Hello, I've had an issue after replacing my battery with a 3rd party one where the processor would slow down to 0.8Ghz. I...

I've had this issue when installing a third party battery, though it wasn't a sensor problem as the CPU would go back to full speed when plugging in the old (horribly performing) battery. I've found a solution just by turning the laptop on without a battery and then plug the new one in while it was running. It definitely doesn't feel right to plug the battery in while the system is running, though it did work and tried turning off/restarting without having the CPU issue anymore. I shall mention that when the new battery was causing the CPU throttling, the new battery was recognised on system profiler or coconut battery without any problems. The issue might stand with the SMC/EFI software not being happy with the different battery.