Keep your laptop battery healthy with TLP

I wrote about my ThinkPad X270’s battery troubles a few years ago. Since then, I have learned techniques that have extended my battery lifespan so that I’m still using this same laptop today.

The battery is typically the first component to fail in a laptop. Every laptop I’ve owned has shown significant battery degradation within a year, and after a few years, battery runtime often dropped to half of its original capacity.

Charge depth significantly impacts battery lifespan. Keeping the battery at extreme levels—either fully discharged or fully charged—reduces its lifespan.

When I’m done with my laptop I dock it and leave it until my next use. One problem with this is that the battery remains at 100% for an extended period before I pick up the laptop again. This ages the battery and reduces its lifespan. It’s better to stop charging when the battery is at 80%. To keep the battery levels on my ThinkPad below 80%, I use TLP.

TLP is a Linux power management tool that extends battery runtime and lifespan by optimizing system-level power settings and preventing overcharging.

Here’s how to configure TLP’s charge thresholds. Two parameters control the charge level thresholds: START_CHARGE_THRESH_BAT0 and STOP_CHARGE_THRESH_BAT0. I added the following to my /etc/tlp.conf:

START_CHARGE_THRESH_BAT0=70
STOP_CHARGE_THRESH_BAT0=80

START_CHARGE_THRESH_BAT1=70
STOP_CHARGE_THRESH_BAT1=80

The X270 has two batteries, which is why I have the BAT1 thresholds in addition to the BAT0 ones. Most laptops only have one and only need the BAT0 thresholds.

TLP sets these threshold values in the laptop’s embedded controller’s registers, the low-level firmware that manages hardware functions, meaning that these thresholds work even when the operating system isn’t running.

Setting the battery charge thresholds between 70% and 80% is the optimal range for me. I rarely need to use my laptop for long periods of time before I charge it. I usually use it for less than 4 hours. The ThinkPad X270 has two batteries: an internal 24 Wh battery and a removable 48 Wh battery—and both retain at least 80% of their original capacity. With the 70-80% charge limits, this gives me about 45 Wh of usable capacity. That’s enough for 4 to 5 hours of work with the Wi-Fi on. This is good considering these are 6-year-old batteries!

After six years, both batteries retain 80% of their capacity, something I attribute largely to TLP’s charge management. The results speak for themselves: after six years, my ThinkPad’s batteries still perform like new. If you’re running Linux on a laptop, TLP’s charge management is a simple investment that can significantly extend your hardware’s lifespan.