When Toyota's Prius first hit Japanese showrooms in 1997, I was highly skeptical that hybrids would catch on. Not only was the technology really expensive, I thought the nickel-metal hydride batteries would prove to be the Achilles Heel in the system. Sooner or later you'd be facing an expensive replacement bill, right?

Well, here we are more than a decade later and those batteries are proving to be amazingly reliable. Toyota now has sold over 520,000 hybrids in just the American market. Honda has sold over 300,000 worldwide. Ford is just about to break through the 100,000 mark. The only reason they could sell so many hybrids is that the technology is working exactly like it's supposed to, including the batteries.

While these batteries were designed to last 10 years or 150,000 miles, in many cases they're even doing better than that. Ford brags that some Escape hybrid taxis now have anywhere from 200,000 to 300,000 miles on them and are still running strong with the original batteries.

John McElroy is host of the TV program "Autoline Detroit" and daily web video "Autoline Daily". Every week he brings his unique insights as an auto industry insider to Autoblog readers.


The key to their longevity is that these batteries do no go through deep discharges. They still retain something like 40% charge when the engine comes on to re-charge them. But it may be possible to push that envelope. Though Ford isn't talking, some believe it got such jaw-dropping fuel economy numbers with the new Fusion hybrid by pushing the battery into deeper discharges.

We'll want to keep an eye on that one, because yes, there have been some issues. Toyota ran into copper contamination issues with early batteries in the first generation Prius. And there was a recall of the second generation Prius, but that was an ECU problem that had nothing to do with the batteries. Toyota also has 60 special battery chargers located around the country for recalcitrant batteries that the car just can't seem to recharge. If dealers run into this problem, they can ask for a charger to be sent over. But they don't ask for it much.

Once you get past infant mortality issues, [these batteries] seem to last a lifetime.
Toyota, Honda and Ford are pretty cagey talking about warranty replacements, but Toyota did tell me that for out-of-warranty customers the failure rate is only 1 out of 35,000. That's a pretty impressive number, but it also translates into a parts-per-million failure rate of 28. I know Toyota pushes its suppliers to hit a PPM rate of 10 or less, so as good as it is, I'm sure Toyota is pushing for better durability.

These batteries are behaving like other electronic devices. Once you get past infant mortality issues, they seem to last a lifetime. Just as importantly, the cost to replace the batteries has dropped a lot. The cost of a 1st or 2nd generation Prius battery pack is $2,299 from the dealer. That's just for batteries and does not include installation. But it's a lot cheaper than when the Prius first came out and they cost over $4,000. Honda says the replacement cost for the Civic hybrid batteries is now about $2,000.

This still calls into question how well hybrids will hold up in the used car market. Even though the price of the batteries is dropping, it still costs more to replace them than to go to the junk yard and replace an engine. A used Prius engine, for example, costs anywhere from $700 to $1,500 at a junk yard www.car-part.com which, if you haven't checked it out yet, is a terrific online resource). Some buyers are going to be very wary of well-used hybrids if they think they're going to get socked with a big battery replacement bill.

Toyota sells all its returned batteries at very low cost to... a huge recycling company.
And then there's the question of what happens at the end of their life. Toyota sells all its returned batteries at very low cost to Kinsbursky Brothers, a huge recycling company in Anaheim, California. In fact, Toyota started recycling batteries with them in 1998 when it sold the EV RAV-4 in California. Kinsbursky disassembles the battery pack and shreds and recycles the polypropylene in the casing. The plates and inter-cell connectors are sold to smelting operations that remove the nickel, which is then sold to stainless steel producers. But Toyota's goal is to directly use that nickel to make new batteries.

Honda puts labels under the hood, and under the seat where the batteries are located, which instruct you to call an 800 number at American Honda. They'll pick up the batteries free of charge, and then Honda recycles them in house.

Ford will recycle its batteries with its battery supplier as long as they're under warranty. It expects customers to contact a local recycling center if they're out of warranty.

The nickel-metal hydride battery is about to be challenged by lithium-ion. There are plenty of questions about the durability, reliability and cost of these new batteries. Perhaps they will prove to be as good as the nickel-metal ones. But right now they're much more expensive, and it takes more energy to recycle lithium than it does to get virgin lithium. As a result, there is no market for post-consumer lithium. That's why some automakers, notably Toyota, believe that nickel-metal batteries will be around for a long time to come.

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