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Portable station power
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by KB9UMT on January 13, 2005
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GE All,
I was wondering if some of you could give me some ideas on portable station power. I'm putting together a QRP Hf digital station that I would like to use for emergency's, fieldday, or just a 'take it anywhere' deal. I have larger generators for power outages, I have larger marine batteries but I want something lighter and more portable...any ideas? Again..wanting to power 10w or less qrp HF rig and maybe at most the addition of a small IBM laptop if the battery dies for maybe a few hours to up to 6 hours. What would it take? Solar panel...with smaller motorcycle battery....either seperate or together....any detail ideas would be appreciated...Thanks
de kb9umt Don
http://www.HamRadioHelp.com
have some ideas on this but want some others also please
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RE: Portable station power
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by KC8VWM on January 13, 2005
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Got the answer for you.
Try building this solar powered emergency generator on my website.
2 models to choose from. Free diagrams.
http://www.angelfire.com/on/cbushell/solar/solar1.html
73
Charles - KC8VWM
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RE: Portable station power
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by K1CJS on January 14, 2005
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Just remember--the more power you want or need, the heavier the battery unit to supply it will be.
With that being said, have you considered one of the ready made "jump start units" used to get cars started? Those should do the trick nicely for you--and they're ready made!
If you want more reserve, a 12 volt deep cycle battery may be what you need.
Consider current draw and useage as a starting point. You did state six hours, so figure the needed reserve to power your rig and the computer, most laptops use 70 to 100 watts of power through a 110 volt connection depending on the use.
Good luck!
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RE: Portable station power
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by K5LXP on January 14, 2005
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> most laptops use 70 to 100 watts of power through a
> 110 volt connection
More like 15-20W...
Mark K5LXP
Albuquerque, NM
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RE: Portable station power
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by N2MPT on January 14, 2005
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you may be interested in seeing the battery power setup in my portable RACES box:
http://losdos.dyndns.org:8080/public/ham/RACES+ARES-portable-box.html
jim / n2mpt
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RE: Portable station power
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by N2NFG on January 14, 2005
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Hi Don, I second the idea of using a portable jump start unit. Sears has a number of them in different capacities, other department stores and auto parts stores have them also. I bought the largest unit offered by Sears. You can draw voltage from either the jump start cables supplied or a cigarette lighter socket. (plugs available at Radio Shack) I made two copper plates from flattened copper pipe and attached wires to the radio. You just slip the plate under the jumper clamp while it's still attached to the unit. There is space provided on the back to velcro an inverter in place for 110, but a better way to go for the laptop would be a circuit to up the voltage to what the laptop needs. There was a recent article on this in either QST or CQ magazine, should be easy to find. The unit I have can be charged from either 110 or by your vehicle battery. They can be left attached to the charge source which will float charge them as needed. Most of these units have charge and status indicators as well as other accessories. Mine has a red flashing light as well as a bright white adjustable light. I have also seen them with built in air compressors for flat tires. All in all, probably one of the most useful acessories I have ever bought for the hobby and emergency use. I keep mine in the house plugged in, ready to go at a moments notice either here or portable. BTW, the price is very reasonable on these units. Paired up with a solar device as Charles mentions in his post, you could probably operate a QRP or low power station nearly forever! 73, Bob
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RE: Portable station power
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by WB6BYU on January 14, 2005
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My standard backpack power source was a 4.5 Ah lead gel
batter. This operated my HW-8 or Argonaut for a week of
occasional evening operation, or about 24 hours of Field
Day single-op (since I need to sleep sometimes...)
A set of Alkaline or Lithium penlight cells is a good
alternative in many cases. For longer trips and/or more
operation, 7 aH gel cells are quite common.
But with many of the newer rigs, it is the receive current
draw that limits the operation time more than the actual
transmit power. One of my transceivers draws 22ma on
receive, and, having recently built receivers that only
draw 10ma, it may be worth looking at to see if I can
save some more current.
For a home station you can use a much larger battery,
such as a standard deep cycle RV or Marine battery.
Solar charging is a good option, as is a small wind
generator (since we tend to lose power much more often
in storms than in sunny weather around here.) A further
backup would be a pedal generator: a 24V gear motor
driven by a stationary bicycle can put out 5 amps at
14V even in a dead calm in the middle of the night.
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RE: Portable station power
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by KC2MMI on January 15, 2005
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Don-
Most of IBM's laptops fall into one of two power groups. One uses 75W power bricks, which roughly supply 35-40W to recharge the battery and that much more again to power the laptop. So, the laptop is consuming about 40-45W with full screen brightness, CPU and drive use. The second group of "desktop replacement" laptops with P4 (not "mobile") CPUs generally take twice as much power, they can consume 75W while running. You'd have to check which group yours falls into.
If the first...then you're looking at 45W for the laptop plus maybe 15W (10W plus inefficiencies) for your rig, about 60W for both, more or less 5Amps at 15 volts while tx'ing. Assume that for a worst case, times six hours, and you'd need 30AH of battery power.
If you use a marine AGM battery in a "car" size, i.e. Group 27 to Group 31 about 80#, the capacity is rated about 80AH and for AGM or wet lead batteries, the recommendation is not to run them past the 50% discharge point for repeated use. (Running them further reduces overall battery life way out of proportion.)
So, one option is the deep cycle battery. Another would be to use gel cells, which I think are more forgiving on deep cycling--haven't been able to confirm that directly.
Other than that...I think the compromise is "How much can you carry?" and then you stop operating when it is flat. Do whatever you can to conserve the laptop's power (i.e. eject any unneeded devices, cards, even the CD-drive so they take no power, dim the screen, etc.) since that's the main power drain.
A motorcycle battery is still a "starting" battery and not as well suited as a gel or small AGM. The best bargain on AGM's is usually to find a "traction" battery, sold for wheelchair power, or a small marine deep cycle intended for trolling motors.
Of course, if you don't need as much power for the computer, something like a pair of 17AH gel cells might be mighter and cheaper, and give you the option of taking just one or both depending on the event.
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RE: Portable station power
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by K1CJS on January 15, 2005
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> most laptops use 70 to 100 watts of power through a
> 110 volt connection
>>More like 15-20W...
Should have said most NEWER laptops......sorry.
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RE: Portable station power
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by KB9YUR on January 20, 2005
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Don,
for the last several years I've been using the Nomad 300 portable power supply from
www.solarsense.com. It's an all-in-one inclusive unit that not only provides 12v DC from
an 18ah battery but also has a 300 watt inverter. There are also connections on this
unit for connecting additional batteries and an input for a solar panel. I usually take the
Nomad 300 and a 21 watt solar panel with me on field days(s) and it's been able to
power an Icom 275H and a Yaesu FT-290RII radio with no problems.
George ...
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