I'm building a PS for my shack, and the receive only current draw of
all of my equipment is in the 2A range. QST a few years ago had a
great charger/battery circuit where the PS/charger generated up to
500ma and, depending on the voltage state of the battery (he used a
SLA) would apply the charger voltage, limited to 500 ma (minus anything
used for running equipment, about 220 ma max for him) to the attached
battery in an increasing duty cycle as battery voltage went down. When
he transmitted, his load was about 2A, and it would come out of the
battery.

I'd like to do something similar, but larger. I'd like to build a
charger/PS capable of supplying about 3A max, and use a deep-cycle
marine battery as a reserve supply. Are there any circuits out there
that allow a battery charger to run on a battery that can possibly be
operating?

Thanks.

Marc

I'm building a PS for my shack, and the receive only current draw of
all of my equipment is in the 2A range. QST a few years ago had a
great charger/battery circuit where the PS/charger generated up to
500ma and, depending on the voltage state of the battery (he used a
SLA) would apply the charger voltage, limited to 500 ma (minus anything
used for running equipment, about 220 ma max for him) to the attached
battery in an increasing duty cycle as battery voltage went down. When
he transmitted, his load was about 2A, and it would come out of the
battery.

I'd like to do something similar, but larger....

Even simpler (and the way I do it): look up "float charging". Adjust
output of whatever regulated and reverse-protected DC power supply you
have handy to the proper "float voltage" of your battery (I use a plain
ol' car battery, not even a "deep cycle", as one of my HF radios starts
FM-ing when the battery drops to about 11 volts, so the increased capacity
of a deep cycle battery is totally wasted) and connect it and your
equipment across the battery!

When battery is low and equipment is off, battery is charged.
When battery is high and equipment is off, battery quits charging.
No special "charge controller" or other electronics beyond that
already in most DC power supplies is/are needed.

One can also use an "automatic" charger which cycles on and off as
necessary to keep the battery charged, but this will probably cost more
because most junk boxes probably aren't as well supplied with automatic
chargers as they are with regulated DC power supplies. But they are NOT
particularly expensive; Wal-Mart use to sell a 1.5-amp version to mount
under the hood of a car for about $25-30.

The radio (and two emergency lights) in my shack have been powered by
either of the above two ways for over 25 years.

The only two times I've had to use some kind of "charge controller"
were when the sourse was a:
* wind generator - when the wind blew, it created whatever voltage
was necessary to force about 15 amps into whatever was connected!
(I used a zener and a few transistors -- two of them big! -- to
"dump" excess current into two 100-watt 1-ohm resistors.
* solar panel - except that my panel only produced about 2 amps in
bright sunlight, the sun shown much more often than the wind blew,
so this was basically the same problem: dump excess current.

Incidentally, for not-too-big DC power supplies, I've not found it
particularly necessary for them to be very "pure" DC; a 60-amp-hour
car battery acts like a pretty-big filter capacitor!

--Myron, W0PBV.
--
--Myron A. Calhoun.
Five boxes preserve our freedoms: soap, ballot, witness, jury, and cartridge
PhD EE (retired). "Barbershop" tenor. CDL(PTXS). W0PBV. (785) 539-4448
NRA Life Member and Certified Instructor (Home Firearm Safety, Rifle, Pistol)

It's not necessary to provide a "dump" for a charge controller when a
solar panel is used for charging (at least the ones we use at work don't
require a dump). It appears the charge controller shorts the "array"
connections and the panels circulate their "short circuit current"
around the array loop.

Scott
N0EDV


The only two times I've had to use some kind of "charge controller"
were when the sourse was a:
* wind generator - when the wind blew, it created whatever voltage
was necessary to force about 15 amps into whatever was connected!
(I used a zener and a few transistors -- two of them big! -- to
"dump" excess current into two 100-watt 1-ohm resistors.
* solar panel - except that my panel only produced about 2 amps in
bright sunlight, the sun shown much more often than the wind blew,
so this was basically the same problem: dump excess current.

Incidentally, for not-too-big DC power supplies, I've not found it
particularly necessary for them to be very "pure" DC; a 60-amp-hour
car battery acts like a pretty-big filter capacitor!

--Myron, W0PBV.

The comment below is valid if there are only solar panels involved.
However ,when these are used in combination with a wind generator a current
dump is required.
My battery operated station has its batteries charged by this combination of
sources.
The home brew charger comprises a zener referenced comparator ( 741 opamp)
driving a number of power transistors ,with the rest of the load being a
number of car head light bulbs.
When the batteries are fully charged ,all current generated is dumped .its
resulting heat making a minor contribution to shack heating.

Frank GM0CSZ / KN6WH

===========================

It's not necessary to provide a "dump" for a charge controller when a
solar panel is used for charging (at least the ones we use at work don't
require a dump). It appears the charge controller shorts the "array"
connections and the panels circulate their "short circuit current" around
the array loop.

Scott
N0EDV


The only two times I've had to use some kind of "charge controller"
were when the sourse was a:
* wind generator - when the wind blew, it created whatever voltage
was necessary to force about 15 amps into whatever was connected!
(I used a zener and a few transistors -- two of them big! -- to
"dump" excess current into two 100-watt 1-ohm resistors.
* solar panel - except that my panel only produced about 2 amps in
bright sunlight, the sun shown much more often than the wind blew,
so this was basically the same problem: dump excess current.

Incidentally, for not-too-big DC power supplies, I've not found it
particularly necessary for them to be very "pure" DC; a 60-amp-hour
car battery acts like a pretty-big filter capacitor!

--Myron, W0PBV.

Hi Frank,

OK, I see. I made an assumption on my part that you meant only one or
the other (solar or wind) was being used. So, what you are saying is
that one charge controller is being used with two sources attached to
it? If so, I would agree...

Scott
N0EDV


Highland Ham wrote:
The comment below is valid if there are only solar panels involved.
However ,when these are used in combination with a wind generator a current
dump is required.
My battery operated station has its batteries charged by this combination of
sources.
The home brew charger comprises a zener referenced comparator ( 741 opamp)
driving a number of power transistors ,with the rest of the load being a
number of car head light bulbs.
When the batteries are fully charged ,all current generated is dumped .its
resulting heat making a minor contribution to shack heating.

Frank GM0CSZ / KN6WH

===========================


It's not necessary to provide a "dump" for a charge controller when a
solar panel is used for charging (at least the ones we use at work don't
require a dump). It appears the charge controller shorts the "array"
connections and the panels circulate their "short circuit current" around
the array loop.

Scott
N0EDV



The only two times I've had to use some kind of "charge controller"
were when the sourse was a:
* wind generator - when the wind blew, it created whatever voltage
was necessary to force about 15 amps into whatever was connected!
(I used a zener and a few transistors -- two of them big! -- to
"dump" excess current into two 100-watt 1-ohm resistors.
* solar panel - except that my panel only produced about 2 amps in
bright sunlight, the sun shown much more often than the wind blew,
so this was basically the same problem: dump excess current.

Incidentally, for not-too-big DC power supplies, I've not found it
particularly necessary for them to be very "pure" DC; a 60-amp-hour
car battery acts like a pretty-big filter capacitor!

--Myron, W0PBV.