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Comment by digikata | Hacker News Reader

It's a shame that so many products default to built in, non-replaceable LiIons now. For many products, it's nicer to have a replaceable rechargeable so you can pop in charged battery and go instead of having to plan for state of charge of yet another device.

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I suspect building them is in an environmental benefit in a lot of cases, a lot of people just buy huge packs of alkaline disposables and can't be bothered with rechargeables unless they're built in. I'd be interested to see the statistics but I wouldn't be surprised if 80% of people use disposable batteries given the opportunity.

I just don't get why replaceable standard-sized lithium ion batteries have pretty much completely failed to take off other than those 18650 flashlights and vape pens.

The proprietary replaceable batteries are an improvement over non-replaceable but in anything other than cameras the replacements seem to get discontinued by the manufacturer by the time you actually need one.

The problem with bare 18650 cells is in their chemistry. A bad charger + good cell = nasty fire and a good charger + bad cell = the same. Considering the fact that every major online retailer including Amazon has trouble policing fake cells, the liability risks are fairly extreme. If there was a way to completely block all non-UL rated products as well as those with fake UL stickers, I'd say your idea has merit. Unfortunately, the near frictionless world of online markets allows for too much counterfeit risk to enter the picture for such an idea to be workable.

I’m building a solution: integrated bike lights on my bike (various strips, etc.), with a 3S 18650 battery holder that’s supposed to let me run nearly unlimited amperage (but with protection).

I’ll probably just recharge over USB, but I could swap the cells if on a longer trip.

The plan might include a motorcycle horn.

It will be nice to have hard-mounted lights and 1 central battery that I can stow-and-go at any time, rather the attaching and detaching everything to avoid theft.

Li-ion cells provides 3.6V, which makes them incompatible with traditional alkaline or NiMH. I don't think we've invented a standard for Li-ion batteries yet.

One concern about lithium cells is safety. Shorting alkaline cells won't do much, and even nimhs are relatively benign, but lithiums can start fires or explode when mishandled. Shipping lithum cells is for that reason bit of a hurdle too.

I think that's why the raw cells aren't used as the level of swappable unit very often. If the battery is at all removable, they're often integrated into packs which have some level of built-in protection.

E-cigs and Teslas, that is.

Aren’t Teslas running on 21700?

Only the Model 3. Model S and X are still using something close to 18650 (although I haven't followed Tesla's batteries for the last 8 to 9 months).

Probably true, but if the LiIon batterypacks/modules were required to be replaceable, that would keep that benefit while reducing the waste of lights that are thrown away after the LiIon battery degrades.

Though I'm not sure how much of a factor that is - I don't know how often lights are discarded because the battery life because too short versus lights are discarded because someone wanted a newer/smaller/brighter light.

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