[ICOM] Powering Icom rigs

[D C Macdonald]

Actually, the manufacturers state a float voltage of
anywhere between 2.25 and 2.3 Volts per cell for
gelcell batteries.  This gives you a tolerable range
for nominal 12V gelcells between 13.5 and 13.8 V.

Less than 2.25V does not give maximum capacity
and over 2.3V leads to shortened cell/battery life.

I worked with devices that used gelcells in the
aviation, 2-way, and air-traffic control radios.  For
what it's worth, it seems that a PROPERLY float-
charged gelcell should last for at least 5-6 years.

73  ---  Mac, K2GKK/5




----Original Message Follows----
From: Adam Farson <farson at shaw.ca>
Reply-To: ICOM Reflector <icom at mailman.qth.net>
To: 'ICOM Reflector' <icom at mailman.qth.net>
Subject: RE: [ICOM] Powering Icom rigs
Date: Wed, 28 Jul 2004 17:58:06 -0700

Hi Vic,

Sealed lead-acid (gel-cell) batteries work very well in float service; we
used to use them in the telecom industry. It is recommended to connect a 50A
fast-blow fuse directly in series with the battery, to protect the system in
the event of a short-circuit. In addition, a diode rated for at least twice
the maximum load current should be connected in series with the power-supply
output and the battery, to prevent the back EMF from the battery from
exceeding the maximum reverse base-emitter voltage rating of the pass
transistors.

If possible, the voltage-sense lead of the regulator should be moved to the
load (cathode) end of the diode, to include the diode's forward voltage drop
in the regulation loop. Otherwise, the power supply can be set to (13.8V +
diode drop), or around 14.6 ~ 14.7V.

The float voltage is set at 13.5 ~ 13.8V. An equalising charge should be
applied annually (typically at 14.3 ~ 14.5V) in accordance with the battery
manufacturer's instructions.

The float-charging power supply should have a maximum (foldback) current
rating equal to the maximum desired charging current, as recommended by the
battery manufacturer. There is a lot of information about float-charging on
the various battery manufacturers' websites.

Cheers for now, 73,
Adam VA7OJ/AB4OJ


-----Original Message-----
From: icom-bounces at mailman.qth.net [mailto:icom-bounces at mailman.qth.net] On
Behalf Of Vic/Johanna Culver
Sent: 28 July 2004 08:19
To: ICOM Reflector
Subject: [ICOM] Powering Icom rigs

Corps Groupus Delicious:  I'm trying to reconcile insecurities about caring
for a couple of huge 12 v. gel-electrolyte batteries as emergency back-up
power for an Icom 706MkIIG and an Icom 2030H.  I've looked up the situation
in my '96 RA Handbook and find nothing more than this:  "Once charged, the
battery may be safely maintained at the "float" level, 2.3 v/cell.  Thus, a
12-v gel-cell battery can be "floated" across a regulated 13.8-v system as a
battery backup in the event of power failure."  No caveats whatsoever.  I've
powered my at-home radios from Astron RS-35-M and RS-50-M power supplies for
many years.  I'm pretty sure I couldn't float BOTH batteries from one P.S.,
but am I just overcautious in wondering if something should go WRONG -- as
in a power line drop (it happens, and is one of the reasons for this whole
exercise) or etc. -- that I'll blow up either the power supply or the ICOM
rig(s) or both if I simply parallel one battery with the PS and the radio?
If anyone deems this worthy of a reply, I'd be glad of any comments you
might make.  I'm a digest subscriber, so I may not see your reply for a day
or so if you don't send comment to me direct (as well as via list).  Thanks
for the bandwidth.  Vic  W4VIC
---
Outgoing mail is certified Virus Free.
Checked by AVG anti-virus system (http://www.grisoft.com).
Version: 6.0.726 / Virus Database: 481 - Release Date: 7/22/2004

----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net Icom Users
Net: Sundays, 1700Z, 14.316 MHz Icom FAQ: http://www.qsl.net/icom/

----
Your Moderator: Dick Flanagan K7VC, icom-owner at mailman.qth.net
Icom Users Net: Sundays, 1700Z, 14.316 MHz
Icom FAQ: http://www.qsl.net/icom/