Before doing any service to a battery, keep in mind that the storage battery in your car produces gases that can explode if a spark or flame ignites them. Also keep in mind that the fluid inside the battery is acidic; it can eat away paint, metal and skin. Wear heavy chemically resistant rubber gloves and eye protection when working near a battery. A full face shield is better than goggles because it protects your facial skin.
Even if your collector car was manufactured before sealed batteries became standard equipment, you can use a sealed battery in it today. However, if you want the car to appear authentic under the hood, you may have purchased an old-fashioned-looking “tar-top” battery with removable filler caps. These are sold at many flea markets and through hobby publication ads.
On batteries with filler caps, battery fluid levels need to be checked regularly and maintained. To inspect the fluid level, twist the battery cell caps counter-clockwise to remove them and check the fluid. It should be level with the filler ring, which is about an inch down in the opening. If the fluid is low, add distilled water.
If you discover that the fluid level drops rapidly and constantly, it can indicate three problems: The electrical system may be over-charging the battery; the battery case may be cracked and leaky; or the battery could have suffered some internal damage. The last two problems require replacement of the damaged battery.
If your battery fluid level seems OK, the next step is to clean the terminals. Remove the battery cable connectors to get at the terminals. To avoid making a spark, disconnect the negative cable first. Later, it should be the last cable that you reconnect.
You can use a commercial terminal cleaner or a solution of baking soda and water to clean the battery terminals. After applying the cleaner, brush the terminals until they’re clean and shiny – and be careful not to get cleaner or baking soda in the battery.
When reconnecting the cables, add a light coat of petroleum jelly, light grease or spray protectant to protect against future corrosion. You can also buy red and green felt rings, impregnated with protectant, that slip over the terminals.
To determine the battery’s state of charge, measure the specific gravity (density) of the fluid in each cell with a hydrometer. Simple battery testers are also available in auto parts stores. A hydrometer reading of 1.275 indicates a fully charged battery. Some hydrometers have floating balls inside the tester and give a reading based on how many balls float in a test sample of the battery fluid. If one cell gives a reading 10 percent less than other cells, it indicates high resistance in that cell and the battery needs to be replaced.
Carefully clean the top of the battery of dirt, corrosion and battery fluid. Also be sure that the vent holes in the battery filler cups aren’t clogged. If you see cell-damaged cell caps or battery warpage, the battery is no good; it’s either been over-charged or over-heated. There should be no cracks in the battery case either.
A battery should never be installed loosely in a car. Some type of battery hold-down system is a must. A loose battery can cause acid spills or it can short out causing a fire. In an accident, a loose battery can go flying through the car. The hold-down system should be tight enough to secure the battery, while not putting so much pressure on it as to crack the battery case. Rusty hold-down systems invite the formation of corrosion. Make sure the hold-down mechanism has a heavy coat of paint and coat bolts and nuts with grease or spray-on protectant so they remain easy to remove.
Be aware that designs of some old-car batteries have changed slightly. For instance, the long, narrow EEE batteries used in some ‘40s and ‘50s cars are being manufactured today with the terminals spaced further apart. If the battery still has a factory-installed metal cover, the terminals on the newer-design battery may hit against the metal cover. This condition has been known to cause electrical shorts and fires. Make sure that your battery terminals and bare braided cables aren’t touching any part of a metal hold-down system.
When installing a battery in an old car, make sure that it’s of the proper voltage for the car and correctly grounded. Many old cars used 6-volt electrical systems and require a 6-volt battery. Some old cars also came from the factory with positive-ground electrical systems. If you own a positive-ground vehicle, the + cable is the one that goes to the car’s frame – not the one that goes to the solenoid or starter! Reversed polarity can cause an explosion or damage the car’s electrical system.
If you give your storage battery a spring check-up, you should be able to rely on it for sure-starts all summer long. If problems do show up during check up, you’ll be able to replace the battery at home and avoid getting stuck on the road with a dead battery.
John "Gunner" Gunnell is the automotive books editor at Krause Publications in Iola, Wis., and former editor of Old Cars Weekly and Old Cars Price Guide.