The system was designed to have the battery present, when you removed it you disconnected the batteries sensor from SMC, at which point SMC placed the system in CPU safe mode to protect the system from overheating, first was to lower the CpU’s clock cycles which is what you are seeing within kernel_task running with quite a few cycles. I’m suspecting the fan is also running harder as well.
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The system was designed to have the battery present, when you removed it you disconnected the batteries sensor from SMC, at which point SMC placed the system in CPU safe mode to protect the system from overheating, first was to lower the CPU’s clock cycles which is what you are seeing within kernel_task running with quite a few cycles. I’m suspecting the fan is also running harder as well.
Time for a new battery
Also note you should stick with macOS High Sierra (10.13.x) as the highest this system can support. While there are ways to go beyond this version, the limitation of RAM (8GB) and a slow drive SATA III (3.0Gbps) won’t offer the performance one would like.
The system was designed to have the battery present, when you removed it you disconnected the batteries sensor from SMC, at which point SMC placed the system in CPU safe mode to protect the system from overheating, first was to lower the CpU’s clock cycles which is what you are seeing within kernel_task running with quite a few cycles. I’m suspecting the fan is also running harder as well.
Time for a new battery
Also note you should stick with macOS High Sierra (10.13.x) as the highest this system can support. While there are ways to go beyond this version, the limitation of RAM (8GB) and a slow drive SATA III (3.0Gbps) won’t offer the performance one would like.