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18650 Protected Or Unprotected For Scubapro Nova Light 720r

Discussion in 'Lights' started by erbedo, Mar 17, 2016.

  1. tbone1004

    tbone1004 ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: I'm a Fish!
    Location: Greenville, South Carolina, United States
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    the nitecore is no slower with 4 batteries than the xtars. The VC4 is still .5a*4, though if you're charging two, you do get 1a charging which is nice
     
  2. Alastor

    Alastor Liveaboard

    # of Dives: 200 - 499
    Location: Italy
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    Technoline BC 700 - german charger. amazon sells it and is able to charge a large number of format at the same time.
     
  3. eelnoraa

    eelnoraa DIR Practitioner

    # of Dives: 100 - 199
    Location: San Francisco Bay Area
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    Depends on which Xtar. I have SP2, 2 channel charger, will charge up to 2A each channel. If 2 channel is what you need, there is no reason to get NiteCore. If you need 4 channel, it is tough to get 2A capability without paying a lot, but 1A capability options are out there. I still think 0.5A is too slow. Personally, if I need to charge 4 18650, I will take 2 SP2 over 1 D4 even if this cost more
     
  4. eelnoraa

    eelnoraa DIR Practitioner

    # of Dives: 100 - 199
    Location: San Francisco Bay Area
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    This one does NOT do Li-ON cell. So don't use it for 18650
     
  5. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
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    What the "protection" does is limit the over and over discharge. A decent charger deals with overcharge. Ideally the user limits over discharge. Over discharge only 'ruins' the cell, it will not explode, the energy is all gone. That happens with overcharge.

    Technoline BC 700 is the same as La Crosse BC-700 and Accupower IQ-128, which are NiXX only.
     
  6. eelnoraa

    eelnoraa DIR Practitioner

    # of Dives: 100 - 199
    Location: San Francisco Bay Area
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    Not so accurate. Over discharged by very smaller current, such as internal leakage, then the cell will just die. If you over discharge the Li-ON cell by draw large current, like when the cell reach ~2.8V or so, you still try to draw 1A, the cell will heat up and cause leakage or explosion. In fact, over discharge is much more dangerous than overcharge in practical scenario
     
  7. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
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    The original question had to do with a light that is pulling maybe 1A. We are not talking about a Vape unit pulling LOTS and LOTS of amps hopefully with a battery that is not crap. By over discharge I meant in the more usual sense of it, not in the worst case scenario. Protection circuits definitely have their limitations. I don't use any at all, but that's me and I've been dealing with batteries for a good while.
    Some protection circuits are fine, some aren't much better than having nothing at all. This is the unfortunate result of open world trade and most of the battery sourcing having moved to Asia.

    The 'average' user just needs to buy a decent battery, a better charger, know a few rules, and get on with their life. It's unlikely they are going to do much more anyway.
     
    Last edited: Mar 17, 2016
  8. miketsp

    miketsp Solo Diver

    # of Dives: 500 - 999
    Location: São Paulo, Brazil
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    Quite frankly the protection circuit in a dive light is a bit meaningless. The highest probability failure scenario is a leak. Once salt water wets the circuit it will no longer offer any protection whatsoever. I have a couple of larger cells 26650 where the circuits became wet and corroded, I tore them off the batteries and the batteries were still good to go. The dive lights in question are still basically ok many dives later (after thorough cleaning and a rebuild with new o-rings and lubrification) although the reflectors have some stains.
     
  9. fmerkel

    fmerkel Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Salish Sea (Seattle)
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    True that. When the light starts to dim > turn it off.
    OTOH, people are pretty used to alkaline and NiMh and may not notice a light getting dim until it's about dead and not realize the consequences. Over discharge chemically changes lithium ion cells and they may become more unstable some sources claim.
    Lithium Battery Failures
     
    Last edited: Mar 18, 2016
  10. Hatul

    Hatul Solo Diver

    # of Dives: 500 - 999
    Location: Tustin, California, United States
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    Some recommend unprotected for backup light, because a protected battery will suddenly just cut out when the voltage drops below a threshold. Personally I use protected cells and just take an extra backup light when night diving.
     

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