18650 spot welding -how to- ULTIMATE REPOSITORY

Batteries, Chargers, and Battery Management Systems.
up0   10 mW

10 mW
Posts: 34
Joined: Apr 02 2014 4:31am

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by up0 » Mar 10 2016 6:41pm

> I also wonder if a good amount of hot glue surrounding the cells adds some thermal advantage or disadvantage.
> On the other hand, it probably adds unwanted insulation to the cells,

It really depends on if your finalized battery block will be allowing air to flow through it like this rare pack:
https://www.facebook.com/media/set/?set ... 886&type=3
Image

This is not very typical though - usually the battery packs are covered in one big shrink-wrap, almost air-tight.
I read in one of the Pack-Building guides that people make the mistake of assuming that it is good to have some Air-Gaps between the cells for cooling.
So they use Spacers between cells instead of packing them tight in a honeycomb pattern.

But air is a very good insulator when it cannot move:
Just look at this list: https://en.wikipedia.org/wiki/List_of_t ... uctivities
Air has 0.024
Hot Glue: I would estimate from similar substances ~0.25
So Hot-Glue passes on heat roughly 10 times better than air!
-> The easiest way for a battery in the middle of the pack to lose heat is to pass on the heat to glue and other cells towards the outermost cells.
Any non-moving air-layer in between is not helping...
Ulli

User avatar
Cowardlyduck   100 MW

100 MW
Posts: 2614
Joined: Jun 26 2011 8:41pm
Location: Canberra, ACT, Australia

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Cowardlyduck » Mar 10 2016 9:27pm

Thanks Up0. This is good to know.

So lots of hot glue it is. :)

The only remaining drawback with all that hot glue is the extra weight it adds. :roll:

Cheers
Custom made 18650/21700 battery packs

Modified Stealth Fighter - Force air cooled motor @ 6KW, Adaptto Mini-E. 49AH, 52V 18650 - 2.5Kwhr
Cowardlyducks - Stealth Fighter Videos

BikeE recumbent commuter - 9C, 6Fet Grinfineon, internal 17AH, 52V, + on-board solar.

Ebike Garage - My YouTube Ebike ramblings.

High Power LiPo wiring harnesses - 4P - XT90, HXT4mm, 5.5mm. 200Amp+ capable. Global shipping.

bikegeek   10 W

10 W
Posts: 85
Joined: Oct 07 2015 10:38am
Location: Bucharest, Romania
Contact:

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by bikegeek » Mar 11 2016 12:25am

I think all battery that has space/spacers between cells has it for not touching from each other. And every big manufacturer dose that, it has some type of spacer, it is safer. If the glue snaps (small probability although) you will get cells rubbing from each other and finally short out.

LikeToRideMyBike   100 W

100 W
Posts: 151
Joined: Jan 09 2016 9:00pm

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by LikeToRideMyBike » Mar 12 2016 11:09am

Hey guys, I've got a problem. I just hooked up my BMS. When I reached a full charge some lights came on where the balancing cables went in. It was a little warm while these lights were on. It was strange. I don't know, maybe that was normal. But overnight it lost charge from 67.2 volts down to 66.6 volts. That's definitely not normal. What is going on? Do I need to disconnect this BMS and get a new one? I scared that it's going to ruin my brand new Samsung 25r cells. What do you think?

Here is the link to the BMS I used: http://www.aliexpress.com/item/16S-Li-i ... 28170.html

thanks all

User avatar
Offroader   10 MW

10 MW
Posts: 2461
Joined: Sep 08 2013 9:03pm
Location: USA

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Offroader » Mar 12 2016 11:33am

LikeToRideMyBike wrote:Hey guys, I've got a problem. I just hooked up my BMS. When I reached a full charge some lights came on where the balancing cables went in. It was a little warm while these lights were on. It was strange. I don't know, maybe that was normal. But overnight it lost charge from 67.2 volts down to 66.6 volts. That's definitely not normal. What is going on? Do I need to disconnect this BMS and get a new one? I scared that it's going to ruin my brand new Samsung 25r cells. What do you think?

