In article ,
"Lynn Coffelt" wrote:

The Ancor calculator Matt mentioned is about right. Things to keep in mind
are that a 25 foot length of wire is only good for 12.5 feet of
distance..........out and back, right?

And the type insulation is worth considering, particularly if it's
going to be near any heat, oil, sunlight, etc, etc.

Remember also that under emergency conditions (no alternator turning)
there isn't going to be that comfortable 14.7 volts to fall back on, but
something like 12.3 or 12.4 from a good, recently charged battery. Lots of
high class SSB radios will start jumping frequency or channels with 11 volts
at the radio, and the tuner will also be trying to retune everytime you
holler "Heeeelp" in the mic.

Welding cable is worth considering. Fine, cable laid wire with good
tough neoprene jacketing. Terminals deserve good swedged tools, and wicking
a little solder in after the swedging is super around salt water and
batteries.

Old Chief Lynn



I agree with "Old Chief Lynn" here, if the appliance we're discussing
here is an MF/HF SSB Radio. The thing that needs to be understood
is that Battery Voltage at the terminals is NOT Voltage at the back
of the Radio, or at the PowerAmp DC Terminals, especially at the 20
to 25 Amp draw of a 100 to 150 watt Peak Envelope Power Radio.
It is commonly understood that for each volt dropped from 13.6 VDC
at the radios PowerAmp DC Terminals, you lose 50% of your PEP Power.
So if your at 13.6 Vdc you get your 150 PEP, and at 12.6 VDC you
get 75 PEP, and at 11.6 Vdc you get 35 PEP and below 11.0 VDC
the internal Voltage Regulators drop out of regulation and the
radio goes OFF.
So any voltage drop associated with the wiring between the battery and
the radio at the the Demand Input Current of the radio, effects the
available output power. How many times have I seen a radio that receives
perfectly, but dies whenever you press the PTT and modulate the Mic.
LOTS. This is one of the reasons that the Powersupplys for FVSA
(Fishing Vessel Safety ACT) and SOLAS requires that any batteries
used for powering these MF/HF SSB Radios be on or above the same deck
as the Radio, and Battery Condition be certified each year by a
Discharge Test, in the case of SOLAS Required Vessels. When FVSA
was out for Public Comment, there was a bit of a uproar about this
requirment, as no one had that type of power system aboard, but
it was made LAW anyway, and most of the fleet installed the required
battery under the wheelhouse floor, right behind the wheelhouse
on that deck, or on top of the wheelhouse. These locations will
tend to keep the wire runs short, and any installer woirth his Salt,
should and would DOUBLE the wiresize on the MF/HF SSB Radio that
any table stated would be good enough.
Most of the vessels I Inspected had AC PowerSupplies, or DC/DC Converters
running from Ships Power of 120Vac or 32Vdc and Power leads of a foot or
two, before the FVSA, and we just added an 8D battery between the two.

Bruce in alaska
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