5 Years ago, I designed and built a 12V battery based on cells sold at battery hookup. It’s been running every day since October 17 2021. The cells are 3.2V 600mAh. I have a battery balancer attached to the cells which very rarely illuminates. The arrangement is 9 in parallel, 4 Series so 4S9P. It works great in winter and summer, no issues at all. If you are planning on doing something like this, you can definitely do it on your Prius. I cannot say the same for other cars. I would not jumper other cars from a battery like this either. But anyway, screw lead acid batteries, they never last 2 years in Washington State weather. Here I have proven that LifePo4 can do 5 years without any issues. The battery looks like new on the outside and on the inside. It changes fine and the car has not stalled or left me anywhere stranded since. Original post a the other place before I was banned for whatever stupid reason. https://www.reddit.com/r/prius/comments/qacx7w/im_testing_my_32650_12v_lifepo4_battery_after/
Battery spot welders can be had for really cheep now. I just picked one up for $40 so I can make my own packs for solar projects. Just need to get me a lot of cells.
Yup, I got one at a later date for a different pack. Its generally a good idea to not heat the terminals on lifepo4s or other batteries with the safety cap.