18650 Battery cell weld-free connectors?

[scoot-e]

Having contacted several Chinese distributors of 18650 batteries (many from the "recommended lists" posted in various areas on this forum) they are either exhorbitantly expensive to buy AND ship to California a complete welded pack w/bms or the loose cells without tabs are very reasonably priced but one has to either acquire the spot welding and metalworking skills to make their own pack. So...I was wondering if there were a weld-free option that is readily available and/or that others are using with any regularity that doesn't cost an arm and a leg? I know some in the forum have made rather complex copper or nickel strips with buttons punched into them but the combination and wiring still seems rather involved and not quite the plug and play option I was looking for that allows for removal of cells (if one were to have an issue possibly) as well as allow for many combinations of cells in series or parallel:

Found this:

http://www.dx.com/p/3-7v-1-x-18650-battery-holder-case-box-with-leads-100999#.U_Df-0hIPog

Is it possible to simply use the following spring and clip style battery holders (similar to the AA style battery holders in flashlights and other toys) for 18650 battery cells in a 12s5p configuration (for say, a 2.0ah 18650 cell of LG, Samsung, Panasonic etc) to get a 44.4v nominal and 10ah pack or are the included wires and spring/clips too flimsy/narrow gauge to support the amp draw, say, of an e-bike pulling 30-35amps without burning up or melting the wiring/clips?

Also, if one were to re-solder thicker gauge wiring but use the existing springs/clips in the battery holders shown, would that be able to handle the current and voltage? What are the issues surrounding using these kinds of snap together weld-free holders besides possible vibration/loose spring and tab connections, specifically surrounding the wiring and current handling abilities?

Thanks!

Dan

 

[jonescg]

I believe the problem is the 'springiness' of the springs is compromised under high current discharge. High currents being more than about 2 amps per cell. So perhaps t's OK for low powered ebikes, but for anything over about 350 W you might find some loose connections before too long.

 

[scoot-e]

That makes sense that the spring coils, which are thinner metal wires, could lose their "spring" but what about a thicker "tab" style spring like this?:

http://www.keyelco.com/category.cfm/Battery-Coin-Cell-Holders-Contacts-Clips/18650-Holders/p/404/id/413
http://www.keyelco.com/userAssets/file/M60-2p17.pdf

 

[scoot-e]

It looks like a reliable no-weld/no-solder tabs connection was made on instructables some time ago:

http://www.instructables.com/id/Make-an-inexpensive-Lithium-Ion-Battery-Pack/?ALLSTEPS

These packs replace thin coiled springs with thicker nickel tabs on both ends and the guy rewired/soldered all the connections and balance leads himself to the exterior of the cases at the tabs.

Here are some closeups of the cases - I've ordered 15 packs of 4 battery holders (60 cells total) and will attempt to make a 12s5p block (44.4v 12.5ah with Samsung 25R 2.5ah tabless/pcb-less cells I ordered) and will run them at a max 30-35amps continuous discharge and report back how the tabs do heat-wise, etc. This is right around 3c for these batteries at the max continuous so they should hold up just fine for hill riding, etc. Am hoping these cases, which I will modify and stack to prevent movement of the cells, will make a great way to remove cells if need be without having to deal with spot welding, etc...

At about $1 a cell holder they aren't outrageously expensive and the tabs shouldn't have a problem with the 6-7amps going through each string max as they might/would with the coil spring connections commonly used for AA batteries in simple flashlight setups, etc as discussed and tried in this previous post from a year ago:

http://endless-sphere.com/forums/viewtopic.php?f=14&t=48746&start=25