FANUC Series 0i-F / 0i-F Plus alarm DS0306: APC ALARM: BATTERY VOLTAGE 0
DS0306 (APC ALARM: BATTERY VOLTAGE 0) on a FANUC 0i-F means the absolute position detector battery voltage dropped to a level at which position data can no longer be held, or the Pulsecoder was powered for the first time. FANUC points to the battery or its cable and says to replace the battery with the machine turned on.
Diagnose this with AI
Try Free CNC Alarm Diagnostic Upload a keypad photo, the fault history or a parameter export from your FANUC Series 0i-F / 0i-F Plus. InduQT compares the evidence and suggests the next useful checks.
When it happens
- At power-up after the machine was off with a flat battery
- After a battery or cable was disconnected
- First power-up of a new motor or Pulsecoder
Likely causes and checks
1Battery exhausted while the machine was off
- Points to it
- DS0307/DS0308 warnings were ignored earlier; machine was off over a weekend or longer.
- Check
- Read DGN 3019 for the affected detector, replace the battery with power on and E-stop applied, then set the reference position (DS0300).
2Battery replaced with power off
- Points to it
- Alarm right after a battery change.
- Check
- Replace again with power on next time; the position must now be re-established.
3Battery cable or connector fault
- Points to it
- Battery is new and measures good but the alarm returns on one axis.
- Check
- Check the battery cable and connector to the amplifier for that axis.
4New Pulsecoder powered for the first time
- Points to it
- Motor or encoder just replaced.
- Check
- Expected; set the reference position per the builder’s procedure.
Telling it apart
- DS0307 (BATTERY LOW 1) is the early warning that replacement is due while data is still held; DS0306 means data could not be held.
- DS0308 (BATTERY LOW 2) records that the voltage was low at some point in the past, including while powered off.
Relevant parameters
| Parameter | Name | Why it matters |
|---|---|---|
| DGN 3019 (diagnosis) | Detector battery exhaustion | ABP, INP and EXP bits show which detector battery is low. |
Evidence to collect
- Alarm history (were DS0307/DS0308 shown earlier?)
- DGN 3019 bits per axis
- Battery type, age and voltage
- How long the machine was powered off
Work on fuel trains, burners, pressure vessels and electrical equipment must be done by qualified personnel following the manufacturer’s documentation and local codes. Never bypass a safety device or interlock.