In last week’s edition of Kibbles and Bytes, I talked about how crucial batteries are for all the gadgets we use today. I started our look at batteries by talking about the ubiquitous lead acid battery.
I’d like to thank one reader, Gene, who informed me that back in 1989, Apple actually released its first battery-powered laptop, the Macintosh Portable, which used a lead acid battery. The Mac Portable was a predecessor to the PowerBook series. Even the PowerBook 100 still used a lead acid battery. That’s a pretty incredible feat for the trusty little lead acid battery, but these were big and heavy machines, especially by today’s standards.
The next real step up in battery technology were the nickel chemistries Ni-MH (Nickel Metal-Hydride) and NiCd (Nickel Cadmium). Many older laptops also used these battery technologies. They’re certainly much lighter than lead, but they suffer from their own unique drawbacks. NiCd batteries were developed around 1900, but didn’t see widespread production and adoption until around 1950 or so in the U.S. For much of the latter half of the 20th century, NiCd batteries were the go-to battery for rechargeable consumer devices.
If you ever used a cordless drill, cordless phone, or any other battery powered device in the 80s and 90s, it was most likely NiCd. And if you remember using one of those devices, you should remember how you had to run the batteries all the way down before recharging them. Otherwise, the battery wouldn’t last as long the next time you used it. This is called the “memory effect” and it’s one of the biggest disadvantages to NiCd cells. Another problem with NiCd batteries is their toxicity. Much like lead, cadmium is a toxic heavy metal. NiCd batteries should never be thrown away. Always recycle or dispose of them properly.
When the Ni-MH battery started to become widely available in the early 1990s, it marked the beginning of the end of the NiCd battery. Ni-MH batteries have much greater capacity than NiCds and are far less toxic. If you’ve ever bought AA-sized rechargeable batteries, they were almost definitely Ni-MH. They are well-suited to today’s high-demand electronics like digital cameras and MP3 players because of their ability to deliver high amounts of power efficiently. They’re also very safe to use and their low cost means they see use in a wide array of applications, from robots like Honda’s ASIMO to production electric cars like GM’s EV-1. While they aren’t toxic, it’s still important to recycle Ni-MH batteries because nickel is a valuable metal and recovering it in recycling processes has a far smaller impact on the environment than mining it.
So how come we don’t use nickel batteries for our iPads and other devices? Well, as I said, NiCd batteries suffer from the memory effect. Imagine if you had to run your iPad all the way down before you could charge it again. Not very convenient. While they would work well in power hungry technology like an iPad, Ni-MH batteries self-discharge at a rate of 4% per day. This means your iPad would lose power even as it was just sitting there unused.
By now, you may have figured out the punchline in this battery article series: lithium (no, not the Nirvana song, the metal). Check back next week when I’ll explain why we pass over all three battery types in favor of that light, soft, and energetic metal when it comes to making batteries for the latest technologies.