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[aprssig] Considering buying a D7 - Some Basic Questions

Steve Noskowicz noskosteve at yahoo.com
Tue Apr 1 00:50:07 UTC 2008



OK.  Thanks to all.  I am the OP.  No more answers are needed.

    I understood all the responses.  I read them all carefully and understood
the context in which each answer was given; they were clear.  Even if an answer
did not address the question as asked, it gave the context such that it
provided some additional information - and I still understood it.
   If I worded a question poorly, an answer atempting to address it still
provided some information either new, or supporting other responses, or
supporting the conclusion I came to by putting all the pieces together. 
  I actually just wanted to know what came with the radio, but decided to take
advantage of the opportunity and threw in some other questions.

  I found an on-line manual so now I can read what Kenwood says about charging
and interpret it against my knowledge on batteries and charging.  No need to
provide any more information about the D7.

   I'll probably order it as soon as I finish the tile floor, solder the
toilet's water supply piping and install the tiolet, vanity and sink and grout
the floor in the powder room...and finish the oak baseboard trim in the hall
and can relax again.  Brain numb (no wise cracks, please).... . . .. ..   .   .
    .     .

  RE:
> [snip]  the D7/factory wall-wart combo was so
> low-current that it could be floated indefinitely without damaging the
> battery.

A clarification on terminology.
    "Float" is the term used for Lead acid batteries and refers to a constant
_voltage_ or "float voltage" (approx. 2.3 V per cell) which can be applied to
the cells indefinitely.  This chemistry has an cell terminal voltage
proportional to charge state.  These can essentialy "top themselves off" from
this constant voltage.  The current drops as the cell charges up down to the
self discharge rate.  Lithium chemistry has a similar characteristic, though I
don't know if the same term is used, but current limiting is much more
important.
  Cadmium chemistries have no such terminal-voltage/charge-state
characteristic.  They are constant voltage vs. charge-state and, therefore, are
"trickle charged" at a low (constant) current (approx. 1/100C) to make up for
the self discharge.  They are usually made so as to absorb a little more
currnet than this, long term.  This allows one current level to both produce
some charging, yet allow long term trickle.


-- 
73, Steve, K9DCI


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