Author Topic: kWeld - "Next level" DIY battery spot welder  (Read 47791 times)

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Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #100 on: July 16, 2017, 02:05:48 AM »
Quote from: tatus1969
It will not be possible to place an order for that before
I'll have to take that back, I just wasn't familiar enough with that system.

Sorry for the confusion!!!

WOW, that's an endless world of possibilities there! If someone needs a guide to setting up a Wordpress + Woocommerce server, here is another expert   ;)

Okay, no more products added there yet, but I managed to set up the full chain for the electronics module, including
- accepting pre-orders now - I'll serve them in the order that they come in
- the option whether you want me to complete it (solder LCD and dial pot), or you want to do that
- world wide automatic shipping rate calculator
- safe credit card payment via stripe

I'll add Paypal as well, but my business account there needs verification and they told me that this would take 2-3 weeks  :shock:

I've set the limit to 20 copies now, to accomodate the possibility that not all of the 25 ordered are good.

Please order only one per person for now, in order to allow others receiving one. I need to refuse larger orders for the first batch. No problem of course later, after successful ramp up!

If you plan to purchase other options that are not in the store yet, please wait and you'll be offered a combined shipping rate. So you don't need to pay shipping twice.

I've activated the website again and do accept orders  8)
« Last Edit: July 16, 2017, 04:52:39 AM by tatus1969 »
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens.

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Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #101 on: July 16, 2017, 02:49:27 AM »
I just went to pre-order. The price has gone up from 89 Euro to 99 Euro.

Is this correct please ?

Fraser
 

Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #102 on: July 16, 2017, 02:54:53 AM »
I just went to pre-order. The price has gone up from 89 Euro to 99 Euro.

Is this correct please ?

Fraser
No, I separated it differently before. It was
- 89€ for the partially soldered board
- 10€ for the additional components LCD / dial pot / pin header / knob

Now it is everything included in one package. I thought that it didn't make much sense to sell these separately. I initially did that because, if you want to design a housing for it, then you will want to use a different potentiometer type. This one does not have a mounting thread. But that part is worth less than 1€, so I canceled that now.
« Last Edit: July 16, 2017, 02:57:12 AM by tatus1969 »
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens.

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Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #103 on: July 16, 2017, 03:15:18 AM »
 No worries :)

I see from your letter you will be adding additional items. I have one controller board in my basket. I will add to that later.

Best Wishes

Fraser
 

Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #104 on: July 16, 2017, 07:06:25 AM »
The remaining items are online as well. As I will be doing all the soldering, machining, and assembly work by myself for the time being, I need to set the prices for that relatively high. When this product is ramping up nicely, then this may change in the future.
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens.

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Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #105 on: July 16, 2017, 07:49:12 AM »
I have just placed my pre-order. I went for the partially unassembled PCB, two 300A fuses (one and a spare) plus the raw bus bars. The rest I can sort out for myself.

This design is exactly what I have been searching for :) Perfect !
I know the parts for the PCB were not cheap so thanks for the hobby friendly pricing.

There was mention of a programmer for updating the firmware on the unit. Some details of the required programmer would be appreciated.

Best Wishes from the UK

Fraser
 

Online Kjelt

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #106 on: July 16, 2017, 08:27:04 AM »
I'll order tomorrow, have to figure out what to get, are those high current connectors shown in any video already?
 

Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #107 on: July 16, 2017, 08:35:16 AM »
I have just placed my pre-order. I went for the partially unassembled PCB, two 300A fuses (one and a spare) plus the raw bus bars. The rest I can sort out for myself.
Got it! Thanks!

I know the parts for the PCB were not cheap so thanks for the hobby friendly pricing.
Yes, especially the MOSFETs. But I decided pro robustness and to accept a higher price for that. Also the microcontroller had to be a bit beefier because it has to do the entire energy calculation algorithm and all safety measures in a 10µs cycle.

There was mention of a programmer for updating the firmware on the unit. Some details of the required programmer would be appreciated.
It's very simple, a FTDI RS232 adapter and a cable. The red socket on the welder is a combined UART / JTAG interface. The firmware will run a dedicated in-application-programming code. I cannot show this part yet because it is not ready yet. That will take some more days to implement, the framework and the theoretical design is finished.
« Last Edit: July 16, 2017, 08:37:31 AM by tatus1969 »
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens.

