JP spot-welder, FET-switched, timed adj. pulse
- Thread starter okashira
- Start date
@Vicens - I've welded first and then soldered, but cells don't heat at all since nickel is getting all the heat, you can see it by the way that the solder is spreading, and by touching the cell after, it's dead cold. Yeah, 110 Ah should be great for that!
@okashira - great stuff, thanks! That's some serious current, I really have to compliment these mosfets
8)
@netpro - now you have two sets of osc. shots
@okashira - great stuff, thanks! That's some serious current, I really have to compliment these mosfets
8) @netpro - now you have two sets of osc. shots
okashira
10 kW
riba2233 said:@Vicens - I've welded first and then soldered, but cells don't heat at all since nickel is getting all the heat, you can see it by the way that the solder is spreading, and by touching the cell after, it's dead cold. Yeah, 110 Ah should be great for that!
@okashira - great stuff, thanks! That's some serious current, I really have to compliment these mosfets
@netpro - now you have two sets of osc. shots
The 3,900 amp test would instantly blow the mosfets normally.
With the diode - I was able to do it repeatedly - did like 20 times in a row rapidly, no blown mosfets yet.
The diode is really helping. :-D
I did look at source to drain voltage and it's still hitting avalanche for sure. It spikes to 28V for a few microseconds when the fets turn off.
okashira
10 kW
3900 amps for 20 ms..
I'm using 8.2V..
That's 32kW of power and 0.02 * 32000 = 640 Watt Second of energy total peak weld energy.
Energy imparted into the weld is probably ~20% of that - 130 Watt Second or so.
I'm using 8.2V..
That's 32kW of power and 0.02 * 32000 = 640 Watt Second of energy total peak weld energy.
Energy imparted into the weld is probably ~20% of that - 130 Watt Second or so.
Diesel Dave
1 mW
Master class in soldering batteries, good use of de-solder braid as connector too.
http://youtu.be/IelXfcrIXCc
http://youtu.be/IelXfcrIXCc
vicens
100 W
riba2233 said:@Vicens - I've welded first and then soldered, but cells don't heat at all since nickel is getting all the heat, you can see it by the way that the solder is spreading, and by touching the cell after, it's dead cold. Yeah, 110 Ah should be great for that!
@okashira - great stuff, thanks! That's some serious current, I really have to compliment these mosfets
@netpro - now you have two sets of osc. shots
I could not buy the battery 110Ah. It was shabby.
I can use one of 70Ah 540A CC. I have in my car. And put another smaller battery in my car.
The battery 70ah be a good welding 0.2 milimeters Nikel strips?
It would be better to look for a battery of 95 / 110Ah?
It would be better to buy two batteries of 45Ah. Connect batteries in parallel? the 45Ah batteries are almost given away. Bought second hand 15 euros each. With guarantee.
vicens said:riba2233 said:@Vicens - I've welded first and then soldered, but cells don't heat at all since nickel is getting all the heat, you can see it by the way that the solder is spreading, and by touching the cell after, it's dead cold. Yeah, 110 Ah should be great for that!
@okashira - great stuff, thanks! That's some serious current, I really have to compliment these mosfets
@netpro - now you have two sets of osc. shots
I could not buy the battery 110Ah. It was shabby.
I can use one of 70Ah 540A CC. I have in my car. And put another smaller battery in my car.
The battery 70ah be a good welding 0.2 milimeters Nikel strips?
It would be better to look for a battery of 95 / 110Ah?
Connect batteries in parallel? the 45Ah batteries are almost given away. Bought second hand 15 euros each. With guarantee.
I would do what is cheapest, if two 45AH battery are cheaper I would get two of those. Then if you need to weld .3 nickel you can get a 3rd 45AH battery.
I believe .2 nickel strip will require a larger / higher CC battery. I can do it on my 875 CA / 700 CC battery. When using .2 nickel you can't push down too hard with the probes or it won't weld.
Nobody has really given me a straight answer on if it is better to use higher amps when welding, or a longer pulse time and lower amps. I get the feeling it is better to use a lower pulse time and higher amps or be able to weld around 5-10ms pulse time. But you can't have too many amps because you will just burn holes.
The other thing which complicates everything is how hard you push with the probes makes a big difference in the welds. Lightly pushing you can weld with lower amps. Another factor is a lot of people are probably using nickel plated steel and don't even know, which is much easier to weld than 99% nickel strips. I would be surprised if you actually found 99% .2 nickel, seems most .2 nickel are nickel plated steel.
All these things seem to complicate getting any set numbers on what battery, pulse time you need to use. So I believe it is best to experiment, start with a smaller battery and keep adding until your welds are good. Two 45AH batteries are a good start. The most important thing is to see how pushing down on the probes makes a big difference, push lightly and weld and then push hard and you will see a big difference in the welds.
markz
100 TW
Go to your local automotive scrap/junk yard.
Pick yourself up a $20 heavy duty truck battery, which are wider, longer and heavier then a car battery.
Then you can have 500 or more amps running centimeters from your skin in an insulated material.
