Cummins/Onan — 2-Ampere SCR Float Charger Adjustment
Adjustments
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- This float charger is not designed to recharge batteries quickly; a discharged battery must have a minimum voltage of four volts for battery charger operation
Procedure
- Connect the fully-charged battery (verify charge condition with the hydrometer).
- Connect the voltmeter directly to the battery terminals.
- Measure the battery voltage; if above the recommended float voltage go to Step 4, if below go to Step 6.
- Insert a small screwdriver through the hole in the front panel of the charger module and turn counterclockwise in small increments to decrease float voltage.
- After five minutes, measure the battery terminal voltage again; repeat Steps 4 and 5 until voltage stabilizes at the recommended float voltage.
- Note charge current rate on the charge ammeter.
- Turn the adjustment screw clockwise in small increments to increase float voltage; note increase in charging current.
- In approximately one hour or when charge current has decreased to the initial value, recheck battery terminal voltage; repeat until voltage stabilizes.
- Check the battery with a hydrometer and check terminal voltage periodically during the first few weeks of operation.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Float voltage 13.3 V (12 V lead-acid), 26.6 V (24 V lead-acid), 13.8 to 14.5 V (10-cell nickel cadmium), 27.6 to 29.0 V (20-cell nickel cadmium)
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.