Difference Between a Hybrid Battery and a Regular Car Battery

You may be wondering what makes a hybrid battery so different from a regular battery? I thought initially that a battery pack for a hybrid car was just a series of regular batteries strung together to supercharge the car at a high voltage.  I guess that I had seen too many strange videos on the internet where people were trying to make their own home version of an electric car on the cheap.

What in the world is the difference between a hybrid battery and a regular car battery? A hybrid battery is vastly different from a regular car battery.  A regular car battery is a 12 volt 40 Ah lead-acid battery.  The hybrid battery is actually a series of cells that operate together to provide high voltage power.  A regular car battery typically lasts about 6 years.  The lifespan of a hybrid can be 10 or more years. 

How big is a hybrid car battery compared to a regular battery?

The size of the hybrid high voltage battery is considerably larger than that of the regular car battery.  Is it not as if you can walk into a store and buy one and simply throw it into your truck after wheeling it over to your car in a shopping cart.  They weigh usually close to 100 pounds.

The weight is decreased each year.  One hybrid in 1997, used to have a battery that weighed 1200 pounds. I noticed that the third generation of Prius has its battery weighing in at only 93 pounds.

I have a Hyundai Sonata hybrid plug-in car, and I just recently watched a guy lift the battery out of the back of the car and place it onto a  table.  He was showing viewers have to safely remove the battery without the worry of getting a shock.  He was not a large man, so I expect that the battery was also around 93 pounds.

The other battery in a hybrid is just a 12v battery.  Your grandmother could probably lug it around easily. I will now highlight the dimensions of these two types of batteries.

The dimensions of the hybrid battery for a Sonata Hybrid:

8.3″  x 13.9″ x 28.6″

The measurements of the Auxilary battery in a Hybrid:

6 15/16″ x 7 7/8″ x 9 1/16″

Why do hybrid cars still need a regular battery?

The hybrid car also has a 12v battery.  It is close to being a 12v battery that you can find in regular cars although sometimes it is a small version.  Its function is to power the accessories.  Accessories such as the lights, the electric windows, the radio.  It also is required to turn on the ECU which is the onboard computer.

Items such as the clock, the security system, and the memory that is stored in the computer are activated by its 12-volt battery.

You may be wondering why not just have the hybrid high voltage battery turn on these devices? They cannot require a high amount of power? It actually takes a lot more power than you would think to turn on these electrical devices.  If you were to allow the high voltage battery pack to do so, it will reduce somewhat its charge, which is not good a thing for a hybrid car that you wish to run in electric mode as much as possible.

It makes sense that the manufacturers added the 12v volt battery.  If the accessories are going to drain a battery, it is much better to have it drain the 12v instead of the high voltage battery.  Replacing the hybrid battery is a costly prospect. So, sacrificing a cheap battery is logical.

Since the smaller battery can be drained easily, the hybrid designers had to figure out a way to charge it up.  A hybrid does not have an alternator like a normal car that can keep the car battery charged.  What happens is that once the larger battery is activated when the car starts, it then sends a charge to a 12v converter and that charge is sent to the smaller regular sized battery. The voltage is usually around 14 volts when it reaches the small battery.  It does take some time to charge the battery but at least it will not be overcharged.

Can you put a regular battery in a hybrid car?

In some hybrids, you can just replace the regular battery with another that you can purchase on your own.  Nevertheless, there are some models that have a more specialized battery that is hard to find on your own.

For instance, the Prius 12v battery is smaller than the normal car battery that you could buy at your local car parts store.  It usually has to be ordered by the Toyota dealership. It is a little strange that you cannot get your hands on one easily, but that is just the way that it is.

The Prius 12v battery is designed to fit into a small compartment in the trunk of the car, which means that it is not the same size as a standard automotive lead-acid battery.  It is called an AGM battery.  These batteries do not have the punch that a regular has since the Prius is not equipped with a starter.  It is actually the 220v larger hybrid battery that starts the car.

