Is A Bigger Car Battery Better?

by: Dean Janse Van Vuuren
November 2020
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Some car owners have a tendency of exploring different options and practices that may improve their car’s performance. One of the areas of experimentation for such individuals is the battery of the car. A general perception is that a bigger battery is actually better for the car in terms of increasing its ability to perform better in everyday life. BPZ aims to satisfy the queries and concerns of all types of our customers. That is why we would explore this topic in detail. First, we would look at the impact a bigger battery on car’s performance along with any possible issues. Then we would look at the possibility of adding a second battery for achieving the same purpose of increasing the overall battery power.

Let us start with a quick clarification on what is meant by a bigger battery. In most cases, it is implied that a bigger battery means that battery has larger voltage output or Ah rating. However, some may assume that it is referring to a battery that is physically bigger in size. If all specifications of the battery are the same, there is essentially no advantage of a physically bigger battery. In fact, it is better that the battery is smaller to suit the limited space available in a car. A bigger battery may become loose from a smaller slot and start to move around due to the vibrations caused by movement of the car. In such a situation, the battery can easily get damaged and the electrolyte can leak from the battery. Since the electrolyte is normally acidic and corrosive in nature, it can cause damage to other components in the engine compartment.

If the bigger battery implies higher voltage rating than the standard 12V then it may cause some problems for the car. The other common battery apart from the 12V variant is the 24V battery which is normally used for trucks and larger vehicles. For the sake of argument, we would use the 24V battery as the higher voltage rating alternative. Firstly, as discussed earlier, the battery may not fit in the car’s battery slot as it would be bigger. If we somehow manage to accommodate the battery in the car, it can create problems for the electronic components of the car. This is because they are designed to function with a 12V battery so a 24V battery may damage them or cause them to malfunction.

Bigger batteries could also mean that one of their specifications has a higher value. In other words, the battery is bigger in terms of that specification. Perhaps the most common specification is the Ampere-hour (Ah) rating of the battery. It measures the battery’s capacity to provide a particular magnitude of current for a particular amount of time. For instance, if a battery has a 40 Ah rating, it can provide a current of 40A for 1 hour or 20A for 2 hours and so on. Given that the battery is of the same voltage rating, having a higher Ah rating means that battery would be able to last longer without charging. This would mean that the alternator would be used less frequently and experience lesser wear and tear.

Similar to the above situation, it is possible to get a battery with a higher cold cranking amp (CCA). CCA is a relevant specification in areas which experience cold climate. Generally speaking, it is easier for car batteries to start the car in warmer temperatures. During winters, batteries struggle to start the car and may require multiple attempts. This is where CCA rating can help us determine if a battery can be used in colder climates. The rating refers to the number of amps a 12-volt battery can deliver at -18°C for 30 seconds while maintaining a voltage of at least 7.2 volts. The higher the CCA rating, the greater the starting power of the battery. As a result, one would face lesser battery related issues in cold climates with a reasonably high CCA rating.

Another possibility is to add a second battery in the car. The second battery is helpful in providing backup for the electrical components when the car is in the stationary state. For instance, if one plans to install a high-power audio system and use it while the car is parked for an extended time then a second battery becomes highly important. This would ensure that the primary battery is always ready for performing its role of a starter battery. It is a good idea to use a deep cycle battery as the secondary battery as it is suited for providing steady currents over long durations. One possible downside of this option is the fact that it may place an additional strain on the alternator and may result in its premature end of working lifespan. The steps for adding a second battery are listed below:

Start off by selecting the location for installing the battery. The engine compartment is normally the first option but if it is short on space then the trunk is a good option too especially in cases where the second battery is going to be used to power the audio system.
After selecting the location, the next task would to be to install the battery tray and drill a hole nearby for creating a pathway for the cables.
Disconnect the primary battery from the car. First remove the connection of the negative terminal and then remove the connection from the positive terminal which is connected to the alternator.
Now install the battery isolator which would separate the 2 batteries from one another on the alternator wire.
Using additional wiring, connect the alternator and the positive terminal of the second battery (present in its tray) with the terminals of the isolator.
Connect the negative terminal of the battery with its relevant load like the audio system.
Use wire clamps to organize the all the new wiring connections.
Reconnect the primary battery first and then the new secondary battery to the car.

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