What can you do with the retied HV battery cell?

The cars sensors will throw error codes and go into limp mode if you do that... But it's hard to understand what you're saying because language is not clear... But yes, you can use old battery modules for other uses as long as its not used in the car... Just have to make sure you clamp the sides down so they don't expand. For example, I rewired these two packs to run a 12v power inverter:

 

What's the amperage of your inverter? It appears you did a parallel-serial connections, to get a 12V and the expected capacity to match your inverter isn't?
Next question would be are you grid charging the packs, or how are you charging them!

 

Bus bars on the back of the packs, so 2 modules in series and 14 blocks wired up as parallel going into a Bestek 2000watt inverter with a input range of 10-15v... As for charging, the 12v trickle charger didn't work and the RC hobby chargers didn't work either, but we had a mild winter so it didn't matter. This was set up in early winter for power outages and we didn't have any this year. By next year I hope to have some kind of solar system to charge them, but for Spring and Summer I want to rebuild them into loaner packs so when weather heats up and hybrid batteries fail I can temporarily solve people's battery pack problem in an hour.

Thoughts? Suggestions?

 

Hard to match panels to that, but I Midnite solar charge controller could allow you to configure for 12, 24, or 48 volts