What Is The Internal Resistance Of A 12V Car Battery?

A 12 V car battery has the same amount of current as eight 1.2 V AA batteries. One may wonder if you could use these batteries to start a car It is futile to use eight AA batteries in place of a 12v car battery. This is because the eight AA car batteries will have a high internal resistance.

How do you determine the internal resistance of a 12 v car battery? For your car battery to have optimum performance there should be a low resistance. Voltage is calculated by adding external resistance to internal resistance. The primary responsibility of internal resistance is to determine the runtime of a battery.

The most urgent requirement of a car battery is for it to have low internal resistance. If your battery internal resistance reads with high ohms, it means that your battery is low and might need a recharge. A car has energy requirements for it to run efficiently thus the internal resistance should be low.

Can the Internal Resistance Affect the Performance of the Battery?

As time moves, there are new technological advancements that create new demands for the battery. Analog portable devices get a consistent amount of current. On the other hand, digital equipment on the car will load the battery with short spikes.

Does Internal Resistance Vary With the Level of Charge of a 12v Car Battery?

Internal resistance will always vary with the amount of charge that is in your battery. The most significant changes are noticed in nickel types of batteries. The internal resistance is high when there is a low amount of charge and vice versa.

When the car battery discharges, the level of internal resistance will decrease, thus making it reach its lowest points at half charge. At this point, resistance will start increasing steadily.

Which Aspects of a 12v Battery Will I Learn After Reading its Resistance?

Internal resistance gives us critical information about our car battery. A high reading of resistance should be a cause for alarm to notify you that your car battery is nearing its death.

This is a common indicator of nickel-based systems. However, measuring the amount of resistance is not the only way to indicate the health of your battery as there are other methods of determining your car battery life.

The method of determining the status of the battery by measuring resistance will work best when one is comparing the different readings from the time when the battery was new to when it starts wearing out.

The internal resistance of a car battery is not at any instance related to the capacity of the battery, as many people believe it. The resistance of any battery (especially lead-acid and lithium-ion batteries) will stay flat throughout its lifetime. The corrosion is only compared to a parasitic reaction towards the internal resistance of a lithium battery.

What Is the Meaning of Impedance?

Ohms is the single unit used to measure resistance, and it was named after a German physicist, George Simon Ohm (1798- 1854). Impedance affects reactive elements like coils and capacitors. The resistance is the same as the direct client and with alternating current.

The capacitive reactance will reduce as the frequency increases while the inductive reactance increases. Every car battery has got capacitance, inductance and resistance. Impedance includes the three terms.

What Level of Resistance Load Works Best for My 12v Car Battery?

The maximum power transfer theory states that it is possible to transfer power when the external resistance load is equal to the internal resistance of the source. For this condition to be possible, the load should be o.o2 ohm.

The power that will get transferred to the external load of this power, 1800 W and the remaining 1800W will get dispersed for consumption in the battery. The average voltage of an automatic battery terminal is 12.8 V. You can determine the maximum power transfer of a circuit by combining both types of resistance.

How Can I Measure the Internal Resistance of My 12v Battery Using the DC Load Method?

Ohm is one of the oldest units of measurement and the most recommended for measuring resistance. A car battery will have some discharge for some seconds. A small battery has current of 1A.

A voltmeter is used to measure the amount of current in an open circuit. Ohm’s law is used to calculate the amount of resistance. DCI load method is used to measure resistance in instances where one needs to check broad types of stationary batteries. The ohmic values are very accurate and consistent with this method.

How Does Electrochemical Impedance Spectroscopy Determine the Resistance of a 12v Car Battery?

Many research laboratories have used this method for a long time to evaluate different characteristics of a car battery and other types of batteries. However, to the high cost of equipment and the technical know-how required to carry out the test successfully, the method has mostly been left to laboratories.

A qualified professional is necessary to carry out the analysis and operate the equipment successfully due to a large amount of data that is collected.

What Does it Mean by “Overworking the Car Battery?”

A car battery is said to be overworked when you run a single component that has high energy demand on the battery. For example, headlamps, car music systems and other additional gadgets that may have energy requirements on a car battery.

If the current needs of the car are high, the voltage of the vehicle will go down. If the battery has low electrical energy, then the car has a low voltage. The voltage of the battery will drop if you make it run or feed something that has high demands of current and low resistance.


For optimum performance of the car battery, ensure to leave it on its own for a few hours after a full charge. This is contrary to popular belief that a car battery’s best performance is when it has immediately been charged to the maximum amount.