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  1. #1
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    Do I realy need protected batteries?

    My torch has low voltage warning and shutdown.

    I'm using a "smart" charger. (Nightcore Intellicharge i4 v2)

    Do I really need protected batteries?

  2. #2
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    Yes. For example, if you short the terminals inadvertently the current could go to dangerous levels. The protection circuit would shut this down. This is true for either direction - discharge or charge.

    The problem with Li-ion batteries is they are exceedingly flammable. The can overheat with too high a charging current or too high of a discharging current.

    Here's the TI datasheet for their protection circuit.

    http://www.ti.com/lit/ds/snos902/snos902.pdf

    J.

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    Posting it twice is a good way to drive home the point!

  4. #4
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    Quote Originally Posted by Ian_C View Post
    My torch has low voltage warning and shutdown.

    I'm using a "smart" charger. (Nightcore Intellicharge i4 v2)

    Do I really need protected batteries?
    I suppose it's an individual choice. The only danger I see is if the driver in the torch somehow shorts out. Such a thing is rare but stuff can happen. That said I will probably buy a couple of the new Panasonic 3400 ( unprotected ) cells next year at the start of the riding season with the intention of using them in my bike torches. I will only use them for bike rides and watch to make sure I do not overly discharge them. The torch I use for work will continue to get the protected batteries as it often goes for a long time before I decide to charge it.

    There is a big difference in price when it comes to protected vs. unprotected for the better Panasonic cells. If you're just going to buy the run-of- the-mill cheap Chinese 18650's than by all means, buy the protected. Not a big price difference in those.

    If you know how to properly handle Li-ion cells there should be no big problem. I've used 18650 cells for years ( in torches ) and have yet to have one cut out while using them. That being the case I am going to give the nice unprotected Panasonics a try and see how it goes.

  5. #5
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    Quote Originally Posted by Cat-man-do View Post
    I suppose it's an individual choice. The only danger I see is if the driver in the torch somehow shorts out. Such a thing is rare but stuff can happen. That said I will probably buy a couple of the new Panasonic 3400 ( unprotected ) cells next year at the start of the riding season with the intention of using them in my bike torches. I will only use them for bike rides and watch to make sure I do not overly discharge them. The torch I use for work will continue to get the protected batteries as it often goes for a long time before I decide to charge it.

    There is a big difference in price when it comes to protected vs. unprotected for the better Panasonic cells. If you're just going to buy the run-of- the-mill cheap Chinese 18650's than by all means, buy the protected. Not a big price difference in those.

    If you know how to properly handle Li-ion cells there should be no big problem. I've used 18650 cells for years ( in torches ) and have yet to have one cut out while using them. That being the case I am going to give the nice unprotected Panasonics a try and see how it goes.
    Not quite true. The danger is when the current gets out of spec during charging or discharging. Either one of those is likely not an issue of "proper handling". For example, if the charger fails, the idea is that the cell then has a failsafe capability so that the battery doesn't explode or burst into flame.

    The problem is that while Li-ion are so attractive for their power density/weight they are really pretty dangerous - more so than other chemistries - when things get out of hand.

    This is one of those "don't try this at home" sort of things for most people.

    J.

  6. #6
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    I dunno John, the few cases of li-ion cell explosions that I've read about (on BLF and CPF) have been with protected cells and result from using crappy/ crazy chargers. If the PCB is a decent one (and that's a big if with any but the highest quality cells) then it might stop that from happening, but I'd rather get a better charger

    A short in a light with a single li-ion cell is going to dump at most 6A (if that's an exceptionally good cell) which will quite quickly burn that short out and won't, of itself, cause any harm to the cell. Parallel set ups are a bit different, but the point is that most, if not all, li-ion explosions happen while charging.

    I'm still umming and ahhing about whether or not to put a PCB in my next pack (2S1P). I've built stacks of packs with unprotected Panasonic cells, but then I use taskled drivers (excellent voltage warnings) and a quality hobby charger. The only lights I've used PCBs in have been those with simple AMC7135 drivers where I'm less sure of the voltage cut out levels and also use USB charger boards.

    So, Ian, personally I think you'll be fine, just buy quality cells and pay attention to the light so you can swap out cells when it starts dimming. Also, charger your cells in a li-po sack or a bucket of sand in a covered outdoor space. It's cheap, it's easy and it'll save your bacon if something ever does happen

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    Quote Originally Posted by mattthemuppet View Post
    I dunno John, the few cases of li-ion cell explosions that I've read about (on BLF and CPF) have been with protected cells and result from using crappy/ crazy chargers. If the PCB is a decent one (and that's a big if with any but the highest quality cells) then it might stop that from happening, but I'd rather get a better charger

    A short in a light with a single li-ion cell is going to dump at most 6A (if that's an exceptionally good cell) which will quite quickly burn that short out and won't, of itself, cause any harm to the cell. Parallel set ups are a bit different, but the point is that most, if not all, li-ion explosions happen while charging.

