Battery Desync Fix NX Switch

Battery Desync Fix NX
General
Author	CTCaer
Type	System Tools
Version	1.5.1
License	Mixed
Last Updated	2025/11/17
Links
Download
Website

Battery Desync Fix NX is a homebrew application that allows you to calibrate your Fuel Gauge IC with values based on your Switch's factory calibration data. This fixes issues with battery percentage being wrong.

During power off or reboot, HOS saves the calibration values, which are then restored during boot.

The issue is believed to be a hardware bug in the Fuel Gauge that is triggered by HOS. Specifically, it can happen on restore when Fuel Gauge has significantly different values from HOS last saved context.

Disclaimer: Please use at your own risk. This is a specialized app that must only run if user has real issues with capacity full and percentage. Easiest way to identify the issue is random up/downs on battery percentage and the "capacity now" not matching voltage avg/oc.

User guide

You must run this app in succession to your sysMMC and every emuMMC (if they exist). Otherwise the moment you switch to another one, it will desync again.

You can start from whichever you want. Assuming you start with SYS CFW or OFW/Stock:

1. Boot SYS CFW.
2. Run the app.
3. Press X button for forcing init.
4. Exit the app properly (press B).
5. If you want this for OFW, reboot and boot OFW or Stock.
6. Do 2 full charging cycles (??% > 100% > 0% > 100% > 0%).
7. After it's done and values are now good, enter the app and press A to save calibration to sd card.
8. Reboot into emuMMC, enter the app and press Y to restore the calibration from sd card.

Notes when using:

• Do not reboot to something else until done.
• When HOS forces a sleep because battery is too low, wake it again and again until it shows red battery icon.
• In case HOS powered off, put charger to enter HOS.
  • If it's stuck on black screen and charger icon, unplug/plug after a bit so you can enter inside.
  • Do not fully charge in there because it HOS will restore the previous Fuel Gauge context.

Order doesn't matter. If you started with emuMMC for steps 1 to 7, you do the 8th step on sysMMC CFW/OFW instead.

Do not switch in-between SYS, EMU and anything else without finishing the 2 charging cycles and saving the calibration to sd. Always be careful when rebooting until done.

If the process was done wrong, you will need to start from scratch.

Changelog

v1.5.1

• Added Voltage limit info that shows HOS battery voltage limit for charging.
• Added battery chemistry info. If it shows in yellow value in CAL0 does not match what HOS sees.
• Added a way to reset charge cycles for replacing battery with new via the save and restore options. Edit batt.cal last 4 bytes to FF FF FF FF.
• Updated to latest libnx for fixing the TLS allocation slot index issue when used in threadExit.
• Various other improvements.

v1.5.0

• Added a way to fix battery reliability for Nintendo Switch Lite.
• Applies on devices that were improperly wiped before and lost all calibration data.
• In such devices, the app will ask for the correct charge cycles. Choose carefully.

v1.3.0

• Added save/restore of calibration to/from sd card.
• It greatly simplifies and time taken to finish the procedure.
• Added more checks on relevant parts.

v1.2.2

• Added a mitigation for users that have corruption in system save data.
• Recompile with newer libnx.

v1.2.1

• Recompile with newer libnx.

v1.2

• First Release.

External links

• Twitter - https://twitter.com/CTCaer/status/1540028516477157376
• GitHub - https://github.com/CTCaer/battery_desync_fix_nx