel such as the optional Spark SX5 belt pack, is this multi cell warning still germane to this setup? Can cells in parallel still suffer the same fate at either the charge or discharge cycles?
    Last edited by Norm; 01-22-2013 at 06:55 PM.

  24. #84
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    Default Re: Using Li-ion cells in LED flashlights safely

    Parallel li-ion is a lot less things to deal with than series, you could get away without protection easier, as long as you know what you doing. It works out good.

    If it is "non-protected" the least is having a cut-off to keep it (all of them) from the deep discharge.
    Charging goes ok and is simple, with parellel li-ion (using the same proper charge methods). One huge parallel setup I use has just one mondo doubled up protection and fusing for the whole parellel setup, has worked for years, uses proper charging and non-operation cut-off.
    If there was any issues it comes when more of the cells are going bad, and the parallel array is still treated as if all the cells are there and working.

    Some scenarios to think out:
    if . . One cell item is bad, and the whole pack is getting a "Pack" charge, the bad cell is not fully charging, and taking on a lot of waste heat. If the charge rate was normal for one cell (takes forever to charge) then the heat buildup would be way lower. If the charge rate instead was 4X for the 4X batts, then one bad cell could end up with a very high charge rate hitting it, only because it is bad.
    When you parellel 4 cells in, and 4X a high charge rate TOO, then you would want to be more aware of any bad cell in the group. One bad cell can take a majority of the current going in, and end up very hot.

    If . . the whole group is going bad all at the same time, and they all are not "accepting charge" they will all heat up more uniformly. It took a lot of current to get a parellel set that was all bad to get hot. If the cells were originally matched in age and brand and type and mostly in capacity and all. And all the cells were used uniformly together (Parallel), there is a better chance that they will all be dying about the same way. And from the outside of the pack, what is happening would be easily observable.

    if . . All cells are bad , except one, and one is doing the work of 4. on discharge. that should be noticable in a lot of things, before someone charged it again.

    If . . any of the cells Popped, if that anode disconnect is "activated" due to a single pressure buildup, the cell that popped is no longer "in that curcuit", and what is left takes on the discharge and charge. Whatever that would mean to the way it is being used. If any of them pop, that could be from the cells being bad, or the charge or discharge rates or heat, or anything that caused it to build up that kind of internal pressure.

    Bad cell: referring to one that will not charge fully, does not finish charging using standard charging, does not "accept charge" as it should, and instead wastes the power going in, the wastes being internal heat in the cell. A cell that self discharges, and the voltage drops, the other paralelled cells will keep discharging into it.
    Popped: one that reads no voltage always, because the safety pressure thing disconnected the cell from its innards.

    parellel ni-?? charging not so simple.
    Last edited by VidPro; 01-22-2013 at 10:15 PM.

  25. #85
    Administrator Norm's Avatar
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    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by TSellers View Post
    My only thought now is as that thread was originated in 2008, would an updated version be warranted now?
    All the information in this thread is still relevant.

    Norm

  26. #86
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    Default Re: Using Li-ion cells in LED flashlights safely

    Thanks for the updates, good to know.

  27. #87
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    Default Re: Using Li-ion cells in LED flashlights safely

    I'm not an expert and cannot say the information in this excellent thread is still relevant. But I can say that the information is very useful.

    A lot of the noise in this thread is because people focused on the point that Li-ion cells can be dangerous. As clearly stated, the key word is can. and it is true.

    I also think it is important to emphasize the point that Li-ion cells don't have memory problems. I can put freshly charged cells (4.2 V) in my light and go play in the dark. When I come back, the cells are at 3.7 or something similar, and I can pop in them in a high quality charger (CC/CV) and charge them back to 4.2 V with minimal impact on their long term life. No need to get close to the edge (2.5 - 3.0).

    Treat your Li-ion cells with respect and they won't become terrorist cells.

  28. #88

    Default Re: Using Li-ion cells in LED flashlights safely

    I have stopped using loose cells based on LiCO for some time. I now use only LiFePO4 based batteries from K2Energy. I found there capacity to be very competitive to LiCO batteries & furthermore usable in more devices without issues. Forget using LiCO regulated batteries as even if the do work in devices that would not be compatible with LiCO otherwise the regulator contributes to the heat signature pushing the battery closer to the temperature limit of the battery itself. Run time tests I've done have shown the K2 Energy batteries to have greater capacity than all the regulated LiCO type RCR123 batteries I have tested. The LiFePO4 batteries do not contribute to the heat signature of the light as the regulated LiCO type batteries do. The battery compartment stays much cooler with the LiFePO4 batteries & the runtime was 50% higherwith the K2 energy LFP123 (RCR123) than all the regulated LiCO types I have tested. This is a battery that is at least somewhat abuse tolerant & suitable for most devices that take CR123 batteries

  29. #89
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    Default Re: Using Li-ion cells in LED flashlights safely

    germanium,

    I had a look at the K2Energy site, and some of your previous posts, it is apparent you are a crusader for this cause, which is fair enough. It seems difficult to determine how many people have been field testing the use of these cells and I'll do some more research. Is it correct for me to assume that there are 2 options for many LED devices, you could use either their 18650E which would give you 3.2v and 1500mah, and the other option may be to use 2 LFP123 cells in series, which would only give you 600mA but a bright light while it lasted? Would the only downside being the need to carry 8 cells and change them 4X more than the equivalent LiCo 18650 cell?

  30. #90

    Default Re: Using Li-ion cells in LED flashlights safely

    Quote Originally Posted by TSellers View Post
    germanium,

    I had a look at the K2Energy site, and some of your previous posts, it is apparent you are a crusader for this cause, which is fair enough. It seems difficult to determine how many people have been field testing the use of these cells and I'll do some more research. Is it correct for me to assume that there are 2 options for many LED devices, you could use either their 18650E which would give you 3.2v and 1500mah, and the other option may be to use 2 LFP123 cells in series, which would only give you 600mA but a bright light while it lasted? Would the only downside being the need to carry 8 cells and change them 4X more than the equivalent LiCo 18650 cell?
    An LFP18650 has only slightly less than triple the energy storage as the LFP123. Since you can use 2 of the LFP123 batteries in the place of 1 LFP18650 the 2 LFP123 batteries will last slightly more than 2/3rds as long as the LFP18650. On most LED flashlight there is a switch mode regulator & this regulator draws half the current when being fed twice the voltage so if the light draws 2 amps on the LFP18650 it will only draw 1 amp from the set of 2 LFP123 batteries. You would need about 6 LFP123 batteries to match the 2 LFP18650 batteries & would have to change them 3 times instead of 2.
    The reason I'm so impressed with the LFP123 batteries is that they seem to deliver the promise of 50% of the capacity of the nonrechargable counterpart where the LFP 18650 is not there yet. They are about 50% or less of the capacity of LiCO 18650 batteries.
    Last edited by germanium; 01-24-2013 at 06:03 PM.

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