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I replaced 12x 12v batteries in my UPS stack this weekend and ONLY insta-welded two connectors.
(lemmy.world)
I see this as an absolute win. Be careful, folks. Just because it's DC doesn't mean it won't cause serious damage.
Edit for Clarification: When done correctly, the batteries should not arc. My problem is I did not wire the array correctly the first and a-hem second times. It only cost me one battery, which is a lot cheaper than a trip to an American ER.
Hm I have not heard about such an issue so far but I also don't have as many UPS as you.
I see you holding a red cable which could be +. When I switch UPS batteries, I do it the same way as it's recommended for car batteries to avoid sparks/arcs. Remove - (black) first, as it won't spark/arc. Then remove + (red) as it can't get a circuit closed any more, so also no spark/arc.
When plugging a car battery in, it's the other way around. + (red) goes in first and only then you connect - (black) to avoid spark/arc for both connectors again that way.
Either polarity will arc the same, the reason on cars for doing negative first is because you're supposed to attach it to the frame, so a spark doesn't set off any hydrogen in the battery and cause an explosion.
Additionally, if you where to drop a clamp or touch something by accident, it is most likely to contact negative, as that is the whole chassis. If you adhere to this order and drop the negative clamp, it will most likely just reconnect to negative. If you drop the positive clamp on the negative chassis nothing happens anymore, as you broke the circuit beforehand.
That's a good point as well.