Quote:
Originally Posted by TomC
...A 25 watt radio for 8 hours requires 200 watt-hours...
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Excellent information, but a clarification on power requirements.
The 25 watt radio referenced by the original post is for a VHF marine two-way radio. The 25 watts specifically refers that at high power output the radio produces
25 watts of RF power. To do this requires approximately 6 amps DC at 13.8 volts, or about 83 watts hours
while transmitting.
Obviously actually transmitting is only done during a very small portion of the unit's on time, the vast majority of the time the radio is receiving or just in stand-by mode. Receiving a signal at full volume requires about 1 amp DC at 13.8 volts or 13.8 watt hours. When in stand-by (neither transmitting or receiving) the unit consumes about .25 amps at 13.8volts or less than 4 watts. Since the radio spends the majority of it's time actually drawing around 4 watt hours it changes the storage batteries requirement drastically.
The concern to me would be the type and power requirements of the stereo system being considered. Wattage will increase with volume selected, type of display used and length of time it is operated. In my experience with mobile and marine electronics it would be the stereo system's requirments that consume the majority of the calculated wattage.
In my experience your suggestion on solar panels is an excellent option to minimize battery consumption while the boat is being operated, and to recharge the battery during off time.
Ah, but the battery. No way around that one, you will need a deep cycle, prefereably a gel type with no spill capabilities. Therefore you are looking at a battery in the 50 pound range.
Or, you could always by a portable boom box and a decent handheld marine vhf with an external antenna installation!
