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Extend BatteryMeter display - #1967

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@BenBE

@BenBE BenBE commented Apr 19, 2026 •

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This is the beginning of a series of commits to extend the BatteryMeter to provide additional information like battery capacity, charge rate and (dis)charge time estimates.

For the BSD parts of this PR I'll need some input from the people on these platforms regarding the actual interface to use to get the following values:

  • current power draw (voltage + current OR direct)
  • battery capacity and current charge
  • time to (dis)charge (can potentially be filled in generically if the power draw is available)

Pointers for sample code on each of the different platforms would be nice.

@BenBE BenBE added enhancement Extension or improvement to existing feature Linux 🐧 Linux related issues FreeBSD 👹 FreeBSD related issues MacOS 🍏 MacOS / Darwin related issues BSD 🐡 Issues related to *BSD PCP PCP related issues Solaris Solaris, Illumos, OmniOS, OpenIndiana NetBSD 🎏 NetBSD related issues OpenBSD 🐡 OpenBSD related issues DragonflyBSD 🪰 DragonflyBSD related issues labels Apr 19, 2026
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.oO(Nice, quite a stunt, to cover all of the BSD's with this. :)

@BenBE
BenBE force-pushed the battery-extension branch from 1dc77c5 to 4d3bece Compare April 23, 2026 05:17
@BenBE
BenBE force-pushed the battery-extension branch 2 times, most recently from 98680b3 to 422d5f3 Compare May 1, 2026 08:38
@BenBE
BenBE force-pushed the battery-extension branch from 422d5f3 to dca06ec Compare May 15, 2026 13:19
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📝 Walkthrough

Walkthrough

This PR adds a unified BatteryInfo structure for AC status, percentage, power, and energy values. BatteryMeter classifies battery state, calculates optional time estimates, and renders expanded or compact output. Platform collectors now populate BatteryInfo through native battery APIs, sysfs, procfs, ACPI, IOKit, sensors, or PCP metrics. PCP adds Denki battery metric identifiers and mappings.

Suggested reviewers: germanaizek

Priority: ➖ Normal

Change: Feature

Merge Risk: 🟡 Moderate · up to f7a23

Battery displays can show contradictory capacity values on macOS and falsely report AC power under PCP. These telemetry regressions should be corrected before merge.


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❤️ Share

One struct gathers charge and power,
Across each platform, hour by hour.
AC states and energy align,
Displays report the changing line.
Battery data now shares one design.

Comment @coderabbitai help to get the list of available commands.

@BenBE
BenBE marked this pull request as ready for review May 15, 2026 18:04
@BenBE
BenBE force-pushed the battery-extension branch from dca06ec to 853701f Compare May 15, 2026 18:04
@BenBE BenBE added this to the 3.6.0 milestone May 15, 2026

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Actionable comments posted: 7

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)
netbsd/Platform.c (1)

471-485: ⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Release the proplib objects on every exit path.

prop_dictionary_recv_ioctl() returns a dictionary owned by the caller, prop_dictionary_iterator() and prop_array_iterator() create iterator objects that must be released explicitly, and iterators retain their underlying collections. Currently, dict, devIter, and each fieldsIter are never released, causing a memory leak on every call to this function. With repeated battery polling, this accumulates over time.

All three objects must be released:

  • dict via prop_object_release() (owned by caller from prop_dictionary_recv_ioctl())
  • devIter via prop_object_iterator_release() (created by prop_dictionary_iterator())
  • fieldsIter via prop_object_iterator_release() (created by prop_array_iterator())
Possible fix
 void Platform_getBattery(BatteryInfo* info) {
-   prop_dictionary_t dict, fields, props;
+   prop_dictionary_t dict = NULL, fields, props;
    prop_object_t device, class;
+   prop_object_iterator_t devIter = NULL;
+   prop_object_iterator_t fieldsIter = NULL;
@@
-   prop_object_iterator_t devIter = prop_dictionary_iterator(dict);
+   devIter = prop_dictionary_iterator(dict);
    if (devIter == NULL)
       goto error;
@@
-      prop_object_iterator_t fieldsIter = prop_array_iterator(fieldsArray);
+      fieldsIter = prop_array_iterator(fieldsArray);
       if (fieldsIter == NULL)
          goto error;
@@
       while ((fields = prop_object_iterator_next(fieldsIter)) != NULL) {
          ...
       }
+
+      prop_object_iterator_release(fieldsIter);
+      fieldsIter = NULL;
    }
+
+   prop_object_iterator_release(devIter);
+   devIter = NULL;
+   prop_object_release(dict);
+   dict = NULL;
 
 error:
+   if (fieldsIter != NULL)
+      prop_object_iterator_release(fieldsIter);
+   if (devIter != NULL)
+      prop_object_iterator_release(devIter);
+   if (dict != NULL)
+      prop_object_release(dict);
    if (fd != -1)
       close(fd);
 }
🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@netbsd/Platform.c` around lines 471 - 485, The code leaks proplib objects:
the dictionary returned by prop_dictionary_recv_ioctl (dict) and the iterators
created by prop_dictionary_iterator (devIter) and prop_array_iterator
(fieldsIter) must be released on every exit path; update the function so that
before jumping to the error/exit label or returning you call
prop_object_release(dict) when dict is non-NULL and
prop_object_iterator_release(devIter) and
prop_object_iterator_release(fieldsIter) when those iterators are non-NULL (also
release any fieldsIter created inside the loop before continuing), ensuring you
don't release objects twice and that fieldsArray/device handling remains
unchanged.
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@BatteryMeter.c`:
- Around line 116-141: The compact-mode token concatenation happens because the
AC/bat labels written by xSnprintf (the calls that print "%s" with "AC"/"AC+bat"
and the "bat" literal) lack a trailing separator; change those format strings to
include a space (e.g., "%s " and "bat ") so tokens don't get glued, and when
printing power in the xSnprintf call that uses info.powerCurr (inside the
isCharging || isDischarging branch) normalize the sign by printing the absolute
value (use fabs(info.powerCurr) or equivalent) so discharging shows positive
watts consistent with text mode; update the xSnprintf invocations that append to
buf/len accordingly.

