Sounds like you need some girth…
I’d recommend some 8-4awg CE Auto Electric Supply cable.
3 Likes
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.
2 Likes
yes I am, was planning on buying a kcap when available. Threaded posts are nice.
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 
7 Likes
some people flex money… We flex amps hahaha
I’m also wondering about Kcap availability as I don’t have it yet. Could all this be available from the US reseller?
3 Likes
The manufacturer is doing SMD component soldering at the moment. I expect to receive them by end of next week! No, my resellers don’t have stock either, they are waiting as well.
1 Like
quick update: still haven’t received the kCaps yet, since the manufacturer realized a problem with wave soldering the capacitors: the conveyor belt is slanted, causing the caps to tilt. Solving this with a clamp that will sit on top of them. New expected arrival April 3.
And I want to share a new video with you, from a fellow guy in New Zealand: https://youtu.be/DX1U3UnCej0
I’m very impressed by his video, it is such good that it can even replace my kWeld assembly document.
5 Likes
What happens, if someone shorts the NC cable from foot pedal to the main bus bar?
probably nothing as the pedal will just blow a wire or something, the bus bar and its mosfets can handle a shit load of amps 
But the voltage readings are a bit apart. .1 higher than in reality.
Depends on where COM is connected on the welder. One terminal is GND → nice flames. Other terminal is logic input, that is protected against overvoltage. That’s the answer to more or less all accidental shorts: either the unit survives, or it fails 
2 Likes
This is no precision multimeter, 2% voltage reading error can happen.
1 Like
It survived. (Kumpel hatte vergessen das nc kabel abzuschneiden. Ich normal benutzt. Aber funzt weiterhin tadelos 
)
At 5min 36 he suggests trimming off part of the crimp this compromises the strucal strength and electrical connection of the crimp by adding weak point in the crimp wall that is likely to deteriorate over time. I strongly advise agains this and his crimpers need recalibration/ replacing
1 Like
Thanks, very true and good input, would you mind to post this in the video comments?
Wondering if the kcaps will work with my malectrics arduino welder? I dont see why not if I understand it correctly the caps simply store current and release it when you go to do a weld, am I right in thinking this?
What’s the voltage of it?
1 Like
3s
10 char
Kcapps limited to 8.2v max
1 Like
I just got my Kweld and I bought some 600F Ultra caps with screw terminals. I wonder if I need some balance thing for them or could I just put the caps in series and apply my 3S Lipo to it (with some resistor to slow the current flow)?
1 Like