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Battery Power – Pt1 Don Bradbury presents part 1 of a guide to choosing and maintaining batteries. The need for storing electricity is ubiquitous in computing, whether it be in the desktop PC itself (the CMOS battery), a notebook or laptop, a PDA (Personal Digital Assistant), or a digital camera and so on. Each needs self-contained power, and electrical storage batteries of one type or another have provided that power for decades. Things have moved on, however, since the early days of Lead/Acid accumulators. Non-rechargeable alkaline batteries, or Nickel Cadmium (NiCad) rechargeables, steadily ousted the old non-rechargeable and dangerous Zinc batteries (they tended to leak and ruin your equipment), and NiCads are being replaced by even better rechargeable battery technology in the form of Nickel Metal Hydride (NiMH) or Lithium Ion (Li-Ion). Other types will doubtless follow.
Locked in, or free to choose? Power for notebooks, PDAs, and digital cameras is the main source of concern for most, and some applications will lock the user into fixed technology. Your notebook probably offers a dedicated battery type and charger, as may the PDA, so in terms of choice that would leave the digital camera and allied fields. We’ll concentrate on those for now. Although they present different working voltages, as I indicated before, designers can accommodate different battery technologies and work around them. So the trouble begins when you have to select a particular technology; how to choose it; how to purchase it; how to use it; and how to maintain it. Those are the questions. Each battery technology offers advantages over the others. For example, Alkaline batteries may bring a charge capacity advantage, but they cannot deliver the high current drain of good rechargeable alternatives such as NiMH or Li-Ion. Hence, although the makers of many digital cameras suggest that you use Alkaline batteries, users soon catch on to the fact that in doing so they are simply pouring money into the pockets of the manufacturers of such sources of power, though there are other points to consider. Improvements NiCads, or better still, NiMH or Li-Ion are far better. They may cost more initially, but they have the huge advantage of being rechargeable hundreds of times at next to no cost, hence their cost-effectiveness can be several orders of magnitude better. So you’ve made a decision to uprate your battery technology from the manufacturer-recommended AA size Alkalines, to something a little more accommodating, reserving the Alkaline type for emergency use only. I don’t knock Alkalines – they’re still a most useful backup source of power as you can walk into almost any type of shop and buy some if your rechargeables let you down while away from base and their life-giving charger. We therefore have to look at the advantages and disadvantages of battery types, their purchasing, and their maintenance. That’ll be the subject of our next foray into the subject of portable power for your computing gear.
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Computing
devices can be designed to run on any of these sources of power, and
each has its advantages and disadvantages The trouble is, as ever,
cost effectiveness and life. ‘Life’ may mean shelf life, running
life, or total period of operation, for, again, each technology
differs from the others. Alkaline batteries can last well on the
shelf for years, while Ni-Cads, Ni-MH, and Li-Ion cells will run
down (self-discharge) slowly.