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Date: Sun, 09 Jun 2002 22:35:32 -0700
From: "John Grebenkemper, KI6WX" <KI6WX at pacbell.net>
Subject: Re: [Elecraft] K2/100 Emergency field battery
To: Elecraft Mailing List <elecraft at mailman.qth.net>

Tim;
I just purchased a 'Yuasa' NPX-150R sealed lead-acid battery from HSC
www.halted.com for $29.50.  Its designed to put out a peak energy of 150
watts and has a 40 AH 10 hour rating.  It should work fine for running the
KPA100 for short transmissions at higher power.  I just checked the one I
brought this weekend and it does have a capacity near 40 AH so its a pretty
good deal for the price (these types of batteries have a list price closer
to $100).
-John
 KI6WX


> Hi folks -
>
> I would like to hear anyone's recommendation for a battery to be used in
> the field that could power the K2/100 on moderate emergency
> communications traffic for 3 days if solar recharging was not available.
> I realize that "moderate" is extremely subjective, but I think you get
> the idea. I'm obviously not talking about a backpacking item. Any help,
> particularly from those with emergency field experience would be most
> appreciated. Thank you. Regards, Tim NZ7C
>

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Date: Mon, 10 Jun 2002 03:57:35 -0400
From: Bob Patten <n4bp at netzero.net>
To: CYR999 at extremezone.com
Cc: Elecraft <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] K2/100 Emergency field battery

TIM LOGAN wrote:
> 
> I would like to hear anyone's recommendation for a battery to be used in
> the field that could power the K2/100 on moderate emergency

-- snip --

Simple solution..  Go to Pep Boys (or check other stores for sales) and
pick up a 110 A/H marine battery.  About $50 and should easily run the
K2 for three days.
No, not recommended for backpacking!

-- 
73,     Bob Patten, N4BP                Plantation, FL

E-Mail: n4bp at netzero.net                Website: http://www.qsl.net/n4bp
QRP ARCI #3412    SOC #1    ARS #799    Whiners #6   FISTS #7871

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Reply-To: "Don Wilhelm" <w3fpr at peoplepc.com>
From: "Don Wilhelm" <w3fpr at peoplepc.com>
To: <CYR999 at extremezone.com>, "Elecraft" <elecraft at mailman.qth.net>
Subject: Re: [Elecraft] K2/100 Emergency field battery
Date: Mon, 10 Jun 2002 06:46:11 -0400

Tim,

I would suggest you use your vehicle battery.
I have thought of wiring my vehicle battery with a short wire with fuses
wirh an Anderson Powerpole connector on the end - and also making up an
extension long enough to reach the interior of the vehicle with the
Powerpole connectors on each end.

I would complete the emergency setup with some kind of quick mounting socket
for a mobile antenna - I already have a bunch of hamsticks.

When the need arises, I could pick up the K2/100, the Powerpole extension
cord, and the hamsticks and go.

73,
Don Wilhelm  - Wake Forest, NC   W3FPR home page: http://www.qsl.net/w3fpr/
  QRP-L # 485   K2  SN 0020   mailto: w3fpr at arrl.net

*** Life is what happens when you're making other plans -- Mike Cross  ***

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Date: Mon, 10 Jun 2002 07:43:02 -0500
To: CYR999 at extremezone.com, elecraft at mailman.qth.net
From: Tom Hammond =?iso-8859-1?Q?N=D8SS?= <n0ss at earthlink.net>
Subject: Re: [Elecraft] K2/100 Emergency field battery

Tim:

>I would like to hear anyone's recommendation for a battery to be used in
>the field that could power the K2/100 on moderate emergency
>communications traffic for 3 days if solar recharging was not available.

-- snip --

In the past (about 18-20 years ago) I used a Deep-Cycle RV-type (or Marine) 
battery to power a solid state rig. Kept it on a regular automotive-type 
charger (Schauer, 25A Automatic Charger) all the time, and monitored the 
electrolyte levels on a monthly (maybe bi-monthly) basis.

When off the charger, the battery allowed me to run the rig for well over 
48 hours before it really started to show signs of degradation in the 
terminal voltage. When ON the charger, the charger loafed along, just 
supplying 'top-off' charge 99.9% of the time, but when in use, the charger 
went up to about 18A of charge during key-down times and then (almost) 
immediately dropped back to about a 5A to 7A charge rate until it could 
replace enough of the lost charge that the 'top-off' voltage had again been 
reached. At which point the charger went into what I call 'pulse' mode, 
only periodically supplying a 1A (or so) pulse charge, just to maintain the 
topped-off charge. I NEVER(!) ever experienced any problem with AC ripple 
(hum) from the charger... apparently the battery was more than up to the 
task of acting as a big fat filter for the charging pulses.

Unfortunately, it's been long enough ago that I no longer recall the actual 
Ampere-Hour rating of the Deep-Cycle battery, but it was moderately 
heavy-duty. After having used the battery/charger combo for probably 4-5 
years, I finally killed the battery by taking if off the charger for an 
extended period of time (over a year) when I no longer had a 12VDC powered 
rig. The battery self-discharged, sulfated up, and eventually developed a 
short between several plates, thus rendering itself un-recoverable by any 
means available to me at the time.

