How a car battery is designed

All drivers know that you need a battery for the car to start. But how is a battery actually constructed? The basic components of a battery are, the electrolyte solution – 37% sulfuric acid in most cases – and the lead plates, which are attached to the casing in alternating layers. The plates are connected alternately to the positive pole (red) and the negative pole (blue). 

In order for the plates with the opposite charge not to touch each other and cause a short circuit, there are separators between them. The gases created during the chemical reaction can leave the battery via a valve in the housing.

Read the battery tips

Information about the design of car batteries

  • Mounting
  • Weight
  • Plus / Minus
  • Volt
  • Voltage
  • Date of manufacture
  • Life span
  • Parallel connection


Mounting If you want to install a car battery, you do not need to go to the nearest battery replacement store, as anyone can install a new starter battery yourself with the help of a few tools. If you follow these steps, nothing can go wrong and you will also save a lot of money. Follow these steps to install a new battery:

  1. Remove the protective covers from the poles of the new battery and put them away
  2. You can now place the new battery in the car’s battery compartment. Make sure the battery is upright. Also make sure that there are no foreign objects in the battery compartment that could damage the battery. In most vehicles, the battery is mounted under the bonnet by the engine, but in some vehicles it can also be located in the boot.
  3. The battery can now be put in place using the included bracket.
  4. Then connect the red cable to the positive terminal and the black cable to the negative terminal. Both cables must be attached to the poles with screws.
  5. When this is done, the poles can be protected from corrosion with pole grease or pole grease spray, which also ensures that voltage transfer takes place safely.


These batteries are not lightweight. A car battery is relatively heavy and nothing for weak arms. They weigh on average between 10-30 kg, depending on design and storage capacity. The heavyweight of the car battery is pressed down against the battery holder, and when you drive on uneven roads, this pressure becomes even greater. 

A battery compartment that is in poor condition can also pose a danger to the battery itself; if it breaks, the battery will fall out on the road, and this of course poses a danger to other drivers. For safety reasons, it is therefore recommended that you regularly perform a visual inspection of the battery compartment.

Plus / minus

What do pluses and minuses mean for car batteries, and why are one pole red and the other black? This is perhaps a question that many motorists ask themselves. The answer is, fortunately, quite simple: the positive pole of the battery must always be connected to the red cable, and the negative pole must be connected to the black cable. 

When removing the battery, first disconnect the terminal from the negative terminal, and then the positive terminal. When installing a new starter battery, you must do the process in the other direction: first, connect the positive terminal to the wiring system and then connect the terminal to the negative terminal and fasten it securely.


How do you measure volts in a car battery and how do you determine if your battery has a high enough voltage? There are two options: you can push your car against a house wall when the engine is off, start the low beam and observe if the light is dimmed shortly after you put it on – or you can measure the voltage with a multimeter. 

To do this, hold the red cable to the positive terminal and the black cable to the negative terminal at the same time. If the multimeter shows between 12.7 and 12.4 V, your battery is in good condition. If it shows below 12 V, it’s time for a battery change.

Battery Voltage

Most electrical systems in modern cars often have a voltage of 12 volts. The battery must have at least this voltage (or preferably higher) so that the battery has enough power to start the car. It is quite easy to make a measurement of the battery voltage and it can be done by anyone in a home garage: just make sure the vehicle is off for 1-2 hours before the test is performed.

 Then you can measure the battery voltage using a multimeter that is set to the correct voltage range. To do this, hold the multimeter’s red cable to the positive terminal while holding the black cable to the negative terminal. A fully charged battery will show between 12.4-12.7 V. If the voltage is below 12 volts, it is no longer sufficient and the battery should therefore be charged or replaced as soon as possible. If the voltage is too low, it can also be a sign that the generator is faulty and that it can no longer charge the battery properly.

Date of manufacture

The date of manufacture of the battery is important as a battery that has not been connected or used for more than 12 months may be discharged. Even if it does not drain the battery, it can still be discharged. To determine the exact date of manufacture, look closely at the negative pole. 

There is often a four-digit number engraved there; the first two digits indicate the week of manufacture, and the last two digits indicate the year of manufacture. There are also batteries that have a sticker that indicates the month and year.

Battery Life span

One of the most common causes of engine failure is that the battery is defective. But how can you extend the life of a battery? Above all, you should avoid short trips: this drains the battery faster because the generator cannot charge the battery for such short periods of time. If possible, also check the fluid levels in the battery once a year and top up with distilled water if necessary to prevent the battery from drying out. It also helps minimize power leakage from the car’s system; for example, turn off the heating of the front and side windows as soon as they can be seen through.

Parallel connection

To increase the battery capacity, you can make a parallel connection. It is logical, for example, when it comes to the power supply for a trailer , caravan, or sports car with a large engine. This makes it possible to increase the storage capacity and at the same time maintain the right voltage. In the case of a parallel connection, the negative poles are connected, and the same applies to the positive poles. This adds up the capacity of both batteries while the voltage remains the same as for each individual battery, in this case 12 volts. Usually, only batteries that have the same voltage and density on the acid, as well as the same charge level, can be used in a parallel connection. The length of the cables and the cross-section itself should also be identical.