    I'm still umming and ahhing about whether or not to put a PCB in my next pack (2S1P). I've built stacks of packs with unprotected Panasonic cells, but then I use taskled drivers (excellent voltage warnings) and a quality hobby charger. The only lights I've used PCBs in have been those with simple AMC7135 drivers where I'm less sure of the voltage cut out levels and also use USB charger boards.

    So, Ian, personally I think you'll be fine, just buy quality cells and pay attention to the light so you can swap out cells when it starts dimming. Also, charger your cells in a li-po sack or a bucket of sand in a covered outdoor space. It's cheap, it's easy and it'll save your bacon if something ever does happen
    Ok then.

    J.

  8. #8
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    well, it's not like I'm making them out to be fluffy large eyed kittens that'll never hurt you even if you pull all the hair out of their butts with a pair of tweezers now is it?

    they're incredibly dense stores of energy, treat 'em with the respect you'd treat a flux capacitor or something like that

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    highly flammable and explosive "incredibly dense stores of energy". That's all.

    J.

  10. #10
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    Quote Originally Posted by JohnJ80 View Post
    Not quite true. The danger is when the current gets out of spec during charging or discharging. Either one of those is likely not an issue of "proper handling". For example, if the charger fails, the idea is that the cell then has a failsafe capability so that the battery doesn't explode or burst into flame.

    The problem is that while Li-ion are so attractive for their power density/weight they are really pretty dangerous - more so than other chemistries - when things get out of hand.

    This is one of those "don't try this at home" sort of things for most people.

    J.
    John, I think you took my comment out of context. When I spoke of "proper handling" I was referring to actually using the battery in the torch ( and not over-discharging the cell while in use ).

    I'm not disagreeing with what you said about charging the cells. There are crap chargers out there. If the charger fails I think the major issue would be with the charger itself burning out and perhaps causing a fire. Whither this could cause a runaway current condition on the cells in the charger I would have to think it unlikely ( but not impossible ) Chances are that the charging output current would drop to zero when the charging circuits burn out. Of course the issue is moot if the cells are sitting right over ( or next to ) the charging circuits that are about to melt down. In that situation I don't think it will matter if the cells are protected or unprotected. If a protected battery is exposed to fire the the PCB's on the cells will likely fail as well.

    I've had a cheap charger go up before so I know they can fail. I suppose if someone were really worried about the batteries ( while on the charger ) you could buy the chargers with the charging circuits built into a separate wall plug which then connects to the battery ( cell ) holder via a separate wire. With a little DIY you could easily splice in a fuse to protect the cells from runaway current. With a better charger this shouldn't be a worry though.

  11. #11
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    Quote Originally Posted by JohnJ80 View Post
    highly flammable and explosive "incredibly dense stores of energy". That's all.

    J.
    hence the precautions..

  12. #12
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    Wouldn't it just be better to use a simple protection circuit?

    J.

  13. #13
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    Quote Originally Posted by JohnJ80 View Post
    Wouldn't it just be better to use a simple protection circuit?

    J.
    (smacks forehead) didn't I already point out that batteries with PCBs can still blow up? I'm sure that you're not being that obtuse.

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    (smacks forehead) Why didn't I think of that? Charging in a fireproof environment!

    It's a LOT less likely to happen with a protection circuit.

    J.

  15. #15
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    ah feck this, another argument with some stubborn git on the internet. Sign me out from offering advice in the future.

    Ian_C - get cells with PCBs and charge them with whatever you like, the battery from your car if you wish, perhaps even sitting in a small pool of gasoline, because the PCBs are completely failure proof.

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    Let me help you with english. "Less likely" means:

    likely = such as well might happen or be true; probable:

    less |les| = a smaller amount of; not as much:

    "less likely" means "less probable."

    So what's the point of having a protection circuit if they don't do anything? And, no, nothing is 100% fail safe.

    J.

  17. #17
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    Quote Originally Posted by JohnJ80 View Post
    ....So what's the point of having a protection circuit if they don't do anything? And, no, nothing is 100% fail safe.

    J.
    ...as I see it, the primary purpose of the protection circuit is to protect the battery from being overly discharged when used in single cell applications. Now if you have enough experience with Li-ion battery usage then you should know that when the light output on your single cell lamp starts to get very dim it is time to switch out the battery. For most people this would be a no-brainer but there are always knuckle-heads out there who would just completely run the cell all the way down thus damaging the cell. The protection circuit helps eliminate the guess work if you lose track of how much charge is on the cell. On the best Panasonic cells the PCB ( printed circuit board ) might cost another $4 to $5 per cell. If you're the forgetful type person, get the protected cells. If you charge your cells before every ride then you might not need the protection.

    I've often wondered why no one has ever designed a torch with a PCB built into the switch housing.

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