In `@darwin/Platform.c`:
- Around line 734-761: The code is incorrectly assigning raw percentage values
(cap_current/cap_max) into Wh fields info->energyCurr and info->energyFull;
remove the two assignments so only info->percent = 100.0 * cap_current / cap_max
is kept and leave info->energyCurr and info->energyFull as NaN (do not populate
them from cap_current/cap_max). Update the block that checks cap_max > 0.0 (the
lines that set info->energyCurr = cap_current; and info->energyFull = cap_max;)
to remove those assignments and keep only the percent calculation.

In `@linux/Platform.c`:
- Around line 1095-1104: Reverse the probe order so sysfs is tried before
procfs: when Platform_Battery_method is BAT_SYS call
Platform_Battery_getSysData(&Platform_Battery_cache) first and if
isNonnegative(Platform_Battery_cache.percent) leave method as BAT_SYS; if that
fails set Platform_Battery_method = BAT_PROC and call
Platform_Battery_getProcData(&Platform_Battery_cache) as a fallback and only
then set Platform_Battery_method = BAT_ERR if percent is still not nonnegative.
Use the existing symbols Platform_Battery_method, Platform_Battery_getSysData,
Platform_Battery_getProcData, Platform_Battery_cache, BAT_SYS, BAT_PROC, BAT_ERR
and isNonnegative to implement this change.
- Around line 841-844: Platform_Battery_getProcData currently replaces a valid
procfs percent with NAN whenever procAcpiCheck() fails; change it to always read
the procfs battery percentage and only set percent to NAN if
Platform_Battery_getProcBatInfo() itself indicates failure. Concretely, call
Platform_Battery_getProcBatInfo() unconditionally to populate info->percent,
assign info->ac = procAcpiCheck() but leave info->ac as AC_ERROR if adapter
detection failed, and do not overwrite a valid percent with NAN based solely on
procAcpiCheck() failing; only set percent to NAN when
Platform_Battery_getProcBatInfo() reports an error.

In `@openbsd/Platform.c`:
- Around line 391-457: The code only calls findDevice("acpibat0", ...) which
collects battery metrics from a single pack; change the logic to iterate over
all acpibat devices (e.g., for i = 0; findDevice(name, mib, &snsrdev, &sdlen);
++i) using a formatted name like "acpibat%d" and accumulate totalFull,
totalRemain and totalPower per-device (the blocks that read SENSOR_WATTHOUR,
SENSOR_INTEGER, SENSOR_WATTS and update batteryFull, batteryRemain,
batteryState, batteryPower) into the existing totals; keep the final
percent/energy/power calculations using the aggregated totals (referencing
findDevice, totalFull, totalRemain, totalPower, and the sysctl queries for
SENSOR_WATTHOUR/SENSOR_WATTS/SENSOR_INTEGER).

In `@pcp/Platform.c`:
- Around line 880-883: The AC state logic is inverted: instead of setting
info->ac = AC_PRESENT when count < 1, set AC_PRESENT when there is at least one
battery (count >= 1) and then override to AC_ABSENT if any battery is
discharging (power < 0). Update the block that currently checks count and
assigns info->ac so the flow is: if count < 1 set a fallback/ERROR state (or
return appropriately), otherwise set info->ac = AC_PRESENT, iterate battery
instances to check power and if any power < 0 set info->ac = AC_ABSENT; apply
the same fix to the analogous block around the second occurrence (the block
referenced at lines ~912-914). Use the existing symbols info->ac, AC_PRESENT,
AC_ABSENT, count and the battery power checks to locate and change the logic.
- Around line 892-893: The code uses batteryEnergyFull[i].d directly as the
CLAMP upper bound which can be negative and cause info->energyCurr to go
negative; compute a non-negative full value first (e.g., double full =
isNonnegative(batteryEnergyFull[i].d) ? batteryEnergyFull[i].d : 0) and then use
CLAMP(batteryEnergyCurr[i].d, 0, full) to update info->energyCurr and add full
(not the raw batteryEnergyFull) to info->energyFull so both updates guard
against negative full-capacity samples (references: info->energyCurr,
info->energyFull, batteryEnergyCurr, batteryEnergyFull, CLAMP, isNonnegative).

---

Outside diff comments:
In `@netbsd/Platform.c`:
- Around line 471-485: The code leaks proplib objects: the dictionary returned
by prop_dictionary_recv_ioctl (dict) and the iterators created by
prop_dictionary_iterator (devIter) and prop_array_iterator (fieldsIter) must be
released on every exit path; update the function so that before jumping to the
error/exit label or returning you call prop_object_release(dict) when dict is
non-NULL and prop_object_iterator_release(devIter) and
prop_object_iterator_release(fieldsIter) when those iterators are non-NULL (also
release any fieldsIter created inside the loop before continuing), ensuring you
don't release objects twice and that fieldsArray/device handling remains
unchanged.
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📒 Files selected for processing (21)
  • BatteryMeter.c
  • BatteryMeter.h
  • darwin/Platform.c
  • darwin/Platform.h
  • dragonflybsd/Platform.c
  • dragonflybsd/Platform.h
  • freebsd/Platform.c
  • freebsd/Platform.h
  • linux/Platform.c
  • linux/Platform.h
  • netbsd/Platform.c
  • netbsd/Platform.h
  • openbsd/Platform.c
  • openbsd/Platform.h
  • pcp/Metric.h
  • pcp/Platform.c
  • pcp/Platform.h
  • solaris/Platform.c
  • solaris/Platform.h
  • unsupported/Platform.c
  • unsupported/Platform.h

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An unexpected error occurred while generating fixes: Not Found - https://docs.github.com/rest/git/refs#get-a-reference

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Actionable comments posted: 1

🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@BatteryMeter.c`:
- Around line 83-88: The block that appends an extra separator (the if (ret &&
len > 2) { *buf++ = ','; *buf++ = ' '; *buf = 0; len -= 2; }) causes a double
comma in TEXT_METERMODE output because the AC prefix written earlier already
includes ", ". Remove this entire conditional block (references: variables ret,
len, buf and the TEXT_METERMODE output path) so no additional ", " is appended;
no other changes are needed to the surrounding code.
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Comment thread BatteryMeter.c
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BenBE force-pushed the battery-extension branch from 0e7353e to debe731 Compare May 15, 2026 21:45

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Actionable comments posted: 1

♻️ Duplicate comments (1)
BatteryMeter.c (1)

137-141: ⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Normalize discharging watts sign in compact mode.