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Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #108 on: July 16, 2017, 08:43:18 AM »
Wonderful news on the programmer. Thank you for keeping it simple. I have lots of FTDI RS232 converters  :)

I shall start planning my version of the probes, case and power source. I have plenty of time to source the required parts.

Best Wishes

Fraser
 

Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #109 on: July 16, 2017, 09:02:40 AM »
Wonderful news on the programmer. Thank you for keeping it simple. I have lots of FTDI RS232 converters  :)
You need one without level shifter that uses 3.3V TTL levels. The pinout of the red connector is here in the thread:

http://www.eevblog.com/forum/projects/guesses-on-what-i-am-attempting-here/msg1240839/#msg1240839

Not to forget: the schematic there is not up to date anymore, nor is it working like that 8)
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens.

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Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #110 on: July 16, 2017, 09:46:35 AM »
Many thanks. I have 3V3 types as well as 5V so all sorted on that front :)
Will the documentation that comes with the unit contain a schematic and brief theory of operation please ?

Best Wishes

Fraser
 

Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #111 on: July 16, 2017, 08:28:13 PM »
I have now ordered the following via eBay:

1m Red 8AWG Turnigy Silicone coated cable
1m Black 8AWG Turnigy Silicone coated cable
Ten 100mm Brass tubes - 6mm with 1mm wall
300mm x 4mm copper rod
Ten high quality solder/crimp lugs. 10mm2 / 6mm

I wanted more parts than are actually needed to enable me to experiment a little. The cost mounts up though. The kits offered by the OP are very good value and recommended for most users of the unit.

With regard to terminating the cables with the large lugs. There are two options open to me, Soldering or Crimping. Crimping can be a reliable connection, but only if a quality crimp is made. This normally requires an expensive high quality crimper. The crimp needs to be sit tight to avoid oxidation issues. Where such a high quality crimp is not possible, soldering is the preferred method, even in high current applications. The solder fills the voids and provides an excellent connection to all cable strands. The down side of soldering is that the solder can travel down the cable making the area adjacent to the connector stiff. I am going to so,dear mine with my high powered soldering iron.

Fraser
 

Offline TheAmmoniacal

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #112 on: July 16, 2017, 10:03:51 PM »
Great little device you've made  :-+

I'm just curious, would it help to use flux? Common solder one or plumber type? Sure it will just burn into smoke rapidly, but will the surface finish/oxidation, and color look better? Any difference in the quality of the weld?
I collect [corporate] mugs.
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Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #113 on: July 16, 2017, 10:33:15 PM »
Will the documentation that comes with the unit contain a schematic and brief theory of operation please ?
Noted, I'll include that.

This normally requires an expensive high quality crimper.
I've ordered one of these, they are not as expensive as you might think. They develop huge force and should make reliable, gas-tight crimps.



Great little device you've made  :-+

I'm just curious, would it help to use flux? Common solder one or plumber type? Sure it will just burn into smoke rapidly, but will the surface finish/oxidation, and color look better? Any difference in the quality of the weld?
Thanks  :)
Its welding not soldering, the temperatures are way higher here, maybe 1000degC. I think that flux will just vaporize or burn.

The welds actually look better than many of those which I showed in the videos. That was letting you participate in me experimenting, and of course to discover the limits. A typical weld of 0.1mm nickel strip to an 18650 cell typically does not produce any coloring.

I just made these welds on a dead battery to show how a regular weld looks like: this is 0.2mm 0.1mm nickel strip, the energy is set to 30J. It can probably still be lowered.



EDIT2: Okay, I'll have to take back everything that I said about using flux. The below welds are with 0.2mm nickel strips, and you can see the coloring which cannot be prevented when doing it as usual. Except both leftmost welds per cell, where I added a drop of flux! Awesome, I can definitely recommend that to everyone! The used flux was Chipquik SMD291.



« Last Edit: July 16, 2017, 10:47:12 PM by tatus1969 »
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens.

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Offline TheAmmoniacal

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #114 on: July 16, 2017, 10:36:26 PM »
Those welds do look great, no improvement needed! Maybe try a few with flux for fun? :)
I collect [corporate] mugs.
MTBF ~ 700.000 h
 

Online tautech

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #115 on: July 16, 2017, 10:48:10 PM »
Those welds do look great, no improvement needed! Maybe try a few with flux for fun? :)
I don't see any point, if you watch the vid there's an attempt to tear the spot welded strip off and to apply additional force than what was shown would only tear the strip or the battery.
This IMO gives the same result as professionally welded battery packs and you never see flux on them.
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Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #116 on: July 16, 2017, 10:55:11 PM »
Those welds do look great, no improvement needed! Maybe try a few with flux for fun? :)
did that, updated my previous post  ;)
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Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #117 on: July 17, 2017, 12:34:27 AM »
Regarding cell surface condition.......

