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Tough love for the industry's lithium addiction

Discussion in 'General Scuba Equipment Discussions' started by 2airishuman, Sep 4, 2019.

  1. 2airishuman

    2airishuman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Greater Minnesota
    Lithium ion batteries are the most dangerous battery chemistry in widespread use. They have resulted in numerous fires, some serious, and have been subject to recalls and to various restrictions on transportation. @Wookie has written in several threads that, while operating m/v Spree, he routinely threw lithium batteries overboard that were overheating, smoking, etc., because of the hazard posed to those aboard.

    Many have engaged in informed speculation that the loss of the m/v Conception, with considerable loss of life, could have been caused by a lithium battery fire.

    Lithium batteries aren't necessary for diving and could easily be entirely eliminated from the sport.

    How we got here

    Lithium batteries have the highest specific power capacity of any battery technology, with the common 18650 cells -- that weigh 50 grams -- capable of delivering as much as 80 watts for a few minutes. They also have the highest specific energy capacity, typically delivering around 10 watt-hours over the course of a discharge cycle. Most underwater lights and camera equipment use 18650 cells -- either individually, in removable packs, or as an integral part of the equipment.

    Li-ion batteries are used in high-end equipment not because they are necessary but because it is a competitive differentiator to have a device that is smaller and lighter, even when these differences have no effect on the convenience or usability of the device.

    Nickel-metal hydride

    NIckel-metal hydride (NiMH) batteries are much safer. The AA size is most common, and has almost exactly half the weight and volume of an 18650 cell. The best NiMH cells for photography (and diving), including Eneloop Pro and similar competing cells, deliver a maximum of 4.5 watts per cell, and can deliver 1.6 watt-hours per cell over the course of a fairly rapid 20 minute discharge cycle, and 2.5 watt-hours if discharged over the course of two hours.

    If you do a little math, you can see that, for comparable size and weight, lithium batteries deliver 2-3 times the amount of energy and around 10 times the amount of power, compared to NiMH. Before the hazards posed by lithium batteries were well understood, this seemed like an easy tradeoff. The only real drawback was cost, and dive gear is expensive enough that the battery cost isn't much of a factor.

    For products that are designed to operate for 30 minutes or more on a charge, the energy limit determines how many batteries are needed to meet the needs of a particular device and application. Nearly all diving gear falls into this category, since equipment is expected to function for the typical 50 minute duration of a dive.

    NiMH as a good-enough alternative

    For most diving applications, NiMH batteries are good enough.

    For this discussion, keep in mind that rechargeable batteries can be combined into packs for ease of handling when more than a few cells are required.

    A typical handheld dive light uses one 18650 cell and weighs about 200 grams. A well designed alternative using four AA NiMH cells would have similar performance. The weight of the extra batteries would add 50 grams. The change in bulk would be insignificant.

    The largest handheld dive lights (billed as "handheld primary lights") use four 18650 cells. With careful design, NiMH batteries could still be accommodated without having to resort to a canister design.

    The only SCUBA product where the energy density requirement is so compelling that lithium-ion batteries are the only practicable solution is scooters.

    Other benefits of NiMH

    NiMH batteries offer practical benefits insofar as there are no restrictions on transporting them. There are long-life versions available that will last ten years or more even with regular use.

    Withering defenses of Li-ion

    Many of the problems with lithium batteries can be traced to poor quality control at the time the batteries were manufactured. Some can be traced to poorly designed charging and utilization circuits. Some are caused by impact or other damage to the battery. They are fragile, dropping them on a concrete floor from waist height can cause latent damage.

    So there are going to be people who say that if you use high quality batteries and are nice to them, everything will be OK.

    And for people who believe that, I'm going to say that there are some really smart people at Samsung and Apple and other high-end electronics manufacturers that work in huge volumes, and they couldn't figure it out. Are you smarter than they are? Do you know your supply chain better than they do?

    Tough love

    Got lithium? Get rid of it. Don't buy any more.

    Use lights that operate on AA cells and use NiMH cells in them. When shopping, reviewing, etc., insist that vendors use the safest technology. You wouldn't buy a regulator that weighs less if it were less safe, so why would you buy a dive light that weighs less but is less safe?

    Got a dive boat? Don't allow lithium batteries on it. Period. There are alternatives.

    Got a dive shop? You get the picture....
  2. Jay

    Jay Need to dive more!

    # of Dives: 100 - 199
    Location: Melbourne, OZ.
  3. Ministryofgiraffes

    Ministryofgiraffes Loggerhead Turtle

    # of Dives: 1,000 - 2,499
    Location: Toronto
    I would like to get rid of lithium batteries, are you saying I can/could run 2x 15,000 lumens videolights on non-lithium? For 45 mins on full or 2+ hrs on 50%? I’m seriously asking..
    rjack321 likes this.
  4. runsongas

    runsongas Great White

    # of Dives: 500 - 999
    Location: California - Bay Area
    this is an over-reaction. newer IMR/INR batteries are not as reactive as the ICR batteries. And even if IMR/INR ultimately still aren't safe enough, IFR (LiFePO4) is another option before we go back to NiMH
    rjack321, kelemvor, KWS and 3 others like this.
  5. Brian G

    Brian G Barracuda

    # of Dives: 100 - 199
    Location: Pittsburgh
    Billions of lithium batteries are used and charged every day. All cell phones and laptops use them (I can't think of any exceptions). If you want to feel safer, charge them in a metal box like the rc folks used to. We still use propane, gasoline, and diesel on boats, so I can't imagine that lithium is so much more dangerous that it can't be managed.

    On the other hand, nimh is perfectly good technology too. It can start a fire if shorted as well, but the battery itself doesn't burn like a lithium. I don't know of a way to get an alkaline battery to start a fire unless you are being deliberate about it.
  6. 1isNone

    1isNone Solo Diver

    # of Dives: 0 - 24
    Location: 12' above the fun stuff

    Good golly, I must have missed the report that was issued. Can't believe it's out already! Do you have a link to the official findings?
  7. Wookie

    Wookie Secret Field Agent ScubaBoard Business Sponsor

    Are you being kind, or nice? I can’t tell which?
    Cali_diver, Pweintz and RainPilot like this.
  8. cerich

    cerich ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 5,000 - ∞
    Location: Georgia
    A decade ago when doing some canister lights for my last gig, I choose to do ni cad as they were safer for application and the size increase to get same burn time as lithium was nothing in actual use than anyone would notice. They sold like crap because everyone was on the lithium bandwagon.

    Here we are a decade later and the large capacity lithium can, video lights etc are much cheaper, especially Chinese ones and frankly the quality is all over the place in an alarming way. Not just the poor quality cells, construction of packs but also amazingly cheap chargers that put fast over sane safety.

    I recently switched my own video lights to lights that use single cells that I charge individually over the packs on a slow and smart charger. I still don't charge them unattended but sure feel better as I know what quality individual batteries
    drbill, Texas Torpedo and 2airishuman like this.
  9. 2airishuman

    2airishuman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Greater Minnesota
    Not the lights you have now. They would have to be designed for it.
  10. 2airishuman

    2airishuman ScubaBoard Supporter ScubaBoard Supporter

    # of Dives: 100 - 199
    Location: Greater Minnesota
    Show me a USCG inspected vessel that has any of these things in any passenger compartment and we'll continue the conversation.
    markmud likes this.

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