Battery Modes¶
Hara Hachi Bu controls your laptop's charging threshold — the maximum percentage the battery charges to. Three modes are provided, each optimised for a different use case.
The Modes¶
| Mode | Charge Range | Optimised For |
|---|---|---|
| Full Capacity | 95–100% | Maximum runtime when you need it |
| Balanced | 75–80% | Good runtime with improved longevity |
| Max Lifespan | 55–60% | Maximum battery longevity |
These ranges are defaults. You can adjust the exact percentages in Preferences → Thresholds.
Why It Matters¶
The Science¶
Lithium-ion batteries degrade faster when kept at high charge levels. Limiting the maximum charge — even slightly — can dramatically extend battery lifespan.
Data from Battery University:
| Peak Charge Voltage | Approx. Capacity | Cycle Life |
|---|---|---|
| 4.20 V (100%) | Full | 300–500 cycles |
| 4.10 V (~75%) | ~85% | 600–1,000 cycles |
| 4.00 V (~60%) | ~75% | 850–1,500 cycles |
Every 0.10 V reduction in peak charge voltage roughly doubles cycle life.
Depth of discharge matters too: cycling 100% of capacity yields ~300 cycles (NMC chemistry), while cycling only 40% yields ~1,000 cycles.
Storage has a similar effect. A battery stored at 40% charge and 25°C retains 96% capacity after one year. At full charge and the same temperature, only 80% remains. At 40°C and full charge, capacity drops to 65%.
Environmental Impact¶
Battery manufacturing produces 54–115 kg CO₂-eq per kWh of capacity, depending on chemistry and sourcing (Nature Communications, 2024). Around 80% of a notebook's total lifetime greenhouse gas emissions come from manufacturing, not use (TCO Certified).
Extending a laptop from 3 to 6 years of service roughly halves its annualized carbon footprint.
Globally, 62 million tonnes of e-waste were generated in 2022, with less than a quarter (22.3%) properly collected and recycled — leaving an estimated US $62 billion in recoverable materials unaccounted for (UN Global E-Waste Monitor, 2024).
Economic Impact¶
Laptop battery replacements cost $50–200 when available, but a degraded battery often prompts full laptop replacement ($300–850+). Charging within the 40–80% range can extend usable battery life from ~300–500 cycles (~2 years of daily cycling) to ~1,000–1,500+ cycles (~4–5 years).
How to Use the Modes¶
Use Max Lifespan when you're working at a desk plugged in — you don't need more than 60% capacity to get through the day if AC is always available.
Use Full Capacity before traveling — you want maximum runtime when you're away from a power outlet.
Use Balanced as a default middle ground that protects the battery without sacrificing too much runtime.
Or better yet: let the Docked and Travel profiles handle the switching automatically based on whether an external display is connected or you're on battery. See Profiles and Auto-Switch Rules.
For one-off needs (a day trip, a long flight), use Boost Charge to temporarily charge to 100% and have it revert automatically.
Hardware Requirements¶
Battery mode control requires your laptop to expose the standard Linux sysfs interface at /sys/class/power_supply/BAT0/charge_control_end_threshold. Most ThinkPads, Framework laptops, and many ASUS models support this. See Hardware Compatibility for details.