We finished a big job a couple days ago: replacing all 100 batteries in the enormous UPS (Uninterruptible Power Supply) that protects out telescope and camera electronics from short power outages or glitches. Because we use so much electricity (between 50 and 100kW), we need a lot of batteries to run the system when the power goes off, even briefly.
To do this, we have 100 12V batteries that are about two or three times the size of a car battery. They each weigh 57lbs. Five of us spent a day and a half disconnecting and pulling out all 100 of the old, bad batteries, and then installing and reconnecting all 100 of the good, new batteries. What a job!
Thankfully, it worked; when we were done the battery life was much longer, and our system can now stand short power outages.
About 20 of the 100 batteries in that cabinet. Each battery is about 3 feet long and weighs 57lbs! In this picture you can also see the vertical (gold colored) and horizontal (red colored) metal bars that make the electrical connections between the batteries. There’s another set of connections similar to this on the other side of the cabinet. That’s a lot of bolts to undo and then put in again!