Buttons & Flats

[snork]

When I started vaping it seemed all 18650 batteries were button top, regardless of brand. These days most are flat top.
What is the reason for this shift in configuration? I can speculate, but I'd rather hear from someone who might know rather than speculate. Personally I wish we had remained with button tops because they seem less prone to damage.
What say Ye?

 

[Barkuti]

As far as I know, button tops are a consumer market driven ignominy of sorts. They're added before the actual manufacturing of the cells, probably in some alternative “facility” where those sloppy high resistance stainless steel tops are added, usually connected with spot welded nickel strips.
My advice is: stay away from that clunky crap whenever possible.

Cheers
P.S.:

 

[snork]

As far as I know, button tops are a consumer market driven ignominy of sorts. They're added before the actual manufacturing of the cells, probably in some alternative “facility” where those sloppy high resistance stainless steel tops are added, usually connected with spot welded nickel strips.
My advice is: stay away from that clunky crap whenever possible.

Cheers

In my experience all batteries are clunky crap, but flat top positives dent even more easily than buttons.

 

[Barkuti]

In my experience all batteries are clunky crap, but flat top positives dent even more easily than buttons.

A tad biased PoV, fellow.
Just be a tad more careful with your inserting and removal gaming, and keep your contacts clean. Use one of those metal polish cleaning juices if needed.

Cheers

 

[snork]

A tad biased PoV, fellow.
Just be a tad more careful with your inserting and removal gaming, and keep your contacts clean. Use one of those metal polish cleaning juices if needed.

Cheers

Nah, it's more like dents occur when I drop stuff. I need to be more careful in different ways.
Any who, back to my original and now more specific question, what TECHNICAL reasons lead to the evolution from button tops to flat tops?

 

[MarkyD]

The only real difference is for the mechanical considerations of whatever equipment they're being used in. Several of my 18650 flashlights, as well as a few of my older tube mods take only button-tops. Similarly, in most recent box mods, the button tops simply wont fit. Of course many cells come in both button top and flat top flavors. Just because it has a button doesnt mean its a lower quality cell.

 

[MarkyD]

'Sup with the pic above, those arent button tops, these are...

 

[Barkuti]

... what TECHNICAL reasons lead to the evolution from button tops to flat tops?

In the ancient beginning of the cylindrical battery times, there were no button tops at all. The button top involution probably was a response to the needs of the consumer market, mainly because flat tops can't be stacked in series, I believe. Some cells may seem to be flat tops, yet actually be large button tops (see the pic I posted above). Certain flat tops from sub-top tier manufacturers may protrude a bit outwards, though generally this doesn't guarantees problem free in series stacking.
It's actually not hard to turn a flat top into a low resistance button top, but you may need a powerful soldering iron with a big tip (thermal inertia build-up), aggressive flux/fine grit sandpaper and preferably some low temperature solder (Bi58Sn42, Rose's metal, etc). And of course, a tad of skill. The positive end of the cylindrical batteries is generally a small hollow space, something which helps with the task of adding the (preferably generous) solder blob because it delays thermal transfer to the actual cell innards. You need to momentarily heat up the hollow top of the cell just enough to reach fused solder temperature, allowing the solder to pool as it is meant, and then quickly remove the heat source. I have not done this particularly, but it is a piece of cake.

Cheers
P.S.: MarkyD, that pic of yours shows sinned small button (sb) top 30Qs, these perform slightly worse than flat top 30Qs because of the sb added resistance. My pic shows large button (lb) top cells, and yes they a̶r̶e̶ were button tops. Don't try to mess with the actual flat top of a cell with your Dremel style tool... because something not good at all may happen.

 

[MarkyD]

Series stacking was likely a consideration for the use of button-tops, guess thats not an issue now for flat-tops because of the use of battery sleds. I have series-stacked flat-top 18350's in the past, but like you said their tops were slightly raised more so than on other cells. Perhaps factory tooling also plays into the widespread use of flat-tops, if they're cheaper or easier to produce and offer less resistance than buttons. I'll still continue to use the buttons as long as theyre being made, and I still have gear that needs them.

 

[DaveP]

Button tops date back to flashlights of the 20th century and later just because they needed spacing where a battery had to hit a center contact and not touch the outer ring of the bulb holder. Early ecig mods used similar contacts (think Provari) where button tops were needed. I still have some AW button top 18650's for my Provari V2.

I think most every other mod I own uses flat tops.