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wattage of radios???
- Thread starter jawnn
- Start date
Aren't all that many radios out there equipped to be plugged directly into 12 VDC. Good chance you're running it off an inverter which is a power hog when compared to running a radio directly. Some years ago I had a remote cabin in Alaska that ran off a couple of small solar panels. Best arrangement I had for radio was an inexpensive "portable" that held eight "D" cells. I just soldered leads onto the terminals that normally contacted the batteries, put a fuseholder/fuse in the + lead and slipped directly onto one of my solar system batteries. Very efficient; hardly noticed battery drain even when running at moderately high volume to be heard over power tools. If you're out for maximum loud and high quality, get a quiet generator with 120 VAC output and dig deep to buy fuel.
To answer your question, if a radio states 50 watts audio output, then the actual power consumption will be somewhat higher, between 70 - 80 watts depending on what sort of circuitry the amplifier section uses.
As Bojcha says, keep the volume down. Most class A/B outputs use almost no power at low volume. The more you wind the volume up, the more power the system will use.
The only time a radio that can produce 50 watts will actually do so, is when the volume is up near maximum. How often do you listen to a radio like that? Not very often.
At moderate listening levels, the power amplifier section may be producing 5 - 10 watts, and consuming around 8 - 15 watts from the supply.
As mentioned above, you can use home stereo / radio systems that run off mains voltage, and drive them with an inverter, or you can go the other way and focus on 12 volt systems.
A lot of people who go off-grid choose to use 12 volt appliances and audio systems. You can go the easy way and use a car stereo (and associated amplifiers if required) or if you hunt around you can actually find radios and amplifiers that run on 12 volts.
An amplifier that can produce 50 watts per channel will not do it from 12 volts however, so amps this size generally have their own inverter built in to give +35/-35 volt rails or there abouts.
As Bojcha says, keep the volume down. Most class A/B outputs use almost no power at low volume. The more you wind the volume up, the more power the system will use.
The only time a radio that can produce 50 watts will actually do so, is when the volume is up near maximum. How often do you listen to a radio like that? Not very often.
At moderate listening levels, the power amplifier section may be producing 5 - 10 watts, and consuming around 8 - 15 watts from the supply.
As mentioned above, you can use home stereo / radio systems that run off mains voltage, and drive them with an inverter, or you can go the other way and focus on 12 volt systems.
A lot of people who go off-grid choose to use 12 volt appliances and audio systems. You can go the easy way and use a car stereo (and associated amplifiers if required) or if you hunt around you can actually find radios and amplifiers that run on 12 volts.
An amplifier that can produce 50 watts per channel will not do it from 12 volts however, so amps this size generally have their own inverter built in to give +35/-35 volt rails or there abouts.
Some of the modern car radios employ class D amps which are very efficient at the cost of higher distortion figures. Some of those radios have efficiency in the 90% range, but the more common designs are still class AB with about 65% efficiency. Without looking inside, it's hard to know what model is AB and what's D. As was also already mentioned, higher powered amps require internal switching supplies. By applying Ohm's law, you can tell why. A 12V, class A/B radio operating into 8 Ohms can produce no more than about 12W per channel (which is actually pretty loud, BTW). The formula is E(squared)/R times efficiency ([12x12]/8 x.67=12). A class D amp will produce about 15W at 12V. If you want more power, you have to use higher voltages, thus the switching supply requirement for any radio over 15W. Four Ohm speakers is another way to get more power from a 12V amp.
Note also that power ratings are not universal. As was pointed out in another thread recently, there's peak power and RMS power. The standard measurement is RMS. Believe nothing about an amp rated in peak power.
Note also that power ratings are not universal. As was pointed out in another thread recently, there's peak power and RMS power. The standard measurement is RMS. Believe nothing about an amp rated in peak power.
A car radio, with a couple of efficient speakers in enclosures, would be a good choice. As mentioned above, even if the radio & amp is rated at 50 watts, you wouldn't want to listen to it that high. More to the point, a visit to your neighborhood junkyard would provide a wide selection of radios for next to nothing that would meet your needs. (Some excavation/extraction required!)
Remember that the typical radio relies on a ground attachment to a large hunk of metal to compensate for a fairly short antenna. A good ground and a whip antenna should work well, even for AM. Especially for AM, since if you are far enough "off the grid" you've just eliminated a lot of electrical interference.
