On 22 Apr 2004 21:37:37 -0700, (Mark Keith) wrote:
I only spent about $50 bucks for a 12/2 amp automatic charger. I ran a
battery and a 3 amp trickle charger for years using a ic-730. It will
keep up in most instances as you don't talk all the time. Neither the
730, or the 706 I use now have any problems with the slightly lower
voltage. Both are 100w radios. MK

My experience with automotive 12/2 automatic chargers is they drop to
trickle charge, not float charge. If you leave them hooked up
permanently, they kill the battery in a month or so. Also, they can't
be used with SLA, but marine chargers can -- and they drop to "float,"
not trickle. This is necessary because boat owners hook up to shore
power for long periods of time and don't want to bother switching the
battery charger on and off. Because of that -- and their built-in
isolators to handle more than one (non-parallel) battery -- they cost
$150 instead of $50.

The radios you have that run well off batteries, What do the specs
recite as the required supply voltage? I know that my FT990 wants
13.8 volts and really drops off quickly on 105AH battery power. OTOH,
my FT817 is happy with anything down to 9.6V (if memory serves).

Apparently, there is a [possibly small] market for the battery
boosters:
http://www.eham.net/reviews/detail/3404

Ken KC2JDY


Ken
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Ken wrote:
: I have been using a big switching supply for my shack. I intend to
: change over a to deep-cycle, flooded lead-acid battery if the grid
: goes down. It is, however, problematic operating a 13.8 volt radio on
: a lead-acid battery showing a voltage of 12 volts under load.

: I am thinking of replacing the power supply with a 20 amp marine
: battery charger that will automatically drop to float charge, charging
: a 105AH flooded deep-cycle battery. The battery would feed a "battery
: booster" -- a DC-to-DC converter that will maintain 13.8 volts at 85%
: efficiency. The booster would feed my equipment.

: Are there any drawbacks to this arrangement -- other than it requires
: a battery? The advantage is it won't boil the battery and will be
: immune to outages and brownouts. Also, it will do a fast recharge
: after an outage.
(snip)

How many amps is the "battery booster" rated for?

Astron sells something for similar use. Some of their power supplies are
available with the BB (Battery Backup) option. This is a circuit that will
float charge a battery, then protect the power supply when power fails and
the battery is called upon to power your rig.

I have this setup on my APRS WX station running 24/7. If commercial power
fails then the battery will take over. The computer running APRS will not
be powered, but at least the radio and TNC will still be up .. possibly
providing need network capability during an emergency. But, I'm running an
HT for a transmitter so it will work with less than 13.8 volts.

As I said above .. I think you should look into the possiblity of damaging
your charger if battery voltage is put into it the "wrong way"

Richard in Boston, MA, USA

Ken wrote in message . ..
I have been using a big switching supply for my shack. I intend to
change over a to deep-cycle, flooded lead-acid battery if the grid
goes down. It is, however, problematic operating a 13.8 volt radio on
a lead-acid battery showing a voltage of 12 volts under load.

Shouldn't be.

I am thinking of replacing the power supply with a 20 amp marine
battery charger that will automatically drop to float charge, charging
a 105AH flooded deep-cycle battery. The battery would feed a "battery
booster" -- a DC-to-DC converter that will maintain 13.8 volts at 85%
efficiency. The booster would feed my equipment.

Are there any drawbacks to this arrangement -- other than it requires
a battery? The advantage is it won't boil the battery and will be
immune to outages and brownouts. Also, it will do a fast recharge
after an outage.

I've been doing it for years. Except I don't use the dc-dc converter.
Voltage should not be a problem if you are constantly charging the
batteries.

It seems to me to be superior to the "PWRGate" (isolator?) arrangement
promoted by West Mountain Radio:
http://www.westmountainradio.com/PWRgate.htm

I think I can put together a system that will provide long-run, 13.8V
UPS to a 30-amp-max rig for around $175, not counting the battery.
Comments?

I only spent about $50 bucks for a 12/2 amp automatic charger. I ran a
battery and a 3 amp trickle charger for years using a ic-730. It will
keep up in most instances as you don't talk all the time. Neither the
730, or the 706 I use now have any problems with the slightly lower
voltage. Both are 100w radios. MK