Author Topic: kWeld - "Next level" DIY battery spot welder  (Read 159394 times)

0 Members and 3 Guests are viewing this topic.

Offline tatus1969

  • Super Contributor
  • ***
  • Posts: 1238
  • Country: de
  • Resistance is futile - We Are The Watt.
    • keenlab
Re: kWeld - "Next level" DIY battery spot welder
« Reply #675 on: November 29, 2019, 11:32:43 am »
I built kweld, ksupply, kcap, and HP DPS-1200FB power supply into an old shuttle computer case.
Looks awesome! One note: if you rotate the kCap by 180 degrees then you can make the wires between it and kWeld shorter. Long cables like in your picture will add too much resistance.
We Are The Watt - Resistance Is Futile!
 

Offline anishkgt

  • Frequent Contributor
  • **
  • Posts: 746
  • Country: qa
    • George Hobby
Re: kWeld - "Next level" DIY battery spot welder
« Reply #676 on: December 16, 2019, 08:12:53 pm »
How did you manage to balance the Caps ? Are you using SAB MOSFETS because i can see two SOIC-16 in here -> https://endless-sphere.com/forums/download/file.php?id=235316 ? then one IC can balance 4 you would just need one. Isn't it 3s3p rather than 3s2p mentioned in your webpage ?
 

Offline tatus1969

  • Super Contributor
  • ***
  • Posts: 1238
  • Country: de
  • Resistance is futile - We Are The Watt.
    • keenlab
Re: kWeld - "Next level" DIY battery spot welder
« Reply #677 on: December 17, 2019, 12:30:33 pm »
How did you manage to balance the Caps ? Are you using SAB MOSFETS because i can see two SOIC-16 in here -> https://endless-sphere.com/forums/download/file.php?id=235316 ? then one IC can balance 4 you would just need one. Isn't it 3s3p rather than 3s2p mentioned in your webpage ?
No, and I'm also not really a fan of this technique. Doable as a one-off, but if you look closer at the specs of these devices then you'll see that this is not suitable for larger scale manufcaturing. The balancer on kCap uses a solution based on opamps and comparators and is accurate within +/- 75mV.

Where did you read that 3S3P? I checked the docs and can't spot it. kCap is 3S2P.
We Are The Watt - Resistance Is Futile!
 

Offline anishkgt

  • Frequent Contributor
  • **
  • Posts: 746
  • Country: qa
    • George Hobby
Re: kWeld - "Next level" DIY battery spot welder
« Reply #678 on: December 17, 2019, 12:44:48 pm »
Not Suitable in Large scale manufacturing? they can be daisy chained as mentioned here -> https://www.aldinc.com/pdf/SABMB16.pdf to have more caps.

I meant isn't it a 3s3p rather than a 3s2p 6caps of which 3 in series and other 3 in parallel. How does it work with 3s2p one would be left out of the six caps.
 

Offline tatus1969

  • Super Contributor
  • ***
  • Posts: 1238
  • Country: de
  • Resistance is futile - We Are The Watt.
    • keenlab
Re: kWeld - "Next level" DIY battery spot welder
« Reply #679 on: December 17, 2019, 03:00:41 pm »
Not Suitable in Large scale manufacturing?
I had the reason wrong in memory for not using them. Rechecked the datasheets - it's the V/I curve that I didn't like. The device with 2.7V threshold (ALD810027) draws 1uA at 2.7V, 1mA at 3.14V, and 10mA at 3.7V. Thats far too slopply for big caps like the ones that I am using, which can require 100mA+ of balancing current when worn out. The parts are run at their full rated voltage, and I don't want to exceed that.

It is a 3S2P. Two caps in parallel at each level, and three of these pairs in series.
We Are The Watt - Resistance Is Futile!
 
The following users thanked this post: anishkgt

Offline ealex

  • Frequent Contributor
  • **
  • Posts: 288
  • Country: ro
Re: kWeld - "Next level" DIY battery spot welder
« Reply #680 on: December 25, 2019, 08:34:20 am »
Hello

I've recently got my unit (version 3.3) and I'm trying to make a case out of MDF.
It's basically a 3 layer box that will hold the batteries at the bottom and the unit on top.

Is there any chance you can share the PCB hole patterns ? It's the last part of the build - everything else is modeled and assembled

(edit - typing errors)
« Last Edit: December 25, 2019, 09:49:58 pm by ealex »
 

Offline anishkgt

  • Frequent Contributor
  • **
  • Posts: 746
  • Country: qa
    • George Hobby
Re: kWeld - "Next level" DIY battery spot welder
« Reply #681 on: December 27, 2019, 12:04:22 am »
Aren't the supercaps rated for a specific current, here i think its 240A. Though the short circuit current is about 1200A, which should never be used for operation. How do you control or limit the current draw ? each cap in parallel is 240A x 2 = 480 and that multiplied 3 times is about 1400A and those series would be lower.
 

Offline socke

  • Newbie
  • Posts: 1
  • Country: de
Re: kWeld - "Next level" DIY battery spot welder
« Reply #682 on: December 27, 2019, 12:22:56 pm »
Hey,

where do I get the schematics? I've scrolled through this thread for a while and googled for it but didn't find anything. Even on the website where the kit is sold I've seen no schematics. The website was btw "hard" to find as well (had to google for it, didn't find any link in the first post of this thread).

Best regards!
 

