i'm a big noob so if theres flaws in this plan please tell me.
i'm planning a safety cap for my unprotected 18650
Li-Ions.
Attaching a so called protection board to the end add as much danger as it prevents. the board is asking to get broken if used in a flashlight its bound to happen..
needs a crush proof shell.
they must never be shorted or recieve a reverse current
so i'm planning a fuse and a high capacity diode soldered to
+ and tucked into a pvc plumbing cap to be epoxy'd onto the cell to stay.
the diode will prevent reverse current and act as a CUTOFF to prevent depletion past the cell and safety limits so it needs to appropriately rated.
the fuse will prevent dead short and excessive drain rate
but will kill the unit if the cap cannot be removed so big fuse will be protected by smaller fuse outside the cap. now you may repair YOUR DEAD SHORT BOOBOO.
also inside the cap will be a wire for charging tied to the diode before comes out of the cap. it will be a like a cordless phone wire with a tiny connector that is keyed or shaped to prevent reverse connection or improper insertion. a waterproff connector mounted under the cap would be ideal but not enough room for that i fear..
the cap cannot block vents under the + button so will near equal the cell diameter butted to the outer rim and attached with something like fuel tank repair epoxy "clay" .
the cap will have holes equal or exceeding the vent holes
under +. the holes will be wax sealed
these are only partial Li-Ion precautions but very important ones that everyone should consider before tinkering with these. the rest can be handled by the charger and/or a protection pcb outside the light or device.
am i missing any important dangers in this plan?
i'm planning a safety cap for my unprotected 18650
Li-Ions.
Attaching a so called protection board to the end add as much danger as it prevents. the board is asking to get broken if used in a flashlight its bound to happen..
needs a crush proof shell.
they must never be shorted or recieve a reverse current
so i'm planning a fuse and a high capacity diode soldered to
+ and tucked into a pvc plumbing cap to be epoxy'd onto the cell to stay.
the diode will prevent reverse current and act as a CUTOFF to prevent depletion past the cell and safety limits so it needs to appropriately rated.
the fuse will prevent dead short and excessive drain rate
but will kill the unit if the cap cannot be removed so big fuse will be protected by smaller fuse outside the cap. now you may repair YOUR DEAD SHORT BOOBOO.
also inside the cap will be a wire for charging tied to the diode before comes out of the cap. it will be a like a cordless phone wire with a tiny connector that is keyed or shaped to prevent reverse connection or improper insertion. a waterproff connector mounted under the cap would be ideal but not enough room for that i fear..
the cap cannot block vents under the + button so will near equal the cell diameter butted to the outer rim and attached with something like fuel tank repair epoxy "clay" .
the cap will have holes equal or exceeding the vent holes
under +. the holes will be wax sealed
these are only partial Li-Ion precautions but very important ones that everyone should consider before tinkering with these. the rest can be handled by the charger and/or a protection pcb outside the light or device.
am i missing any important dangers in this plan?
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