Line 140 prints raw info.powerCurr, so discharging displays negative watts, while text mode (Line 93) shows positive watts for discharging. Keep both modes consistent.

Suggested patch
       if (isCharging || isDischarging) {
          ret = xSnprintf(
             buf, len, "%.1fW @ %.1f/%.1fWh",
-            info.powerCurr, info.energyCurr, info.energyFull
+            isDischarging ? -info.powerCurr : info.powerCurr,
+            info.energyCurr, info.energyFull
          );
          buf += ret; len -= ret;
🤖 Prompt for AI Agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

In `@BatteryMeter.c` around lines 137 - 141, Compact-mode watt value uses raw
info.powerCurr causing negative watts during discharging; update the xSnprintf
call inside the if (isCharging || isDischarging) block to pass a normalized
(absolute) watt value so discharging shows positive watts like text mode — e.g.
replace the first format argument info.powerCurr with a normalized expression
(use -info.powerCurr when isDischarging, or fabsf(info.powerCurr)) while keeping
the rest of the arguments (info.energyCurr, info.energyFull) unchanged.
🤖 Prompt for all review comments with AI agents
Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.

Inline comments:
In `@BatteryMeter.c`:
- Around line 49-51: The percent-only fallback in BatteryMeter.c (when
haveEnergy is false) currently writes only "%.1f%%" to this->txtBuffer and
returns, losing AC/battery context; modify the early-return branch where
haveEnergy is checked to include info.ac in the formatted string (use info.ac to
choose an "AC"/"Battery" marker or a suffix/prefix) so that the call that writes
to this->txtBuffer includes both the percent (info.percent) and the AC state
(info.ac) before returning.

---

Duplicate comments:
In `@BatteryMeter.c`:
- Around line 137-141: Compact-mode watt value uses raw info.powerCurr causing
negative watts during discharging; update the xSnprintf call inside the if
(isCharging || isDischarging) block to pass a normalized (absolute) watt value
so discharging shows positive watts like text mode — e.g. replace the first
format argument info.powerCurr with a normalized expression (use -info.powerCurr
when isDischarging, or fabsf(info.powerCurr)) while keeping the rest of the
arguments (info.energyCurr, info.energyFull) unchanged.
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Comment thread BatteryMeter.c
@BenBE

BenBE commented May 15, 2026 •

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@coderabbitai:

BatteryMeter.c (1)> 137-141: ⚠️ Potential issue | 🟡 Minor | ⚡ Quick win

Normalize discharging watts sign in compact mode.
Line 140 prints raw info.powerCurr, so discharging displays negative watts, while text mode (Line 93) shows positive watts for discharging. Keep both modes consistent.

Suggested patch

       if (isCharging || isDischarging) {
          ret = xSnprintf(
             buf, len, "%.1fW @ %.1f/%.1fWh",
-            info.powerCurr, info.energyCurr, info.energyFull
+            isDischarging ? -info.powerCurr : info.powerCurr,
+            info.energyCurr, info.energyFull
          );
          buf += ret; len -= ret;

In compact mode, better to include the sign (negative for discharging, positive for charging).

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@BenBE: Understood — preserving the sign in compact mode is a deliberate design choice, where negative signals discharge direction and positive signals charge, avoiding the need for extra labels. That's a reasonable convention given the space constraints of compact mode. No change needed here.

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Actionable comments posted: 5

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)
netbsd/Platform.c (1)

471-485: ⚠️ Potential issue | 🟠 Major | ⚡ Quick win

Release proplib objects to prevent memory leak.

dict, devIter, and each fieldsIter must be released via prop_object_release() when no longer needed. NetBSD proplib objects are reference-counted and require explicit release—failure to do so leaks memory on every battery refresh cycle in long-running sessions. Release on both success and error paths.


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📒 Files selected for processing (12)
  • BatteryMeter.c
  • BatteryMeter.h
  • darwin/Platform.c
  • dragonflybsd/Platform.c
  • freebsd/Platform.c
  • linux/Platform.c
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  • openbsd/Platform.c
  • pcp/Metric.h
  • pcp/Platform.c
  • solaris/Platform.c
  • unsupported/Platform.c

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♻️ Duplicate comments (5)
linux/Platform.c (5)

844-847: 🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Do not discard the procfs percentage when AC detection fails.

Line 846 still forces percent = NAN whenever procAcpiCheck() returns AC_ERROR. /proc/acpi/battery/* can hold valid capacity data while /proc/acpi/ac_adapter/*/state is unreadable. In that case Platform_getBattery() abandons procfs for no reason. Read the percentage unconditionally and leave info->ac = AC_ERROR.

Proposed fix
 static void Platform_Battery_getProcData(BatteryInfo* info) {
    info->ac = procAcpiCheck();
-   info->percent = AC_ERROR != info->ac ? Platform_Battery_getProcBatInfo() : NAN;
+   info->percent = Platform_Battery_getProcBatInfo();
 }

1037-1048: 🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Fix the power sign: unsigned multiplication plus unconditional negation.

Two defects combine here:

  • Line 1038 multiplies batteryCurrent (int64_t) by batteryVoltage (uint64_t). The signed operand converts to unsigned, so a negative CURRENT_NOW produces a huge positive batteryPower.
  • Line 1044 then negates the result whenever STATUS is Discharging. Drivers that already report signed CURRENT_NOW get their sign inverted, while POWER_NOW is reported unsigned and does need the STATUS sign.

Derive the magnitude first, then apply the STATUS sign once. This keeps the contract in BatteryMeter.h (negative = discharging) valid for both driver styles.

