kWeld - "Next level" DIY battery spot welder

Batteries, Chargers, and Battery Management Systems.
ossivirt   1 W

1 W
Posts: 62
Joined: May 18 2016 2:08pm

Re: kWeld - "Next level" DIY battery spot welder

Post by ossivirt » Jan 21 2020 3:37am

Qachi wrote:
Jan 21 2020 3:02am
Silly question but has anyone made up their own supply pack for their kweld using 18650s?
Will likely use a ~65AH car battery most of the time but it would be great to use them for a more portable setup.

On another note, drew this electrode holder up for anyone that may find it useful, shaped to be easily held, one piece and no exposed metal
https://www.thingiverse.com/thing:4117601
Hb powerwall on YouTube used his 18650 powerwall modules that are something like 100p laptop cells.. He also had similar electrode holder but that design has problem that its difficult to keep pressure equal between tips. That can cause sparks and problems..

User avatar
tatus1969   1 kW

1 kW
Posts: 320
Joined: Mar 17 2017 7:36am
Location: Germany
Contact:

Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Jan 22 2020 5:17am

Compoundbike wrote:
Jan 20 2020 2:13pm
I have some problems with my K-Weld. It stopped making welds.. it sparks but the weld is not there.
I checked the battery, calibrated again and again.. however it doesnt weld, any known issues what i can look for ?
That's not much info to diagnose :wink: Can you post all the info that the welder displays after calibration OPEN and SHORT, and after a welding attempt? When you calibrate, please make sure to have clean electrodes for the SHORT step (use fine sand paper to clean them), push the tips together hard, and make sure that you don't get any sparks at all.
Resistance is futile - We Are The Watt.

User avatar
Compoundbike   10 W

10 W
Posts: 75
Joined: Aug 25 2016 3:22pm
Location: Switzerland

Re: kWeld - "Next level" DIY battery spot welder

Post by Compoundbike » Jan 22 2020 12:30pm

Ok i will check out at the weekend, when im in my Workshop, thank you.

User avatar
tatus1969   1 kW

1 kW
Posts: 320
Joined: Mar 17 2017 7:36am
Location: Germany
Contact:

Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Feb 17 2020 3:19am

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.
Resistance is futile - We Are The Watt.

999zip999   100 GW

100 GW
Posts: 9091
Joined: Jan 10 2010 1:40pm
Location: Dana Point So. Cal

Re: kWeld - "Next level" DIY battery spot welder

Post by 999zip999 » Feb 19 2020 3:58pm

You have a picture or link.

User avatar
flippy   1 MW

1 MW
Posts: 1631
Joined: Aug 12 2015 3:07pm

Re: kWeld - "Next level" DIY battery spot welder

Post by flippy » Feb 20 2020 1:47am

tatus1969 wrote:
Feb 17 2020 3:19am
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.
i would buy a dozen
Lithium beats liquid dinosaurs.

User avatar
tatus1969   1 kW

1 kW
Posts: 320
Joined: Mar 17 2017 7:36am
Location: Germany
Contact:

Re: kWeld - "Next level" DIY battery spot welder

Post by tatus1969 » Feb 26 2020 1:19pm

The Maxwell caps arrived last week, I have got roughly 800 of them and have put them up in the shop: https://www.keenlab.de/index.php/product/bcap0650/

I am currently doing measurements with them, but so far they appear to be in perfect condition. Measured internal resistance is approximately 0.5 milliohms (!) at 50A test current, which is quite a bit lower than their rated "initial max" of 0.8 mR. Scope screenshots and my setup attached to the post. Capacitance is spot on, leakage current is ongoing (I need to wait a few hours to allow the voltage settle)

Very important: this is the laser weldable variant, which either needs a bit of creativity or a decent welder to attach bus bars or cables to them. Andrew from hiketech (my AU reseller) plans to do tests with his TIG welder, but if you are fine with this hardcore DIY route then a few of them in series (4S should be optimal) would make up a very decent pulse power supply for kWeld. Or, some other kind of project that needs lots of current - the combined short circuit current of all ~ 800 cells that I have here is 2,720,000 amperes 8) 8) 8) 8)
bcap0650.jpg
bcap0650.jpg (105.73 KiB) Viewed 37 times
Attachments
esr-di.jpg
esr-di.jpg (73.59 KiB) Viewed 37 times
esr-dv.jpg
esr-dv.jpg (73.19 KiB) Viewed 37 times
capacity-i.jpg
capacity-i.jpg (69.8 KiB) Viewed 37 times
capacity-v-t.jpg
capacity-v-t.jpg (74.58 KiB) Viewed 37 times
IMG_20200226_180059.jpg
IMG_20200226_180059.jpg (104.08 KiB) Viewed 37 times
Resistance is futile - We Are The Watt.

User avatar
flippy   1 MW

1 MW
Posts: 1631
Joined: Aug 12 2015 3:07pm

Re: kWeld - "Next level" DIY battery spot welder

Post by flippy » Feb 26 2020 2:38pm

tatus1969 wrote:
Feb 26 2020 1:19pm
Very important: this is the laser weldable variant, which either needs a bit of creativity or a decent welder to attach bus bars or cables to them.
if only there was some way to spot weld tabs on these things.... :roll: :mrgreen:
Lithium beats liquid dinosaurs.

Post Reply