Be safe guys!
Pick yourself up a $20 heavy duty truck battery, which are wider, longer and heavier then a car battery.
Then you can have 500 or more amps running centimeters from your skin in an insulated material.
Be safe guys!
> Then you can have 500 or more amps running centimeters from your skin in an insulated material.
Haha, that was funny
We are only talking about 12V here.
The Amps are: I=U/R=12V/100,000Ohm=0.00012A
In your chart that is below the "Threshold of Sensation" level
The 500Amps will only ever flow in the metal that is "parallel" with your skin because the metals resistance is so low..
No insulation is needed.
Cheers, Ulli
Haha, that was funny
We are only talking about 12V here.
The Amps are: I=U/R=12V/100,000Ohm=0.00012A
In your chart that is below the "Threshold of Sensation" level
The 500Amps will only ever flow in the metal that is "parallel" with your skin because the metals resistance is so low..
No insulation is needed.
Cheers, Ulli
vicens said:riba2233 said:@Vicens - I've welded first and then soldered, but cells don't heat at all since nickel is getting all the heat, you can see it by the way that the solder is spreading, and by touching the cell after, it's dead cold. Yeah, 110 Ah should be great for that!
@okashira - great stuff, thanks! That's some serious current, I really have to compliment these mosfets
@netpro - now you have two sets of osc. shots
I could not buy the battery 110Ah. It was shabby.
I can use one of 70Ah 540A CC. I have in my car. And put another smaller battery in my car.
The battery 70ah be a good welding 0.2 milimeters Nikel strips?
It would be better to look for a battery of 95 / 110Ah?
It would be better to buy two batteries of 45Ah. Connect batteries in parallel? the 45Ah batteries are almost given away. Bought second hand 15 euros each. With guarantee.
Well in this case 2x45 should be optimal, if they are still alive
Voltages up to 24 V are considered safe, so you can touch electrodes even if there is 1000000 amps flowing
Current just wont enter body because voltage is not enough to break the isolation of body.
Yes, you won't ever get electrocuted by this welder but there are hazards to be careful of. Always wear eye protection. If the FETs blow, you might have some wires getting really hot, creating a burn/fire hazard. Some kind of slow blow fuse might be a good idea.
tomjasz
1 GW
Case, 60 hg2, and new BMS arriving soon. Woohoo!
markz
100 TW
All I am saying/typing is to be safe.
tomjasz
1 GW
Jeebus, rubber gloves, safety glasses and no jewelry. We'll all live.
vicens
100 W
How big must be the cable connecting the two batteries?
¿25 millimeters in diameter?
¿25 millimeters in diameter?
I only had a tiny 13Ahr, 10-year old lead-acid battery in the garage, so I added some capacitors that I did have:
Seems to work OK with .15mm nickel at 15ms.
View attachment 1
I'll be getting a bigger battery, but it's pretty impressive how well it works with the small one. I do get some sticking of the positive electrode but it's not too bad.
Now on with the project:
Seems to work OK with .15mm nickel at 15ms.
View attachment 1
I'll be getting a bigger battery, but it's pretty impressive how well it works with the small one. I do get some sticking of the positive electrode but it's not too bad.
Now on with the project:
riba2233 said:[
@fechter - very interesting, so it gives performance in range of ~30-35 Ah lead battery
I guess I should try it without the capacitors and see if there is a difference. The Enersys battery has a pretty low internal resistance, so might be doing all the work.
OK, I tried disconnecting the caps and it still makes good welds. I don't think those caps were helping much. They're only 9600uF each. If they were more like 1F each, it would help.
I do have another of the same size battery. I'll try adding that instead of the caps and see how it goes.
I do have another of the same size battery. I'll try adding that instead of the caps and see how it goes.
Yes, these were exeptionally good at high rates. This is a sealed AGM type.
I wanted to install a diode so I don't need to worry about inductive spikes. I made one from a pair of FETs I had lying around. The gate and source are shorted so the FET is off, and we are using the intrinsic body diode. FDP8860 are only good for about 500A each. Later I found some IRFB7430 which have a body diode pulsed rating of 1,576A each! That should be enough. I could have bought some diodes, but I had FETs in stock and they might actually perform better than most diodes in this application.
I just took the FETs and snipped off the middle (drain) leg. The remaining legs just get soldered together. Pretty much all FETs in this package have the same pin out.
Diode Assembly:
Connection detail:
I wanted to install a diode so I don't need to worry about inductive spikes. I made one from a pair of FETs I had lying around. The gate and source are shorted so the FET is off, and we are using the intrinsic body diode. FDP8860 are only good for about 500A each. Later I found some IRFB7430 which have a body diode pulsed rating of 1,576A each! That should be enough. I could have bought some diodes, but I had FETs in stock and they might actually perform better than most diodes in this application.
I just took the FETs and snipped off the middle (drain) leg. The remaining legs just get soldered together. Pretty much all FETs in this package have the same pin out.
Diode Assembly:
Connection detail:
