This truck battery is “maintenance free,” but you still have to add water occasionally. To check water level (and add water if necessary), you’ll need to use a straight-edged screwdriver to remove the caps.

If you don’t maintain the battery in your truck and trailer, you could become stranded. Diesel trucks use two 12-volt batteries for extra power to start a diesel engine. This also gives you reserve power going down the road. Living-quarters trailers usually have two deep-cell batteries that last a long time. With four batteries between your truck and trailer, proper maintenance is important.

Your trailer's batteries may be enclosed in a box (top) or may be exposed to road grime (bottom). If the batteries are grimy, cleaning is essential.

The three basic battery maintenance musts are: (1) keeping the water level at the fill line; (2) cleaning any corrosion off the battery terminals; and (3) keeping the batteries charged.

Maintain Water Levels
To maintain the water level, use distilled water; tap water’s minerals can corrode the battery. Don’t overfill your battery with water, or the battery acid could overflow, damaging any metal.  

Note that in the last 20 years, battery manufacturers have come out with “maintenance-free” batteries that they claim don’t need additional water. However, while you may not need to add water as often, you do need to add it from time to time. Unfortunately, now it’s harder to take off the cell caps to check the water level! To remove, insert a straight-edge screwdriver in the slot, and pop off the hidden caps.

Only gel-filled batteries, such as Optima, don’t need additional water.

Clean the Terminals
To clean corrosion off the battery terminals, follow this procedure:

Step 1. Pour warm water on your battery posts to start the cleaning process

Step 2. Use a wrench to take the battery cable terminal clamp off the battery post. Remove the negative side first, for safety.

Step 3. Stir two tablespoons baking soda into a cup of warm water.

Step 4. Dip the battery cable terminal into the mixture to remove the green corrosion.

Step 5. Pour what’s left of the baking soda solution onto the battery posts.

Step 6. Use a battery-cleaning tool to scrub the posts and inside the terminals. (Note: There’s a cleaning brush available for GM side terminals at your local auto-parts store.)

Step 7. Re-clamp the terminals to the battery posts.

Step 8. Hose off the battery.

Step 9. Apply grease or a battery-terminal sealant to the terminals.

Battery-cleaning tools, like the one shown here, ease the cleaning process.

Expert tips: In an emergency, you can also use a cola product to eat some of the corrosion off battery terminals. Gel batteries don’t corrode their terminals, which is a big benefit on a diesel trucks and living-quarters trailers, which have all the accessory electric leads anchored to the battery terminals.

Keep the Batteries Charged
Keeping your batteries charged is fairly simple. Your truck’s battery will charge as you drive. Then your truck’s batteries trickle-charge your trailer’s batteries as you go down the road. Solar panels are becoming increasingly popular to charge living-quarters trailer batteries.

Keep your batteries clean, dry, and charged and you’ll forget what booster cables are for. Good luck!