But
replacing a UPS is usually done to right time pressures. the problem is, you can rarely de-energise UPS batteries before replacing them, you just need to be really careful when you do it.
Depending on the UPS, Bus bars can be a mother fucker to get on, and of they touch energised they tend to weld together.
With lead acid, its pretty bad (think molten metal and lots of acidic, toxic and explosive gas, with lithium, its just fire. lots of fire that is really really hard to put out.
Obviously for rack based UPSs you'd "just" take out the UPS, or battery drawer, and replace somewhere more safe, or better yet, swap out the entire thing.
For more centralised UPSs that gets more difficult. The shitty old large UPSs were a bunch of cells bolted to a bus bar, and then onto the switchgear/concentraitor.
for Lithium, I would hope its proper electrical connectors, but you can never really tell.
> 27th of September 2025, The fire is believed to have been caused while replacing Lithium-ion batteries. The batteries were manufactured by LG, the parent company of LG Uplus (the one that got hacked by the APT).
Could the battery firmware have been sabotaged by the hacker to start the fire?