Stupid Question: Can I solder 18650 cells?

LewTwo

LewTwo

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Location
Houston, Texas
OK ... reason for asking. I started to order my mini battery pack from EM3EV and was shocked by the shipping cost for the tiny battery.
I can acquire said 18650 cells locally in Houston, texas for a reasonable price. I can get a BMS off ebay for a reasonable price.
However I do not have and would rather not purchase a pulse welder for a one time use.
I was thinking I might use WBT #0800 4% Silver Solder and 12 GA copper wires between the cells.
Melting point of the WBT 4% Silver Solder is 180 degrees C -- somewhat lower than the 237 degrees C for the more common 60/40 electrical solder.

Yes I do realize this would be a bit dicey and I would have to be extremely careful about NOT overheating the end of the cell but .... ???


EDIT 14 Jan 2017:
DIY 18650 Battery Packs https://endless-sphere.com/forums/viewtopic.php?t=26383
Battery in a Tube https://endless-sphere.com/forums/viewtopic.php?f=2&t=85548
 
You can solder cells that have the nickle plate spot welded on the top, or are tabbed.

I heard of some cells where the top *IS* nickle, but I'm not sure sure how to identify those.
 
dnmun said:
you can buy a lifepo4 pouch pack from sunthing guy free shipping because he ships surface freight.
Click to expand...
Sun-thing28 on ebay?? http://www.ebay.com/usr/sun-thing28?_trksid=p2047675.l2559
I am building a Weight Weenie bike and would like to have a very small 2P10S 18560 battery pack. This guy does not have anything close.
 
If you have a powerful soldering iron ie 80w plus it is possible to do it safely. Rough up the connection points with sandpaper. Pre solder the cell and the wire with a thin coat and then join them. Immediately after soldering on the cell use an air blast to cool it down.

Honestly though if you have to ask your likely better off doing something else. You have to be incredibly fast to do it safely. I've done it enough before I bought my pulse welder. It sucks. Oh ya and building packs is very time intensive. If your on the fence definitely just buy one.
 
Grizzl-E said:
If you have a powerful soldering iron ie 80w plus it is possible to do it safely. Rough up the connection points with sandpaper. Pre solder the cell and the wire with a thin coat and then join them. Immediately after soldering on the cell use an air blast to cool it down.

Honestly though if you have to ask your likely better off doing something else. You have to be incredibly fast to do it safely. I've done it enough before I bought my pulse welder. It sucks. Oh ya and building packs is very time intensive. If your on the fence definitely just buy one.
Click to expand...

WOW 80 Watts ... I thought those were only used for making stained glass windows.
Actually I need a new iron anyway but I was contemplating something a bit smaller :(
 
Buy the cells preassembled into pairs.
You can then solder your series connections onto the link tabs without touching the cells, and arrange the pack any way you like.
Many vendors have a very small charge for adding tabs to pair up cells.
 
Hillhater said:
Buy the cells preassembled into pairs.
You can then solder your series connections onto the link tabs without touching the cells, and arrange the pack any way you like.
Many vendors have a very small charge for adding tabs to pair up cells.
Click to expand...

OH yes --- Now I remember seeing some listed with that option. Very helpful. Thank you.
 
For a small job, like replacing a weak 18650 cell in a string, you can use this stainless steel flux (http://www.amazon.com/gp/product/B007BGYQEC) and standard lead tin solid wire solder.

Pre-tin the battery ends using the flux and solder, then clean the batteries thoroughly with Isopropyl alcohol and a cotton cloth. This flux is corrosive !!! Laying the batteries on their sides to pre-tin will keep the flux from running into the "well" under the positive terminal. Once the cells are pre-tinned, put the flux AWAY and go back with copper wire and standard ROSIN CORE electrical solder (e.g. Kester 44). With pre-tinned batteries, the soldering will go VERY nicely, and the rosin flux is low activity and does NOT need perfect cleaning afterward, rubbing lightly with a cotton cloth damp with Isopropyl alcohol will be fine.

That said, for any reasonable project, a little spot welder would probably pay for itself in convenience and speed.
 
LewTwo said:
Hillhater said:
Buy the cells preassembled into pairs.
You can then solder your series connections onto the link tabs without touching the cells, and arrange the pack any way you like.
Many vendors have a very small charge for adding tabs to pair up cells.
Click to expand...
OH yes --- Now I remember seeing some listed with that option. Very helpful. Thank you.
Click to expand...

Found one: supowerbattery111 on ebay
http://www.ebay.com/usr/supowerbattery111?_trksid=p2047675.l2559
Welding Service
We offer free-charge Welding Service!
You may send message to us if you need solder the tabs or Series / Parallel - Connected spot welding.
Its better if you could send us a drawing or picture by mail.
Remember to leave the message again on transaction by ordering that we will not miss the information.

