I know this question has probably been beaten to death, nevertheless I hope
you will still indulge me.

During a power outage, which occurs frequently in Florida, I would like to
use a battery to power some communication gear. Although the battery is 12v
and not 13.8v, I think that the gear will still work OK (hopefully).

Question 1. I believe that car batteries have a low internal resistance
because their primary function is to provide a lot of current for a short
time. There are other 12v large battery types that will last as long as a
typical car battery. They are designed not to provide peak current, but to
supply steady state current for a long time.
For the life of me, I can't remember the name of those type batteries so I
can't do a google to find a supplier. I hope this is making some sense.

Question 2. Where can I find articles & schematics for a solar cell to
provide a trickle charge for the aforementioned battery?

Thank you very much.

Cordially,
west

"west" wrote in message
.. .
I know this question has probably been beaten to death, nevertheless I
hope
you will still indulge me.

During a power outage, which occurs frequently in Florida, I would like to
use a battery to power some communication gear. Although the battery is
12v
and not 13.8v, I think that the gear will still work OK (hopefully).

Question 1. I believe that car batteries have a low internal resistance
because their primary function is to provide a lot of current for a short
time. There are other 12v large battery types that will last as long as a
typical car battery. They are designed not to provide peak current, but to
supply steady state current for a long time.
For the life of me, I can't remember the name of those type batteries so I
can't do a google to find a supplier. I hope this is making some sense.

Question 2. Where can I find articles & schematics for a solar cell to
provide a trickle charge for the aforementioned battery?

What you want is a deep cycle battery. Sometimes called a marine battery if
it is about the same size of a car battery. Used for trolling motors among
other things. Also used for powering golf carts.

During a power outage, which occurs frequently in Florida, I would like to
use a battery to power some communication gear. Although the battery is
12v
and not 13.8v, I think that the gear will still work OK (hopefully).

Question 1. I believe that car batteries have a low internal resistance
because their primary function is to provide a lot of current for a short
time. There are other 12v large battery types that will last as long as a
typical car battery. They are designed not to provide peak current, but to
supply steady state current for a long time.
For the life of me, I can't remember the name of those type batteries so I
can't do a google to find a supplier. I hope this is making some sense.

Question 2. Where can I find articles & schematics for a solar cell to
provide a trickle charge for the aforementioned battery?
====================================
1) If radio still works at 12 V you can use a 12 V battery

2)If a lead acid battery is charged to 13.8 V and subsequebtly discharged it
still has 70 -80 % of its full charge when the voltage has dropped to 12.6
V.

3) The construction of car - versus leisure (deep cycle) batteries is that
the plates of a car battery have a larger area but are thinner . This
enables the chemical reaction to be stronger resulting in a high current
capability (engine start) ,be it for a relatively short time. A leisure
battery has thicker plates but with a smaller area ,hence these batteries
can provide a more modest current ,but for a longer time .
Marine batteries have similar characteristics.
Leisure batteries are available as 'wet' units which can be topped up , with
distilled or de-ionised water ,or are of the sealed type (as used in UPS
=Uninterruptible Power Supply units and for example golf carts )
It is recommended by some manufacturers to charge SLAs = sealed lead acid
batteries to 13.5 -13.8 V ,not higher ,when used for stand by service .
( I restrict the SLAs I use to 13.5 V)

4) If only a solar panel is used for charging a lead acid battery , a simple
comparator circuit with any opamp ,sensing (a fraction of ) the battery
voltage against a zener reference can operate a relay disconnecting the
battery from the solar panel and shorting the solar panel . Alternatively
,when battery is fully charged the generated current is dumped via a
transistor - resistor or transistor- car bulb arrangement .
The current dumping system is necessary when other renewable energy sources
are used as well ,like a wind generator. The latter system is the one I use
..

Frank GM0CSZ / KN6WH

You may be thinking of a "deep cycle battery", which make good batteries
to power communication gear. They are commonly called 12 Volt batteries
(just the same as car batteries are) but in reality, when fully charged,
they are really 13.8 Volts (just as car batteries are), so they will
work fine for powering gear designed for 13.8V.

