JP spot-welder, FET-switched, timed adj. pulse

[Offroader]

That .375" by .005" is equivalent to 10mm x .127mm. It is nothing compared to .3mm nickel, extremely easy to weld.

It's probably steel plated and really cheap low amp rated stuff. I actually bought similar stuff on ebay.

Buy this instead, takes less than 2 weeks to arrive.

Unless you are building a really low powered battery I would get at least this below. I personally tested this stuff and its 99% nickel.

http://www.aliexpress.com/item/Free-shipping-18650-battery-nickel-strip-0-15mm-nickel-plate-li-ion-cell-nickel-belt-Cylindrical/2050759694.html?recommendVersion=1

 

[Hwy89]

The strip from Sunstone engineering is listed as .99 nickel. This was the third time I've purchased it from them and have put together five bike packs. I have always used pre-tabbed 18650's and soldered the nickel strips to the tabs. This will be my first go at welding to the cells. It should be much quicker than soldering my 16p 12s packs.

 

[Offroader]

I have a welder on order that should arrive in a few days. I have also purchased a spool of nickel strip from http://www.sunstoneengineering.com. The strip is .375" by .005". I've determined that .005" = .127mm.
I admit to being dumb about metric measurements but I would like confirmation that the .3 nickel that Offroader had problems with is .3mm not .003".
Also where does one find the current carrying capacity of different strips?
Thanks Riba for all that you have done and I hope you get well soon.

Yeah, that's 0.3 mm, and thank you!

I don't know why AU version is cheaper, it should be even more expensive. They are electrically 100% the same, and sometimes I had to buy AU version because regular version was out of stock.

Thanks Riba, If they are cheaper and the same, why didn't you always buy the AU version? You mentioned you only bought them when the regular version was out of stock.

 

[okashira]

okashira, since you mentioned blowing a lot of your fets. Do you have any tips for finding which fets are bad? Or do I have to desolder and remove them out of the welder?

I do notice one fet has continuity between drain and source.

But it looks like there could be burn marks on others, but very slight.

Should I just pull them all out and replace them all?

Thanks.

That is interesting, are all your crimps good and is the diode pointing right direction?
I have gotten almost 10,000 welds since adding diode and no blows yet. I run about 2,900 amps

 

[Offroader]

okashira, I was actually going to ask you about how to check the diode.

Yes the diode has to be right because I shorted my fets and now get 12 volts between the two probes. If the diode wasn't right I would for sure have melted it.

But is there a way to check the diode?

I didn't have a crimper so I filled the connector with some solder and pushed in my connector and solder came out, It is in there tight so I believe my connections are fine.

Is this a possibility? Could I have damaged a fet before and had maybe been running on 5 fets?

Before I added the diode I had my micro controller chip fail, and when it did I went to weld and I had a huge spark explosion without even pressing on the foot pedal. But everything seemed to be fine after the micro controller replacement.

But I am wondering if could be possible that I damaged my fets and weakened them?

 

[okashira]

okashira, I was actually going to ask you about how to check the diode.

Yes the diode has to be right because I shorted my fets and now get 12 volts between the two probes. If the diode wasn't right I would for sure have melted it.

But is there a way to check the diode?

I didn't have a crimper so I filled the connector with some solder and pushed in my connector and solder came out, It is in there tight so I believe my connections are fine.

Is this a possibility? Could I have damaged a fet before and had maybe been running on 5 fets?

Before I added the diode I had my micro controller chip fail, and when it did I went to weld and I had a huge spark explosion without even pressing on the foot pedal. But everything seemed to be fine after the micro controller replacement.

But I am wondering if could be possible that I damaged my fets and weakened them?

Yes!! running with a bad fet will ensure the other 5 fets are quickly destroyed.
always replace all 6 fets at once. Riba taught me this, I resisted, and learned my lesson.

 

[okashira]

If you have the same diode as me, looks like you have it right. What do you mean filled with solder? You did put a torch on it to actually solder it right ?

 

[Offroader]

Well, I didn't know if a FET was bad, I just say there may have been a possibility of some bad fets. But most likely there probably wasn't.

I did burn a hole through my battery when my welder failed and that could have damaged them, but I have no proof.

I held the solder iron to the side of the connector to heat it, then I filled it partially with solder and stuck in my wire while the solder was still liquid.

 

[Offroader]

okashira, when using the DVM diode tester function on that diode, what value do you get?


Normal diodes read about .5

This one reads about .1 something.

 

[okashira]

okashira, when using the DVM diode tester function on that diode, what value do you get?


Normal diodes read about .5

This one reads about .1 something.

It's a big ass Schottky diode. It should read nice and low.

 

[ridethelightning]

im about to start testing the jp welder with some headway cells.
i have 30 or so from an old pack.
im hoping to weld 0.1mm copper.
I found it quite easy using a dn10, but the key is tungsten tipped electrodes.

what would be the max number cells in parallel if using headways, and diode, to get the power required for 0.3nickel(im hoping this will be good for0.1Cu), ~2900A like fetcher is using?

and what voltage will it tolerate?

thanks.

 

[riba2233]

Thanks Riba, If they are cheaper and the same, why didn't you always buy the AU version? You mentioned you only bought them when the regular version was out of stock.

AU had even worse stock :lol:

 

[macribs]

Thread tl;dr.

Earlier in the thread someone was gonna use HK Lipo rather then car battery for the welder.
Did that work out? What kind of Lipos was in use and how many welds could be done before needing to charge the Lipo?

