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Classic Car Batteries & Electrical Problems

Posted by: Erik Bjornstad

Note: This is Part I of a 2-part blog series covering classic car batteries and electrical problems. 

The use of lead acid batteries goes back over 100 years and the principal used to store and unlock chemical energy is basically the same as it was a century ago. For car batteries, the life span of a battery depends on how it is used. You can expect good battery life to be anywhere from a year to 48 months, yet only about 30% of these batteries will reach the 48 month mark.

classic-car-batteries.jpgThis can definitely affect classic cars.  Most classic cars are not driven 365 days a year, and in most cases, they sit in storage more than they are driven.  This has a negative effect on battery life.

You can extend the life of your battery with some good common sense maintenance practices. Battery and electrical problems were the second most common problem during the yearly classic car Glidden Tour that I used to work with.  So let’s talk about some of these common problems, their causes and the solution steps you can take.

What battery to select – Wet or Gel?

When purchasing a battery for your classic car, you should select one with the highest reserve capacity or the highest amp hour rating. Batteries come in two types, wet cell and gel cell. The wet cell also comes in two different types: serviceable and maintenance free. Gel cell batteries usually cost twice as much as a wet cell, but the advantage of a gel cell battery comes when storing your classic car for a period of time. These do not sulfate or degrade as easily as a wet cell battery, which makes them more desirable for use in sporadic use vehicles like classic cars.

Another thing that is very important to consider when selecting a battery is how long it has been sitting on the shelf at your local parts store. Batteries that sit for long periods of time without being recharged will experience sulfating of the internal plates. The most common situation where you find sulfating is in a battery that has not been charged for an extended period of time. The sulfur molecules in the battery acid become so deeply discharged that they begin to coat the battery plates. In time, the plates in the battery will become so heavily coated that the battery dies. In most cases the battery will not recover from this condition and will need to be replaced.

How to tell how old the battery is

Most batteries have a date code on them indicating when they were manufactured.  The letter (A) is for January and the letter (M) is for December. The letter (I) is not used because it can be confused with the number (1). So, for example, if you see a code B5, that means the battery was manufactured in February 2005. To avoid a battery that has begun to sulfate, be sure to select the newest battery available.

Battery warranties are pretty much the same throughout the industry. They are pro-rated based on the retail price of the battery and a credit is given towards a new battery based on how many months the battery was used against the length of the warranty.

Practices to extend battery life

Good maintenance practices can extend the life of your battery in your classic car. The battery should be kept clean by using a baking soda and water solution. Battery acid that settles on the top of a battery will create a minor short between the positive and negative terminals and shorten the life of the battery. You can check this with a digital volt meter by touching the positive terminal of the meter with one lead and touching the top of the battery in different places with the other. If you get a voltage reading, the battery should be cleaned. The battery terminals should be cleaned and tightened because starting problems commonly can be traced to bad connections at the battery.

The type of terminals used also affects the starting power of the battery. Inexpensive lead battery terminals do not work very well because they tend to loosen in time and corrode at the connection points. Brass terminals are far more desirable because they maintain a tight connection on the battery terminal. Battery terminals should be coated with grease or petroleum jelly to prevent oxygen from coming in contact with the terminal and contributing to corrosion.

Read part 2 of our blog series covering classic car batteries and electrical problems

Image Credit: Antique Auto Battery of Youngstown, OH

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This post was published on October 3, 2017 and was updated on October 9, 2017.

Topics: Classic Cars