Recently, I brought my laptop with me on vacation. I started my trip with my bags packed and the batteries fully charged. When I made it to the airport and through security nearly two-and-a-half hours later, I pulled my computer out for a stellar game of solitaire. To my surprise, I noticed that the battery was half depleted. Not long after playing an intense game of Free Cell, a notification message jumped out of the corner of the screen demanding that I Connect to a charger immediately: Only 15% power remains.
My computer was off the "juice" and powered down for no more than three hours and the batteries began their descent into death. "WTF!" I murmured, "If the batteries in my laptop can barely make it out of the starting gate, what chance do the batteries in electric cars have?"
Later, I consulted my step-brother (a brilliant engineer) on this. First he explained to me that the failure of my laptop batteries was my fault.
"How often do you unplug your computer and run down the batteries?" he asked.
A little ashamed, I responded, "Almost never."
He then explained, "Batteries these days require minor maintenance in order to function properly. If you don't let them run down somewhat before you charge them or, leave them plugged in all the time, their ability to hold a charge diminishes. When you leave your laptop plugged in all the time, you're not exercising your batteries. Just like you, little or no exercise can lead to bad health."
While I was bummed that I'd need a new computer battery, there was a silver lining. My step-brother's (did I mention he's an engineer?) explanation makes perfect sense for the use of battery power in electric cars. Unlike a laptop, to get any use from an electric automobile, it needs to be unplugged. Batteries work best when they are used.
Some folks may argue that batteries are unreliable because they have a tendency to lose their charging capabilities over time. This adds to concerns over battery range and performance. With proper battery maintenance, however, batteries stand to lose very little of their original charging capacity in the long run (a great article on Li-ion battery degradation testing).
Electric car and battery seems to be a great marriage of complimentary technologies. Exercising batteries properly extends their life. What better place to put them to work than in a device that requires many charges and discharges? My laptop on the other hand, maybe not so much.