Proposed fix
       if (!haveBatteryPower && haveBatteryCurrent && haveBatteryVoltage) {
-         batteryPower = (batteryCurrent * batteryVoltage) / 1000000;
+         batteryPower = ((int64_t)(llabs(batteryCurrent) * batteryVoltage)) / 1000000;
          haveBatteryPower = true;
       }

       if (haveBatteryPower) {
+         if (batteryPower < 0)
+            batteryPower = -batteryPower;
          if (batteryIsDischarging)
             batteryPower = -batteryPower;

1049-1063: 🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Aggregate every AC supply instead of keeping the first result.

Line 1050 returns early once info->ac differs from AC_ERROR, so readdir() order decides the outcome on systems with several mains supplies. An offline entry visited first pins info->ac to AC_ABSENT even when another supply is online. Line 1056 is also dead: the guard above guarantees info->ac is already AC_ERROR.

Let AC_PRESENT win over AC_ABSENT.

Proposed fix
       } else if (type == AC) {
-         if (info->ac != AC_ERROR)
-            goto next;
-
          char buffer[2];
          ssize_t r = Compat_readfileat(entryFd, "online", buffer, sizeof(buffer));
-         if (r < 1) {
-            info->ac = AC_ERROR;
+         if (r < 1)
             goto next;
-         }
-
-         if (buffer[0] == '0')
-            info->ac = AC_ABSENT;
-         else if (buffer[0] == '1')
+
+         if (buffer[0] == '1')
             info->ac = AC_PRESENT;
+         else if (buffer[0] == '0' && info->ac != AC_PRESENT)
+            info->ac = AC_ABSENT;
       }

1072-1076: 🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Capacity-only batteries still report NAN percent.

A power supply may expose POWER_SUPPLY_CAPACITY without any ENERGY_* or CHARGE_* attribute. That is a valid kernel configuration. totalFull then stays 0, info->percent stays NAN, and Platform_getBattery() promotes the method to BAT_ERR although a usable percentage was parsed. Publish batteryLevel as a fallback when the aggregated energy totals are unavailable.

This needs an accumulator for the parsed capacity values (for example levelSum and levelCount filled inside the BAT branch), then:

Proposed fix
    if (totalFull > 0) {
       info->percent = ((double) totalRemain * 100.0) / (double) totalFull;
       info->energyCurr = (double) totalRemain / 1000000.0;
       info->energyFull = (double) totalFull / 1000000.0;
+   } else if (levelCount > 0) {
+      /* no energy/charge attributes exposed: fall back to reported capacity */
+      info->percent = (double) levelSum / (double) levelCount;
    }

1099-1108: 🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Probe sysfs before procfs.

Platform_Battery_getProcData() fills only ac and percent. It never sets powerCurr, energyCurr, or energyFull. With the current BAT_PROC-first order, every host that exposes both interfaces keeps the new rate, capacity, and time-estimate fields at NAN, and BatteryMeter falls back to the percent-only output. Try sysfs first and keep procfs as the fallback for legacy setups.

Proposed fix
-   if (Platform_Battery_method == BAT_PROC) {
-      Platform_Battery_getProcData(&Platform_Battery_cache);
-      if (!isNonnegative(Platform_Battery_cache.percent))
-         Platform_Battery_method = BAT_SYS;
-   }
    if (Platform_Battery_method == BAT_SYS) {
       Platform_Battery_getSysData(&Platform_Battery_cache);
       if (!isNonnegative(Platform_Battery_cache.percent))
+         Platform_Battery_method = BAT_PROC;
+   }
+   if (Platform_Battery_method == BAT_PROC) {
+      Platform_Battery_getProcData(&Platform_Battery_cache);
+      if (!isNonnegative(Platform_Battery_cache.percent))
          Platform_Battery_method = BAT_ERR;
    }

The initial value of Platform_Battery_method must become BAT_SYS for this order to take effect.


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BenBE force-pushed the battery-extension branch from 55a56a0 to 98e6748 Compare August 16, 2026 22:08
@ravi-arnan

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Tested the head of this branch (98e6748) on real Darwin hardware, since the thread so far has no
hardware measurements on the macOS side.

Machine: MacBookPro12,1, macOS 12.7.6, Intel, Apple clang 14.0.0 (Command Line Tools 14.2),
ncurses from the SDK. Battery pack bq20z451, 6830 mAh design, 6379 mAh full charge, 292 cycles.

Build: ./autogen.sh && ./configure && make -j2 completes with zero warnings under the
default warning set (-Wall -Wextra -Wcast-align -Wcast-qual -Wfloat-equal -Wimplicit-int-conversion -Wnull-dereference ...).

Runtime, one-column header, discharging on battery:

TEXT mode:   Battery: Using bat, discharging at 5.9W, 49.9/71.8Wh (73.0%), time remaining: 8h28m
BAR mode:    the bar carries the label   bat -7.3W @ 50.0/71.8Wh, 6h48m

Numbers cross-checked against the registry sampled at the same moment
(Voltage=11262 mV, Amperage=-652 mA, AppleRawCurrentCapacity=4437 mAh,
AppleRawMaxCapacity=6379 mAh): power -7.34 W, energyCurr 49.97 Wh, energyFull 71.84 Wh,
ETA 6.81 h. Every field the meter printed matches.


1. Amperage sign, answering your question at darwin/Platform.c:750

Measured rather than argued. Discharging, no adapter connected (ExternalConnected=No,
IsCharging=No), read exactly the way this PR reads it, CFNumberGetValue(ref, kCFNumberDoubleType, ...):

Amperage  -1571  -1542  -2289  -1580  -652  -523  mA     (six samples over ~15 min)

IOKit's higher level power source API agrees: kIOPSCurrentKey in the same power source
description is -461 mA while discharging. So on an Intel Mac, negative means energy leaving the
pack, which is the convention this PR already assumes and the one BatteryMeter.c uses to pick the
discharging branch. No sign flip needed for Darwin.

