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Warning· MBB / BMS log file

12V Battery Low

Auxiliary 12V battery voltage is low

SystemSource: MBBLog file condition
Last updated: July 30, 2026

What it means

Auxiliary 12V battery voltage is low

WarningMonitor the situation, may self-resolve.

Likely causes

  • 12V battery aging
  • Parasitic drain from accessories
  • DC-DC converter issue

What to do

  1. 1Check 12V battery terminals
  2. 2Charge or replace 12V battery
  3. 3Check for accessories left on

Which bikes use this table

Recorded in the binary log rather than shown on the dash — every generation writes them.

Questions

What does "12V Battery Low" mean in a Zero log?

Auxiliary 12V battery voltage is low. It is written by the MBB. It is classed as warning: monitor the situation, may self-resolve.

What should I do about it?

Check 12V battery terminals. Charge or replace 12V battery. Check for accessories left on.

See when this actually happened on your bike

A dash code tells you the fault; the log tells you the pack temperature, the state of charge and the ten minutes leading up to it.

Upload a log

Community reference: ZeroManual wiki entry

The code and its name are transcribed from Zero's own owner manuals; the severity, category and troubleshooting notes are ours. For official diagnostics, consult an authorized Zero Motorcycles dealer.