Remember that the typical radio relies on a ground attachment to a large hunk of metal to compensate for a fairly short antenna. A good ground and a whip antenna should work well, even for AM. Especially for AM, since if you are far enough "off the grid" you've just eliminated a lot of electrical interference.
The amp I've linked below is cheap and very efficient and runs on a wide range of voltages without an inverter. At moderate output it uses about 6 watts or .5 amps at 12v. Get a set of efficient speakers like Klipsch and you will have rock concert volume potential.
http://www.amazon.com/LP-2020A-Lepa...?ie=UTF8&qid=1359116111&sr=8-1&keywords=lepai
http://www.amazon.com/LP-2020A-Lepa...?ie=UTF8&qid=1359116111&sr=8-1&keywords=lepai
car radios?
OK I do want a car stereo, even if I have to make boxes for the components.
I do not use an inverter.
But I am afraid that I will have to get a larger battery to even out the days of low power production.
That looks like a good little amp, but if I need a radio with MP3 recording....
Seems like there should be place that spcializes in off grid items and they should have a the right stereo. But I have not seen any such place.
OK I do want a car stereo, even if I have to make boxes for the components.
I do not use an inverter.
But I am afraid that I will have to get a larger battery to even out the days of low power production.
That looks like a good little amp, but if I need a radio with MP3 recording....
Seems like there should be place that spcializes in off grid items and they should have a the right stereo. But I have not seen any such place.
I tend to agree with the previous poster who sooldered leads onto the 8 D cell battery connector. Modern 'boom boxes' use 4 to 6 D cells and produce loud enough volume. Speakers are very efficient on those. A power resistor and a Zener should give you a voltage to replace the D cells. But if mono sound works there are 'emergency' radios that have the solar cells built in. Don't know if they take rechargeables.
I used to run an old car radio off a battery and a set of speakers. It was vacuum tiube and I got about three days out of the battery. Sicne I was way off the grid, I swapped the 'dead' battery into a standard shift car and let it roll down the hill to start the engine. Charged that battery back up while I used the fully charged battery I got out of the car. Antenna was 50' of wire in the trees. Difficult though to make the installation look really neat.
I recommend the 'boom box' approach. BTW, see http://kaboom.jvc.com/usage05.html
I used to run an old car radio off a battery and a set of speakers. It was vacuum tiube and I got about three days out of the battery. Sicne I was way off the grid, I swapped the 'dead' battery into a standard shift car and let it roll down the hill to start the engine. Charged that battery back up while I used the fully charged battery I got out of the car. Antenna was 50' of wire in the trees. Difficult though to make the installation look really neat.
I recommend the 'boom box' approach. BTW, see http://kaboom.jvc.com/usage05.html
A solar-cell crank radio up uses VERY little power, but may need to be teamed with another amp as discussed to produce
meaningful output. Five watts is really loud in an efficient speaker, and there is no substitute in this case for making
speaker enclosures as LARGE as you can accomodate, for that will accent efficiency in the lower frequencies, where
it is hardest to obtain otherwise.
I have a "broken" AM FM Shortwave "freeplay" where the springmotor on the wind up flew apart.
I lay the cicuit board and solar cell on top of a little open back PA speaker with a 12 inch wide range speaker.
Then when working in the backyard, I set it in the sun and I have a very good sounding solar radio,
much louder than when it was in the lunch-box sized molded plastic cabinet.
Still not very loud, but perfectly servicable for a small backyard.
meaningful output. Five watts is really loud in an efficient speaker, and there is no substitute in this case for making
speaker enclosures as LARGE as you can accomodate, for that will accent efficiency in the lower frequencies, where
it is hardest to obtain otherwise.
I have a "broken" AM FM Shortwave "freeplay" where the springmotor on the wind up flew apart.
I lay the cicuit board and solar cell on top of a little open back PA speaker with a 12 inch wide range speaker.
Then when working in the backyard, I set it in the sun and I have a very good sounding solar radio,
much louder than when it was in the lunch-box sized molded plastic cabinet.
Still not very loud, but perfectly servicable for a small backyard.
K6JHU said:
Most solar radios that operate on alkaline batteries will operate from rechargables, although I have yet to see one that will actually charge the NiMH cells from the built-in solar panel.
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