The recent brouhaha over defective Sony batteries in Dell and Apple laptops has at least served one useful purpose: it’s reminded people of what nasty devices batteries really are.
Ever since someone worked out how to generate electricity chemically and package it in a user-friendly mass-produced format, buyers have been demanding batteries that are smaller, do more work and have a longer lifespan. Unfortunately, packing more and more chemical energy into smaller and smaller containers is not generally a good idea, and sophisticated measures are needed to make batteries safe.
These measures depend on the particular type of battery chemistry. The lithium-ion (Li-ion) battery was a breakthrough that has enabled laptops and mobile phones to become pervasive technologies. It stores a high amount of energy per unit of volume, doesn’t suffer from “memory effects”, maintains a steady voltage during discharge, is low maintenance and doesn’t lose a lot of charge when stored correctly.
But of course nothing’s perfect, and the penalty for all this goodness is that Li-ion batteries are very fussy about how they’re charged and discharged. Special safety circuits are needed to prevent overcharging or over-discharging, which otherwise could cause runaway heat build up and catastrophic failure. Pressure vents and weak points in the battery casing are designed to allow the battery to rupture rather than explode if the safety circuits fail, but such a rupture can still allow a stream of burning chemicals to escape.
This is probably what happened in the “Dellplosion” – the physical safety measures were actually doing their job. It’s not a sight you want to see in a boardroom (or anywhere for that matter) but it’s still preferable to an explosion.
Modern batteries are pretty safe, despite the abuse we give them, although the ever-increasing demands for longer battery life in portable devices continues to drive scientists to look for even more potent mixes of chemicals.
One item on many people’s wishlist is the “all-day laptop”. This is invariably mentioned whenever I meet laptop makers, but I think it’s a misguided project. I’ve always found that the major benefit of a laptop is its portability rather than long battery life.
Admittedly, I’m probably not a typical user as I don’t work on trains or planes, but these vehicles are starting to offer power sources for laptops. And the lifespan of Li-ion batteries will be longer if they are not constantly being kept at full capacity, so perhaps it’s time to show users how easy it is to remove batteries.
On the other hand, dropping a battery on the floor is not a good idea, either.
