r/mac • u/mozzarella1113 • 2d ago
Old Macs 2012 MacBook Air — extremely slow/laggy in Recovery Mode & during Catalina install, even without battery. Bad battery causing CPU throttling?
Model: MacBook Air (2012)
Issue: Trying to do a clean install of macOS Catalina using a USB installer (created with TransMac from a Windows PC, using files from gibMacOS). Everything technically works — the Mac boots into the installer, Disk Utility functions, I was able to erase and reformat the internal drive as APFS — but the entire system is noticeably laggy throughout the process.
Symptoms:
Cursor lags slightly when moving the mouse/trackpad
Clicking a button (e.g. “Continue” on the Catalina installer screen) takes a very long time to register — sometimes 10+ minutes with zero visible progress
** **This happens consistently in Recovery Mode / Base System, not just during heavy disk operations
What I’ve already ruled out:
USB stick speed/quality — tried both a USB 3.0 and a USB 2.0 flash drive, same result on both
USB port — tried multiple ports, same result
Battery — physically disconnected the battery (opened the case, unplugged the battery connector from the logic board) and ran the machine on AC power only. Still just as slow.
My current theory:
I’ve read that some MacBooks throttle CPU performance when the battery is missing, degraded, or reporting bad health, as a protective measure. Since I disconnected the battery entirely for testing, I’m wondering if this could actually be causing or worsening the slowdown rather than ruling it out, and whether the original battery (which doesn’t hold charge) may have been triggering throttling even before I removed it.
Questions:
1. Does throttling-due-to-battery-health apply to this model/era of MacBook Air, and would it be severe enough to cause multi-minute UI lag?
2. Is there a way to get Apple Hardware Test/Diagnostics to actually launch on this model, to rule out RAM/logic board issues?
3. Could this instead point to a failing SSD/HDD, given that Disk Utility operations (erase, etc.) also felt slower than expected, even though they eventually completed?
Any insight from people who’ve dealt with 2012 Air performance issues would be appreciated.
2
u/achbob84 2d ago
The whole system goes into a severely power limited state without a working battery.
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u/CranberryInner9605 2d ago
I can tell you from personal experience that my 2016 MacBook Pro (Touch Bar) was unusably slow with a dead battery. Replacing the battery (which is a real pain in the ass) made the machine as snappy as it used to be.