[bookport] FYI - rechargeable batteries

  • From: "Mike Justice" <m.d.justice@xxxxxxxxxxxxx>
  • To: <bookport@xxxxxxxxxxxxx>
  • Date: Wed, 16 Aug 2006 11:08:28 -0400

This general information for the list is taken from a daily Email I receive as 
part of my web subscription to Smart Computing magazine.  I recommend the 
subscription for blind users since it is easily accessible with screen readers, 
and the annual fee for twelve issues plus other 
features is less than $20.  Full articles can be transferred to the Bookport 
for reading at your convenience.  The web site is currently offering a free 
trial subscription.  

Smart Computing
Daily Information For Wednesday, August 16, 2006

Daily Tip:
Li-Ion Battery Advice

Avoid frequent full discharges. The reason this is an issue is because 
performing frequent full discharges puts additional strain on the battery. 
partial discharges with frequent recharges are better for Li-Ion batteries than 
one deep one. Recharging a partially charged Li-Ion battery doesn't cause
harm because there is no memory. (In this respect, Li-Ion differs from 
nickel-based batteries.) Short battery life in a notebook computer is mainly 
by heat rather than by charge/discharge patterns. Batteries with fuel gauges 
(notably notebook computers) should be calibrated. You should calibrate these
batteries by applying a deliberate full discharge once every 30 charges. 
(Running the pack down in the equipment does this.) If ignored, the fuel gauge
will become increasingly less accurate, and in some cases, it can cut off the 
device prematurely. Keep the Li-Ion battery cool. Avoid a hot car. For prolonged
storage, keep the battery at a 40% charge level. Consider removal. Perhaps you 
should think about removing the battery from a notebook when you're running
the computer on fixed power. This isn't because the battery will overcharge; 
it's to save the battery from the extra heat. (Some notebook manufacturers
are concerned about dust and moisture accumulating inside the battery casing, 
whereas others warn that in the event of a power outage, or if you disconnect
the notebook forgetting that the battery isn't there, you may lose data.) Avoid 
purchasing spares. Don't just buy Li-Ion batteries for later use. You must
observe the manufacturing dates. Also, don't buy old stock, even if it's sold 
at clearance prices. If you have a spare. If you happen to have a spare Li-Ion
battery, use one to the fullest and keep the other one cool by placing it in 
the refrigerator. (Just make sure you warm the battery to room temperature
before use.) Do not freeze the battery. For best results, store the battery at 
a 40% state-of-charge. 
Mike Justice, 

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