Charging with a solar panel is pretty easy. All you need is a solar
panel, a charge controller and the battery. The charge controller will
have positive and negative connection points labeled "Array" or
something similar. Hook up the solar panels positive and negative leads
there (positive to positive and negative to negative). The other
connection points will go to the battery (again, positive to positive
and negative to negative). Aim the solar panel due South and tilt it (0
degrees being horizontal) at an angle that is your location's lattitude
+ 15 degrees. In Florida, that would be about 43 degrees in Central
Florida. So the panel would be placed at a 43 degree angle up from
horizontal and so that the solar cells are facing South. Be careful to
have the batteries located in a place that is vented since they will
give off a little hydrogen as they charge (even the sealed batteries do)
and hydrogen is explosive (aka Hindenburg). A small vented box outside
it good and run the wires inside (be sure to use a large enough wire to
avoid dropping the voltage at the radio to a level that is too low to
operate it). 10 or 12 gauge wire should be fine for short runs of 10 to
20 feet for an HF radio that draws something like 20 Amps in transmit.

More info on this can be found at http://www.homepower.com and I
whole-heartedly suggest you subscribe if you are at all interested in
alternative power sources for other things around the home. You might
check your local library and see if they have the magazine (I can get it
at my local Border's Book Store).

Scott
N0EDV

west wrote:
I know this question has probably been beaten to death, nevertheless I hope
you will still indulge me.

During a power outage, which occurs frequently in Florida, I would like to
use a battery to power some communication gear. Although the battery is 12v
and not 13.8v, I think that the gear will still work OK (hopefully).

Question 1. I believe that car batteries have a low internal resistance
because their primary function is to provide a lot of current for a short
time. There are other 12v large battery types that will last as long as a
typical car battery. They are designed not to provide peak current, but to
supply steady state current for a long time.
For the life of me, I can't remember the name of those type batteries so I
can't do a google to find a supplier. I hope this is making some sense.

Question 2. Where can I find articles & schematics for a solar cell to
provide a trickle charge for the aforementioned battery?

Thank you very much.

Cordially,
west

Although most posts have suggested what you are thinking of is a deep cycle
marine battery or similar, you might consider using an SLA for your purpose.

SLAs will probably be more expensive, per amp-hour, than a marine battery.
However, most lead acid batteries are intended to be operated outdoors.
SLAs are a lot more housebroken.

With an ordinary lead-acid battery, you have two problems. The obvious one
is leaking acid, which could be a real problem in the house. The other is
outgassing hydrogen. Hydrogen is extremely easy to ignite, and if the
concentration gets within the flammable range, it will almost certainly find
an ignition source. Outdoors it is pretty tough (relatively) to get the
concentration high enough to burn, but not so indoors. Hydrogen burns very
quickly, so the result of a hydrogen fire, even in an open space, is often
much like an explosion. The good news is that is has relatively little
energy, so while it burns very hot, it tends to be over with very quickly,
so it is (relatively) unlikely to ignite things around it. Still, I'm not
the biggest fan of indoor explosions .. at least in my house.

With SLAs, neither the hydrogen nor the acid gets out, so they are a little
more friendly indoors.

...

"west" wrote in message
.. .
I know this question has probably been beaten to death, nevertheless I hope
you will still indulge me.

During a power outage, which occurs frequently in Florida, I would like to
use a battery to power some communication gear. Although the battery is
12v
and not 13.8v, I think that the gear will still work OK (hopefully).

Question 1. I believe that car batteries have a low internal resistance
because their primary function is to provide a lot of current for a short
time. There are other 12v large battery types that will last as long as a
typical car battery. They are designed not to provide peak current, but to
supply steady state current for a long time.
For the life of me, I can't remember the name of those type batteries so I
can't do a google to find a supplier. I hope this is making some sense.

Question 2. Where can I find articles & schematics for a solar cell to
provide a trickle charge for the aforementioned battery?

Thank you very much.

Cordially,
west

Looks like you have some good info from others. Here's a little more.

What you will be doing is not "trickle" charging, but it is called "float"
charging. Lead acid chemistry, similar to Li-ion (unlike ni-Cd & Ni-Mh) has
the characteristic that it has a voltage charactistic such that the terminal
voltage rises between dead and full charge. You can safely put a constant
voltage (but also with a current limit) on the battery and it will seek its
own full charge and the current will taper off, when it gets enough, to what
it needs to stay at full charge. CAUTION -- This voltage is typically
around 13.8, HOWEVER you MUST consult the manufacturer's specs. This
voltage also changes slightly as the temperature of the battery changes.

A commercial device designed for this service is recommended.

73, Steve, K,9.D;C'I





"west" wrote in message
.. .
I know this question has probably been beaten to death, nevertheless I
hope
you will still indulge me.

