[aprssig] Re: D7 battery
Stephen H. Smith
wa8lmf2 at aol.com
Fri Mar 24 14:32:46 CST 2006
pagreen at gmail.com wrote:
> When you get to that low of voltage, it gets distorted at lower
> volumes than when you are running 9.6 and higher. I definitely notice
> more distortion on the lower voltage battery than on the high power
> ones at the same audio levels. Sounds to me that you are getting a
> dead cell and it's getting lower than it used to.
This is an issue of using rechargable NiMH batteries in the drycell AA
instead of non-rechargeable AA alkalines.
The alkalines are 1.5 V per cell for a total of 6 volts.
The rechargable NIMH cells are only 1.2 V per cell for a total of
only around 4.8 volts *FRESHLY CHARGED*. This causes the
5VDC regulators in the radio's logic circuits to start dropping out.
This is a chronic problem in devices with 5VDC logic circuits, normally
from 4 non-rechargeable alkalines. Low-dropout regulators can barely
5 VDC from a 6-volt source. The rechargeable AAs, Cs, and D cells simply
an alternative as a direct one-for-one replacement for alkalines, since
produce a high-enough voltage for the 5VDC regulators to work.
Unless of course, you use 5 or more cells in series. Or if the device
has a more
sophisticated DC-DC converter that can produce a constant output voltage
a supply voltage higher or lower than the output.
I have found this issue very frustrating with the Kenwood VC-H1 SSTV
runs on 4 AA cells (i.e. 6VDC) which it eats in about 2 hours. I would
love to use
rechargeable NI-Cd or NiMH cells in it but they simply won't work -- it
thinks that at
at 4.8 VDC are already dead.
Stephen H. Smith wa8lmf (at) aol.com
EchoLink Node: 14400 [Think bottom of the 2M band]
Home Page: http://wa8lmf.com
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