Here is the link to the BMS I used: http://www.aliexpress.com/item/16S-Li-i ... 28170.html

thanks all
Should be normal, the BMS balances the cells to the lowest cell, so it discharges all the other higher cells and will lower your pack voltage. This discharging will cause heat.
If all your cells are balanced the voltage shouldn't drop anymore and nothing should feel warm. If the voltage continues to drop then you have problems.

markz   100 GW

100 GW
Posts: 7401
Joined: Jan 09 2014 11:38pm
Location: Alberta Canada

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by markz » Mar 13 2016 10:11pm

How are you suppose to size up heat shrink.
I got 14cm x 22cm x 6.5cm (140mm x 220mm x 65mm)
Basically I need to find someway to convert flat dimensions to round dimensions.
These are 2:1 or 50% shrinkage.
So I should buy something that is a diameter of ~250mm

http://stores.ebay.com/Atop-Authentic-A ... op=2&_sc=1

User avatar
Offroader   10 MW

10 MW
Posts: 2461
Joined: Sep 08 2013 9:03pm
Location: USA

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Offroader » Mar 14 2016 12:23am

markz wrote:How are you suppose to size up heat shrink.
I got 14cm x 22cm x 6.5cm (140mm x 220mm x 65mm)
Basically I need to find someway to convert flat dimensions to round dimensions.
These are 2:1 or 50% shrinkage.
So I should buy something that is a diameter of ~250mm

http://stores.ebay.com/Atop-Authentic-A ... op=2&_sc=1
The way I figured it, they give you the flat diameter dimension. So say it is 250mm

Use one of those sewing measuring tapes and bring 0mm to the 500 mm end. That is exactly the size the shrink wrap will be when you then make a circle with the measuring tape holding it at those marks.

You can then try and circle it around your battery, or something with your battery dimensions.

They also give you the round dimensions, but you won't be going totally round so it isn't that useful.

User avatar
Offroader   10 MW

10 MW
Posts: 2461
Joined: Sep 08 2013 9:03pm
Location: USA

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Offroader » Mar 14 2016 2:21pm

Is there an easy way to remove cells that are hot glued together?

markz   100 GW

100 GW
Posts: 7401
Joined: Jan 09 2014 11:38pm
Location: Alberta Canada

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by markz » Mar 14 2016 2:23pm

Use one of those sewing measuring tapes and bring 0mm to the 500 mm end. That is exactly the size the shrink wrap will be when you then make a circle with the measuring tape holding it at those marks.
I just can not envision what you are saying right now. My length is 220mm, but the diameter shouldnt be much more then that, based on my width. OK After reading it several times I see what you mean now.
You mean make a loop or circle with the measuring tape. Why did you pick 500mm?
I was trying to do it using math, but the width of the pack makes it a complex eqaution rather then the simple equation.
Your way is easiest with a "manly mans" construction measuring tape and making a loop. Better then putting a pencil of the end and randomly picking a length to scribe a circle.

From the looks of this heat shrink stuff, its like $10 USD or more for a meter (3.3') so $13 CAD per meter. If its thick PVC then it might be worth it. I have a feeling this aint thick PVC heat shrink, because thick PVC from the store I buy mine at is more expensive then this China product.

I am thinking extra wide Gorilla Duct Tape should work better!!
Perhaps with some card board type material between the batteries and the sticky tape.
I need to reopen the packs when I get a new Weller soldering tip, and another pound of solder. My current soldering job is horrible.

markz   100 GW

100 GW
Posts: 7401
Joined: Jan 09 2014 11:38pm
Location: Alberta Canada

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by markz » Mar 14 2016 2:25pm

Offroader wrote:Is there an easy way to remove cells that are hot glued together?
Rotary tool with cut off wheel would work for the outter cans.
A hot air gun might work.
A razor blade perhaps to get into the second row/column.

