The overall condition of your car depends on a good condition of the battery. Unfortunately, many drivers play down battery-related problems until serious failures occur.

And such failure will probably happen on a cold morning, when you are rushing to work, or the car simply won’t start. How to avoid it? The solution is simple: check the battery. We try to answer the question why it is best to do it in a repair shop.

The basics – how to care about the battery?

Regular battery diagnostics is one of the ways to care about its condition. Furthermore, it is worth following certain rules of use, which will allow to keep your car’s battery in good condition even for a few years.

First of all, try to keep the battery clean. Neglected and tarnished poles and clamps may result in voltage fluctuations. Minor dust and soil can be removed with an antistatic cloth. You can remove the elements which are more resistant to cleaning with a special brush or small sandpaper. Remember to be careful when cleaning.

If you have a basic serviceable battery, it is worth twisting off the fuses and checking the level of electrolyte. The shortage, if any, should be supplemented with distilled water. Use this opportunity to also check electrical connections, i.e. stability of clamps, as they can loosen or totally disconnect on some larger uneven surfaces. Tighten them up as needed.

The drivers who in the winter use their cars very seldom and park them outdoors should disconnect the battery and store it in a dry and warm room to avoid self-discharge. What is more, in warm conditions the battery’s plates become sulphated, which ensures the battery’s durability. In low temperatures, on the other hand, the battery’s performance drops dramatically, even by up to 20-30 percent! The effect is amplified by insufficient charging, e.g. covering short distances to work, shopping etc.

Not always can the alternator fully charge the battery during short operation. Therefore, it is recommended to cover a longer distance from time to time. The alternative is to charge the battery using a rectifier. In winter, it is also advisable to reasonably use all the other functions, most of all heating and ventilation, which is a significant burden on the battery.

Checking the battery in a repair shop – what should it look like?

When leaving their cars in a repair shop, most drivers do not think about what happens to them or what the repair, check and diagnostics look like. Of course, many people know what tyre, silencer or oil change looks like, but how to check the battery? How is the test performed and what is needed? Can you do it at home?

Why is it better to check the battery’s condition in a repair shop?

Let us start by answering the last question. Yes, you can, provided that you have the right equipment, which is unfortunately very expensive. Investing in it only to check your battery from time to time is pointless and exceeds the cost of several new batteries. An absolute must to conduct the check is digital voltmeter, hydrometer and a testing device which will enable you to load the battery with current of at least three times the battery’s capacity. For example, for a battery with capacity of 70 Ah, the intensity should be 210 A.

Checking the battery step by step

The process starts with a traditional check. A repair shop worker should check the battery’s visual condition, i.e. if the poles are not tarnished and whether there are no electrolyte spills etc. Perhaps already at this stage it will turn out that there is no other choice than to replace the battery.

The next step should be to measure the density of electrolyte in each cell and control voltage at the poles. The obtained result should in large part identify potential problems and allow to propose further actions.

If the electrolyte density is low even only in one or two cells, and voltage reading shows ca. 11 V, most likely there has been an internal short circuit and the battery is not fit for further use. If electrolyte density is the same in all cells, the voltage must be at least 12.5 V, and the battery is charged, it is recommended to run load tests in order to confirm the battery’s efficiency and possibly turn attention to other electrical subassemblies.

Another signal may be uniform but low electrolyte density in all cells. In such situation, the battery should be charged and a load test should be performed. Another factor preventing the battery from further use is brown colour of the electrolyte in all cells. In such case, further voltage tests are pointless and the only solution is to replace the battery for a new one.

What is a load test and how it is performed?

A properly performed battery load test consists in actual loading of the battery with current, proportionally to its capacity, for 10 seconds. While the generally available electronic testers can to some extent indicate the battery’s start-up capability, they are not able to provide fully reliable information in this respect.
Depending on the obtained results, their interpretation and conclusions may vary. On the other hand, the obtained results clearly show whether the battery will “live on” or its replacement is unavoidable.

Thus if the battery voltage is 0 V, it is impossible to charge it, which most likely means that there has been an internal break and the replacement will be necessary. If voltage is lower than 10 V and continues to drop, and despite that there is “gas discharge” of the electrolyte in at least one cell, most likely there has been an internal short circuit. In such case, the battery needs to be changed.

Another hardly optimistic situation is when voltage is low and continues to drop, but electrolyte is boiling in all cells. This may mean that the battery has not been charged for a long time and has been kept in improper conditions, which in turn resulted in sulphation of plates and permanent damage.

The only situation which does not involve battery change is voltage of at least 10 V without drops and fluctuations.

How to assess the battery’s condition on your own?

Undoubtedly the best way to check the battery’s condition is to go to a professional repair shop where experienced employees will check our car’s battery in a reliable manner using relevant tools. However, there are ways to at least initially diagnose defects on your own.

Regardless of whether you have a serviceable or non-serviceable battery, the first step is to carefully observe the engine’s start-up process. If the starter’s revolutions are clearly lower, sluggish and uneven, you may assume that the battery needs to be charged. If, despite charging, the situation persists, replacement might be needed. It is also worth switching off the headlights while the engine is running. Uneven operation or poor brightness may indicate the same problem, i.e. battery wear.

If you have a serviceable battery, you can assess the colour and density of the electrolyte. A very dark colour is the first signal of the need for immediate replacement. Another hint should be low electrolyte density even in a single cell. You can assess the density with your naked eyes, but without experience and specialist equipment you will not be able to make a valid judgement. A useful device is a hydrometer. During tests, operational density of common electrolytes is 1.28 kg/l with temperature of +25 degrees Celsius. The battery in which the measured electrolyte density is lower than 1.25 kg/l should be charged or replaced.

These and other “home-made” testing methods should be part of prevention. Still, remember that you can get reliable results only in a repair shop. A professional check at a repair shop will help clarify your doubts. Perhaps your concerns will be dispelled and you will avoid replacement. On the other hand, a seemingly minor defect may turn out to be a serious failure.

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