They are also in Hong Kong but have both surface (slow boat) and air shipment options.
 
Can solder them. You just can't solder them without damaging them to some extent between minimal to critical.

Ordering with tabs or even better doing a well designed pressure contact system enables cells to be assembled and not damaged.
 
Invest in a JP welder and forget the solder. I went through that phase and did a build like Keplers. It worked but buying a hobby welder will pay off and produce a far better product.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=65719&hilit=solder+battery
 
LewTwo said:
WOW 80 Watts ... I thought those were only used for making stained glass windows.
Actually I need a new iron anyway but I was contemplating something a bit smaller :(
Click to expand...
I was able to do just as poor a job with a 40W iron. The 80-100W irons are hard to find small tips for. The tips available are to big, IMO, for making nice small solder joints. For those of us planning to stay in the hobby, a welder is really the way to go.

https://endless-sphere.com/forums/viewtopic.php?f=14&t=68005&hilit=jp+welder

https://endless-sphere.com/forums/viewtopic.php?f=31&t=68865
 
tomjasz said:
Invest in a JP welder and forget the solder. I went through that phase and did a build like Keplers. It worked but buying a hobby welder will pay off and produce a far better product.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=65719&hilit=solder+battery
Click to expand...

Thanks for the link. That answered my question that it is possible and I could probably do it. I do not think that buying the welder would pay off for one 10S2P pack and really do not intend to get into building more. SuPower had exactly the pack I was looking for and their shipping charge was considerably less. Problem solved :)
 
LewTwo said:
tomjasz said:
Invest in a JP welder and forget the solder. I went through that phase and did a build like Keplers. It worked but buying a hobby welder will pay off and produce a far better product.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=65719&hilit=solder+battery
Click to expand...

Thanks for the link. That answered my question that it is possible and I could probably do it. I do not think that buying the welder would pay off for one 10S2P pack and really do not intend to get into building more. SuPower had exactly the pack I was looking for and their shipping charge was considerably less. Problem solved :)
Click to expand...
Would you mind linking to the pack? Can't find it...
 
tomjasz said:
Would you mind linking to the pack? Can't find it...
Click to expand...
Here you go ...
36V, 6.4Ah, Lithium ion Li-ion Battery Pack
Dimensions: 50 x 188 x 70 mm (1.9 x 7.4 x 2.8 inches), Weight: 1.15kg (2.53 pounds), Max. Continuing Discharge Current: 20A
http://www.batterysupports.com/36v-37v-42v-6400mah-64ah-20a-lithium-ion-liion-battery-pack-p-378.html
 
dnmun said:
at 20A how far would a fully charged battery take you before it reached the 3.5V level people here demand. about 40% SOC.
Click to expand...
Please to note that my name is NOT Tim Taylor. I am not as much concerned about 'what people here demand' as as what I am looking for.

I get about 20 miles per a full charge on my current ebike:
weight: 65 plus pounds
battery: Golden Motor 36 Volt 12 Ah
motor: GM 36 volt 350 watts (nominal) smart pie

This pack is half the power and one fourth the weight of my GM battery.
I am guessing it will get my 36 volt 250 watt (nominal) weight weenie ebike about 10 miles (maybe a tad more).
I will convert the GM pack to XT-60 plugs and use the same on this one as well.
 
LewTwo said:
I am not as much concerned about 'what people here demand' as as what I am looking for.
Click to expand...
Thanks for the laugh. So often ES forgets we don't all need a gazillion Ah and light speed....
I really like my little stealth battery build.
 
Re-assuring
Grizzl-E said:
If you have a powerful soldering iron ie 80w plus it is possible to do it safely. Rough up the connection points with sandpaper. Pre solder the cell and the wire with a thin coat and then join them. Immediately after soldering on the cell use an air blast to cool it down.

Honestly though if you have to ask your likely better off doing something else. You have to be incredibly fast to do it safely. I've done it enough before I bought my pulse welder. It sucks. Oh ya and building packs is very time intensive. If your on the fence definitely just buy one.
Click to expand...


Until I read this
liveforphysics said:
Can solder them. You just can't solder them without damaging them to some extent between minimal to critical.

Ordering with tabs or even better doing a well designed pressure contact system enables cells to be assembled and not damaged.
Click to expand...

I'm still confused, $140 is a lot to spend on just a tab welder. Plus another $40-$60 for some used car batteries. So $200, thats like a 15Ah worth of battery cells!
I just dont know how much heat is too much, and to what degree does the battery actually degrade.
 
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