How to: Maintain your batteries

Test and clean routinely

For power needed to run cab accessories, most trucks today need deep-cycle batteries with a lot of reserve capacity rated at a low amperage draw. A battery with, say, 200 hours reserve capacity has fewer, thicker plates than traditional batteries designed mainly for cranking the engine. It will last much longer with overnight shutdowns. Testing of batteries and cleanup of their connections every six months, or sooner if corrosion is noticed, will prevent no-starts while also minimizing electrical system repair costs.



• Battery cable connection cleaning brush set • Electric drill • Hydrometer

• Voltmeter • Socket wrenches • Spray protectant or dielectric grease

1.  Disconnect the hold-downs and remove the battery box cover.

2.  If doing this for the first time, draw a diagram of the cable connections before proceeding. Then, remove all the negative terminal attaching nuts and disconnect negative cables to prevent a short circuit.

3.  Loosen all the battery hold-down nuts and remove the hold-down bracket for access.

Four Untitled 14.  Remove the cell covers. Test each cell by drawing the electrolyte fluid into a hydrometer. In a healthy cell, all the balls float near the top.

5.  Balls floating near the bottom of the hydrometer indicate a bad cell. In this case, you should measure voltage with the engine off. A battery is dead at 12.1 volts, and fully charged at 12.6 volts. Even if only one battery in a group is bad, it’s best to replace them all to make sure they all do the same amount of work.

Six Untitled 116.  If any of the hold-down bolts or other parts break during disassembly or show signs of severe corrosion, replace them. Secure mounting means less vibration and longer battery life.

Seven Untitled 17.  Clean all cable connections with a male drill-mounted wire brush.

Eight Untitled 18.  Clean all the battery posts with the corresponding female brush – even on a new battery, to ensure good connections.

9.  After replacing all the caps and the mounting bracket, tighten the bracket mounting nuts securely. Then install and gently tighten each positive cable and post connector.

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10.  Install negative post connections and coat each with dielectric grease or spray protectant. Reinstall the battery box cover hold-downs. n

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