[bookport] Re: battery life, alkaline versus rechargable

  • From: "Gary Wunder" <gwunder@xxxxxxxxxxxxx>
  • To: <bookport@xxxxxxxxxxxxx>
  • Date: Sat, 11 Dec 2004 12:18:46 -0600

Fantastic post Jerry. Thank you.


----- Original Message ----- 
From: "Jerry Neufeld" <jerry.neufeld@xxxxxxxxxx>
To: <bookport@xxxxxxxxxxxxx>
Sent: Saturday, December 11, 2004 6:53 AM
Subject: [bookport] Re: battery life, alkaline versus rechargable


Good morning folks.

Although I am certainly no electronics engineer, some rather straight
forward facts about batteries may help to clear up some of the confusion
that seems to persist about potential harm from non-alkaline batteries.

Potential damage.
To my knowledge, damage to the BookPort or any device like it will result
under two conditions only, excessive voltage and battery leakage. Typically,
the majority of non-rechargeable double a batteries, recently produced and
unused, generate a voltage of approximately 1.5 volts, nowhere near high
enough to damage the BookPort in any way. Although the capacity of these
batteries varies from unit to unit and type to type, this factor is not
relevant to damage. Its only significance is the amount of life one may
expect, i.e. 60 hours versus 45. The dc voltage produced by these batteries
can only decline, either from use or from prolonged storage. For
hypothetical purposes, assume the minimal threshold voltage, necessary for
the BookPort to run, is 2 volts, two fresh double a batteries, in series,
producing just over 3 volts. The battery level indicator in the BookPort
checks the combined voltage of its two batteries to see at what point
between 2 and 3 volts the reading is. Based on the result, a percentage of
remaining life is estimated. The reading is, indeed, only an estimate since
standard double a batteries do not all decrement in a linear way, that is,
their progressive drop in voltage as they are used, is not strictly
proportional to the amount of time elapsed. Typically, these batteries will
generate a greater number of useable hours if used briefly each time an
apparatus is turned on, the number of potential hours less if a unit is on
for hours each run rather than minutes. This, plus other factors related to
the physical properties of the battery, then, allow for only an
approximation of remaining time, good as the estimates normally are.
Rechargeable batteries behave very differently. To begin with, typically,
their starting voltage is less than their non-rechargeable counterparts,
varying between 1.2 and 1.4 volts. Of importance to us in terms of battery
level indication is that, unlike other double a batteries, the voltage does
not drop steadily but only minimally. When there is no life remaining in the
rechargeable, the voltage falls percipitably, leaving only seconds or a few
minutes, once a warning has sounded, before dropping below the minimal
threshold. Those who have cell phones will surely have noticed this, the
battery low warning sounding only seconds before signal cutout. So, battery
level readings in the BookPort, when rechargeables are used, will be
erroneous.
The important point here, in terms of potential damage, is that it matters
little whether the double a battery is alkaline, standard or rechargeable
since the only significant variable is voltage drop. Voltage drop cannot
harm the BookPort. It simply will cease to function, once the voltage drops
below minimum acceptable levels.
Much more important is the physical integrity of the battery from the
standpoint of its tolerance for temperature change and long storage. Unless
very low in quality, nearly all batteries no longer leak although it is wise
to follow manufacturers' admonitions to remove them is lengthy periods of
non-use are anticipated.

In short, your choice of battery should have absolutely no effect at all
upon the life of the BookPort, provided that leakage is not a factor. The
only thing that will vary with different types of batteries is the number of
hours they will keep the BookPort alive, this and, as mentioned earlier, the
extent to which battery level indication is reliable. If, as Pamela has
noted, the manufacturer of the BookPort recommends alkaline batteries, their
suggestion must be based upon battery life and not potential damage.

Sorry it took so long to say all of this. Hopefully, some of what I said
will clear up some misapprehensions about potential damage from non-alkaline
batteries.

All the best,

Jerry

Other related posts:

  1. Home
  2. bookport
  3. Archive
  4. 12-2004