using multiple 1S packs...

[turbocad6]

ok so I'm looking to build a bottom feeder reo style mod with the dna200 and battery space is a big deal.need to keep it as compact as possible while still housing a 9ml bottle of juice, anything I do with those 950- 1,000 packs out there most are using is going to wind up being a big fat mod. don't want that, so I'm using smaller individual cells. first one I'm doing is 3X 600mah 35C. I'll probably limit this one to 150 watts or so


now I'm thinking that I should be able to just wire up the 3 cells as a 3s pack is wired and connect up the balancing leads. I realize that ideally the cells should be as matched as practical to be balanced, but using brand new cells I don't think it should be too much of a problem? should I bother putting more effort into cell matching? should I charge and discharge and recharge each cell individually before stringing them together?  I'm thinking they'll just balance out once connected together anyway. what about some module thing I've heard is needed when 3 18650's are used, why wouldn't they also work by just wiring them up as a 3S pack is wired? what is this add on module?

ok now second part of the question is, what about using 6 individual cells? I mean using 3 pairs of cells that are parallel pairs then wired in series and tapped for the balancing leads, would charge as 3 pairs and each pair would naturally be balanced to each other. would this be fine to do? 

[VapingBad]

It is still important to have them matching as they will all share the same discharge current it will shut off once the smallest cell hits the soft limit and would they need more balancing during charging.  You can use 6 cells in 3s2p config as you describe.  There are batteries as thin as 18 mm out there and I would think it is not worth the effort.  The wire between the cell needs to be rated 23 A or more the same as the main battery leads os it is going to take up some space if the cells are not stacked like in a battery pack.

[turbocad6]

thanks vapingbad... yeah I've looked at all the pre configured packs I can and they're all just not ideal for what I have in mind. I do realize that they need to be somewhat matching but I guess my main concern is, would just using brand new cells that are hopefully from the same batch be good enough or should I buy a whole bunch of cells and then buy a good battery tester to try and match them closer? I'm thinking just using new cells from the same batch should be good enough but then again truth is even ordering all of them at the same time is no guarantee that the cells will all be from the same batch anyway.

also, as far as cells "puffing", how much extra room is required to allow for this? I was thinking of adding 10% extra space for clearances, would that be enough? should I almost "expect" the lipos to puff after a bit or is this not so common really? I can almost see my wooden mod cracking open like a walnut when they puff up as much as some of the pics I've been seeing of puffed up lipos is this only something to worry about when cells are abused or should I be concerned about this even when staying within operating specs? 

[Warben]

Hi there. I've got some info regarding how balance connectors work. So thinking of an idea to diy some battery sleds based on 18650 batteries in three pieces.
The link to the info:

http://www.tjinguytech.com/charging-how-tos/balance-connectors

So is it possible to do away with the jst connectors instead and direct solder battery balancing wire to the board?

[Brandon]

Yes, the JST-XH connector ships detached from the board for that reason.