My fairly new battery sometimes fails to start

Thursday November 7 2019


By Paul Kaganzi

Hi Paul, My Toyota Harrier’s car battery has failed to start in the morning on two occasions yet it was replaced three months ago. The mechanic says it’s bad and needs to be replaced. However, the car alternator works fine. Why should a fairly new battery fail and how can I be certain the next one won’t disappoint me. Catherine. S

Hello Catherine, there are reasons why a new battery may not last long on your car, even when your alternator works fine. A battery is a device that turns chemical energy into electricity. To maintain this energy the battery needs to be amply charged.

The car charging system may have corroded or loose battery connections, this will not allow the battery to charge fully, hence suffer premature failure. Persistent battery drain which happens with cars that are not regularly driven, have accessories like radios switched on for a long time without the engine running or have short circuits which drain the battery.

There are a few important points to note before you buy a new battery, lest it does not serve you well. It is important to buy a reputable brand of batteries recommended by mechanics, online reviews or other users and offering a good warranty of at least one year with terms and conditions.

It is crucial to buy the correct battery. The new battery should fit on the car battery seat while the size and terminal location should be the same as the old original one. If in doubt refer to an online user manual. Recognize what type of climate you operate your car and buy a battery that takes that into consideration. Batteries built for hot summer conditions are sometimes marked “S” for (south) while those for cold winter conditions are marked “N” for North.
In summer conditions like ours it is important to buy a battery designed to withstand frequent high temperatures which tend to increase plate corrosion and vaporization of electrolyte (leaking acid).

In cold climate areas like Kabale the cold cranking amps (CCA) will determine how well your battery starts during very cold starts. Know the difference between ordinary and high performance batteries. Lead acid maintenance batteries are the common ones while Absorbed Glass Mats (AGM) are the maintenance free gel or lithium type (no acid top ups).