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What kind of batteries are in a Prius? Why are they different than the ones in the Tesla Roadster? Why is Honda changing the kind of batteries in its hybrid Civic? Thanks to a burgeoning market for hybrids and electric vehicles, batteries are the latest automotive technology to leave consumers scratching their heads. Electric and hybrid vehicles do not all use the same type of batteries, and some automakers even use different types of batteries in different models.

So here are some battery basics that should help explain today's in-car battery technology and what it means to you.

Lead Acid

This is the conventional automotive battery, the oldest type of rechargeable battery that has been around since the 1800s. Basically every automobile uses a lead-acid battery to run its electrical system and accessories like the radio and headlights. Even hybrids like the Toyota Prius use a lead acid battery to run these secondary systems. Early electric cars were powered by lead acid batteries, and even General Motor's EV1 was initially powered by lead acid.

But lead-acid batteries have serious limitations. They don't have great energy storage abilities, they're heavy, and the chemicals inside are hazardous. Also, lead-acid batteries have a relatively short lifespan.

Nickel Metal Hydride (NiMh)


NiMh has a higher storage capacity than many types, including lead acid. This is good because the more energy that can be stored in a small space, the easier it is for designers to pack enough batteries onboard to power the car. NiMh batteries have fewer toxic chemicals than lead acid batteries as well. NiMh technology has been around since the 1970s so it's proven and relatively inexpensive. That's part of the reason some automakers are sticking with it.

For example, Honda pointed out that the Honda CR-Z met all the company's performance, fuel economy and price-point goals using NiMh batteries, which is why it didn't opt for fancier, more expensive batteries. The same goes for Toyota, which has said that the Prius will continue to use NiMh batteries for the foreseeable future.

The disadvantages are that the NiMh batteries need to be fully discharged regularly to avoid "memory" which shortens the battery's life. They also generate more heat than NiCad or lead-acid batteries while charging. Heat and heavy loads can also reduce battery life.

Lithium-ion (Li-ion)

Lithium-ion batteries are safer and less toxic than the others. Compared to NiMh and lead acid batteries, Li-ion allows for the most energy storage in the smallest space, which makes it ideal for automotive uses. Li-ion batteries aren't affected by "memory" so they don't need to be fully discharged to maintain a long life, making them basically maintenance free. Li-ion batteries can also be stored for a long period of time without losing their charge.

Li-ion is the newest of the battery types and is being used in cars like the Chevrolet Volt and Nissan Leaf. Tesla also uses Li-ion batteries in its Roadster. But Li-ion batteries are more expensive than NiMh batteries – one reason why Honda chose to stick with NiMh in the $20,000 CR-Z.

Both the Nissan Leaf and Chevy Volt are notably more expensive. This is, in part, because both cars have much larger battery packs, but it's also because those packs are made with more expensive Li-ion batteries. The 2012 plug-in Prius will use all Li-ion batteries, and Toyota says the plug-in version will be at least $3,000 more expensive than the standard Prius, no doubt in part because of the more expensive Li-ion batteries onboard. However, General Motors thinks the extra cost is worth it saying "...the fact that lithium-ion batteries have a higher energy-to-weight ratio and as a result weigh less than nickel metal hydride systems in similar applications means that they are cost competitive."

Honda has said publicly that the next generation Civic Hybrid will use Li-ion batteries which should allow for a boost in fuel economy. It will be interesting to see how Honda pulls this off, however, because the new Civic Hybrid certainly won't be a $30,000 car, not when the current model costs about $24,500 and the Prius sells for about the same amount.

Li-ion batteries do have drawbacks. They work best if they're never fully charged or discharged. That means an electronic monitor or protection switch must be installed, adding complexity and cost. Finally, Li-ion batteries do not work well in extreme temperatures. So the Chevy Volt has a system in place that heats and cools the batteries to prolong their life.

The Future

While there are other battery technologies being developed, progress on this front is not moving as rapidly as automakers would like. So for the foreseeable future, hybrids and EVs are going to be powered by either NIMh or Li-ion batteries. Like every new technology, battery prices will eventually come down, but it's going to take time, as right now global battery manufacturing capacity is still fairly constrained.

Lithium-ion is obviously a better and more efficient way to power modern hybrids and EVs, but it's also more expensive. Li-ion batteries are sort of like a post-modern overhead cam, multi-valve, high-output V8 -- expensive but worth it. NiMh technology is like a reliable and affordable four-cylinder engine -- adequate for sure, but not the top dog.


