Want to rebuild my traction battery

So I recently bought a pair of gen2 Priuses, one for each daughter. Both apparently have bad batteries, but I already have a wrecked gen 2 with a 2 yr old rebuilt battery that seems really good. So, I put the rebuilt battery from the wrecked gen 2 into Prius #1, and got it back on the road. Now I have 2 bad batteries that I’d like to combine into one good one and put into Prius #2. If it works, I’ll have two running Priuses without having to buy a battery. Battery out of Prius #1 has 5 cells with extremely low voltage, 2-3 volts. Obviously bad. What’s the best way to test/recondition the cells to have the best chance of building a good battery? I’ve watched a lot of videos on using hobby chargers to cycle the batteries to recondition them, but everyone has a different idea/method to do it. Btw, I’m an electrical engineer and have worked on industrial vfd inverters for 30+ years, so I’m capable of working on a Prius without killing myself. Also a pretty good diy mechanic, have rebuilt and swapped out engines etc. Anyone who can point me in the right direction would be greatly appreciated.

 

Thanks to both of you for the replies. I know each module consists of two cells, I’ll try to use the correct terminology going forward to avoid confusion.
I Just had a long day swapping inverter cooling pumps around until I finally found one good one out of the three Prius’s I own. So, I didn’t have time to look at the traction battery modules, But I got Prius A (Alexis) going with the use of the inverter pump from Prius B (Brittany) after the aftermarket one in Prius P didn't work.
I need to do a quick combination of good cells to get Prius B going. Should I just look for highest volrage/closest balance?

 

Ok, let’s try this one more time. I have one bad battery that I have already disassembled down to the module level, and checked the voltage on each module. Most of the modules show what you’d expect, somewhere around 7.2 V, but a few are much lower, about 1.5 - 4 VDC. These modules are obviously bad.

Short term: I have a second bad battery pack that I want to disassemble and use to replace the obviously bad modules on the first battery. I don’t yet have the time or equipment to do charge/discharge and load test on them, so I want to find the 28 best modules out of the 56 I have with the test equipment that I have on hand to give me the best chance of success.

Long term: test/recondition all of my modules with the goal of having a good battery in each Prius and a spare battery for when one of my mine start giving trouble. This probably means buying a hobby charger and possibly a grid charger.

1. what’s the best way to achieve my short-term goal and get the Prius with the bad battery back on the road?
2. What’s the best bang for the buck hobby charger and do I need a grid charger to really evaluate/repair the modules?

 

Ok, sounds like a grid charger is the way to go. I’ve never bought one, so is there a particular model that is recommended? Pretty sure I can rig up a halogen headlight load tester. Sounds like it may be some trial and error to find 28 serviceable modules. Would it improve my odds to load test the modules without first charging them? I’m thinking put a headlight load tester on each module for 2 minutes and record beginning voltage and ending voltage for each module. Then select the modules with the least amount of voltage loss during the test. Or maybe just the ones with the highest ending voltage. Would that be feasible?
Also think I need an elm-type interface to connect to Dr Prius and Torque app. Any suggestions on that?