Conversation
Martijn Braam
martijnbraam@fosstodon.org
None of my 18650s are actually 65mm long. The longest 18650 I've found in my battery box is 70mm long even..
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Pavel Machek
pavel
@martijnbraam I have even seen them advertised as "18650, 19mm wide, 7cm long". My headlight (Zebralight) expects right size and I have trouble getting cells that fit :-(.
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Martijn Braam
martijnbraam@fosstodon.org@pavel I have a power bank that takes 18650 cells but you specifically need flat-top ones to make them fit. a properly sized 18650 with button top is already too big
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Pavel Machek
pavel
@martijnbraam Zebralight has a bit more tolerance -- even some protected cells fit -- but newer cells tend to be protected and too big. And sellers don't advertise size :-(
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Martijn Braam
martijnbraam@fosstodon.org@pavel sellers should start making 18600 protected cells to deal with this or something :D
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Pavel Machek
pavel
@martijnbraam So actually Zebralight seems to like unprotected cells. It has protection, and two protections tend to interfere with each other in bad ways. When I'm in the middle of woods somewhere, I _need_ light, and unprotected cell can power 0.1lm output pretty much forever. OTOH in subzero temperatures you can easily trigger protection on nearly full cell with 700lm attempt, and you are in dark, with no way to recover.
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Martijn Braam
martijnbraam@fosstodon.org@pavel That actually makes a lot of sense for a light. On my boards I generally also add a protection chip for the cells because you never know what will actually be attached.
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Pavel Machek
pavel
@martijnbraam Well, at least protection in the light can be reset by reinserting the cell. But if you trip the cell protection, its dark. It is same mistake as adding over-g protection to fighter plane: you protect the hardware, but endanger the human.
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