[bookport] Re: beta 22 Battery Drainage
- From: "Mike Justice" <m.d.justice@xxxxxxxxxxxxx>
- To: <bookport@xxxxxxxxxxxxx>
- Date: Thu, 31 Mar 2005 18:13:06 -0500
Rob, Larry, et al,
My Ni-MH batteries dropped to absolutely dead in 12 hours in idle mode,
after I stopped using book Port last night at 33% indication. I inserted
two
Duracell alkalines today and the battery level was 100%, so for the present
time I will remove
alkaline batteries when the unit is in idle mode. I had purchased two more
Ni-MH batteries, but neglected to note the print instruction on the package
that
they needed to be charged before use. When the Book Port was still dead
with the new batteries inserted, I asked my wife to read the print on the
battery package as I should have from the beginning. I then placed all four
of my Ni-MH batteries in the charger I
had earlier purchased from Radio Shack, and my wife confirmed that the
selector switch is in Ni-MH mode (not Ni-Cd). The battery charger is
labeled indicating a 13 hour charge period. When the Ni-MH batteries are
ready again, I will resume making observations under varied use conditions.
Keep up the good work, Book Port team.
Miscellaneous Battery Notes:
1) Since the Book Port is programmed to report percent battery level
relative to 1.5 volt alkaline batteries, the 1.2 volt Ni-MH should report
around 80% when fully charged (unless the 100% level is actually referenced
to a little less than 1.5V, but caps the report to 100%).
2) If 100% actually indicates a voltage less than 1.5, this would also
explain why it is possible to use the Book Port for some time before the
battery level drops below 100% using alkaline batteries, or other 1.5V rated
batteries such as lithium. NOTE: the lithium batteries have a good
milliamp-hour rating, but also a higher price to go with it.
3) The different types of batteries (alkaline, Ni-Cd, Ni-MH, etc.) have
different voltage drop characteristics through their milliamp hour usage.
If the battery level report is based on voltage alone, the overall battery
lifetime can be skewed as a percentage report.
4) I believe Ni-Cd batteries maintain a pretty straight line of voltage as
they drive the milliamps, until the battery is near the end of the discharge
cycle, then the voltage drops rapidly, but I am not familiar with the
voltage curve for alkaline, Ni-MH, or lithium batteries.
5) Since the "E" key is the max volume (or volume up) key in normal reading
mode, but is the dot 7 key in Braille mode, there may be some program
malfunction
that is setting volume to max in idle. This is not very likely, but maximum
volume would definitely require more milliwatts and drain batteries faster.
6) The higher volume MP3 and WAV files, with more concentrated audio
delivery, definitely sucked the power from my Ni-Mh batteries faster than
did the text files.
7) Perhaps an actual power off function may be needed as the programming
becomes more complex and expands multiple key functions.
Mike Justice.
www.MPNHome.net
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