During a power outage, which occurs frequently in Florida, I would like to
use a battery to power some communication gear. Although the battery is
12v
and not 13.8v, I think that the gear will still work OK (hopefully).

Question 1. I believe that car batteries have a low internal resistance
because their primary function is to provide a lot of current for a short
time. There are other 12v large battery types that will last as long as a
typical car battery. They are designed not to provide peak current, but to
supply steady state current for a long time.
For the life of me, I can't remember the name of those type batteries so I
can't do a google to find a supplier. I hope this is making some sense.

Question 2. Where can I find articles & schematics for a solar cell to
provide a trickle charge for the aforementioned battery?

Thank you very much.

Cordially,
west

During a power outage, which occurs frequently in Florida, I would like to
use a battery to power some communication gear. Although the battery is 12v
....[snip]....

Although many have suggested you should use "deep cycle" (also called
"traction") batteries, be aware that the specifications for such batteries
are DIFFERENT in that they are rated to still be producing useable power
when their output voltage is somewhat LOWER than others. If your equipment
poops out before that lower voltage is reached, you won't get all the
output you've paid for. (My TenTek 540, for example, starts FM'ing at
about 11.5 volts, so the remaining output from a deep-cycle is totally
unuseable.)

The following is abstracted from a 3 Oct. 1992 post to
rec.radio.amateur.misc by Brian Kantor :

1. Automotive starting: formulated with thin pasted plates and designed
to supply high peak currents for brief periods of time while cranking
an engine. Designed to be discharged to more than perhaps 75% of
capacity and to be recharged immediately after discharge. Typically
discharged-rated at a 20-hour rate.

2. Traction (e.g., deep-cycle batteries): made with thick pasted plates
and with very rugged separators between the plates to make the battery
more immune to physical shock and vibration and to reduce the chance
of failure due to dendritic growth during recharging. Sold for use in
electric forklifts, golf carts, marine trolling motors, and RV power.
Designed to be discharged nearly fully each day and recharged each
night. Typically discharged-rated at a 5-hour rate.

3. Stationary: made with thick solid plates. Designed to be used as
standby power, supplying minimal power and kept in a state of nearly-
full ("float") charge until needed. Can take deep discharge. Because
of the solid-plate structure, they are bigger and heavier, but their
lifetime is much longer (10 years is not unusual). Typically
discharged-rated at a 10-hour rate.

Each type of battery has a specified voltage at which it is considered
to be completely discharged; if discharge continues below this voltage,
battery life may be considerably shortened, and repeated abuse of this
nature can result in a battery which cannot practically be recharged.
Each battery manufacturer specifies this voltage; in general, the final
voltages for the three general types of batteries a
Automotive: 1.75 volts per cell
Traction: 1.70 volts per cell
Stationary: 1.85 volts per cell

A typical traction-type cell shows the following voltages:
2.12 Fully charged, open circuit, at rest with no charge
or discharge for at least 12 hours
2.00 As soon as load is applied (internal voltage drop)
1.70 Fully discharged, under load
1.99 Fully discharged, open circuit
2.10 Beginning of charging after full discharge
2.35 70-80% charged; gassing begins
2.65 Fully charged

# The following assumes 12 volt negative-grounded "automobile" batteries as
# found in most cars, light trucks, and vans in North America.

Liquid-electrolyte lead-acid batteries can be recharged at any rate
exceeding internal- and surface-discharge rates and which does not cause
"excessive" gassing (liberation of oxygen, hydrogen, and steam).

In NON-float service, there are several simple chargers:
* A single-rate constant-current charger limits its charge rate to about
7% of the battery's ampere-hour capacity. Thus, for a 100 Ah battery,
the charger would supply about 7 amperes and must be able to supply
voltages between 12.6 and 16 volts over the duration of the charge.
Charging is complete when the battery reached 2.65-2.70 volts per cell.

* A simple taper charger is a constant-voltage source set to 2.8 volts
per cell with a series ballast (typically a resistor, but a choke or
the internal resistance of the supply can be used) which limits the
output current to 7% of capacity when charging is started at 2.1 volts
per cell. Again, charging is complete at 2.7 volts per cell.

