Cummins/Onan — Equalize SCR Charger Adjustment
Adjustments · Equalize SCR battery charger
From a Cummins/Onan service manual — check it applies to your exact model before use.
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Before you start
- Discharged battery must produce minimum of 4 volts to allow charger to operate
Procedure
- Connect charger to a fully charged battery.
- Connect a high accuracy meter (preferably 1/2 to 1 percent) to the battery terminals.
- Equalize-charge battery until timer completes (use equalize charger timer).
- Return timer to zero and wait until voltage stabilizes.
- Turn float adjust potentiometer counterclockwise to increase or clockwise to decrease float voltage; adjust in small steps and wait for voltage to stabilize.
- After float adjustment, set timer to equalize charge and wait until charge current drops below 5 amperes.
- If voltage goes above the desired equalize voltage, turn equalize-adjust potentiometer clockwise in small steps until battery voltage drops to desired voltage.
- If current drops before reaching the desired voltage, turn equalize-adjust potentiometer counterclockwise in small steps.
- Disconnect the high accuracy voltmeter.
- Return timer to zero for float charging.
Tools required
- high accuracy voltmeter (1/2 to 1 percent) Amazon
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- 13.2 V float and 14.2 V equalize for 12-volt Amazon eBay $11.99 FridayParts $65.01 lead acid; 26.4 V float and 28.5 V equalize for 24-volt SinoCMP $247.50 lead acid; nickel cadmium float 1.38 to 1.45 volts per cell
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.