I have no real-life experience with gelled-electrolyte batteries, so will 
leave those comments to someone with such knowledge.

73,

Tom Hammond   N0SS

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Date: Mon, 10 Jun 2002 10:01:07 -0500
From: "George, W5YR" <w5yr at att.net>
Organization: AT&T WorldNet Service
To: CYR999 at extremezone.com
Cc: Elecraft <elecraft at mailman.qth.net>,
        "qrp-l at Lehigh.edu" <qrp-l at Lehigh.edu>,
        netxqrp <netxqrp at mailman.qth.net>
Subject: Re: [Elecraft] K2/100 Emergency field battery

Another use for a large RV battery like that is in the shack.

Connect it via an appropriate fuse to the output of your regular a-c power
supply such that the supply will trickle charge the battery at the nominal
13.8 volts. If you have  any line power interruptions, especially the
momentary kind (off and then right back on) the battery will function in
the manner of a UPS to prevent the voltage transients from reaching your
equipment.

There are a couple of gotchas in this arrangement, however, that need
consideration.

First, should the power supply crowbar for any reason, a fuse or fast
breaker must be used to open the battery circuit. Otherwise you will rather
quickly release all the smoke from portions of the power supply and create
a potentionally highly dangerous situation with a shorted battery until
something burns up (or the battery explodes!) to open the circuit.

The second problem area concerns the time during which the supply has its
a-c power removed. The battery could force current back into the supply and
possibly damage the series regulators. To handle this problem, use a large
diode to block current flow from the battery to the supply. 

Of course, with a diode in the circuit, the radio equipment must be
connected directly to the battery - again through a suitable fuse to avoid
an external short-circuit from damaging or destroying the battery - while
the supply is connected to the battery through a fuse and the diode. To
compensate for the diode voltage drop, the supply voltage should be
increased accordingly. Note that this arrangement is not suitable for
charging a large RV or marine battery. It should be at full charge before
being placed into this service.

Two excellent references in this area are the three-part series "Practical
Battery Back-Up Power for Amateur Radio Stations" in March, April and May
1990 QST. The April article is especially relevant.

The second reference is a bulletin put out by the CAP, describing the
approved procedure for battery back-up of Astron supplies, which is
available at

                  http://www.ntc.cap.gov/comm/ntc/RS_Battmod.htm

The procedure consists of inserting a 1/2-watt 10K resistor in the trace
feeding Pin 4 of the 723 regulator chip to limit current and avoid letting
all the smoke out of the regulator. This resistor is inserted by cutting
the trace between the moving contact of the pot R5 (1K) and Pin 4, and
bridging the cut with the resistor.

I have used such an arrangement for some time now and it is comforting to
know that a shack full of gear is protected from power transients due to
line voltage outages. These occur frequently "out here in the country!"   
<:}

73/72/oo, George W5YR - the Yellow Rose of Texas         
Fairview, TX 30 mi NE of Dallas in Collin county EM13qe   
Amateur Radio W5YR, in the 56th year and it just keeps getting better!
QRP-L 1373 NETXQRP 6 SOC 262 COG 8 FPQRP 404 TEN-X 11771 I-LINK 11735
Icom IC-756PRO #02121  Kachina 505 DSP  #91900556  Icom IC-765 #02437

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Date: Mon, 10 Jun 2002 11:04:19 -0500
From: "George, W5YR" <w5yr at att.net>
Organization: AT&T WorldNet Service
To: CYR999 at extremezone.com
Cc: Elecraft <elecraft at mailman.qth.net>,
        "qrp-l at Lehigh.edu" <qrp-l at Lehigh.edu>,
        netxqrp <netxqrp at mailman.qth.net>
Subject: Re: [Elecraft] K2/100 Emergency field battery

Jerry Lofstead W3CDE has been kind enough to point out that my link won't
work!  <:}

Seems that the Fat Fingers here forgot the 'www' at the start, so here is
the complete URL

                http://www.ntc.cap.gov/comm/ntc/RS_Battmod.htm

Just checked and this one does work and the site is still active. BTW, the
site also has a link to the RS-35M Astron schematic showing the added
resistor. The mod also applies to the VS-35M which I use - variable voltage
and current limiting - although some of the schematic is different.

Sorry for any problems . . .

73/72/oo, George W5YR - the Yellow Rose of Texas

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To: CYR999 at extremezone.com, elecraft at mailman.qth.net
Date: Mon, 10 Jun 2002 09:12:47 -0700
Subject: Re: [Elecraft] K2/100 Emergency field battery
From: k6se at juno.com

Tim, NZ7C wrote:

"I would like to hear anyone's recommendation for a battery to be used in
the field that could power the K2/100 on moderate emergency
communications traffic for 3 days if solar recharging was not available."
==========
Sounds like you want a deep-cycle type of battery like those used on RVs.
 I bought one for my RV at Wal-Mart ("Kirkland" brand) a year ago for
$39.  It's rating is 95 amp-hours and should be more than sufficient for
your intended use.  To preclude shortening its life due to overcharging
with run-of-the-mill battery chargers, I keep it fully charged with a
small A&A Engineering (as advertised in QST) "smart charger" when not in
use.

73, de Earl, K6SE
71 countries with K2 #2622 and counting.....

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