Cummins/Onan 4.0 BF-1R/9500 — Testing Battery Charging System
Testing & diagnosis
For the Cummins/Onan 4.0 BF-1R/9500, from the Cummins/Onan service manual.
Browse Cummins/Onan generators & specs →
Before you start
- Charging system tests require a fully charged battery
Procedure
- Battery voltage - unit not running: should be 12 VDC
- Battery voltage after unit running 3 to 5 minutes: 13.6 to 14.7 VDC
- Ohmmeter reading from stator output (unit not running): .2 to .6 ohms
- Measure AC stator output voltage with unit running: 28 VAC
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 12 VDC
- 13.6 to 14.7 VDC
- .2 to .6 ohms
- 28 VAC
Source: Cummins/Onan service manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.