OEM's would reject any cell that showed oxidisation or corrosion on the welding surfaces. I have bought many new Ni-Mh cells at discounted prices because they have suffered some level of corrosion on the end caps. Such cells are easily 'recovered' by cleaning the surfaces before spit welding. An OEM does not want such hassle and does not use flux as a result.

Cleaning of cell end caps is a good idea, especially if they have been sitting around for a while. Oxide layers do effect the way the weld forms as they have to be burnt off. This MAY be the true reason behind the double pulse protocol used by some battery tab welders.

I so no problem with using electronics rated flux when welding, it burns odd and cleans the surfaces in the process.

One matter that needs consideration when welding cells is heat. If too much heat is present on the cells surface, damage can result. This is especially so with button cells. Plastic seals can melt or boiling of the cells electrolyte can result.  The minimum weld current and duration should be used in such cases to avoid cell damage. The thin nickel tabs can be discoloured by the very high temperatures and I would be a bit careful about seeing that if working with fragile cell constructions, such as button cells. When using my Chinese Tab welder the cells surface does not get too hot to touch and the tag rips before the weld breaks. There is no discolouration around the welds but they are a lot smaller diameter ! I do prefer the welds produced by this DIY version. Far more in keeping with those I have seen on commercial batteries.

Fraser
 

Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #118 on: July 17, 2017, 06:10:22 AM »
hmmmm. Fraser that's very interesting, but I'm not sure if you have understood me correctly. I haven't added flux between battery and tab, but between tab and electrode.
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens.

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Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #119 on: July 17, 2017, 06:21:10 AM »
Ooooh, I had not thought of that. Interesting.

Fraser
 

Online Kjelt

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #120 on: July 17, 2017, 06:50:38 AM »
Also placed my pre-order (see your pm)  :-+ .
Just wondering where do you order those metal strips that you use for the batterypack assembly ? Link ?

 

Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #121 on: July 17, 2017, 08:03:17 AM »
Also placed my pre-order (see your pm)  :-+ .
Just wondering where do you order those metal strips that you use for the batterypack assembly ? Link ?
I got them from ebay, the search term is Hilumin strip, or battery spot welding nickel strip. For example http://www.ebay.de/itm/2m-Solid-Pure-Nickel-Strap-Strip-Spot-Welding-battery-12mm-x-0-15mm-12x0-15-40A-/263057602801
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Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #122 on: July 17, 2017, 08:16:10 AM »
I have several types of strip that I bought from eBay. Some are described as pure nickel whilst others are nickel plated steel. I am uncertain whether the nickel plated steel is any good as I have yet to use it. I do know that it is important that the strip is not TOO conductive as that can present a very low tab resistance path to the probes. This may reduce current flow into the battery cap, and may result in a lower quality weld. That is why you do not see copper battery tabs on welded batteries.

Fraser
 

Offline tatus1969

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #123 on: July 17, 2017, 08:58:14 AM »
I forgot to mention, I recently tested these ones:

http://www.ebay.de/itm/10-St%C3%BCck-Hochstrom-L%C3%B6tfahnen-L%C3%B6tbr%C3%BCcken-Akkuverbinder-zb-f%C3%BCr-18650-27x9x0-3/162191637024?ssPageName=STRK%3AMEBIDX%3AIT&_trksid=p2057872.m2749.l2649

Their advantage is that they are 0.3mm and can carry higher battery currents, and they can yet be welded with low energies because of their pre-shaped spots. Just make sure not to repeat my silly mistake and always probe pairs of contacts with the slit inbetween.
Your living is determined not so much by what life brings to you as by the attitude you bring to life; not so much by what happens to you as by the way your mind looks at what happens.

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Offline Fraser

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Re: low cost DIY battery spot welder [guesses on ... - solved]
« Reply #124 on: July 17, 2017, 09:01:35 AM »
 This article caught my eye. How to check what strip material you have been sold ...... pure nickel or the cheaper plated steel.

http://www.ebikeschool.com/how-to-differ-between-pure-nickel-strip-battery-tabs-vs-steel-core/

It looks like for my battery applications, steel tabs will be fine. I am not working at high currents where small resistive losses become a factor.

Fraser
 


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