Toyota Prius 12v Battery Guide (+ How to Replace)

A battery is an essential part of your Toyota Prius. It is the heart of your vehicle, with the most important function of starting the engine. Prius 12v battery supplies the power to the starter, control, safety, computer, and ignition system. He serves as the backbone of the car’s electrical system.

Low voltage battery in Toyota Prius Hybrid keeps all electrical systems running while the car is parked. It is done by converting the chemical into electric energy.

The typical Toyota Prius 12v battery consists of 6 cells. Each cell contains two plates; one is made from lead, other from lead dioxide. Both plates are submerged in sulphuric acid, which acts as a catalyst to trigger the plates’ chemical reaction. The chemical reaction produces electrons, which then produce electricity, and it flows from the battery to start the engine.

By switching the ignition, you signal your battery to start a chemical reaction. The engine is started, but your battery is emptied. It is then gradually recharged by a hybrid system while driving due to the reversibility of the chemical reaction. Those are the basics behind the Toyota Prius 12v battery. In the text below, you will be able to find plenty of helpful information about which 12v battery Prius uses, how to purchase it, and how to replace it.

Types of Batteries

There are several different types of batteries; the right choice can significantly impact your car’s performance.

• Flooded batteries are lead-acid batteries primarily used in Internal Combustion Engines (ICE). They are starting batteries, which provide short, powerful bursts of power needed to start an engine.
• AGM (Absorbed Glass Mat) batteries are slightly different types, made of fiberglass plate separator. They have a much shorter charging time and higher voltage output. They are also more resistant to vibrations, impact, and extreme temperatures. Most hybrid cars use them.
• Deep cycle batteries are rarely used in the automotive industry because they are designed to provide long-term energy delivery. They are used chiefly as marine batteries.
• Gel cell batteries use silica to turn the electrolyte into a gel substance. They are less tolerant of high heat and have long charging cycles. Rarely used in cars unless the manufacturer specifically calls for a gel battery.

Battery Life

Prius 12v battery is an auxiliary battery that works similarly to non-hybrids. It is used to start the engine and power car accessories.

Car batteries wear out over time; they have a finite lifespan. There are 3 key factors to affect the life of the battery – time, temperature, and vibration.

It is known that batteries gradually deteriorate until they cannot generate enough electricity to start an engine. It can take from 3 to 5 years to wear out, depending on the usage. If you use your car only on short trips, the battery may not recharge enough. Also, batteries in cars parked for more extended periods will self-discharge naturally.

Extreme heat and cold will increase the rate of battery degradation. We know that heat improves the chemical processes within the battery. Still, excessive heat will harm the battery’s sensitive components and cause the liquids to evaporate. Cold temperature (usually below the freezing point) will make it more difficult for your battery to produce the initial burst of energy to start the engine.

Preventing an excessive vibration will result in battery’s extended lifespan because it will cause internal battery parts to break down. It is essential to use special hold don hardware (nuts and bolts) to secure the battery in place. Make sure every nut or bolt is tightened correctly to prevent the battery from moving.

Battery Cost

We now know that most hybrid vehicles use AGM batteries because the onboard computer looks for a specific internal resistance of the AGM battery. If you put any other battery type, it will not charge the battery correctly, and it will fail quickly.

The cost of the AGM batteries is much higher than conventional ones simply because the cost of the materials used is higher. The glass mats that are in the cells are much harder to produce than lead-acid separator plates. Lead-acid batteries are also much easier to recycle than AGM.

With all of these factors in one place, we end up with a battery that costs around $200.

You can even conduct a quick battery check by performing a load test. First, you need to turn on the headlight without starting the engine. Then you leave the headlights on for 10 – 15 minutes. After that time, start your engine and watch the brightness of your headlights. If they begin to dim after the engine turns over, your Prius battery 12v does not pass the load test. If it cannot hold enough charge to support lights turned on for 15 minutes, it is time for a change.

The air duct for the primary driving battery goes directly over the auxiliary battery, so it must be removed. There are two 10 mm bolts – one inside by the body and another down on the floor pan. Put aside the vent pipe.

It would be much easier if you move the power brake unit – you need to remove three 12mm bolts, unplug it and move it out of your way.

Then you need to access the cables by removing the plastic cap with the screwdriver. You will be able to get to the actual terminal. Lift the terminal carefully, not allowing it to touch any part of the car. Cover it with an old glove or a rag and set it out of the way.

There is a bar across the top of the battery that holds it down. Unscrew it (a 10mm bolt on one side and 10mm nut on the other) and remove it.

Then remove the negative terminal by unscrewing the 10mm bolt holding it to the car. Then set the vent tube located on the forward side of the battery out of your way. The battery can now be lifted from its place, and you can install a new one.

From this point, you do everything in reverse. Most batteries will come with sufficient charge to start the car. Still, it is advisable to drive the car for a few miles to recharge the battery as soon as possible.