* Trickle-charging (supplying 0.5-1 milliampere per ampere-hour capacity)
of a fully-charged battery can be done to keep it charged. Trickle
charging should be discontinued when it has continued for at least 24
hours and the battery has reached 2.25 volts per cell. Typically,
trickle chargers are set to run perhaps once a week. Because of their
thin plate construction, automotive-type batteries will deteriorate if
trickle-charged for more than perhaps six months. (However, using
pulsating rectified AC or superimposing a small AC current on pure DC
charging current increases battery life by up to 30%. It is postulated
that this reduces gassing, leads to more porous lower-resistance
plates, and lessens the tendency to form dendrites during charging.)

In FLOAT service, where the battery is in parallel with the mains supply,
the supply voltage must be set to 2.15-2.20 volts per cell. This charges
the battery and avoids excessive gassing, but does not serve to "freshen"
the cells--there is not enough gassing activity to move electrolyte
around and clear the beginning of deposits from the surfaces of the
plates. It is recommended that batteries in float service occasionally
(perhaps once a month) be charged to 2.65 volts per cell to freshen and
equalize the charges. In large installations, this is done by switching
parts of the battery banks out of service in rotation; in smaller systems
that can tolerate the voltage excursion (about 16 volts!), it can be done
by simply boosting the output of the mains supply.

Charging inevitably leads to some water loss due to gassing: 100 ampere-
hours of a gassing charge (2.4 or more volts per cell) causes a water
loss of about 1.2 ounces. Hydrocap Corp (975 NW 95th Street, Miami FL,
303-696-2504) makes replacement filler caps ($5-10 each) containing a
catalytic material which recondenses emitted steam and recombines hydrogen
and oxygen gasses back into pure water which then dribbles back into the
cell, greatly reducing the required maintenance.

For further information:
Smith, George. "Storage Batteries, including Operation, Charging,
Maintenance, and Repair". ISBN 273-43448-9, TK2941.S57, 1978.

Aguf, I.A. and M.A. Dasoyan. "The Lead Accumulator" (translated from
Russian byu S. Sathyanarayana). Calcutta, 1968.

Longrigg, Paul. "Rapid Charging of Lead-Acid Batteries for Electric
Vehicle Propulsion and Solar Energy Storage." DOE/NTIS 1981.

Darden, Bill ) battery FAQ's found on the WWW.

--
--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)

Wow Myron,
That was the most comprehensive battery post I ever seen. I makes me want
to add (oh boy, some more drain) a circuit that will cut off the battery
when a small percentage down. Now... how will I do it?

west

wrote in message ...
During a power outage, which occurs frequently in Florida, I would like
to
use a battery to power some communication gear. Although the battery is
12v
....[snip]....

Although many have suggested you should use "deep cycle" (also called
"traction") batteries, be aware that the specifications for such batteries
are DIFFERENT in that they are rated to still be producing useable power
when their output voltage is somewhat LOWER than others. If your
equipment
poops out before that lower voltage is reached, you won't get all the
output you've paid for. (My TenTek 540, for example, starts FM'ing at
about 11.5 volts, so the remaining output from a deep-cycle is totally
unuseable.)

The following is abstracted from a 3 Oct. 1992 post to
rec.radio.amateur.misc by Brian Kantor :

1. Automotive starting: formulated with thin pasted plates and designed
to supply high peak currents for brief periods of time while cranking
an engine. Designed to be discharged to more than perhaps 75% of
capacity and to be recharged immediately after discharge. Typically
discharged-rated at a 20-hour rate.

2. Traction (e.g., deep-cycle batteries): made with thick pasted plates
and with very rugged separators between the plates to make the battery
more immune to physical shock and vibration and to reduce the chance
of failure due to dendritic growth during recharging. Sold for use in
electric forklifts, golf carts, marine trolling motors, and RV power.
Designed to be discharged nearly fully each day and recharged each
night. Typically discharged-rated at a 5-hour rate.

3. Stationary: made with thick solid plates. Designed to be used as
standby power, supplying minimal power and kept in a state of nearly-
full ("float") charge until needed. Can take deep discharge. Because
of the solid-plate structure, they are bigger and heavier, but their
lifetime is much longer (10 years is not unusual). Typically
discharged-rated at a 10-hour rate.