A trap worth a comment in the code: ioreg prints this exact property as

"Amperage" = 18446744073709551247

which is the same value read as unsigned. Through CoreFoundation it is -369. The CFNumber type is
kCFNumberSInt64Type. Anyone comparing ioreg output against this code will think there is an
overflow bug where there is none.

2. Key availability and units, confirmed on this machine

  • AppleRawCurrentCapacity and AppleRawMaxCapacity both exist and are in mAh (4437 and 6379),
    so the mAh path this PR uses works on Intel Macs.
  • The IOPS keys the code no longer uses for energy really are percentages here:
    Current Capacity = 73, Max Capacity = 100. Reading Wh out of them would have been wrong, so
    the switch to the AppleSmartBattery registry is the right call.
  • IsCharging and ExternalConnected come back as CFBoolean, not CFNumber. Nothing in this PR
    reads them, but if a later commit does, they need CFGetTypeID handling rather than
    CFNumberGetValue.

3. AppleSmartBattery refreshes about once a minute

Repeated samples return byte-identical values for 30 to 60 seconds and then step. So powerCurr on
Darwin is closer to a one minute average than an instantaneous reading, and the meter will lag a
load change by up to a minute. Not a defect, but it explains a stale-looking ETA right after
plugging or unplugging, and it means a very short benchmark will not show up in the wattage at all.

4. energyFull drifts because it is scaled by the instantaneous terminal voltage

Ten samples over about fifteen minutes, same battery, AppleRawMaxCapacity constant at 6379 mAh:

min max
Voltage 11022 mV 11319 mV
energyFull as computed 70.31 Wh 72.20 Wh

That is a 1.9 Wh (2.7%) swing in the number presented to the user as the pack's full capacity, with
no physical change in the pack. The sag is largest under CPU load, so the displayed "full capacity"
shrinks exactly when the machine gets busy.

The time estimate is not affected: energyCurr carries the same voltage factor, so voltage cancels
in energyCurr / powerCurr. It is only the two absolute Wh figures that move.

If you want a stable denominator, the fix is a nominal pack voltage instead of the live one. This
pack reports its cells individually, BatteryData.CellVoltage = (3646, 3727, 3727), so cell count
is available and a nominal 3.8 V per cell would give a constant. That does mean hardcoding a
chemistry constant, so it may not be worth it. Documenting the approximation in the existing comment
would also be a defensible answer. Your call, and either way the current code is not wrong, just
noisy.

5. At 80 columns the ETA is the first thing lost

TEXT mode, one column header, discharging. The full line is 85 characters, 74 of them after the
Battery: caption. Rendered at three widths:

cols=80    Battery: Using bat, discharging at 7.3W, 50.0/71.8Wh (73.0%), time remaining
cols=100   Battery: Using bat, discharging at 5.9W, 49.9/71.8Wh (73.0%), time remaining: 8h28m
cols=120   Battery: Using bat, discharging at 5.9W, 49.9/71.8Wh (73.0%), time remaining: 8h28m

At the default 80 column terminal the new number that is hardest to get anywhere else is precisely
the one that gets cut. ETA 8h28m or 8h28m left in place of time remaining: 8h28m would fit at
80 with room to spare.


Everything above is the discharge path. I will follow up with the charging side (sign of
Amperage with the adapter connected, the AC+bat label, and the 95% cutoff in the time-to-full
estimate) once I can measure it on the same machine.

@ravi-arnan

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Follow-up with the charging path measured on the same machine (MacBookPro12,1, macOS 12.7.6, branch
head 98e6748).

Amperage sign with the adapter connected. Positive, as the PR assumes:

ExternalConnected = CFBoolean 1
IsCharging        = CFBoolean 1
Amperage          = +2652 mA, +2717 mA   (two samples)

Together with the discharging samples in my previous comment (-413 to -2289 mA with no adapter),
both directions are now measured on Intel hardware, and they match the convention in
BatteryMeter.c. Your reading of the SBS sign question at darwin/Platform.c:750 is correct for
Darwin.

Meter output while charging, TEXT mode at 110 columns:

  Battery: Using AC, charging at 32.3W, 53.7/75.8Wh (74.0%), time to full: 0h34m

Cross-checked against the registry at that instant (Voltage=11877 mV, Amperage=2717 mA,
AppleRawCurrentCapacity=4521 mAh, AppleRawMaxCapacity=6379 mAh): 32.27 W, 53.70 Wh, 75.76 Wh,
and (0.95 * 75.76 - 53.70) / 32.27 * 60 = 33.97 rounded up to 34 minutes. Every field matches.

The 95% cutoff is visible to the user. At that same moment macOS reported 0:41 remaining while
the meter said time to full: 0h34m. The seven minute gap is exactly the 5% tail this code skips.
Both numbers are defensible, but a user with both on screen will read the meter as wrong rather than
as deliberately conservative. That is the same point raised earlier in the thread about the label,
and this is what it looks like in practice. time to 95% in the label, or dropping the cutoff, both
resolve it.

One correction to my previous comment: the energyFull drift is larger than I reported. With
the adapter connected the pack voltage rises to 11877 mV, so the same 6379 mAh full charge capacity
now renders as 75.8 Wh, against 70.3 Wh measured while discharging under CPU load at
11022 mV. That is 5.5 Wh, 7.8%, not the 2.7% I measured on battery alone. In practice the
displayed full capacity of the pack jumps by more than 5 Wh the moment the charger goes in, which is
the sort of thing that gets reported as a bug. The time estimates stay correct throughout, since the
voltage factor cancels, so a fixed nominal voltage for the two Wh figures would only improve what is
displayed and change nothing else.

@BenBE

BenBE commented Aug 18, 2026

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Thank you very much for the very detailed report.

The display format is actually still up for debate, as even as it is now, it packs very many information in a quite compact space, while still trying to stay comprehensible for a casual observer. I somewhat thought about the ETA label earlier, but it somehow didn't feel proper, while working on that part of the code. But as mentioned: I'm very much open for ideas on how to condense the text information better.

