Stryped wrote:
"The radio says 13.8 v dc but if I get a 12 volt power supply will it
put out the same voltage at the radio:"

No. All supply cables have an IR drop.

Automobiles supply a d-c voltage to charge the battery which cranks the
engine and supplies the accessories when the engine is off.

SETTING THE VOLTAGE REGULATOR IS A PROBLEM. iT MUST BE SET HIGH ENOUGH
TO TOP OFF THE BATTERY AND LOW ENOUGH NOT TO BOIL THE BATTERY WATER AWAY
(OUTGASING).

To complicate matters, at least four different automobile battery
constructions are used. All have different ideal charging voltages at
the same temperature and for the same use.

Battery and charging system manufacturers disagree with each other and
even with themselves.

In the 1970`s , the low-maintenance calcium-lead battery appeared. It
was designed to avoid outgasing and water addition to the battery. The
original battery had had antimony added to its lead plates to strengthen
them for mobilr bumps and shakes.The lead-calcium battery had calcium
replacing the antimony. Battery manufacturers then had a new idea. They
used antimony in the positive lead plate and calcium in the negative
lead plate. They called this the "hybrid battery"

Some car makers then decided to adapt the "gel-cell" to autos. This
should take no water but woiuld not like being overcharged.

I`ve had satisfactory experience with calcium-lead batteries. In several
crosscountry microwave systems these were used to float on the d-c power
supply. The voltage of the supply was set by experiment to a voltage
which would top off the batteries so that they could run the equipment
for several hours when the powerline failed but not gass so much that
they frequently required water. The batteries had very long useful lives
and cost much less than nicads. The cells had no memory problems or
polarity reversals as the nicads sometimes did.

Best regards, Richard Harrison, KB5WZI
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