You might have to do it piece meal, would be able save the holders. They are always a pain to take apart.

bikegeek   10 W

10 W
Posts: 85
Joined: Oct 07 2015 10:38am
Location: Bucharest, Romania
Contact:

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by bikegeek » Mar 14 2016 2:39pm

Offroader wrote:Is there an easy way to remove cells that are hot glued together?
Try this: https://www.youtube.com/watch?v=dNNqSXgj6DE

User avatar
Offroader   10 MW

10 MW
Posts: 2461
Joined: Sep 08 2013 9:03pm
Location: USA

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Offroader » Mar 14 2016 3:50pm

bikegeek wrote:
Offroader wrote:Is there an easy way to remove cells that are hot glued together?
Try this: https://www.youtube.com/watch?v=dNNqSXgj6DE

WOW, this work amazingly well. You spray a little isopropyl alcohol on the edges and let it seep for 20 seconds in and the cell loosens right up..

I honestly didn't think there was any good way to do it but thought I'd ask anyway.

I believe this is also safe on the cells.

User avatar
Nobuo   10 kW

10 kW
Posts: 839
Joined: Nov 21 2014 3:38am
Location: Madrid

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Nobuo » Mar 14 2016 9:25pm

Offroader wrote:Is there an easy way to remove cells that are hot glued together?
Put the glued cells into the freezer (-18ºC or less) for 12h to 24h. Cover all into a semi-vacuum bag (standard plastic bag tied) to avoid a very high temperature change and humidity. Then you can very easily rip off them, even with your hands. You have only 5 minutes to do it properly, then you must put again into the freezer 4h more to have them ready again.

- Use latex gloves to avoid freeze your hands
- a screw driver help good, but you have a high risk of damage insulators (this will happen continuously depending of the quality/type of melt silicone/glue used)
- if you are ripping a piece, put the rest inside the bag while working, this makes you a greater time to work.

This is the easiest and fastest method I've tried
* Lithium + Air = Fire * <-----> ** Lithium + Chemical-Additives + Air = ZERO Fire **
<Battery and EV works>
https://facebook.com/evmadrid1
<Battery building resources>
http://www.endless-sphere.com/forums/vi ... 14&t=68005

User avatar
Offroader   10 MW

10 MW
Posts: 2461
Joined: Sep 08 2013 9:03pm
Location: USA

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Offroader » Mar 14 2016 9:51pm

Question,

I read it is recommended not to solder cells because of the heat.

Will hot glue cause any heat issues to the cells? Should you limit the temperature on the hot glue gun?

User avatar
Nobuo   10 kW

10 kW
Posts: 839
Joined: Nov 21 2014 3:38am
Location: Madrid

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Nobuo » Mar 14 2016 10:34pm

Neither hot glue/ melt silicone or spot welding will make an appreciable harming heat. The important thing is the capacity of the cell to spread the heat quickly so the chemicals have not an increased temperature. All the cells is covered with a metal that will spread the heat quickly over all its surface and insides, making the temperature lowered very quick
* Lithium + Air = Fire * <-----> ** Lithium + Chemical-Additives + Air = ZERO Fire **
<Battery and EV works>
https://facebook.com/evmadrid1
<Battery building resources>
http://www.endless-sphere.com/forums/vi ... 14&t=68005

User avatar
Offroader   10 MW

10 MW
Posts: 2461
Joined: Sep 08 2013 9:03pm
Location: USA

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Offroader » Mar 15 2016 1:52am

Thanks Nobou, I would like to ask you another question.

When you build a pack with the cells touching each other. Is it important to put something between the cells touching each other that will be in a difference series group?

I know that if cells next to each other in a different series group short together (with the outside negative case) that will be bad.

Is using Hot glue and welding tabs good enough that a short will not happen? If it isn't, what do you recommend to put between the cells in a different series group?

User avatar
Nobuo   10 kW

10 kW
Posts: 839
Joined: Nov 21 2014 3:38am
Location: Madrid

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Nobuo » Mar 15 2016 2:53am

Depends closely with your detail level construction. Cells are perfect cylinders, if you make good shapes and patterns where cells are very exactly placed, the weight will perfectly distributed if the battery have an impact for example, and is almost impossible that both insulators of two consecutive cells will be punctured making its cathodes electrically in contact. However if while making the battery you left a grain of sand or any sharp metal between two cells, you could have a strange cathode short before a hard impact

Also the glue/silicone, if it is used in the right quantity (in the way if makes even a small film between cells in contact, will absorb an important part of the energy on any impact.

