3. Battery Technology In A Nutshell

The two most common chemistries today are Nickel Metal Hydride (NiMH) and Lithium-ion (Li-ion). Both of these technologies are an advance over the older Nickel-Cadmium (NiCad) technology due to higher energy density and lack of a memory effect.

The Care And Feeding Of Batteries

By any measure, Li-ion batteries are fussy. As seen in the chart above, it takes very little to piss off a lithium-ion battery. They don't like extreme heat, or extreme cold. They hate to be deeply discharged, fast charged, or fast discharged. If you run them to empty, they break. NiMH batteries on the other hand, are comparatively safe and non-toxic. NiMH batteries don't like to be cooked, and if left unattended on a shelf, can discharge to nothing after a couple of months - then requiring a couple of cycles to wake back up to full capacity.

When it comes down to actual problems incurred by mistreatment, the possibility of a dangerous explosion is rare. In fact, despite what the blogs and the press have said, out of the millions of batteries shipped, fewer than a hundred have flamed out, and out of those, only a small fraction detonated explosively. Your chances are better for being run over by a meteor. However, if you do piss off a Li-ion battery, you usually lose capacity so it does make sense to consider "Care and Feeding."

Method #1 For Reducing Your Battery Life: Cooking

Nearly every new modern notebook has at least one fan discharging heat into the bottom or out the back. Unfortunately, this dumps heat right onto the battery in all cases. For Li-ion batteries, dumping heat essentially cooks the life out of them. A lithium-ion battery kept at 40% charge in the refrigerator can last 10 years. But when cooked constantly on a notebook plugged into the wall, often 12-18 months. If you ever wondered why your notebook run time goes to hell after only a year, here's your answer: It's the heat! The advantage of having the battery in the notebook when it's on the wall is protection from power outages - but, the whole time; you're cooking away the life of the battery. Does this mean there's something to those notebook coolers? Maybe! What if your notebook spends all of its time on your desk? Is it best to keep the battery charged and in the fridge?

Method #2 For Reducing Your Battery Life: Rapid Charging

Regardless of battery chemistry, the trend on a number of notebooks is to do rapid charging of the cells. Rapid charging of a battery introduces heat, and causes the destruction of chemicals inside the battery by way of conversion into gases that are simply lost. If you remember the water analogy, rapidly charging a battery is equivalent to pumping water at a much higher pressure very quickly into a tank. This wears out a battery much quicker. While normally, a typical NiMH battery lasts several hundreds of cycles - rapid charging can reduce this significantly. Additionally, any defect in the battery will be exacerbated by rapid charging. It's too bad notebook makers didn't design a "gas pedal" to throttle the charge rate depending on the context.