When salvaging batteries, biggest bottleneck is testing the battery for capacity. So if you have hundreds of them, it might make you think about that project second time. unless you have something at your rescue.The project is focussed only to test capacity and other parameters. Basic idea is to use a comparator in constant current mode to discharge battery constantly at a specific rate adjusted with a microcontroller(I am thinking of arduino mega 2560 pro - https://robu.in/product/mega2560-pro-atmega2560-16au-usb-ch340g-development-board/) Which is small form factor for production. Has 15 pwm pins to change the voltage of inverting I/P pin so as to change the discharge rate of that cell. and another 16 analog pins to read voltages. Now we have both voltage and current readings and we can go ahead calculate the power dissipated with respect to time