Mac not charging past 80%

Updated 23 August 2026 · the reason codes below were measured on a MacBook Pro M3 Max on 15 August 2026, and the command was run again in zsh and bash before this page went up. Who measures this.

Your Mac's charge controller records why it stopped charging, and macOS does not show it to you. One command reads that record, so instead of inferring a reason from the percentage you can ask the hardware directly.

The command

ioreg -rn AppleSmartBattery -a | plutil -extract 0.ChargerData xml1 -o - - | awk -F"[<>]" '/<key>/{k=$3} /<integer>/{v[k]=$3} END{n=v["NotChargingReason"]+0; i=v["ChargerInhibitReason"]+0; printf "NotChargingReason    %d\n", n; printf "ChargerInhibitReason %d\n", i; if(n==0 && i==0) print "-> charging normally"; if(int(n/128)%2) print "-> bit 7: no adapter connected"; if(int(n/16777216)%2) print "-> bit 24: held by a charge limit"; if(int(i/268435456)%2) print "-> inhibit bit 28: same limit, from the charger side"}'

The fields live inside a nested dictionary called ChargerData, not at the top level of the battery entry. We checked: at the top level they do not exist at all. Read from there and you get silent zeros, which looks exactly like "everything is fine" and never says otherwise. That is why the command asks for 0.ChargerData.

What we measured, and what we did not

A run on 15 August 2026 captured four state changes in a row:

What happened	Current	NotChargingReason	ChargerInhibitReason
On battery, 99%	0 mA	128 (bit 7)	0
Charging, 99%	100 mA	0	0
Charge limit set to 80%	0 mA	16777216 (bit 24)	268439552 (bits 12 and 28)
Limit removed, 97%	1898 mA	0	0

From that, exactly three bits have a meaning we are willing to state: bit 7 of NotChargingReason means no adapter, bit 24 means a charge limit is holding it, and bit 28 of ChargerInhibitReason is the same cause seen from the charger's side. Bit 12 rose together with bit 28 and was never observed on its own, so we do not claim to know what it means.

The dictionary holds more fields than these — SlowChargingReason, TimeChargingThermallyLimited, a 64-byte ChargerStatus blob. Apple documents none of them, and we are not going to invent labels for values we have not seen change.

The three ordinary reasons

A charge limit is set. Since macOS 26.4, Apple silicon Macs can cap charging natively, and a third-party limiter may also be running. This is the case bit 24 names outright.

Optimized Battery Charging is waiting. macOS learns your routine and delays the last stretch until you need it. Nothing is wrong, and it releases on its own.

It is warm. Charging slows or pauses above certain temperatures. This is the case where the machine tells you least, and where waiting is the whole remedy.

If what you actually see in the menu is the phrase "Charging On Hold", that is a different message with its own causes: what "Charging On Hold (Rarely Used On Battery)" means.

Questions people ask

Is stopping at 80% bad for the battery?

It is the opposite: the limit exists to slow ageing. A pack held in the middle of its range ages more slowly than one kept full, which is why both Apple and every third-party limiter converged on the same idea.

How do I charge to 100% right now?

Turn off the limit in System Settings under Battery, or in whichever app is setting it. If Optimized Battery Charging is the cause, macOS offers to finish charging from the battery menu.

Should I reset the SMC?

There is nothing to reset on Apple silicon: the controller is part of the chip and the old key combinations do nothing. If the reason code says a limit is holding charge, the limit is the answer, not a reset.

Why does my Mac charge to 100% sometimes anyway?

In Apple's words, it "will occasionally charge to 100% to maintain accurate battery state-of-charge" — the gauge needs a full charge now and then to keep its own estimates honest.