MacBook Air Mid 2011 with Late 2010 battery makes it go slow
After my battery almost died (service battery warning), I replaced it with a used one (a friend gave me) coming from a Late 2010 MacBook Air that was in a good shape (666 cycles but still at 90% capacity).
After that replacement the CPU frequency doesn’t scale, staying at 0.8 GHz.
I had to remove the MacBookAir4_2.plist from the ACPI_SMC kext in order to make it at least usable (without that, kernel_task was taking all the resources and making the computer totally unusable).
I have tried resetting SMC and PRAM, also re-flashing SMC to the two versions I have found (1.6 and the current 1.8) and using patched kernels and kexts from Hackintosh world without success.
Apple Hardware Test doesn’t find any issue and EtreCheck detects poor performance but no hardware issues.
The battery manufacturer is SMP (Simplo) bq20z451, firmware version 201, hardware revision 000a, cell revision 162.
The easy answer would be to go to an apple dealer and buy a new battery, but … isn’t the one I am using supposed to be compatible with my computer?
Any advice on this will be really appreciated.