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/
You can hook the batteries of the two cars up and just let the other car charge for like five minutes, this way there’s no current surge and presumably nothing should melt.
Learned this when I ran out of battery in the great outdoors and one car that’s rolled around was a Google Maps camera car. The driver said there’s so much electronics hooked up on his car that letting me start mine off his battery would shut his whole thing down.
Yea you also should have the car your are charging from run while charging yours and while starting so the alternator can help out with the current that is needed and the other batterie does not deplete to much.
Hell if you have a diesel with no batterie and a gas car with an empty batterie you could still start both by first starting the diesel with a roll start and then charging your batterie from their alternator while its running.