Which brings me to the 95% cutoff: That one has a bit of reasoning behind it, that's not directly documented in the code itself (apart from the calculations that randomly take the 0.95 factor. But to elaborate on the reasoning there are mostly two reasons: The first one is that the charging isn't done in a linear fashion and actually slows down the more charge is already put into the battery. This causes the charging time to always be an underestimate, and might cause the remaining charging time to "increase". The second one is related to the way batteries can be damaged if always kept at full 100% charge. That's why when looking at the charge of your battery even with AC connected, you will often see only like 97-98% charge. If the cutoff was at full 100%, this would cause the battery to show ridiculous ETA times for charging when in fact that BMS mostly keeps the charge at a near-constant level without over-charging the battery.

One test that might still be worth performing is putting the system under load with a charger that's too weak for the load. With Thinkpads you can usually operate (and charge) the system with a 65W charger, even when the system under load might take like 80W+. This will cause the battery to discharge despite AC being connected and should be reported by the meter accordingly.

Finally, regarding the voltage level: calculating from cell voltage to nominal voltage requires knowledge of the pack topology, which is an entirely different can of worms. Glad to integrate patches for this, but not as part of this first set of patches. This PR is complex enough as it is. And given that most BMS can't even make up their mind about how much capacity their pack actually has, doesn't make this value very reliable either. On my notebook the shown pack capacity changes roughly based on phase of the moon, zodiac sign, number of coffee mugs emptied since last kernel update, Wifi signal strength, and the approximate payout of the retirement plan …

@ravi-arnan

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I tried the weak-charger test. It does not reproduce on this machine, so here is the negative result with numbers, plus two things the attempt turned up.

The undersized-charger case is not reachable here

Four spinners on a 4-thread i5 (MacBookPro12,1, macOS 12.7.6), ps reporting 399.7% total CPU, stock 60W MagSafe. Sampled AppleSmartBattery every 10s through baseline, 2 minutes of load, and cooldown:

idle    amperage=+2473 mA  29.4W  ext=1 charging=1
load    amperage=+2473 mA  29.4W  ext=1 charging=1
load    amperage=+2499 mA  29.8W  ext=1 charging=1
load    amperage=+2471 mA  29.6W  ext=1 charging=1
cool    amperage=+2471 mA  29.6W  ext=1 charging=1

The charge current does not even dip. A dual core i5 at full tilt is nowhere near 60W, so the adapter never runs short and the battery never discharges. Reproducing your Thinkpad case needs an adapter weaker than the load, and I do not have one for this machine.

For what it is worth the code path looks right by reading: BatteryMeter.c:90 prints Using AC+bat when info.ac == AC_PRESENT and isDischarging, and the compact label at :138 does the same. I want to be clear that this is reading rather than measurement, since I could not exercise it.

Reading it did raise one thing. isDischarging requires powerCurr <= -5.0 and isCharging requires >= +5.0, so a weak-adapter case that nets out to a small drain, say -3W, falls between them and prints Using AC, stable at ... while the pack is in fact slowly emptying. Your 65W-against-80W example would be well past the threshold and would read AC+bat correctly; it is only the mild version that reads as stable.

The percent and the Wh pair on the same line come from different subsystems

info.percent comes from IOPS, kIOPSCurrentCapacityKey / kIOPSMaxCapacityKey (darwin/Platform.c:724-731). energyCurr and energyFull come from AppleSmartBattery, AppleRawCurrentCapacity / AppleRawMaxCapacity scaled by voltage (:738-739). Those are two different notions of full, and they disagree. I watched a full charge, sampling every 2 minutes:

time raw Wh pair shown meter line
14:31 61.5/77.5Wh = 79.4% 83.0% charging at 29.9W, time to full: 0h25m
14:41 65.3/77.4Wh = 84.4% 89.0% charging at 14.9W, time to full: 0h34m
15:00 71.0/78.7Wh = 90.2% 95.0% charging at 15.1W, time to full: 0h16m
15:12 74.5/79.4Wh = 93.8% 99.0% charging at 12.4W, time to full: 0h05m
15:14 75.6/79.5Wh = 95.1% 100.0% charging at 11.8W, no ETA

The gap widens from 3.6 to 4.9 points across the run, so it is not a fixed offset a user could learn to discount. Cross-checked against pmset -g batt at one instant: raw was 5144/6379 = 80.6% while pmset, which reads the same IOPS source, said 85%.

The last row is the one I would fix. The meter prints

Battery: Using AC, charging at 11.8W, 75.6/79.5Wh (100.0%)

while FullyCharged is No and 11.8W is still going into the pack, and the Wh pair immediately to the left of that 100.0% is 95.1%. If the percent were derived from the same pair as the Wh figures, the line would be self-consistent, and the cutoff would fire at a displayed 95% rather than a displayed 100%.

A correction to my earlier comment. I wrote that every field matched after cross-checking. Each field does match its own source, but I never checked the percent against the Wh pair, and it did not match even then: 53.70/75.76 is 70.9% where the line displayed 74.0%. The discrepancy was sitting in my own data and I missed it.

Your non-linear charging point is right, and it starts earlier than 95%

This is the part of your reply I could measure, and it supports the design:

raw current power time to full
79.4% 2465 mA 29.9W 0h25m
80.6% 2222 mA 27.0W 0h25m
81.7% 1970 mA 23.9W 0h26m
82.7% 1720 mA 20.9W 0h28m
83.6% 1475 mA 17.9W 0h30m
84.3% 1231 mA 14.9W 0h34m

The ETA grows by nine minutes while the battery is filling, exactly the effect you described. After that the current holds near 15W and the estimate falls monotonically to 0h05m.

So the tail is real, but on this pack it is the 79 to 84 percent band, where the BMS ramps from 30W down to 15W, and the 95% cutoff does not cover it. Whatever the label ends up saying, a user watching this meter between 80 and 85 percent sees the remaining time going up.

One more data point for the nominal voltage question

energyFull drifted from 77.4Wh to 79.5Wh over this single charge, with no change to the pack, purely because the voltage rose from 11900 to about 12200 mV as it filled. That is on top of the 7.8% jump between AC and battery I reported earlier, and it is the same fix: a fixed nominal voltage for the two Wh figures would hold them steady and would not touch the time estimates, since the voltage factor cancels there.