Each type of battery has a specified voltage at which it is considered
to be completely discharged; if discharge continues below this voltage,
battery life may be considerably shortened, and repeated abuse of this
nature can result in a battery which cannot practically be recharged.
Each battery manufacturer specifies this voltage; in general, the final
voltages for the three general types of batteries a
Automotive: 1.75 volts per cell
Traction: 1.70 volts per cell
Stationary: 1.85 volts per cell

A typical traction-type cell shows the following voltages:
2.12 Fully charged, open circuit, at rest with no charge
or discharge for at least 12 hours
2.00 As soon as load is applied (internal voltage drop)
1.70 Fully discharged, under load
1.99 Fully discharged, open circuit
2.10 Beginning of charging after full discharge
2.35 70-80% charged; gassing begins
2.65 Fully charged

# The following assumes 12 volt negative-grounded "automobile" batteries
as
# found in most cars, light trucks, and vans in North America.

Liquid-electrolyte lead-acid batteries can be recharged at any rate
exceeding internal- and surface-discharge rates and which does not cause
"excessive" gassing (liberation of oxygen, hydrogen, and steam).

In NON-float service, there are several simple chargers:
* A single-rate constant-current charger limits its charge rate to about
7% of the battery's ampere-hour capacity. Thus, for a 100 Ah battery,
the charger would supply about 7 amperes and must be able to supply
voltages between 12.6 and 16 volts over the duration of the charge.
Charging is complete when the battery reached 2.65-2.70 volts per cell.

* A simple taper charger is a constant-voltage source set to 2.8 volts
per cell with a series ballast (typically a resistor, but a choke or
the internal resistance of the supply can be used) which limits the
output current to 7% of capacity when charging is started at 2.1 volts
per cell. Again, charging is complete at 2.7 volts per cell.

* Trickle-charging (supplying 0.5-1 milliampere per ampere-hour capacity)
of a fully-charged battery can be done to keep it charged. Trickle
charging should be discontinued when it has continued for at least 24
hours and the battery has reached 2.25 volts per cell. Typically,
trickle chargers are set to run perhaps once a week. Because of their
thin plate construction, automotive-type batteries will deteriorate if
trickle-charged for more than perhaps six months. (However, using
pulsating rectified AC or superimposing a small AC current on pure DC
charging current increases battery life by up to 30%. It is postulated
that this reduces gassing, leads to more porous lower-resistance
plates, and lessens the tendency to form dendrites during charging.)

In FLOAT service, where the battery is in parallel with the mains supply,
the supply voltage must be set to 2.15-2.20 volts per cell. This charges
the battery and avoids excessive gassing, but does not serve to "freshen"
the cells--there is not enough gassing activity to move electrolyte
around and clear the beginning of deposits from the surfaces of the
plates. It is recommended that batteries in float service occasionally
(perhaps once a month) be charged to 2.65 volts per cell to freshen and
equalize the charges. In large installations, this is done by switching
parts of the battery banks out of service in rotation; in smaller systems
that can tolerate the voltage excursion (about 16 volts!), it can be done
by simply boosting the output of the mains supply.

Charging inevitably leads to some water loss due to gassing: 100 ampere-
hours of a gassing charge (2.4 or more volts per cell) causes a water
loss of about 1.2 ounces. Hydrocap Corp (975 NW 95th Street, Miami FL,
303-696-2504) makes replacement filler caps ($5-10 each) containing a
catalytic material which recondenses emitted steam and recombines hydrogen
and oxygen gasses back into pure water which then dribbles back into the
cell, greatly reducing the required maintenance.

For further information:
Smith, George. "Storage Batteries, including Operation, Charging,
Maintenance, and Repair". ISBN 273-43448-9, TK2941.S57, 1978.

Aguf, I.A. and M.A. Dasoyan. "The Lead Accumulator" (translated from
Russian byu S. Sathyanarayana). Calcutta, 1968.

Longrigg, Paul. "Rapid Charging of Lead-Acid Batteries for Electric
Vehicle Propulsion and Solar Energy Storage." DOE/NTIS 1981.

Darden, Bill ) battery FAQ's found on the WWW.

--
--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)

That was the most comprehensive battery post I ever seen. I makes me want
to add (oh boy, some more drain) a circuit that will cut off the battery
when a small percentage down. Now... how will I do it?

Thanks, but all I did was archive and repost! (Although I did incorporate
it in a much-bigger battery "article" I've been accumulating from many
sources [including one video from, IIRC, the Ford Motor Company on the
batteries they put in Ford vehicles] for my own use and for sharing at
the local ham club.)

If **I** had to do that, I'd use a plain ol' 555 "timer" IC as a threshold
voltage detector and use it to drive relay(s) to do the cut-off, but more-
modern designers would use a little more circuitry to drive an FET.

--Myron.
--
--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)