Offline tatus1969

  • Super Contributor
  • ***
  • Posts: 1238
  • Country: de
  • Resistance is futile - We Are The Watt.
    • keenlab
Re: kWeld - "Next level" DIY battery spot welder
« Reply #683 on: December 27, 2019, 12:37:30 pm »
Aren't the supercaps rated for a specific current, here i think its 240A. Though the short circuit current is about 1200A, which should never be used for operation. How do you control or limit the current draw ? each cap in parallel is 240A x 2 = 480 and that multiplied 3 times is about 1400A and those series would be lower.
These ratings are related to their thermal limits, you can exceed them in pulse applications. I was worried that there could be internal hot spots and did long time tests of several 10,000 pulses under full sustatined load (water cooled 1mOhm resistor as load, and lots of fan cooling) and found them to be rock solid.

Is there any chance you can share the PCB hole patterns ? It's the last part of the build - everything else is modeled and assembled
Attached.

where do I get the schematics? I've scrolled through this thread for a while and googled for it but didn't find anything. Even on the website where the kit is sold I've seen no schematics. The website was btw "hard" to find as well (had to google for it, didn't find any link in the first post of this thread).
I'm afraid but kWeld is neither open source HW nor SW. And thanks for that reminder, I know that part is a mess... someone throw a bucket of time over to me :-)
« Last Edit: December 27, 2019, 12:43:24 pm by tatus1969 »
We Are The Watt - Resistance Is Futile!
 

Offline ealex

  • Frequent Contributor
  • **
  • Posts: 288
  • Country: ro
Re: kWeld - "Next level" DIY battery spot welder
« Reply #684 on: December 28, 2019, 06:09:55 pm »
@tatus1969 - thanks
i'll make some photos of the set-up tomorrow, when I have some daylight available.
 

Offline ealex

  • Frequent Contributor
  • **
  • Posts: 288
  • Country: ro
Re: kWeld - "Next level" DIY battery spot welder
« Reply #685 on: January 01, 2020, 08:47:09 am »
I've finally managed to get everything together and start working on a small pack:
Everything is on a clear table - batteries + high power stuff don't go well with my cluttered bench
900224-0

I've used 2 turnigy 3S 2200mAh cells in parallel.
They seem to stand the abuse - they are barely warm when the electrodes get unpleasantly hot 32 welds at 50J, with 1300A average
900228-1

This is how a weld looks, on 5mm wide, 0.3mm thick nickel strip.
900220-2
It seems a little bit to hot, but I've tested on some scrap cells and the weld is strong and the cells are not melted trough

And a microscope photo of another weld:
900236-3

You can see the electrode angle and a little bit of metal flowing away (maybe add some flux - Rossman style)

(edit reason - I can't get the hang of this editor)
« Last Edit: January 01, 2020, 08:51:02 am by ealex »
 

Offline tatus1969

  • Super Contributor
  • ***
  • Posts: 1238
  • Country: de
  • Resistance is futile - We Are The Watt.
    • keenlab
Re: kWeld - "Next level" DIY battery spot welder
« Reply #686 on: January 14, 2020, 10:53:04 am »
You can see the electrode angle and a little bit of metal flowing away (maybe add some flux - Rossman style)
I had actually tried that in the past, this completely eliminates coloring actually.
We Are The Watt - Resistance Is Futile!
 

Offline tatus1969

  • Super Contributor
  • ***
  • Posts: 1238
  • Country: de
  • Resistance is futile - We Are The Watt.
    • keenlab
Re: kWeld - "Next level" DIY battery spot welder
« Reply #687 on: January 14, 2020, 10:54:03 am »
Good news for you guys in Australia and around: Andrew from hiketech.au is starting to sell keenlab products here! https://hiketech.com.au/index.php?route=product/category&path=111

He's also working on introductory videos, and I'd appreciate if you'd support him by watching and recommending them (given that they are good - haven't seen them yet ;-)

His YT channel is: https://www.youtube.com/channel/UC7MuS242JIeOQYY_8V9U89g
We Are The Watt - Resistance Is Futile!
 

Offline tatus1969

  • Super Contributor
  • ***
  • Posts: 1238
  • Country: de
  • Resistance is futile - We Are The Watt.
    • keenlab
Re: kWeld - "Next level" DIY battery spot welder
« Reply #688 on: January 14, 2020, 01:05:59 pm »
Seems to be newstime today... More good news, I finally managed to order new/redesigned kCap ultracapacitor modules and have started offering them for pre-order: https://www.keenlab.de/index.php/product/kweld-ultracapacitor-module/ (will also be available from the above US/AU resellers)!

They now feature protection against overcharging (MOSFET switch) and also prevent backfeeding into their supply (by an ideal diode circuit), which now allows the use of any kind of current limited power supply with any voltage between 8.1V and 14V. The product page lists these options in more detail.
« Last Edit: January 14, 2020, 01:10:45 pm by tatus1969 »
We Are The Watt - Resistance Is Futile!
 

Offline tatus1969

  • Super Contributor
  • ***
  • Posts: 1238
  • Country: de
  • Resistance is futile - We Are The Watt.
    • keenlab
Re: kWeld - "Next level" DIY battery spot welder
« Reply #689 on: February 17, 2020, 08:23:09 am »
I got notified about an ebay auction of 800x BCAP0650P (new unopened, dated 2007, mix of laser weldable and threaded posts), tempted to purchase them. Anyone interested in these? I'd test them and sell for 6€ a piece.
We Are The Watt - Resistance Is Futile!
 


Share me

Digg  Facebook  SlashDot  Delicious  Technorati  Twitter  Google  Yahoo
Smf