Observation window was 14:31 to 15:14 local; I did not capture the transition into stable past that point.

@ravi-arnan

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Addendum, because every number above came from the charging path and I do not want to leave the impression that this is charge-specific.

Same machine a few hours later, on battery with no adapter:

Battery: Using bat, discharging at 8.5W, 68.9/75.7Wh (96.0%)

68.9/75.7 is 91.0%. At that instant AppleRawCurrentCapacity / AppleRawMaxCapacity was 5807/6379 = 91.0%, and BatteryData.StateOfCharge in the same registry entry was 91. So all three AppleSmartBattery witnesses agree on 91 while IOPS, and pmset -g batt along with it, says 96%.

Two things follow. The divergence is in every branch of the meter rather than only the charging one. And it tracks charge level rather than direction: this discharging sample at raw 91.0% sits on the same curve as the charging samples at raw 90.2% (shown 95.0%) and raw 91.4% (shown 96.0%).

So whatever you settle on for the ETA and the label, the percent looks like one change in Platform_getBattery rather than anything per-branch in BatteryMeter.c.

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Comment thread darwin/Platform.c
if (cap_max > 0.0)
*percent = 100.0 * cap_current / cap_max;
if (cap_max > 0.0) {
info->percent = 100.0 * cap_current / cap_max;

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🎯 Functional Correctness | 🟠 Major | ⚡ Quick win

Use one authoritative source for percentage and energy values.

Line 733 derives info->percent from IOPS capacity values, while lines 766-767 derive Wh values from AppleSmartBattery raw capacity values. These sources can diverge, so expanded output can show a percentage that conflicts with energyCurr / energyFull.

Use one source for all three values when it is available, and use the other source only as a complete fallback. PR objectives confirm this divergence in hardware testing.

Comment thread pcp/Platform.c
@BenBE
BenBE force-pushed the battery-extension branch from f7a23a1 to 8e6e6a3 Compare October 3, 2026 12:24
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@BenBE

BenBE commented Oct 3, 2026

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@coderabbitai Are there any major code issues in this PR left, that need urgent addressing; like actual bugs, instabilities, crashes or other important oversights? Only issues that are newly introduced by code or changes from this PR. Please mention (and reference) still-open issues noted earlier in this PR, that fit this filter.

@natoscott Can you check the marked issue regarding PCP and provide a patch for it if necessary?

@ravi-arnan Can you please give this updated PR a test-spin on Linux, too? Didn't update the Darwin code regarding the percentage source yet; plan is to pull in those changes in a separate PR, as this one is already complex enough. If you base a PR addressing the percentage issue on this PR, just drop me a note and this might get pulled early.

Also maybe a quick note regarding the 95%: fully writing 95% all the times in the UI makes things unnecessarily cluttered without much benefit; a note in the manpage is likely best. Suggestions for wording in the docs much appreciated.

@christianhorn Any chance you can test-drive this on some *BSD? Feedback regarding accuracy and (sign) correctness of the values much appreciated.

If nothing major comes up I'll likely merge this in about 2 weeks from now.

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🧩 Analysis chain

🏁 Script executed:

#!/bin/bash
git status --short
gh pr view 1967 --repo htop-dev/htop --json headRefOid,baseRefOid,url
gh api graphql -f query='query { repository(owner:"htop-dev",name:"htop") { pullRequest(number:1967) { reviewThreads(first:100) { nodes { isResolved isOutdated path line comments(first:20) { nodes { author { login } body url } } } pageInfo { hasNextPage endCursor } } } } }'
gh pr diff 1967 --repo htop-dev/htop --name-only
ast-grep outline BatteryMeter.c --items all
for f in linux/Platform.c pcp/Platform.c darwin/Platform.c freebsd/Platform.c dragonflybsd/Platform.c netbsd/Platform.c openbsd/Platform.c; do
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fd -i 'htop.*\.(1|in)$|man' . --max-depth 3

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curl -fsSL https://raw.githubusercontent.com/performancecopilot/pcp/main/src/pmdas/denki/denki.c | grep -n -A10 -B5 'BAT_CAPACITY\|energy_full\|bat.capacity\|power_now\|energy_now'

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@BenBE, yes: I would address the PCP telemetry defects before merging. I also found that the earlier FreeBSD partial-aggregation issue remains in the current code.

I checked head d56a6df against the PR base. This was source inspection, not hardware testing. I did not establish a reproducible crash with normal battery readings.

Fix before merge

  1. PCP uses a percentage as full energy capacity.
    This still-open finding remains valid. pcp/Platform.c, Line 239 maps PCP_DENKI_ENERGY_FULL to denki.bat.capacity. Lines 894–905 then treat that percentage as Wh.

    Upstream Denki reads this metric from sysfs capacity and labels it "percent". This produces incorrect Wh values, percentages, and charging estimates.

    Required change: use a verified full-energy metric. If none exists, leave full energy and ETA unknown rather than mixing units.

  2. PCP assumes that Denki power carries charge/discharge direction.
    This is an additional defect in the new collector. pcp/Platform.c, Lines 914–917 copy denki.bat.power_now directly into signed powerCurr. However, upstream Denki converts negative power readings to positive magnitudes before exporting them.

    Consequently, a discharging battery at 10 W can appear as charging at 10 W. The discharge branch and discharge ETA do not activate.

    Required change: obtain direction from a reliable status or signed-rate source. If direction is unavailable, do not treat a positive magnitude as charging. This is separate from the intentional PCP AC-state logic.

  3. FreeBSD can replace the system percentage with a partial-battery percentage.
    The earlier finding is marked resolved, but the current code still contains it. Failed battery ioctls cause the loop to skip a pack. freebsd/Platform.c, Lines 496–499 then overwrite the valid hw.acpi.battery.life percentage using only the remaining packs.

    For example, if only the full pack reports successfully, a partly depleted two-pack system can display 100%.

    Required change: preserve the valid system percentage. Use the energy-derived percentage only as a fallback, as DragonFlyBSD already does.

