Cummins/Onan — Battery Float Charge

Adjustments · Battery charger

From a Cummins/Onan service manual — check it applies to your exact model before use.

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Procedure

1. Connect the fully-charged battery (verify charge condition with the hydrometer).
2. Connect the voltmeter directly to the battery terminals.
3. Measure the battery voltage. If voltage is above the recommended float voltage, proceed to Step 4. If below, proceed to Step 7.
4. Open right cabinet door of automatic transfer switch.
5. Insert a small screwdriver through the hole in the front panel of battery charger module 6. Turn counterclockwise in small increments to decrease the float voltage.
6. After five minutes, measure the battery terminal voltage again. If voltage is still high, repeat Steps 5 and 6 until voltage stabilizes at the recommended float voltage. Proceed to Step 11.
7. Open right cabinet door of automatic transfer switch.
8. Note charge current rate on charge ammeter on meter-lamp panel.
9. Insert a small screwdriver through hole in front panel of battery charger module 6. Turn clockwise in small increments to increase float voltage. Note increase in the charging current on the charge am
10. In approximately one hour or when charge current has decreased to initial value noted in Step 8, recheck battery terminal voltage. Repeat Steps 8 through 10 until the battery terminal voltage stabiliz
11. Check the battery terminal voltage periodically during the first few weeks of operation. Readjust the float charge rate if necessary.
12. Close the cabinet door.

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.

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