What Happens if a Hybrid Battery Dies

I was wondering what would happen if my hybrid battery pack were to totally die.  I am not talking about malfunctioning or working inefficiently, I am assuming that it is dead in the water.  It sounds scary, but you need to think about the worse case scenarios from time to time.  Is the vehicle going to stop in its tracks, or will you be able to somehow start it up again by triggering the 12v to start the combustion engine?

What will occur of your hybrid battery dies? If your hybrid were to die, you would be ok initially, it would switch over to the gas motor in most cases.  Nevertheless, once you stop the vehicle and try to restart it, it most likely will not start up again because the larger hybrid battery is used to start the vehicle. Even though it also has a conventional 12v battery, this battery does not start up a hybrid in 90 percent of the models.

What are the Signs that the Battery Pack for a Hybrid is About to Die for Good?

What are the signs that a hybrid battery is about to become toast? You are probably assuming that there will be a fancy light that turns on which is a tall tale sign telling you that your battery pack is about to die.  Sadly enough, this is not the case. Although some models, like the Prius, can signal that something is going wrong with the battery, via code P0A80.

Here are a few signs to watch out for:

  1. If you seem to be getting fewer miles per gallon, there could be a problem with your battery pack.  If you had been driving on highways more than you do normally, the difference in miles per gallon may be attributed to that change.  If you are still driving the same amount of time in cities and highways, a constant decrease in miles per gallon may be signifying that the battery pack is about to die.  Have it inspected.
  2. The state of charge, or SOC, of a battery pack, indicates the level of charge left.  I have read that sometimes if the battery is starting to die that it will fluctuate greatly.  It will fluctuate depending on the additional charge added due to regenerative braking, but regenerative braking charge fluctuations are minor.
  3. If there are problems with your combustion engine, it could be related to the battery pack.  For instance, normally a hybrid will make the transition to the use of the electric motor in a smooth way.  If your hybrid is bouncing back and forth between two motors, you probably should have the battery pack inspected.
  4. This next sign is more or less common sense, but I thought that I should mention it.  If your mileage level is close to 200k miles, you should assume that the battery could die at any time.  Even if it is working perfectly, it could just simply fail to charge.  Battery packs have cells that have a lifespan. You are only going to be able to get a finite number of charges out of your pack.

What happens to a Camry Hybrid When the Battery Pack Dies?

If your battery pack dies in a Camry Hybrid, you will not be able to start it.  However, it should switch to the gas engine if the pack dies while it is in use. As mentioned above, before it has died, there will be an error message flashing with the following code: P0A80.  This code means that the battery pack needs to be changed.

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If you do not change the battery pack after seeing the error message, it will die and perhaps very soon.  Just before dying, you might hear a loud noise coming from the battery pack.  I read in a forum that someone heard a loud popping sound because one of the modules had ruptured.  They had known that the battery was on its last legs, but they continued to drive it.  They concluded that a faulty cell had a lot of current going through it which caused a  module to rupture.

Numerous faulty cells will cause the battery pack to become too unbalanced to function. Luckily, there is another error message that a scanner can pick up for a Camry.  The code is P3018.  Sometimes it comes with a description indicating the cell that is faulty.  This is great because maybe you will be able to change the faulty cell before the battery network ceases to function.

What Happens when the Toyota Prius Battery Dies?

When the Toyota Prius battery dies, you can expect that it will not be possible to start it up again.  As with the Camry, it needs the hybrid battery pack to start.

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I tried to find threads in forums from people that had been driving a Prius while the battery pack dies, it was not possible.  I am not saying that it is not possible, but very unlikely. Most people will see the flashing red triangle that states that the battery pack is acting up and that it needs to be serviced.

I did find one person that stated that his Prius died mid-voyage, but he was not able to determine if was strictly due to a dead battery.  He saw many symbols on his dashboard appearing at the same time as he was forced to stop at the shoulder of the road.  One of them was for the battery pack, but others were not related at all to battery failure.  His Prius was an older model, 2005 and it has 500k on it.

Another interesting scenario that I read about in a forum was from an owner that had asked his mechanic to simply disconnect the hybrid battery so that he could drive just using the gas engine.  The mechanic explained that it was not possible because the gas engine is started using the hybrid battery.  I guess that this person thought that this would have been a viable option because he had used his previous hybrid even after the battery was disconnected.  He used to own a Honda Hybrid.  Apparently, there is less integration between the gas and the electric motor in hybrids made by Honda.

What is the Average Lifespan of a Hybrid Battery?

Since you are worried about will happen when your hybrid battery dies, it would be advantageous for you to know approximately how long that they will last.

On average, they seem to last 8-10 years.  I have noticed that many warranties for Honda Hybrids last 8 years, or up to 80k. It just makes sense that they will set this limit. If they were to set it to above the average, then they could end up replacing thousands of battery packs for free.

Nevertheless, you will encounter hybrid owners that have had zero problems with their battery pack even after 200k miles.  In other words, I would not stress out about the lifespan of your hybrid battery.

Also, if a battery pack seems to work at less than prime, you can replace it with a remanufactured version or perhaps you could change out the faulty cells.

What Steps Can You Take to Protect the Hybrid Battery?

If you wish to ensure that you are able to use your hybrid battery pack for as long as possible, there are some precautions that you can take:

  1. Do not let your hybrid sit unused for months at a time.  A hybrid battery does not lose its charge as fast as its auxiliary battery, but letting it sit in a garage for the winter while you are away sunburning in Florida would be silly.  It would advise you to start the vehicle and set it to use the electric motor for about 20 minutes.  You should do so after every  2 months or so.  There is no need to drive it.
  2. This might sound evident, but if there are warning lights, take your hybrid to a mechanic.  Sometimes, the warning lights may be there and then disappear for a few days before coming back.  You should never assume that it is just a faulty indicator.  If you drive around in a hybrid that has weak cells, you are just asking for trouble because you are allowing current to travel through those faulty cells.

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