I’ll try cleaning and testing tomorrow. Will post the results.
I also asked Amy from Spintend to have a look on this thread and see what they can make out of this. I appriciate the help 
The ubox single comes with xt90 connection from the factory, and it looks like youve switched to bullet connectors. Is it possible that the wires warmed up enough to weaken the solderjoint to the pcb when soldering on the new connectors? Enough that the wire came off from that one impact, shorted through something or sparked? Or maybe it was just weak from the factory to begin with.
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I suppose I shouldn’t rule it out. Its a short cable. Could hardly blame Spintend for a weak solder when it might as well be my fault…
Good thinking
I doubt that’s causing this. You’d have to have a very powerful iron to get it hot enough to heat up the wire that far.
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I think a lower power iron would actually be more likely to do that. The short version is that thermal transfer works quite like electrical paths: temperature difference is analogous to voltage (it’s a high thermal driving potential), thermal resistance to electrical resistance, and heat flux to current. A high power iron can drive a high heat flux across a smaller temp difference, so you can quickly bring a joint up to the set temp of the iron without having to slowly cook the wire and bring the whole thing up closer to iron temp.
As an example, look at spot welding. Crazy high power for a very short space of time gives you a very intense but super localised heating effect. I can draw out some diagrams, heat transfer classes actually use electrical drawings with the same resistor symbols sometimes.
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Hmm I super respectfully disagree. For a given power draw, voltage and current draw are inversely proportional. Heat generation = energy loss which correlates directly to current following Joules law.
So in your example, the spot welder is low voltage, high current.
This is the reason power lines carry high voltage (~350kV) to stations who transform it to 69kV who then send it to local transmission lines that are around 15kV and finally to homes where we use only 110/220V.
If the wire is getting hot, a lower current or higher voltage would be needed to not overheat that wire acting as a resistor. Or a bigger wire.
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It kind of looks like when I do a really shitty soldering job. It could be that there is more than one cause. Bad soldering along with bad positioning.
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Looks like the solder did not properly wet the pad. I.e. the copper did not heat up enough during assembly
I’d blame factory soldering.
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but sometime you can burn the thin plated copper also if the soldering iron is to hot, this happen to me fews years ago with my ebike controller , now I use ajustable temperature iron
l 100% agree with linesflag , the leads are soldered very close to the wall of the aluminium enclosure
btw did you use a fuse between the vesc and battery?
Ooooff, does this mean I should’t buy one. Has anyone else had negative experiences with these single ubox vesc?
I recommend using this station
https://www.jbctools.com/cdb-soldering-station-product-1605.html#composition
Has excellent thermal control.
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Looks like one of the fets blew up
This photo shows the + pad a lot better and it looks like the positive may have simply desoldered itself due to high currents. Looks IMHO like the red B+ being loose is a symptom and not a cause.
The thing I am focused on, is what is this from?
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Could it be where the pos wire got shorted after it camed loose?
I mean obviously it could, but if the wire came loose I feel like it’s a lot more likely to be pulled out of the ESC rather than shoved into it.
But that’s just my $0.02
I didn’t see how this was mounted.
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as you said, it depends on how it was mounted. Any loop/excess battery wire it could easily push the wire in
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Could very well be the fet failed, caused a dead short, and the positive wire solder joint became the fuse and desoldered as the fet was burning away. That’s some pretty catastrophic damage. I mean that fet is completely vaporized! Impressive.