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#1
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I'm looking for a portable rechargeable 12-volt battery, probably a gel cell, to
extend my operating time with a VHF/UHF hand-held to about 12 hours of use. I envision that I could power my radio by connecting its cigarette lighter power adapter to the portable battery. The portable battery should be comfortable to carry with me, for example: attached to my belt, or with an over-the-shoulder strap. Any ideas? 73 de Dick, AC7EL |
#2
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Dick Grady AC7EL wrote:
I'm looking for a portable rechargeable 12-volt battery, probably a gel cell, to extend my operating time with a VHF/UHF hand-held to about 12 hours of use. I envision that I could power my radio by connecting its cigarette lighter power adapter to the portable battery. The portable battery should be comfortable to carry with me, for example: attached to my belt, or with an over-the-shoulder strap. Any ideas? Estimate the number of hours out of that 12 hours that you would be transmitting. Multiply that by the current consumption during transmit. Multiply the rest of the hours by the current consumption during receive. Add them together to get an estimate of the necessary ampere*hour rating for the gel cell. Be sure to take into account the minimum operating voltage required by the hand-held. -- 73, Cecil http://www.w5dxp.com |
#3
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On Sep 10, 12:49 pm, Dick Grady AC7EL wrote:
I'm looking for a portable rechargeable 12-volt battery, probably a gel cell, to extend my operating time with a VHF/UHF hand-held to about 12 hours of use. I envision that I could power my radio by connecting its cigarette lighter power adapter to the portable battery. The portable battery should be comfortable to carry with me, for example: attached to my belt, or with an over-the-shoulder strap. Any ideas? 73 de Dick, AC7EL I suggest you start he http://www.batterystuff.com/tutorial_battery.html Then "run the numbers" per Cecil's post above. Then Google "Gel Cell Batteries". http://www.batterystation.com/gelcell.htm http://www.batterymart.com/c-sealed-...batteries.html w3rv |
#4
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In article ,
Cecil Moore wrote: Estimate the number of hours out of that 12 hours that you would be transmitting. Multiply that by the current consumption during transmit. Multiply the rest of the hours by the current consumption during receive. Add them together to get an estimate of the necessary ampere*hour rating for the gel cell. Be sure to take into account the minimum operating voltage required by the hand-held. .... but do consider the possible benefits of using a lower-voltage battery. A lot of popular 2-meter HTs will develop a watt or so of output power on 6 volts, and a couple of watts on 8 volts. You only need 10-12 volts into the radio if you absolutely insist on getting the full 5 watts out. Such an HT, fed from a 6-volt SLA battery, and equipped with a full-length "spaghetti noodle" whip antenna and a rat-tail wire counterpoise, would probably outperform the same radio fed from 12 volts but using only the standard lossy "rubber duck" antenna... and it would do so on both receive and transmit. The battery would weight only about half as much... or, conversely, would allow for twice the amp-hour capacity at the same battery weight. -- Dave Platt AE6EO Friends of Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#5
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On Mon, 10 Sep 2007 13:14:44 EDT, Cecil Moore
wrote: Estimate the number of hours out of that 12 hours that you would be transmitting. Multiply that by the current consumption during transmit. Multiply the rest of the hours by the current consumption during receive. Add them together to get an estimate of the necessary ampere*hour rating for the gel cell. Be sure to take into account the minimum operating voltage required by the hand-held. I just got through trying to get discharge curves for my station's 12V Group 27 AGM batteries (for those not familiar with "group" ratings, this is the size of the battery normally found in compact or larger automobiles). The manufacturer is Trojan Batteries, a very reputable battery manufacturer. What I needed was discharge curves for the battery down to 11.5V which I have found (the hard way) is the minimum voltage below which most of my electronic equipment starts going flaky. From the data that they supplied, for a discharge down to 11.5 V the AH capacity of a battery is to be derated to 68% of the "industry standard" 10.5V AH rating. -- 73 de K2ASP - Phil Kane From a Clearing in the Silicon Forest Beaverton (Washington County) Oregon e-mail: k2asp [at] arrl [dot] net |
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