docs: mention battery management; update sample config

README.md

@@ -111,6 +111,26 @@ sudo superfreq set-min-freq 1200 --core-id 0
 sudo superfreq set-max-freq 2800 --core-id 1
 ```
 
+### Battery Management
+
+```bash
+# Set battery charging thresholds to extend battery lifespan
+sudo superfreq set-battery-thresholds 40 80  # Start charging at 40%, stop at 80%
+```
+
+Battery charging thresholds help extend battery longevity by preventing constant
+charging to 100%. Different laptop vendors implement this feature differently,
+but Superfreq attempts to support multiple vendor implementations including:
+
+- Lenovo ThinkPad/IdeaPad (Standard implementation)
+- ASUS laptops
+- Huawei laptops
+- Other devices using the standard Linux power_supply API
+
+Note that battery management is sensitive, and that your mileage may vary.
+Please open an issue if your vendor is not supported, but patches would help
+more than issue reports, as supporting hardware _needs_ hardware.
+
 ## Configuration
 
 Superfreq uses TOML configuration files. Default locations:
@@ -139,6 +159,8 @@ platform_profile = "performance"
 # Min/max frequency in MHz (optional)
 min_freq_mhz = 800
 max_freq_mhz = 3500
+# Optional: Profile-specific battery charge thresholds (overrides global setting)
+# battery_charge_thresholds = [40, 80]  # Start at 40%, stop at 80%
 
 # Settings for when on battery power
 [battery]
@@ -149,6 +171,12 @@ epb = "balance_power"
 platform_profile = "low-power"
 min_freq_mhz = 800
 max_freq_mhz = 2500
+# Optional: Profile-specific battery charge thresholds (overrides global setting)
+# battery_charge_thresholds = [60, 80]  # Start at 60%, stop at 80% (more conservative)
+
+# Global battery charging thresholds (applied to both profiles unless overridden)
+# Start charging at 40%, stop at 80% - extends battery lifespan
+battery_charge_thresholds = [40, 80]
 
 # Daemon configuration
 [daemon]

src/cpu.rs

@@ -2,7 +2,11 @@ use crate::core::{GovernorOverrideMode, TurboSetting};
 use crate::util::error::ControlError;
 use core::str;
 use log::debug;
-use std::{fs, io, path::{Path, PathBuf}, string::ToString};
+use std::{
+    fs, io,
+    path::{Path, PathBuf},
+    string::ToString,
+};
 
 pub type Result<T, E = ControlError> = std::result::Result<T, E>;
 
@@ -399,7 +403,7 @@ pub fn set_battery_charge_thresholds(start_threshold: u8, stop_threshold: u8) ->
     let power_supply_path = Path::new("/sys/class/power_supply");
     if !power_supply_path.exists() {
         return Err(ControlError::NotSupported(
-            "Power supply path not found, battery threshold control not supported".to_string()
+            "Power supply path not found, battery threshold control not supported".to_string(),
         ));
     }
 
@@ -447,7 +451,7 @@ pub fn set_battery_charge_thresholds(start_threshold: u8, stop_threshold: u8) ->
 
     if supported_batteries.is_empty() {
         return Err(ControlError::NotSupported(
-            "No batteries with charge threshold control support found".to_string()
+            "No batteries with charge threshold control support found".to_string(),
         ));
     }
 
@@ -462,16 +466,20 @@ pub fn set_battery_charge_thresholds(start_threshold: u8, stop_threshold: u8) ->
         // Attempt to set both thresholds
         match (
             write_sysfs_value(&start_path, &start_threshold.to_string()),
-            write_sysfs_value(&stop_path, &stop_threshold.to_string())
+            write_sysfs_value(&stop_path, &stop_threshold.to_string()),
         ) {
             (Ok(_), Ok(_)) => {
-                debug!("Set {}-{}% charge thresholds for {} battery '{}'", 
-                    start_threshold, stop_threshold, battery.pattern.description, battery.name);
+                debug!(
+                    "Set {}-{}% charge thresholds for {} battery '{}'",
+                    start_threshold, stop_threshold, battery.pattern.description, battery.name
+                );
                 success_count += 1;
-            },
+            }
             (start_result, stop_result) => {
-                let mut error_msg = format!("Failed to set thresholds for {} battery '{}'", 
-                    battery.pattern.description, battery.name);
+                let mut error_msg = format!(
+                    "Failed to set thresholds for {} battery '{}'",
+                    battery.pattern.description, battery.name
+                );
 
                 if let Err(e) = start_result {
                     error_msg.push_str(&format!(": start threshold error: {}", e));
@@ -488,7 +496,10 @@ pub fn set_battery_charge_thresholds(start_threshold: u8, stop_threshold: u8) ->
     if success_count > 0 {
         // As long as we successfully set thresholds on at least one battery, consider it a success
         if !errors.is_empty() {
-            debug!("Partial success setting battery thresholds: {}", errors.join("; "));
+            debug!(
+                "Partial success setting battery thresholds: {}",
+                errors.join("; ")
+            );
         }
         Ok(())
     } else {

src/engine.rs

@@ -216,7 +216,9 @@ fn apply_battery_charge_thresholds(
                 } else {
                     // For permission errors, provide more helpful message
                     if matches!(e, ControlError::PermissionDenied(_)) {
-                        debug!("Permission denied setting battery thresholds - requires root privileges");
+                        debug!(
+                            "Permission denied setting battery thresholds - requires root privileges"
+                        );
                     }
                     Err(EngineError::ControlError(e))
                 }