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Will the battery in my hybrid keep going? (http://www.msnbc.msn.com/id/11812910/)

MSNBC contributor - By Herb Weisbaum - March 14, 2006

http://www.cleanmpg.com/photos/data/501/Resize_of_Toyota_Prius_II_Battery_Longevity_Story.jpg

With gas prices still relatively high, more and more people are considering hybrid cars. But some readers are wondering how long the batteries in a hybrid vehicle will last.

I know that hybrid cars get more miles per gallon and pollute less. But these vehicles all have an expensive battery pack that powers them when the gasoline engine isn’t on. How long are these batteries going to last?

Bill H., Princeton, N.J.

The battery pack in a hybrid vehicle contains hundreds of cells. Unlike the lead-acid battery under the hood of a conventional gas-powered vehicle, these cells contain a chemical mixture called nickel metal hydride (NiMH).

These NiMH batteries generally come with a standard warranty of 8 years or 80,000 miles. In California and several other states, the warranty is required to be 10 years or 100,000 miles. From all indications so far, these batteries have been very reliable.

“The number of failures has been really, really low,” says American Honda’s Juan Avilla. “We expect them to last the life of the vehicle.”

Toyota tells me that some of the original Prius models now have battery packs that have gone more than 300,000 miles.

BusinessWeek magazine (http://www.businessweek.com/print/autos/content/jan2006/bw20060131_870391.htm) reports that when the U.S. Department of Energy investigated hybrid batteries, it stopped its tests “when the capacity remained almost like new - after 160,000 miles.”

What will it cost to replace the batteries if they fail after the warranty expires? No one seems to know since that hasn’t been an issue yet. When that day arrives, chances are only some cells will need to be replaced, not the entire battery pack.

And will there be a pollution problem when the batteries come to the end of their useful life? Sooner or later - because they are defective, worn out, or the vehicle is in an accident - the battery pack in a hybrid vehicle will need to be removed or replaced.

Automakers say the batteries will be treated as hazardous waste, similar to any other car battery. That means they will be sent to a recycling plant for proper disposal. The chemicals in the cells will be neutralized and any materials that can be reused will be sorted out. Toyota has established a “bounty” program that pays dealers to send any NiMH batteries they remove to a recycler.

Looking down the road, work is already underway on the next-generation battery for hybrids. The goal is to find a technology that delivers plenty of power, lasts for the life of the vehicle, and is less expensive to make.

** Thanks to Delta Flyer for finding this gem! MSNBC Story on Hybrid Batteries (http://www.cleanmpg.com/forums/showthread.php?t=265) **

I have read the service life design criteria for the Prius Hybrid battery is 19 years. This is primarily due to the limited zone of charge and discharge the Prius places on the battery. Any deep discharging of a Nimh battery will result in shorter life spans while keeping the battery between 40 and 80 percent charged will significantly increase the lifespan of the battery. This is what the Prius does. As a result, Toyota can provide a 8 year, 100k mile warranty on the hybrid parts including the battery.

This, by the way, is the reason why I have not and will not purchase the EV modification. This modification to the Prius, while standard in other countries in the world would provide the ability to go stealth mode more often but it, according the above information, would decrease the service life of my battery in my Prius. I am happy as I can be, just the way it is.

My recent battery pack failure has me less likely I'd get the MIMA mod. For those unfamiliar, someone has a hack that can be installed on Insights that allow you to control the Assist. In the hands of someone that knows what they are doing, a 20-30% increase in fuel economy can be realized. For anyone doing this, they need to be careful not to let the battery back get a charge under 40%.

I have read the service life design criteria for the Prius Hybrid battery is 19 years. This is primarily due to the limited zone of charge and discharge the Prius places on the battery. Any deep discharging of a Nimh battery will result in shorter life spans while keeping the battery between 40 and 80 percent charged will significantly increase the lifespan of the battery. This is what the Prius does. As a result, Toyota can provide a 8 year, 100k mile warranty on the hybrid parts including the battery.

This, by the way, is the reason why I have not and will not purchase the EV modification. This modification to the Prius, while standard in other countries in the world would provide the ability to go stealth mode more often but it, according the above information, would decrease the service life of my battery in my Prius. I am happy as I can be, just the way it is.
I don't have a hybrid, I want one but a recent personal health crisis and resulting financial crisis makes a new car or even used car purchase out of the question at the moment.

I have a number of nickel-metal hydride batteries in use in various things around the house, and the very first batteries I bought years ago still work and pretty much have no noticeable capacity loss.

But there is one thing that will kill nickel-metal batteries and that is overheating or charging at too fast of a rate, it will pop the seal, then they dry out and die.

I suspect this is a bigger issue than deep discharge because the batteries I use in my digital camera basically get fully charged and run to their dead and no problems, but I've ruined one cell on a fast charger.

So in a hybrid applications, jack rabbit starts and fast breaking are things to avoid, but then most people concerned with fuel economy already know that.

With to re-enabling stealth mode, some people add a second battery pack so you can go further before it's deeply discharged, something to consider.

I wonder too if the new nano-particle lithium ion batteries will be readily adaptable to this application. I know other manufacturers are looking at using them in hybrids. Since they store more energy per gram than NiMH that would extend your reach further and from what I've ready they can handle 10,000 full charge/discharge cycles with only a 1% loss in capacity, that's impressive.

This, by the way, is the reason why I have not and will not purchase the EV modification. This modification to the Prius, while standard in other countries in the world would provide the ability to go stealth mode more often but it, according the above information, would decrease the service life of my battery in my Prius. I am happy as I can be, just the way it is.Bit of a correction....

The battery control unit that governs the state of charge of the battery is not changed or effected by the EV mod in any way. It still restricts the battery to the low charge/high charge limitations as every other Prius in the US. Really the only useful thing the EV mod does is turn off the gas engine (which can't be done for the first few minutes of cruising).

I use it as a method to enter my glides to prevent the 500ms of regen required to hit dead-band. Over the course of a tank, this saves me a few minutes of regen.

Point is that the EV button sends a request to the ECU that the battery control logic feels perfectly comfortable refusing.

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I have to agree with Dan as far as the EV switch is concerned. I will also add that I could actually discharge the battery further without the EV switch than with it. This is because, with the proper fancy footwork, you can run faster when EV switch isn't engaged. The EV switch will deny/disengage EV mode at any speed over 34 mph where with the right foot pressure, you can go as fast as 41 mph. Also, if the SoC is below 4 bars, you cannot engage EV mode with the switch where again, by feathering the pedal, you can EV down to 2 bars or less.

There is a thread over on priuschat.com where someone had a bad battery and Toyota initially denied the warranty claim but later agreed to replace the battery for free if the owner removed the EV switch. Something about this smells very fishy since the car we have is the same as Europe/Japan, the programming is still in the car, and the battery is more than likely the same battery as the one in the cars in other countries.

Dan and Larry are on top of it - the EV mod is nice and can be MPG-improving for certain applications, but activating it is just a suggestion to the hybrid computer. All of the programmed battery protections are still in place, and your "suggestion" will be denied (or automatically cancelled later, if allowed now) if protecting the battery is needed or if you're outside the operating parameters of EV. For example:

- SOC too low (2 bars or less, about 45% SOC)
- speed too high (>34MPH)
- throttle demand too high
- battery temperature too high or low