Battery Testing

To test a battery is well and good, but what causes a battery to require testing? There are several causes that we can find to be the reason for a weak battery. Time and abuse are two of the most common.

Extreme temperatures

Excessive heat or cold are both damaging and taxing on a battery. In the heat, Batteries tend to dry up, evaporating the water inside of the battery. In the case of extreme cold, the entire engine becomes more difficult to start as oil thickens increasing the load that a starter motor requires to do its job.

Charging too fast and draining too low

The slower the charge, the healthier the charge, the less a battery is subjected to a low voltage the better a battery can maintain its charge.

Vibrations and other physical abuse

Transport vehicles vibrate. There is little one can do about it. That doesn't mean nothing can be done. Even a cut up mud flap to rest on is less taxing than a metal base. Also, manufacturers don't specify torque ratings for the bolts that secure batteries for nothing. There is a fine line between loose batteries and excessive clamping that squeezes the batteries. That fine line is commonly referred to as the torque specification.

Now, to the point of testing. Most testers are what is called a 'carbon tester' or 'load tester'. Fairly simple machines, and not very expensive. There are, for much more money, high tech testers that don't require any knowledge at all, even if they are plugged the wrong way it will tell you so, and you get a printout of the analysis of the health of the battery. They also will have a line indicating 'good battery', 'bad battery' or 'recharge and retest'. For those exact reasons, we'll focus on load testers, the less obvious ones.

The two names we give these traditional testers are both true. They use 'carbon' stacks to simulate the 'load' of starting an engine.

Battery Council International is a non-profit that counsels for the battery industry internationally. They recommend testing a battery with one-half of the CCA rating found on the label. A battery must be fully charged to perform an accurate test. If you don't know the CCA rating, then you should not be testing it with this method. There is no method to really know for sure if it is healthy if you don't know the CCA rating. Follow the instructions for your particular tester. You will typically be told to test for 15 seconds. You do not want to test longer because this is very tough on the batteries and will often cause the batteries and the tester to overheat. An overheated battery is an incredibly dangerous thing. It can and has caused property damage, seriously injured and even caused the death of people. Always allow time between tests for everything to cool down.

Some things you can do to minimize risk are testing in a well-ventilated area where dangerous gasses can escape. Also, inspect the battery before you begin a test. A crack or deformation in the battery assures you the battery is to be replaced and should not be tested for health, safety and practical reasons.

If ever there is any doubt in the battery, the tester or the person testing the battery, then a professional who is more accustomed and or trained in the task should be sought out to do the work instead.

Some additional safety precautions:

  • Red test lead to red positive terminal followed by the black test lead to the black negative terminal.
  • Perform the test on a flat surface, with proper ventilation.
  • Don't smoke or have anything that can cause a fire nearby.
  • Always refer to the instruction manual. When in doubt, do not perform the test.
  • Leave any and all labels on your tester and battery. Too much information looks better than a dangerous mistake.
  • Reconsider performing these tests with the advice of a doctor if you have a pacemaker.
  • Don't touch the cooling vents. Hot acid or gas is the only thing that can come out of them.
  • If there is limited space in the battery box, remove the batteries to perform the test as to avoid slip-ups and mistakes.
  • Avoid dropping or damaging the tester. It can damage important internal components.
  • There are countless other scenarios that can play out when working on or with batteries. If ever unsure or untrained, refer to a professional who has been properly trained.

Note: If ever a set of batteries are to be replaced and no physical damage or abuse has been identified then the charging system should be suspected and verified with a new set of batteries.

Drive safe,

Kevin Gauthier