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  • 15 Comments
      • 4 Years Ago
      After reading my comment it needs some punctuation and I would like to correct it,please.
      Jim O\'Brien
      • 4 Years Ago
      I enjoyed your very enlightning article on batteries. In my work, I am currently using another battery type that over the last few years, has matured to a level where reliability is high and cost has dropped significantly. Lithium Polymer batteries offer power levels as much as double that of Lithium Ion in the same size package. While some what dangerous now if over charged or discharged, engineering is now successfully addressing that issue. So, new technology is coming along but as was said, it is not keeping pase with demand. For the time being, Lithium Ion may be the best technology for hybrids in the next five years. I believe that we will see a 75 mpg hybrid with a range of 6-800 miles in the next ten to fifteen years. It would be a thrill to tell OPEC to take a hike!
      • 4 Years Ago
      Watch OPEC invest 100 Billion Dollars into batteries and then sell them to us again. Hike turns into Ride.
      • 4 Years Ago
      Strong mention should be about overcharging as they get too hot while being charged.Also mention should be made if the lithium gets loose and tosseed about, damage and exposive force can be developed
      • 4 Years Ago
      Actually, depending upon the pace of progress of battery technologies AND hydrogen fuel cells, we will likely see a combination of fuel cells and batteries. Some see a small fuel cell and a large battery, others see a large fuel cell and a small battery. Remember that a fuel cell vehicle is an electric vehicle, and that a fuel cell is essentially a battery with a fuel tank. Hydrogen prevalent in society is a long way off, but I was surprised this article's mention of "The Future" did not mention hydrogen and fuel cells, however distant they may be.
      • 4 Years Ago
      I was enlightened by your comparison of NiMh vs Li-ion batteries. I was looking at the 2010 Prius but now will wait until the 2012 . On second thought I wonder if it matters given that Toyota provides a ten year warranty....What about the Ford Fusion Hybrid?....
      • 1 Year Ago
      You need to add a "Urim and Thummim battery pack" using a hydro-thermal reactor to make the crystals, or battery pack just like the Guy from New York installed in Texas in 1930's with just 12 radio tubes and 2, 3" inch magnetic rods inversely installed to induce the Magnetic pressure from the sun, it was cabable of doing 90 mph, (who cares what mpg is, we cant get out of radiation from the sun) 14 stones total, 1 white, 1 black (positive and negative) the rest is quantum entanglement, or use a transmitter for the frequency for power or use Ham radio frequency of an antenna of 480 ft ;-) and install a super charged capacitor like the Ark of the covenant. and Build Noaa's ark (faraday's cage) around it to dampen the static charge around the electonics or increase pressure (increases voltage but written in stories). I would build one but dont have half a billion to waste on Solyrindra or enough to finish this project, just read a lot of books.
      Bob
      • 4 Years Ago
      Your story mentions that NiMn batteries have to be "fully discharged regularly to avoid memory..."
      As the owner of a new Honda CRZ, just what does that mean to my maintenance of the car ?
      • 4 Years Ago
      Can you please advise what company supplies the li-ion batteries

      Thanks,
      Robert Mintz
        • 2 Years Ago
        There are a large number of Li-ion battery suppliers in China and Taiwan. In the US, there is A-123 and Dow/Kokam to name a few - there are many many more.
      JOHN LYNN TERRY
      • 4 Years Ago
      WILL GM BRING BACK THE EV1. ALL THE EV1 MODELS MADE WERE TOTALLY DESTROYED EVEN THOUGH THE ELECTRIC CAR WORKED VERY WELL. WITH THE NEW BATTERIES AVAILABLE NOW, WHY NOT SIMPLY BRING BACK THIS WELL BUILT CAR AND PUT THEM IN IT. CERTAINLY IF THE CAR HAD GOTTEN 60 MILES USING OLD FASHIONED LEAD ACID BATTERIES IT COULD GO MUCH FARTHER WITH NEW BATTERY TECHNOLOGY. LETS GIVE THEM A CALL. WHAT THEY DID TO THAT NICE LITTLE CAR WAS A CRIME. LETS HIRE NEW WORKERS FOR DETROIT IN THIS ECONOMIC SITUATION, GIVE THEM A DECENT WAGE AND GET TO WORK BUILDING EV1'S AGAIN.
      JOHN LYNN TERRY
      • 4 Years Ago
      I do not think that Hydrogen will ever make the scene. Even if mass produced, the fuel will be very expensive. It is only a carrott the oil companies helped to come up with. Hydrogen is very costly to make and is wildly expensive. Bring back the EV1. See my comment and watch the movie, "Who killed the electric car". Have a great day.
        • 2 Years Ago
        @JOHN LYNN TERRY
        Sorry John - the cost of hydrogen is not the problem with this "fuel". Hydrogen currently costs $1.10/Kg on the US Gulf Coast, and 1 Kg has the energy equivalent of 1 gallon of gasoline, hence hydrogen costs the equivalent of $1.10/gallon. The problem is that hydrogen is a low-density gas, and must be compressed to tremendous pressures in order to have that 1 gallon equivalent fit into a reasonable space. The other problem is that hydrogen is not a "fuel" in the sense that it does not occur naturally on the Earth, so you can't dig or mine or drill for hydrogen. You have to use up some other fuel to produce hydrogen. The laws of thermodynamics limit the efficiency of any such conversion, so it is impossible to produce hydrogen with 100% energy efficiency. Hydrogen is currently made (mostly) from natural gas. It would be cheaper and easier to just use the natural gas as a fuel, rather than convert it to hydrogen and lose some of the energy in that conversion.
      lead acid battery
      • 3 Years Ago
      Automotive battery is used to start the car. Although many car owners ignored the maintenance of this battery, I just say if you want this battery for a long time use, you must maintain it on a regular basis. I think you will search much information on the internet. More information from Leoch International, http://www.leoch.com
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