picture! no solder twisted wire konion 18650

[Matt Gruber]

I've been experimenting again :lol: changed title as this post is obsolete already! see post 5 for twisted solid wire.
So i took 5 old cells and pealed off 2" of the skin, and put a car hose clamp around them, and i had a real quick 5P pack
well, almost, the + is not connected yet.
The speed of this is what surprised me, next is the low cost of the ss clamp, and they are available at wal-mart and any auto store. and they can be hooked together for larger packs(mine was a 2" clamp)
Next is the stability; 2 clamps and it is really solid, but just 1 was doing the trick on the bench. So it makes a sub- case of itself.
.
And changing a cell is half the work, since the neg comes apart easily with no tabs, welds, wire, or epoxy.
Not sure what to do on the +, but right now i like JB Weld(but curing is slow) since it acts as a thermal fuse, which is hard to improve upon. But 2 fuses on each cell sure is not needed.
It is possible to damage a cell with a very tight clamp. It is also possible to NOT damage it by using a rubber cushion at the screw ears. I've done both. All this testing took 20 minutes. Short learning curve.
So somebody must have done this before, it is too easy. So i must be missing something, so if anybody has ran into a problem with ss clamps, please chime in!

 

[gogo]

Any chance you could post a picture or sketch?

 

[Matt Gruber]

some more tests- ss is sure not a good material for high amps, i saw an 18mv drop between cells at 13 amps. So i will be quick to switch to a solid copper band, tinned, and bolted so as to tighten for high amps
remember, ss has 35-40x the resistance of copper! ss is great for testing this out, buy 2 clamps for $1.59 and play with it before considering copper. actually many could use 2 ss clamps, but not everyone.
no pics, just mock up tests so far.
i like a single clamp on a single cell, with a tinned copper wire under it. then there is no soldering or spot welding or epoxy, yet power goes thru copper.
Just experimenting "out loud". Not sure where this will end up, but it sure beats watching a movie :lol:
edit: i see #10 clamps on ebay $15 for 50, that 30 cents each! extras will hold on my heater hose.

 

[gogo]

Are you putting the cells in a row, or clustered?

What do you think of the way Zero did their large cylindrical cells?:
Subject: Low-power no-solder idea...

 

[Matt Gruber]

gogo
that is clever, but the makita cells i use are known for shorting easily at the + end. only 1/32" depth to -case! ZAP!
.
Looking at clamp prices, and not really wanting steel or ss, i just made my own 14 awg solid copper twist clamp.
got a roll of this wire at a yard sale for $1 years ago. just ordinary construction wire like at home depot. cheap copper wire.
i just wrapped it around and twisted it as tight as i could. i dented the cell so i slid it off and slid it onto a perfect cell. It was snug for a good connection, no slop at all, But could not dent the cell, because when i slid it off the 1st cell, it took the EXACT round size, in order to take it off.
so i learned to use 1 cell as a form. this i like. cheap(free) and all copper. could twist up several and slide them on as one long connection, or solder ends as needed. For a working pack i would coat the copper with solder, to resist corrosion. BUT no soldering to the cell!
the main idea is to cut off a little bit of the skin all around the cell, then it is easy to wrap WHATEVER around the cell. Just try it 1st on a dead cell because they can be damaged!
thanks for chiming in!

 

[gogo]

Its difficult for me to visualize exactly what you describe. Concerning the tight slip-fit, if you plate the copper after forming it will make your slip-fit even tighter.

 

[Matt Gruber]

gogo
it would have to be coated before!
.
this may only apply to sony konions, a pic would help but i'll try to descibe:
1/8" from the + end there is a 1/16"deep groove around the -case. This appears to be some sort of crimp where the thermal fuse was installed. it appears very strong, or at least much stronger than the -case everywhere else.
so i wrapped 14 solid copper around it, and it fits perfect in the groove! twist it and it locks tight without damage!
So this is a possible - location, 1/8" from the top! No need to turn the cell around for series + and minus are next to each other! Maybe easy to short, but with 14 locked in the groove, i need to look into this!
EDIT
So on another cell i used a razor blade to cut the skin off just the groove. It is like having a hidden terminal! So this is it for me for the -. No chance of shorting as long as those cell mounts, the ones with cooling space between each cell, are used. Have to have room for the wire to come out.
I'm not building packs, i just repair the makita packs, usually there is a pair of dead cells, out of 10, that have to be changed. I'm out of spare cells, so the next repair will need either some more used packs, or now i have the option of buying 2 new V3 cells without solder tabs for $9. I'm curious to see how fast they go out of balance mixing new with old cells. Also may try one new V3 with a pair of tired v's. That is one new 2.2ah with 2 tired 1.5ah, it might be ok. worth $9 to me to find out.

 

[Matt Gruber]

pic -(neg) is the RED wire! wrapped in groove and twisted tight. 1st try so it could be neater. But, it is so tight, it can't be rotated. Cell is very strong at this seam(fuse inside)
+ is experiment for no solder twist connection, too difficult imo.
.
i'll be leaving the skin on in the future. (except for the 1/16" groove for the neg. wire)

 

[Hillhater]

Matt, you seem to have a good few ideas for connecting the -ve side of these cells... i particularly liked the hose clamp on a group of cells ,.. can to can contact would be sufficient for parallel contact, with a single trapped "connector wire" as a lead out.
But i dont see the need to worry about solder on the +ve end cap since this is normally a separate component with greatly reduced thermal path to the cell chemicals. This is also the reason for the "groove" you see around the top of the cells
so, soldering on the +ve cap should be a low (negligible) risk to the cell integrity.

 

[Hillhater]

This was another "no solder" option i came across also that may be of interest...
http://www.candlepowerforums.com/vb/showthread.php?314680-Low-cost-DIY-18650-battery-holder

 

[Matt Gruber]

Matt, you seem to have a good few ideas for connecting the -ve side of these cells... i particularly liked the hose clamp on a group of cells ,.. can to can contact would be sufficient for parallel contact, with a single trapped "connector wire" as a lead out.
But i dont see the need to worry about solder on the +ve end cap since this is normally a separate component with greatly reduced thermal path to the cell chemicals. This is also the reason for the "groove" you see around the top of the cells
so, soldering on the +ve cap should be a low (negligible) risk to the cell integrity.

thanks for posting! so the groove is in all 18650's, that makes it easy. the problem w/fuse on sony V is that it will blow sometimes from soldering the +. i blew at least 1, maybe 2 more i'm not sure. I've improved my technique, but i still don't like soldering.
i see back in 2006 SAFE tried a long pipe, cells inside in series. i'd like to know how long they worked from any experimenters testing that easy no solder idea. safe did use copper end contacts, not the spring. he said it did 50 mph in 06 without problems. that would be HIGH amps!
.
UPDATE my solution is to buy tool packs on sale. no soldering and plug and play. I make my own plugs from copper tubing(squeezed flat). Packs have 90 day refund warranty and some have 3 years to exchange for a NEW pack!
I find the individual 18650 cells cost MORE than a ready made pack! Unless u buy from china, then it might be a FAKE!
Have to watch for a sale and be a savvy shopper. I ordered dewalt $129 each packs on sale $49 each! 80 wh is not bad for 49 with a local warranty! (safer chemistry than the cheaper HK, and these could last twice as long, maybe 3x as long.) Do your research on a specific model to be sure they can be paralled, series, without opening it up. Even without the warranty i like some packs, like some bosch and dewalt, and dr.bass used makita!