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

On Fri, 23 Apr 2004 03:07:18 +0000 (UTC), Richard G Amirault
wrote:
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"

I think marine chargers are made to handle the situation when there is
no shore power, but I will make sure. Otherwise a 20 amp diode would
be needed.

Yes, the booster is key. That needs to handle 25 amps on a 30% duty
cycle -- to provide 100 watts FM.

Ken KC2JDY

Ken
(to reply via email
remove "zz" from address)

On Fri, 23 Apr 2004 03:07:18 +0000 (UTC), Richard G Amirault wrote:

: 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.

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"

The best solution is much simpler than those that I've seen here.

I use dual switching p/s through a dual-diode isolator onto a 100 AH
deep-cycle marine gel-cell. Both supplies are set to deliver 13.5 V
to float-charge the battery. Two supplies are used in case one goes
down for overload or any other reason such as my kicking the on-off
switch to "off" accidently as I did once.

All devices are rated for 50 A. Make sure that you use sufficiently
large wire and adequate overcurrent protection (I use marine-rated
circuit breakers) to protect the supplies, the battery, and the
load(s).

The only thing unusual about the setup is that the isolator has to be
one made for positive-ground vehicles (yes, auto supply stores sell
them on special order, same price) because the standard ones for
negative-ground vehicles are for two batteries charged by one supply
(alternator) rather than one battery charged from two supplies. If
you only want to use one supply, you can use one side of a standard
isolator.

Be sure that the supply is a regulated constant-voltage supply, not
a "battery charger" whose output is really semi-filtered DC. If you
can operate the radio on the supply with no hum problems, it will be
OK for float-charging.

The bottom line -- keep the battery on line at no more than its
rated float-charge voltage, and all the isolator is -- is a big
diode on a big heat sink.

--
73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon

On Fri, 23 Apr 2004 03:07:18 +0000 (UTC), Richard G Amirault
wrote:
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"

I think marine chargers are made to handle the situation when there is
no shore power, but I will make sure. Otherwise a 20 amp diode would
be needed.

Yes, the booster is key. That needs to handle 25 amps on a 30% duty
cycle -- to provide 100 watts FM.

Ken KC2JDY

Ken
(to reply via email
remove "zz" from address)

On Fri, 23 Apr 2004 03:07:18 +0000 (UTC), Richard G Amirault wrote:

: 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.

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"

The best solution is much simpler than those that I've seen here.

I use dual switching p/s through a dual-diode isolator onto a 100 AH
deep-cycle marine gel-cell. Both supplies are set to deliver 13.5 V
to float-charge the battery. Two supplies are used in case one goes
down for overload or any other reason such as my kicking the on-off
switch to "off" accidently as I did once.

All devices are rated for 50 A. Make sure that you use sufficiently
large wire and adequate overcurrent protection (I use marine-rated
circuit breakers) to protect the supplies, the battery, and the
load(s).

The only thing unusual about the setup is that the isolator has to be
one made for positive-ground vehicles (yes, auto supply stores sell
them on special order, same price) because the standard ones for
negative-ground vehicles are for two batteries charged by one supply
(alternator) rather than one battery charged from two supplies. If
you only want to use one supply, you can use one side of a standard
isolator.

Be sure that the supply is a regulated constant-voltage supply, not
a "battery charger" whose output is really semi-filtered DC. If you
can operate the radio on the supply with no hum problems, it will be
OK for float-charging.

The bottom line -- keep the battery on line at no more than its
rated float-charge voltage, and all the isolator is -- is a big
diode on a big heat sink.

--
73 de K2ASP - Phil Kane

From a Clearing in the Silicon Forest
Beaverton (Washington County) Oregon