Staff Car Report: Sparkie the 2002 Toyota RAV4 EV Takes a Sabbatical, Awaits New Batteries

Here at Transport Evolved, we don’t just write about cleaner, greener, safer and smarter cars: we drive them every day. And most of the time, that translates to a pretty enjoyable experience. Our 2013 Nissan LEAF is doing just fine, racking up miles on a brand-new set of summer tires (we’ll tell you about them in a future Staff Car Report). The 2006 Honda Insight hybrid owned by correspondent Kate Walton Elliott is proving itself trouble-free. And, despite a recent accident, contributor Steve Noctor’s 2012 Toyota RAV4 EV seems more than happy after racking up its official third birthday.

Since arriving, Sparkie has been making friends and enjoying life.

Since arriving, Sparkie has been making friends and enjoying life.

Yet just as a second 2002 Toyota RAV4 EV joined the Transport Evolved staff fleet in the Pacific Northwest — an as-yet unnamed car that is joining the Walton-Elliott contingent as a daily driver — Sparkie, our 2002 RAV4 EV is somewhat under the weather.

Admittedly, at nearly fifteen years old we can’t complain. And we’ll admit, Sparkie was donated to Transport Evolved as a non-runner with known battery problems. But although we were able to get Sparkie up and charging reasonably quickly following her arrival in Portland, it appears the honeymoon is now over.

Before we get into the nitty-gritty, here’s a quick reminder of what makes Sparkie so special — and what she’s powered by.

We've been able to get 40 miles of range out of the pack, but no more.

We’ve been able to get 40 miles of range out of the pack, but no more.

Back in the late 1990s, around the same time that GM was developing the EV1 electric car, Toyota built limited numbers of all-electric RAV4 EVs based on the gasoline-powered RAV4 being sold around the world at the same time. Initially produced as a test-fleet for Japan and based on the short wheel base RAV4, the RAV4 EV came to North America as a way of satisfying California’s zero emission mandate requiring all major automakers produce and sell (or lease) some form of zero emission car within the state in order to be allowed to sell conventional cars there.

Initially, the RAV4 EV was only available as a lease vehicle to fleet operators, but in 2002, just as Toyota was announcing the end of its RAV4 EV program after successfully lobbying for the end of the ZEV mandate, Toyota began to sell the RAV4 EV to members of the public. While the majority of RAV4 EVs made found their way to the same crushers that most EV1s did at the end of their lease, a few hundred RAV4 EVs escaped the crusher by the virtue of being privately owned.

Which is how Sparkie — and about 350 or so other RAV4 EVs — are still in use today. Many have more than 100,000 miles on the clock, some of them with their original battery packs. That longevity comes courtesy of the EV-95 Nickel Metal Hydride packs used in both the RAV4 EV and the EV1, as well as some Ford Ranger electric pickups from the same period.

But while the NiMH packs allow these vehicles to have upwards of 90 miles of real-world range when in good condition, the battery patent governing these cells — purchased by GM from a company called Ovonics — was then sold on to the oil company Chevron. And as you might guess, it has no interest in building (or allowing anyone else to build) new NiMH battery packs for use in electric cars.

On Sunday, the pack calibrated itself -- but you can see the weak module.

On Sunday, the pack calibrated itself — but you can see the weak module at 11.4 Volts

Consequently, this means that anyone with an elderly 1997-2003 Toyota RAV4 EV (us included) has something of a tough time finding replacement batteries when things go wrong. Luckily however, NiMH batteries are a little like cockroaches. They never die. And even when they do (unlike cockroaches) they can be brought back to life with some careful reconditioning at the hands of battery experts.

Which brings us back to Sparkie.

When we first took charge of Sparkie back in late March, she wasn’t moving at all, thanks to spending nearly a year in the garage of her former owner feeling more than a little under the weather. With some brute force careful coaching and a new 12-volt accessory battery, we were able to get her back to life and, for a brief while, driving around the neighborhood. One thing led to another and before we knew it, we were happily getting 25 miles or range out of the poorly battery pack.

Once the correct diagnostic tools had arrived, we were able to see the problem: one of the 24 battery modules in Sparkie’s battery pack was very sick, probably with two shorted cells. While we didn’t know for sure, each module in the RAV4 EV’s battery pack has ten cells in it and, based on what we could see thanks to the diagnostic cable we purchased online, one of those modules was displaying a voltage around 2.5 volts less than the rest of the modules.

Since the car was essentially obtained as a ‘work in progress car,’ we decided to see what would happen if we exercised the pack, managing to get Sparkie to drive upwards of 30-40 miles with careful use. Carefully keeping an eye on the weakest cell voltage, we made sure not to push the car too far lest it cause damage to the rest of the pack.

