What is the maxium days you can charge storage on a repaired auto?

I'm pretty sure it's indefinitely

Once a customer is given a pick up date (normally that day or the next) anything beyond that can be charged storage fees up until the vehicle is removed.

A lot of repair shops have a maximum length of time they will store a vehicle though, and once that is met or exceeded they reserve the right to repossess the vehicle to cover storage fees.