A motorcycle battery is just too small for any brand of rig run at 50 watts,
or even 25 watts, with the current draw of the Scout. It is not designed to
be a back packing rig. If you want something like that, you need a Wilderness
Radio Sierra kit, or similar. The instruction manual is clear about the rated
voltage, it is designed for something like a fully charged Marine battery, or
AC to DC supply. Most rigs with a computer in them like the Scout, will draw
much more current than the rated Transmitter output. This is true of all the
But the Sierra will only give you CW, so you have compromises. Try a couple
of motorcycle batteries in parallel, in similar and preferably new condition,
fully charged to 13.85 Volts DC. Or try to find a golf cart battery. One of
those, new, is what I have used with the Scout at QRP. Appears to work fine.
But, it is true, that if you run less than 12 volts, or pull the battery down
below that on current peaks, the regulators in the Scout do not have enough
voltage to regulate normally. Now, an old trick to using a battery with a rig
with high peak current demand, is to parallel a large electrolytic capacitor
across the battery, to help even out the peak current draw. This is
particularly useful if the battery is starting to age, and develops higher
internal impedance, which limits the peak current it can deliver.
You should have not troulbe running the Scout on a normal automotive
battery/alternator system. Just do not have any rig "ON" when you are
starting a car, as the voltage spikes and transients can be much more than a
radio can stand.
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