JP spot welder

[bigbore]

Actually, I think Adaptto is working on active BMS.

Hi Allex, do you anticipate this being a firmware update for existing owners?

Surely not. An active BMS must be something completely different from the BMS we have now.

 

[jmz]

Hey welder-afficionados, you might be interested in following the progress of my own capacitive discharge spot welder in my build thread:

https://endless-sphere.com/forums/viewtopic.php?f=3&t=73499&p=1116916#p1116916

It's based on ~420 mF of 50V electrolytic caps, and 12x 60V 1.6 mOhm mosfets.

Went into the lab on a fine Sunday to work on the welder, made some good progress.

I tested the gate drive circuit, hooked up to the 12 BSC016N06NS FETs (3 empty slots on the board due to removing some while debugging, thought 12 will still be plenty for now) in parallel, it made light work of them, driving them at 7 V for a 250 ns rise time and 100 ns fall time.

I made up some welding leads from triple braided speaker cable, hooked up to 8 mm terminals.

Using a 10 amp current-limited source, I made some kelvin measurements of the voltage drop across the whole circuit including the leads. 27 mV total, yielding 2.7 milliohms (!!!) total series resistance. This neglects the ESR of the capacitor bank itself, and the extra lead that will be required from the negative terminal of the ban to the common-source busbar.

Measured busbar-to-busbar, the voltage was 3.8 mV at the 7 V gate drive voltage, or 3.4 mV at a 12 V gate drive voltage, giving a total switch+busbar resistance of 0.34 milliohms. Based on the nominal Rdson of 1.6 milliohms, 0.13 milliohms of that will be the FETs, and the rest will be in the busbars and solder joints.

Pulse testing to begin next week, I'm going to need to get myself an arduino or something. Also find some welding probes that will hopefully bolt straight into those 8mm terminals.

https://imgur.com/a/0zHgh

What are the recommended pulse timings + currents for welding 0.3mm nickel tabs?

 

[riba2233]

Ideally you would have 2500+ amps for less then 7 ms.

What if you burn mosfets on your design, it looks like PIA to repair

 

[jmz]

Yes, massive PIA. So I will try not to blow them up! (Hence snubber design, low inductance bus bars)

 

[999zip999]

Keepler your small pack is interesting. I do like packs without bms, but always 15-20ah of weight. Like to hear how it holds up. High quality cell. Make a worth your time.
I have problems with that hyperion eos sentry as cell 5 is always high. ? Is this jacking a thread ? Sorry I just saw that cell checker and it's 7s a little weird.

 

[riba2233]

Yes, massive PIA. So I will try not to blow them up! (Hence snubber design, low inductance bus bars)

Well, chances are that you are going to blow few sets while still experimenting, I know that from experience :lol:

 

[Golyo]

Hi Riba,
an update on the timeline would be appreciated.

 

[jmz]

Ideally you would have 2500+ amps for less then 7 ms.

What about when using dual pulses? Is it recommended these days?

 

[okashira]

Ideally you would have 2500+ amps for less then 7 ms.

What about when using dual pulses? Is it recommended these days?

Very much so. around 1/3 time for the first pulse

 

[riba2233]

Sure, that's very important! 1/3 might be too much, first pulse shouldn't do welding, only cleaning, but 1/5 or 1/8 is fine.

 

[ecycler]

Keepler your small pack is interesting. I do like packs without bms, but always 15-20ah of weight. Like to hear how it holds up. High quality cell. Make a worth your time.
I have problems with that hyperion eos sentry as cell 5 is always high. ? Is this jacking a thread ? Sorry I just saw that cell checker and it's 7s a little weird.

LOL. I would say that is a total thread jack in the making.

 

[riba2233]

Ok, some news, you can see the manual for the DIY version in the first post, and also there are pictures of new welder in it! I will put photos of electrodes and footswitch soon also.

 

[Allex]

Amazing guide, I want to build one, just for fun

 

[marty]

Good job with manual! Like the pictures!

on Wed Oct 14, 2015 8:28 am
Please put me on the list for a 3d printed case.

Yes I know there is no 3d printed case. If there ever is? I am number 1 on the list.

 

[Craigh85]

Looks good Riba. I'm keen for a DIY kit, hopefully I'm not too far down your list. Already got a huge 120ah battery

 

[riba2233]

Looks good Riba. I'm keen for a DIY kit, hopefully I'm not too far down your list. Already got a huge 120ah battery

I'm glad you people like the manual 8)

Craigh don't worry, you're not to far!

 

[tomjasz]

EXCELLENT job on the manual. I hope you don't run into problems with buyers overstepping their skill level, trying to save themselves $40, and screw up the build. EM3ev stopped selling controllers for BBS0x when asshats "played" programers, burned out their controllers and insisted on warranty coverage.

 

[bigbore]

Amazing guide, I want to build one, just for fun

Would you like to build mine? .... just kidding :lol:

 

[okashira]

Awesome!!!

 

[riba2233]

Thanks 8)

 

[geckocycles]

I would like to get on the list for a DIY or prebuilt kit. Is there a ETA to the US and how do I proceed? I bought one that will barely weld the included .1mm tab material to itself without several hits. I want to weld 40A tab material. Not sure why all these guys use .12mm tab material and double or triple the tab material to itself. Why not just use .3mm material to start with?

When I raced RC cars we soldered heavy copper bars to NiCads for the least resistance and did away with spot welded tabs. I guess these Lion cells can't handle that heat?

 

[riba2233]

They shouldn't handle that heat. You can bypass welding 0.3 or any thick nickel by welding cells in parellel with thin nickel first, and then make series by soldering copper wire on the nickel between cells, this way you wont damage cells with heat in any way, and you'll get more than enough current carrying capacity, which is very hard or impossible with nickel only, any thickness.

As for orders to people outside EU, I need to go through the list to see how many people are still interested, and then I'll know more on time frames and such.

 

[zeremefico]

Hi, I am interested in your welder.
Can you inform me about availability?
I live in Greece.

 

[Lucasimo]

Mine arrived this weekend! Very happy Now all I need to do is find a 12V lead acid car battery and start welding !!! top job.

 

[mushymelon]

Just finished my first custom pack.

Works Awesome thanks JP



Heres a link to the build

Custom Kona

This opens all kinds of possibilities for custom builds great work.

Matt