"Tam/WB2TT" wrote in message
...

"Rob Stampfli" wrote in message
...
In article ,
David G. Nagel wrote:
wrote:

When looking for a power supply for my Alinco dr-590, what type of
power supply would I look for? The radio says 13.8 v dc but if I get a
12 volt power supply will it put out the same wattage at the radio?

12 VDC to 13.8 VDC are nominal voltages. Very few radios are sensitive
to variation of voltage as long as the power supply can supply the amps.


The 'nominal' 12 volts is the voltage of the 6 two volt cells of a typical
auto battery, during normal discharge.
That is two volts per cell.
To charge a typical lead/acid battery a voltage of about 2.3 volts per cell
is required.
Therefore 6 x 2.3 = 13.8 volts.
Controlling to 13.8 volts is the job that the 'voltage regulator' does in an
automobile. To avoid overcharging and/or ruining the auto battery.
Therefore equipment which is designed to operate on nominally 12 volts is
usually designed to operate over the range 13.8 volts down to the point
where that battery is just about flat, at anything less than 12 volts. (If
your battery reads less than say 11.8 volts it's either shot or fully
discharged; BTW voltage is not a good indicator of whether or how well a
battery is charged!).
Large administrations e.g. AT&T, 'float' their large expensive battery
installations at around 2.15 to 2.17 volts per cell to offset 'local
chemical action' which causes batteries to slowly lose their state of charge
over time. For example 6 x 2.16 = 12.96 volts. This ensures the batteries
are fully charged at the start of a power interruption.