Thursday, April 3, 2008

Marine Batteries

"Here's how you can prepare your marine batteries for boating season"

  1. Disconnect the ground (negative) terminal first! THIS IS A MUST. Then disconnect the positive terminal.
  2. Remove the battery from the boat and place it on a work surface.
  3. Clean off the outside of the battery. Make sure the top is free of dirt, grease and oil.
  4. Clean the terminals with baking soda and water, then wipe them dry with a paper towel.
    Remove the caps from each of the cells and check the fluid level. If the fluid is not up to or near the top of the cell, add DISTILLED water ONLY. Then replace the caps.
  5. Take a multimeter and set the dial on the D.C. (Direct Current) setting. Then place the negative lead on the ( - ) terminal and the positive lead on the ( + ) terminal.
  6. Each cell should produce about 2.1 volts at full charge. As a result, your meter should show around 12.6 volts - or better.
  7. If the battery is below full charge, hook up a small, low ampere charger and charge the battery slowly. I remove the caps during this process.
  8. After the battery reaches full charge, replace the caps and let it set for 24 hours. Check it with the multimeter. If it has held its charge, it's good to go.
  9. Using an inexpensive battery terminal cleaning device, shine up both the terminals and the cable ends on the boat. Check the cables for any signs of corrosion or over-heating.
  10. Clean your battery box inside and out. Make sure that it is firmly affixed to your boat.
  11. Put the battery back into the boat. Connect the positive terminal first and the negative terminal last. Make sure they are really tight.
  12. Cover both terminals with nonmetallic grease. You can either purchase battery terminal grease, or use petroleum jelly such as Vaseline.
  13. Replace the battery box cover and secure it.


  1. Batteries produce hydrogen gas. NEVER, have any kind of open flame near them!
  2. Batteries have acid in them. Use rubber gloves, wear clothes that you no longer care about and wear safety glasses when working with them.
  3. When you're moving the battery around, keep it as level as possible. This will help keep the battery acid from leaking.
  4. Make sure there is good ventilation in your battery compartment.
  5. Check your battery's water level often and then make sure the top is clean and dry.

What You Need:

Small adjustable wrench

Battery post cleaner

Distilled water

Nonmetallic grease

Rubber gloves