And then it happened. Last week, following some pretty hard work days in which Sparkie was being asked to drive between 30 and 40 miles per day, Sparkie began to complain about charging. Then, on Saturday, she suddenly declared she had zero charge left when previously stating an 80 percent charge. Despite lighting the dashboard up like a proverbial Christmas tree, we were able to get Sparkie home and plugged in. And to our astonishment, she charged just fine, calibrating her pack as if we’d just put a new battery in.

Just after disconnecting, the red indicates the troubled battery is now really sick.

Just after disconnecting, the red indicates the troubled battery is now really sick.

After discussing the incident with other RAV4 EV owners on the knowledgable RAV4 EV owners’ mailing list, we were warned that the behavior witnessed was the precursor to a full shut down of the car as the weakest battery becomes ever weaker. And how right they were.

Just a day after the battery recalibration, Sparkie was pushed into service for a short 10-mile round trip. Barely out of the Transport Evolved garage with a full charge, we watched as the RAV4 Info program on our handy period Palm Pilot (a program used by all RAV4 EV owners it seems) declare that the battery voltage was no-longer hovering around the expected 320 volts it should have been at, but was now at 60 volts. The battery had died completely, and the car was now destroying its battery pack due to a reversed cell.

For those who don’t know, a reversed cell is what happens when a battery cell essentially switches polarity, normally at the end of its life. When in a string of batteries — such as an electric car battery pack — that cell reversal means that the rest of the battery pack ends up sending its energy into that battery rather than to the motor. Either way, it’s bad for all involved. And when it happens, you have to stop.

So, it’s with great sadness that Sparkie is now officially off the road — at least for a few months — while we source some new batteries. Luckily, we have a contact in Connecticut who recently obtained some of the original, low-mileage battery packs from RAV4 EVs and EV1s which were crushed more than ten years ago. Likely to be in better condition than some of the other reconditioned battery packs on the market, we’re hoping to get our hands on a full, replacement battery pack very soon.

Until then? Well, we’ve got another two RAV4 EVs to tell you about: Sparkie’s 2002 RAV4 EV sibling now in Washington state, and the 2012 RAV4 EV being driven by Steve Noctor down in California.

The rest of our fleet is in operation of course, too. And at nearly 15 years old, we think Sparkie deserves a little rest until we can make her better again.

Sparkie will be back. She’s too special to leave in a garage, especially since we offered her a home in order to keep the electric cars of her age alive and on the road.

In the meantime, if you can help us with any parts or components you think might be useful to her restoration, let us know!


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  • Chris O

    Reading the “Patent encumbrance of large automotive NiMH batteries” article on Wikipedia it would appear that Chevron is tenaciously holding on to some crucial patents involving the automotive use of NiMH even after selling Ovonics to Basf. One wonder why as the technology seems obsolete by now, superseded by lithium based chemistries.

    Anyway looks like no NiMH based automotive batteries will be made until 2020 because of patent encumbrance and I expect neither after that because it’s obsolete. So maybe it’s better to futureproof Sparky by switching to lithium-ion? Surely those ancient NiMH packs still out there won’t live forever? Should certainly get it much better range for the same battery volume…

    It’s probably one of those things that’s easier said than done though.

  • Electric Bill

    Hi, Nikki–

    I usually would not trouble you about misspellings in your articles, but in this case as you were writing about “Sparkle” there was an errant “i” in your spelling of the maker of your car’s battery pack: the correct spelling is “Ovonics”, in the event your readers may be seeking more information.

    Ovonics was named after its quirky, prolific founder and inventor, Stanford Ovshinsky, who was often in the pages of Popular Science and other such publications. I admired him greatly in my youth for his very different approach to problems. He just died recently.

    Mr. Ovshinsky was a genuinely fascinating fellow, not having had a college education yet patenting hundreds of very high-tech products and processes, including the nickel-metal hydride battery, and the amorphous silicon solar cell which was the product that he had invented that first caught my attention so many years ago.

    One of the curious things about his amorphous silicon cells was that until that time, all solar cells were very brittle and expensive and required terribly expensive equipment, and the most exacting of chemistries– they required extreme purity with “dopant ” impurities added as parts per million in order for them to work properly. But his Ovonic amorphous cells were extremely cheap, and could be mixed up very much like cake batter in a mixing bowl; he said that, unlike the brittle crystalline cells before that time, their performance did not deteriorate with time and were more flexible.

    The nickel metal hydride batteries he invented have been made somewhat obsolete with the invention of lithium-based cells which are lighter and have greater energy density, but even today nickel metal hydride cells are still superior in that they do not lose their charge capacity as rapidly over time as lithium cells do. This can be shown to be true by how many RAV 4s are still on the road today with their original battery packs.

    Mr. Ovshinsky had much in common with Elon Musk in his creative approaches, and prolific and diverse products. I would encourage others to read up on him… a fascinating man.