Cummins/Onan OT-A-4060A / OT-C-10050C — Battery Charger Float Voltage Adjustment
Adjustments · Float battery charger
For the Cummins/Onan OT-A-4060A / OT-C-10050C, from the Cummins/Onan service manual.
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Before you start
- Ignition of explosive battery gases can cause severe personal injury. Do not smoke or cause any spark, arc, or flame while servicing batteries.
- Always disconnect the battery charger from its AC source before disconnecting the battery cables.
Procedure
- Turn the generator set operation selector to Stop and disconnect the starting battery (negative lead first).
- Connect the fully charged battery (negative lead last) and verify charge condition with a hydrometer at specific gravity 1.260 at 77 F (25 C).
- Connect an accurate voltmeter directly to the battery terminals and measure the voltage.
- Compare the reading with the recommended float voltage (12 V = 13.3 VDC; 24 V = 26.6 VDC).
- Turn the adjustment potentiometer counterclockwise to decrease or clockwise to increase the float voltage in small steps.
- Wait five minutes for the voltage to stabilize before making additional adjustments.
- Close and lock the cabinet door.
- Disconnect the voltmeter and test battery (negative lead first).
- Reconnect the generator set starting battery (negative lead last) and place the operation selector switch in Auto (three-wire start) or Remote (two-wire start).
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Lead-acid 12 V float voltage: 13.3 VDC
- Lead-acid 24 V float voltage: 26.6 VDC
- Nickel-cadmium float charge per cell: 1.38 to 1.45 volts
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.