I just posted a lengthy reply in the njoy King megathread on this specific topic. I figure it's relevant here so I'll copy what I said in the other thread:
"So many many pages back in this thread I had suggested the design that njoy could use in order to make the Kings rechargeable, with replaceable cartos, basically turning it into a standard cigalike rechargeable unit.
BUT, with some specific goals:
Must not change the outward appearance of the unit
Must keep additional weight to an absolute minimum
The design should be simple and inexpensive to produce
I'm not sure how specific I got in that post, but I know I wasn't as specific as I'd like. So I drew a picture. I would have mocked this up in AutoCad but I wiped it during a reformat of my hard drive, and lost the CD, so I had to use MS Paint. Don't judge me
View attachment 176253
As you can see it's a two piece design. The pic is sort of large, open it in another window and zoom in if you can't see the details. The current materials of the King (soft plastic tube) would still be used. There is very little metal, only two small pieces of metal would be on the carto, and two on the battery. These would be about the thickness of an aluminum soda can, friction fit into a slot in the carto, then bend out and laid flat against the side of the carto's male end.
The battery's female connection would just be the tube, with the same metal contacts laying flat against the inside. When you insert the carto, make sure the contacts are lined up and then just push the carto into the battery. The metal contacts will meet up completing the circuit, as well as acting as springs to keep tension on the joint between the carto and battery. Polarity will not matter as the only thing in the carto is a coil, which doesn't care which way current is flowing.
As you can see this is a very cheap, easy, lightweight method to turn the King into a rechargeable unit. I can't imagine this adding more than a few cents to the total cost of each unit. Replacement cartos could be sold instead of an entire new King. Say, a buck a piece, even if you go through a few a day that isn't much money at all.
Even at $1.50 ea. I think Njoy could still make a good profit and customers would be happy. Standard cartos, with metal tubes, metal 510 connections, sometimes punched holes or flanges sell (on the low end) for that price or lower, so I see no reason why making the carto out of much cheaper materials, with a less complex design requiring fewer tools and machines wouldn't result in a carto with a retail price that is lower than what we are used to seeing for regular cartos.
Is it as strong, reliable, and long lasting as a traditional connection with metal bits and threading? No. But that's the idea. The King is supposed to be light, small, and ideally would be cheap. This design would make the King more of a semi-disposable, as the batteries can be recharged, and new cartos purchased, but the overall construction and cost means that it's no biggie if you battery dies, or you break the connection, or something stops working. Just buy a new unit, they are dirt cheap.
What do you guys think? Do you like the idea of it being a two piece rechargeable, or would you prefer the King exactly as it is right now, just cheaper? Any major flaws with the design? Any better design you can think of? Let me know! (And if anyone at NJoy sees this post, please realize I just did all the thinking and figuring for you, so please, take advantage, produce a product that people would really, really, really like, and be a bit more fair to your customers that want to use your product, yet you refuse to release a reasonable setup)"
"So many many pages back in this thread I had suggested the design that njoy could use in order to make the Kings rechargeable, with replaceable cartos, basically turning it into a standard cigalike rechargeable unit.
BUT, with some specific goals:
Must not change the outward appearance of the unit
Must keep additional weight to an absolute minimum
The design should be simple and inexpensive to produce
I'm not sure how specific I got in that post, but I know I wasn't as specific as I'd like. So I drew a picture. I would have mocked this up in AutoCad but I wiped it during a reformat of my hard drive, and lost the CD, so I had to use MS Paint. Don't judge me
View attachment 176253
As you can see it's a two piece design. The pic is sort of large, open it in another window and zoom in if you can't see the details. The current materials of the King (soft plastic tube) would still be used. There is very little metal, only two small pieces of metal would be on the carto, and two on the battery. These would be about the thickness of an aluminum soda can, friction fit into a slot in the carto, then bend out and laid flat against the side of the carto's male end.
The battery's female connection would just be the tube, with the same metal contacts laying flat against the inside. When you insert the carto, make sure the contacts are lined up and then just push the carto into the battery. The metal contacts will meet up completing the circuit, as well as acting as springs to keep tension on the joint between the carto and battery. Polarity will not matter as the only thing in the carto is a coil, which doesn't care which way current is flowing.
As you can see this is a very cheap, easy, lightweight method to turn the King into a rechargeable unit. I can't imagine this adding more than a few cents to the total cost of each unit. Replacement cartos could be sold instead of an entire new King. Say, a buck a piece, even if you go through a few a day that isn't much money at all.
Even at $1.50 ea. I think Njoy could still make a good profit and customers would be happy. Standard cartos, with metal tubes, metal 510 connections, sometimes punched holes or flanges sell (on the low end) for that price or lower, so I see no reason why making the carto out of much cheaper materials, with a less complex design requiring fewer tools and machines wouldn't result in a carto with a retail price that is lower than what we are used to seeing for regular cartos.
Is it as strong, reliable, and long lasting as a traditional connection with metal bits and threading? No. But that's the idea. The King is supposed to be light, small, and ideally would be cheap. This design would make the King more of a semi-disposable, as the batteries can be recharged, and new cartos purchased, but the overall construction and cost means that it's no biggie if you battery dies, or you break the connection, or something stops working. Just buy a new unit, they are dirt cheap.
What do you guys think? Do you like the idea of it being a two piece rechargeable, or would you prefer the King exactly as it is right now, just cheaper? Any major flaws with the design? Any better design you can think of? Let me know! (And if anyone at NJoy sees this post, please realize I just did all the thinking and figuring for you, so please, take advantage, produce a product that people would really, really, really like, and be a bit more fair to your customers that want to use your product, yet you refuse to release a reasonable setup)"