It depends also about your battery size, use, installation, etc.

Only you could answer if you need serial separators, anode spacers, cell holders, active cooling..
* Lithium + Air = Fire * <-----> ** Lithium + Chemical-Additives + Air = ZERO Fire **
<Battery and EV works>
https://facebook.com/evmadrid1
<Battery building resources>
http://www.endless-sphere.com/forums/vi ... 14&t=68005

User avatar
Overclocker   10 kW

10 kW
Posts: 610
Joined: Mar 17 2014 5:48am
Location: Philippines

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Overclocker » Mar 15 2016 11:47am

nice thread!

gotta restock my nickel. now using 7mm. but the vendor also offers 12mm.

so which one is better for "all-around" use? 7mm or 12mm width?

Skrzypas   10 W

10 W
Posts: 65
Joined: Jun 16 2014 3:08pm
Location: Warsaw, Poland

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Skrzypas » Mar 15 2016 12:22pm

7!

User avatar
Offroader   10 MW

10 MW
Posts: 2461
Joined: Sep 08 2013 9:03pm
Location: USA

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by Offroader » Mar 15 2016 12:55pm

Overclocker wrote:nice thread!

gotta restock my nickel. now using 7mm. but the vendor also offers 12mm.

so which one is better for "all-around" use? 7mm or 12mm width?
To be honest I would recommend the 12mm wide.

15 mm x 7 mm has a 1.05 mm² cross section, .15 x 12 mm has a 1.8 mm² cross section. So you get 70% more current capacity with the .15 x 12 mm.

.15 x 12 mm is similar to .2 x 9 mm strip.

That is a large increase in current capacity and you can use 12 mm wide on 18650 cells and they will not be wider than the cell. The only issue is on the positive side when welding you will slightly overlap where you need to weld and will have to be a little careful to make sure you weld in the center, but this is easy to solve with placing a gasket or template before welding to see exactly where you need to.

Welding the 12mm side strip to the negative side of the batter is easy.

Most people want to go thicker like .3 nickel, but I say go wider as it is so much easier to weld.

DVDRW   100 W

100 W
Posts: 211
Joined: Sep 10 2012 10:57am
Location: Tallinn, Estonia, EU
Contact:

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DVDRW » Mar 15 2016 3:32pm

My first 18650 pack plan. 22s18p
Wish me luck! :D
Attachments
ACDSeeQVUltimate9_2016-03-15_22-17-24.jpg

User avatar
ridethelightning   1 MW

1 MW
Posts: 1869
Joined: Jul 21 2013 9:48pm

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by ridethelightning » Mar 15 2016 5:46pm

wow! that will be some serious power!

joss   10 mW

10 mW
Posts: 32
Joined: Jan 03 2016 1:40am

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by joss » Mar 15 2016 8:55pm

DVDRW wrote:My first 18650 pack plan. 22s18p
Wish me luck! :D
Pardon the expression but, "holy crap" - that's an enormous battery for a bike 352 cells - what are they?

...good luck! :lol:

LikeToRideMyBike   100 W

100 W
Posts: 151
Joined: Jan 09 2016 9:00pm

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by LikeToRideMyBike » Mar 15 2016 10:40pm

DVDRW wrote:My first 18650 pack plan. 22s18p
Wish me luck! :D
WOW! What motor are you running with that ginormous batter?!?

And much good luck to you sir.

DVDRW   100 W

100 W
Posts: 211
Joined: Sep 10 2012 10:57am
Location: Tallinn, Estonia, EU
Contact:

Re: 18650 spot welding -how to- ULTIMATE REPOSITORY

Post by DVDRW » Mar 16 2016 1:52am

joss wrote:Pardon the expression but, "holy crap" - that's an enormous battery for a bike 352 cells - what are they?
...good luck! :lol:
22*18 = 396 cells
NCR18650PF
Tesla S ebike version :twisted:

Post Reply