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Johnson Controls tests its lead-acid batteries in extreme conditions, which helps make a better battery Hot and Cold To travelers the world over, Las Vegas is an adult playground, a place where time seems to stand still—the interiors of casinos and show lounges are devoid of clocks for that reason—and the next good time is a mere taxicab ride away. In fact, Vegas can easily compete with any metropolitan hot spot for the title of “city that never sleeps.” For its nonstop nature and its climate, the city makes the perfect testing environment for Johnson Controls’ lead-acid batteries. After all, the stop-and-go traffic and continual driving of taxicabs allows the company to “torture test” battery designs and components.

“The reason why cabs are a good choice is because you want to use vehicles that are gaining mileage at a fast pace,” says Bob Gruenstern, director of Product Engineering. “From an automotive standpoint, [taxis] are one of the best test subjects.”
In the past, Johnson Controls has also tested police cruisers in sparsely populated states so that long-distance driving can be tracked. But Las Vegas provides a perfect mix of variables for long-term testing: high summer temperatures, heavy traffic and the nonstop activity. That translates to cabs that are constantly in use—a great way to test the durability of batteries.
Las Vegas is not the only extreme environment that Johnson Controls uses. In Europe, lead-acid batteries are tested in extreme cold, usually at 18 degrees Celsius for at least 24 hours and going down to temps as low as minus 29 degrees Celsius.

The Tests
The hot-versus-cold extreme temperature testing measures performance differently. In Las Vegas, testing is done to emulate real-world conditions.
Testing could compare new battery components versus existing ones, or test material from new vendors to determine if switching sources is feasible, among other possibilities, says Gruenstern. In any case, the company controls as many variables as possible—down to manufacturing the two test models in the same plant and on the same assembly line. The batteries are then installed at one cab company’s garage and are tracked via vehicle maintenance logs.
Contrary to controlled laboratory tests, which are conducted over several months, the on-the-road tests can run from six months to more than two years. During that time, Johnson Controls engineers analyze the data to determine if proposed battery changes are worthwhile.
“For us, that data sometimes allows us to release a new design,” Gruenstern says.
In the extreme cold-weather lab, conditions are meant to “quantify better performance,” says Eberhard Meissner, Ph.D., director of Research and Development for Johnson Controls Power Solutions Europe, “not emulate real-world performance.” It tests batteries in conditions more extreme than the real-world uses and provides a consistent evaluation for automakers to compare different makes, different suppliers or different designs by the same supplier. This, too, can help Johnson Controls develop an even better battery.
What it means for customers and automakers is rigorous testing that ensures durability and ever-better performance. And that’s a win for everyone.