Open issue that can remain a follow-up

The Darwin percentage-source finding remains valid. It produces contradictory percentage and Wh output. The supplied hardware tests confirm this, but do not show a crash or instability. Given your explicit follow-up plan, I would not classify it as an urgent stability blocker.

I used the retrieved project guidance to exclude the withdrawn Linux capacity-only fallback, Linux sign-removal, and PCP AC-state suggestions.

Suggested manpage wording

Battery time estimates assume that the current charge or discharge rate remains constant. The charging estimate targets 95% of the reported full energy capacity and excludes the final charging phase. Charging can slow before this target, so the estimate can increase while the battery charges. Battery charge limits can prevent charging to 100%. On some platforms, the displayed percentage uses a different source and can differ from the energy ratio.

Thanks for the guidance on keeping the 95% explanation in the manpage rather than repeating it in the UI.


✏️ Learnings added
Learnt from: BenBE
URL: https://github.com/htop-dev/htop/pull/1967

Timestamp: 2026-10-03T18:56:11.344Z
Learning: In htop's BatteryMeter extension, BenBE prefers documenting the intentional 95% charging-ETA target in the manpage rather than repeatedly adding “95%” to UI labels. The estimate in BatteryMeter.c targets 0.95 * BatteryInfo.energyFull; documentation should explain the target and the constant-rate approximation without requiring a UI label change.

Note: Learnings are effective only in the context of similar code segments. To apply general coding guidelines, please configure review instructions. You can manage existing learnings in the app.


🧠 Learnings used
Learnt from: BenBE
Repo: htop-dev/htop PR: 1967
File: linux/Platform.c:1037-1048
Timestamp: 2026-10-03T13:23:10.871Z
Learning: In htop's Linux collector, `linux/Platform.c`, `Platform_Battery_getSysData` applies STATUS-based discharge sign correction to both POWER_NOW and power derived from CURRENT_NOW. BenBE confirmed this works on tested real hardware. Do not recommend removing this correction based only on an assumption that CURRENT_NOW is already signed; evaluate both input paths and the relevant driver behavior.

Learnt from: BenBE
Repo: htop-dev/htop PR: 1967
File: linux/Platform.c:1072-1076
Timestamp: 2026-10-03T13:20:36.401Z
Learning: In htop's Linux battery collector, `Platform_Battery_getSysData` in `linux/Platform.c` intentionally calculates the combined battery percentage from aggregated energy. Batteries that expose only `POWER_SUPPLY_CAPACITY`, without sufficient energy or charge-and-voltage data, are intentionally excluded because individual percentages cannot be combined meaningfully without capacity weights. Do not suggest an unweighted percentage fallback.

Learnt from: BenBE
Repo: htop-dev/htop PR: 1967
File: BatteryMeter.h:21-29
Timestamp: 2026-07-19T21:36:18.159Z
Learning: In `BatteryMeter.h`, `BatteryInfo.powerCurr` is defined as the derivative of stored battery energy. Its sign convention is therefore implicit: positive indicates charging and negative indicates discharging; future reviews should not request redundant sign wording.

Learnt from: BenBE
Repo: htop-dev/htop PR: 1967
File: pcp/Platform.c:880-883
Timestamp: 2026-05-16T12:16:20.204Z
Learning: In `pcp/Platform.c`, the `Platform_getBattery` AC state logic is intentional by design:
- `count < 1` (no battery instances) → `info->ac = AC_PRESENT`, because if there are no batteries the system must be running on AC power.
- `count >= 1` with non-negative `powerCurr` → `info->ac` stays `AC_ERROR` (indeterminate), because cross-charging means you cannot infer AC presence from charging alone.
- `count >= 1` with `powerCurr < 0` → `info->ac = AC_ABSENT`, as net discharge is the best available signal (though AC may still be connected but insufficient for current load).
Do not suggest changing this logic; it reflects physical constraints of battery/AC systems.

Learnt from: BenBE
Repo: htop-dev/htop PR: 1967
File: pcp/Platform.c:880-883
Timestamp: 2026-05-16T12:16:20.204Z
Learning: In `pcp/Platform.c` (`Platform_getBattery`), the AC state logic is intentional and physically grounded:
- `count < 1` (no battery instances detected) → `info->ac = AC_PRESENT`, because a system with no batteries must be running on external AC power.
- `count >= 1` with non-negative `powerCurr` → `info->ac` stays `AC_ERROR` (indeterminate). AC presence cannot be inferred from charging alone due to cross-charging between battery packs.
- `count >= 1` with `powerCurr < 0` → `info->ac = AC_ABSENT`. Net discharge is the best available signal, though AC may still be connected but insufficient for the current load.
Do not suggest changing this logic; it reflects physical constraints of battery/AC systems on PCP/Denki.

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@ravi-arnan

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Test-spun on Linux at d56a6df: built clean on NixOS with gcc 15 (0 warnings,
htop 3.6.0-dev-3.5.3-39-gd56a6df) and ran the meter against sysfs.

The host battery (BAT0) exposes CHARGE_NOW/CHARGE_FULL + VOLTAGE_NOW +
CURRENT_NOW, and no ENERGY_*/POWER_NOW, so this exercises the
charge-to-energy and current-times-voltage fallbacks rather than the direct
energy path.

Method: HTOPRC forcing the Battery meter in text mode, driven in tmux and read
with capture-pane, with the sysfs values read in the same second:

sysfs: status=Charging capacity=61 charge=2934000/4843000 V=12699000 I=3112000
expect  percent 60.6%   energy 37.3/61.5Wh   power +39.5W   eta 0h33m

main    Battery: 60.6% (Running on A/C)
PR      Battery: Using AC, charging at 39.5W, 37.3/61.5Wh (60.6%), time to full: 0h33m

All four values match what the files imply (energy = chargevoltage/1e6,
power = current
voltage/1e6, ETA from the 0.95 target), the percentage is
identical to main's, and there were no warnings, crashes or asserts.

Caveat: the machine is on AC, so only the charging branch ran. I could not reach
the discharging branch or the |power| < 5W "stable" one from here without
unplugging; both are untested on this box.

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