 

[douglashart]

Thnx again Riba! loving my spot welder. In fact I'm somewhat addicted to it now.(MORE BATTERIES!!!)After 300 or more practice welds I was getting very good welds but they always had a little color. Since they seemed, at least good enough, I started building. Im using a 'red optima' and .02x8mm. About halfway thru the build ,the welds progressively got better as the voltage went down on the battery. Now I'm making pristine welds at 11.5 to 12.5 v. Built a dummy BMS with the cutoff male connectors but not before toasting a couple boards. Another $127 lesson.

 

[douglashart]

Correction, after checking back on my orders, I used .18x8mm. As Offroader mentioned , it seemed too cheap to be the real, but ive tested by grinding and acid and it proves to be good stuff, tho the add quotes two different thicknesses .18 then .15 it actually seems to vary from .17 to.20

 

[Offroader]

I wonder why the welds would get better with lower voltage.

 

[riba2233]

@douglashart: You're welcome! Can you please tell me more about your BMS?


They probably got better because they were too strong at higher voltage (probably not because of voltage, but battery had lower IR). You should adjust pulse time as the battery is more or less charged.

 

[NetPro]

Thread tl;dr.

Earlier in the thread someone was gonna use HK Lipo rather then car battery for the welder.
Did that work out? What kind of Lipos was in use and how many welds could be done before needing to charge the Lipo?

That was probably me.
I bought 4 of these:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=19153
And the welds were great. Nice, clean, strong nuggets but I haven't build any packs yet.
Ran into electrodes problem and haven't had the time to build me a nice set.
Ordered the parts to build one with what I think are high quality components and will post an update when done.
I made 25 or 30 test welds and the LiPo pack went down .2 volts.
The weld time was approx 4 ms for 0.15 mm nickel and 6 ms for 0.2 nickel. Was quite impressed how short the weld time was using these LiPos.

 

[Offroader]

I added two 3s 5000 MAH 20C turnigy packs to my car battery and I assume this added so much power I blew my fets.

When trying to weld .3 nickel, sparks would shoot out with a lot of force.

Lipo cells have a lot of power compared to a car battery.

Make sure you don't use too many or you'll blow your fets.

 

[fechter]

I wonder if bypassing or lowering the value of the gate resistors on the FETs would improve their survival? Normally they put gate resistors to slow down the turn-on to avoid producing RFI and to limit the dv/dt. RFI generation is not really an issue here with single pulses.
Faster turn-on and turn-off might help.

 

[Offroader]

I wonder if bypassing or lowering the value of the gate resistors on the FETs would improve their survival? Normally they put gate resistors to slow down the turn-on to avoid producing RFI and to limit the dv/dt. RFI generation is not really an issue here with single pulses.
Faster turn-on and turn-off might help.

What value resistor would you suggest using?

 

[fechter]

What value resistor would you suggest using?

Zero ohm (jumper wire). Make them go as fast as possible. The driver chip will be the limiting factor.

I've also seen discussions where it's claimed that placing all the gates directly in parallel will tend to make them all switch on at the same time better. From the same batch, they will all be very close even with the resistors, but there are always some variations, like inductance in the gate circuit that cause tiny differences in the turn-on time. If one FET turns on before the others, it's toast. Due to inductance, they only need to be so close to work OK, but they need to be as close as possible.

 

[macribs]

Thread tl;dr.

Earlier in the thread someone was gonna use HK Lipo rather then car battery for the welder.
Did that work out? What kind of Lipos was in use and how many welds could be done before needing to charge the Lipo?

That was probably me.
I bought 4 of these:
http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=19153
And the welds were great. Nice, clean, strong nuggets but I haven't build any packs yet.
Ran into electrodes problem and haven't had the time to build me a nice set.
Ordered the parts to build one with what I think are high quality components and will post an update when done.
I made 25 or 30 test welds and the LiPo pack went down .2 volts.
The weld time was approx 4 ms for 0.15 mm nickel and 6 ms for 0.2 nickel. Was quite impressed how short the weld time was using these LiPos.

Seems Lipo would work and make for one truly portable spot welder
Any reason why you went for the more expensive nano-tech over the ie cheaper 3s zippy flight or 3s multistar? You could have twice the Ah for the same price and pack should last even more number of welds before charging.

I guess what I am asking is the high C rate of the nano tech Lipo really called for when used for spot welding?

 

[Offroader]

What value resistor would you suggest using?

Zero ohm (jumper wire). Make them go as fast as possible. The driver chip will be the limiting factor.

I've also seen discussions where it's claimed that placing all the gates directly in parallel will tend to make them all switch on at the same time better. From the same batch, they will all be very close even with the resistors, but there are always some variations, like inductance in the gate circuit that cause tiny differences in the turn-on time. If one FET turns on before the others, it's toast. Due to inductance, they only need to be so close to work OK, but they need to be as close as possible.

Would be interested to see someone experiment, but after blowing my fets I'm not big on experimenting anymore. Just a pain to replace the fets and costs money to order new ones.

I'd like to see how others are able to weld .3 nickel. Maybe i'm just doing something wrong. It seemed I had big issues with one side welding strong and one side very weak. But I couldn't seem to solve the problem with pressure alone.

I'll do some more experimentation when I replace the fets. I did order 13 of them so I guess I could blow them another time.

The other issue with experimenting with .3 nickel is that if you do get a good weld, almost only one of the two welds, when ripping it off the battery it will put a hole in the battery sometimes because it is so thick. This makes it hard to experiment with.

At this point I'm close to getting everything for my new build so I have to get my pack built soon.

 

[Craigh85]

Finally got round to hooking up my spot welder today. Managed around 200 great welds using a 12v car battery, then for some rrason unknown to me a blue flash came from the welder. Now I'm getting nothing. Green light still shows when I press pedal but that's all. How do I go about fault finding?. I've no idea what went wrong.