Another company that used to use smaller batteries as their 12v battery was Lexus.  It was just a bit larger than a motorcycle battery according to a message that I read on a forum.  The year of this person’s car was 2006, and it was the 400h model.  They were not pleased because they had to jump it several times.

Apparently, their other car, the 2013 RX 450h, is not having problems with its secondary battery.  They did notice that it was a regular sized battery.  I am not saying that the smaller models are faulty, but it is obvious that car manufacturers are changing the type of secondary batteries that they are using for one reason or another.

Is it easy to change the 12v battery in a hybrid?

It is not that easy to change the 12v battery that is usually in the trunk of a hybrid car, at least compared to a regular battery on a regular car.  I would give a difficulty rating of 6/10, 10 being next to impossible for a car owner.

I have heard of dealerships charging people $300 to change the batter in a hybrid, whereas the OEM for the battery was around $150 tops. So, learning how to change one yourself might be a good plan.

I thought that maybe it would be more dangerous than changing the 12vc in a regular car because of the presence of the 200-220v hybrid battery pack, but you will not be touching that section of the car at all.

Here are the steps that are involved for changing the 12v battery in a Prius Hybrid:

  1. In the rear of the car, remove the floor carpeting
  2. Remove the floor panel
  3. Remove the tray that is underneath the floor panel
  4. Now you can remove the covering for the battery, which is on the right-hand side.
  5. Remove the screws to the air intake for the hybrid battery to provide full access the battery
  6. Remove the bracket screws that are handling the battery in place
  7. Remove the negative battery contact
  8. Remove the positive battery contact
  9. Disconnect the vent that is connected on the right side of the battery
  10. Now, just lift it up and out of the car by using its strap
  11. Just the voltage on your new battery to ensure that it is fully charged
  12. Fit it into place
  13. Install the positive connector and then the negative connector
  14. Now reattach the brackets
  15. Connect the vent in the side of the battery
  16. Replace that parts that you had removed to get access the battery’s location

Is it easy to change the high voltage battery pack in a hybrid?

It is not easy to change the high voltage battery pack in a hybrid.  I would suggest that you have a dealership do the change for you.  I would give it a 9/10 in difficulty, 10 being extremely difficult.

Nevertheless, here are the steps that are involved in changing the hybrid battery in a 2013 Sonata Hybrid.  These are not detailed steps, just an overview to give you an idea on the complexity.

  1. it is important that you remove the safety plug before you start to remove the current hybrid battery pack.  It is orange.  You will need to pull up on it.
  2. You are now safe to work on the battery pack.
  3. Disconnect the 12v battery negative connector.  It has a cover that simply pops up.  This will disconnect all power going to the car.
  4. Remove the floor carpeting in the back.
  5. Remove the screws to paneling that is connected to back end of the trunk (this section is the closest section to where the license plate is located)
  6. Remove the floor of the back area (a large piece of rubberlike material).
  7. Now that you have removed the flooring, you can remove the paneling on the back end.
  8. Remove the clips that are holding the rest of the paneling. There are a lot of screws. even seven that you can access only by removing the back seats.
  9. Take off all of the inner paneling that surrounds the battery pack.
  10. Disconnect the ventilation tubing that is connected to the encased battery pack.
  11. Unscrew the covering that is on the right side of the battery pack and remove it.
  12. Disconnect the negative and positive connectors.
  13. Pull out the large black connector that was close to the connectors.
  14. Pull out the connector for the fan that is on the other side.
  15. Unbolt the 12mm bolts on this side of the encasement for the battery pack.
  16.  Unbolt the 12mm bolts that are on the other side (will need to do so from the trunk)
  17. Now you can pull the battery pack out of the car.  It is relatively heavy, so pulling it out it best done by two people. It was about 93 pounds.
  18. Simply install your new battery pack by reversing the above steps.

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