are three distinct types of lead acid batteries manufactured and
any one type can be designed and built for either starting or deep
cycle applications. These types are flooded acid, gelled acid, and
Advanced AGM (Absorbed Glass Mat). There are various quality
levels available in each type. Price is dependent upon the
perceived quality as well as the product design, processing, and
manufacturing costs. This includes the amount of lead, methods of
pasting and curing the plates, degree and type of inter-plate
insulation, quality of the case, and the sealing method used.
Generally, high quality means higher cost.
types of lead acid batteries are flooded cell types. These have
been around for decades. The liquid sulfuric acid solution in
these batteries has destroyed more than a few sets of clothes and
pieces of RV gear. They generate and vent dangerous explosive
gases, acid "mist" during charging, corrode their
terminals, often-acid damage surrounding surfaces, and require
regular watering. They are the least expensive type and therefore
are the choice of many RV owners.
types of batteries are gelled acid (Electrolyte) designs. They
were introduced to American RVs by Sonnenschein of Germany over 30
years ago and widely touted for their increased efficiency and
designed safety features. Their acid is immobilized by adding
"fumed" silica to the sulfuric acid solution and then
sealing the battery. They internally recombine most of the gases
(hydrogen and oxygen) generated during charging and are
maintenance free. Gelled electrolyte battery designs are generally
quite old and few engineering options are left to improve them.
Gel electrolyte is highly viscous and during charge and discharge
the gel can develop voids or cracks. These impede acid flow and
result in the loss of battery capacity. Also the gelled mixture
can liquefy upon charge due to the shearing action of gassing
(this property is called thixotropic"). After termination of
charge, it can take an hour
for the acid to gel again. During this time liquid is moving and
the battery can leak if any opening has developed. Last, gel
batteries may store hydrogen gas that has not recombined. When
overcharging causes a gel battery's vent caps to open, explosive
gasses may be vented into the battery compartment. This vented
hydrogen has caused a number of "fast failures" or
and most advanced battery technology is Advanced AGM, which was
developed to provide increased safety, efficiency, and durability
over all existing battery types. In Advanced AGM batteries the
acid is absorbed into a very fine glass mat that is never free to
slosh around. Secondly, since the plates are kept only
"moist" with electrolyte, gas recombination is more
efficient. (99% AGM). Thirdly, since the AGM material has an
extremely low electrical resistance, the battery delivers much
higher power and efficiency than the other two types. Last,
Advanced AGM batteries offer exceptional life cycles.
gas technology was brought to state-of the-art status at Concorde
Battery Corporation, one of the worlds leading suppliers of sealed
aviation batteries. The first AGM, "Air Worthy"
batteries were delivered to the U.S. Military in 1985 and today
are used on the Stealth Bomber, F- 18 fighter jet, and in other
demanding military applications. The heavier "fat plate"
"Lifelines" were introduced in 1989. Today,
"Lifelines" are the most advanced recreational vehicle
batteries manufactured in the world. They are subject to the same
high standards of design and manufacture as required by FAA and
Military Specifications. Additionally, "Lifeline" is the
only Advanced AGM product available in standard battery
configuration and sizes. They are standard equipment on many U.S.
Navy crafts, fine yachts built by Pacific Seacraft, Island Packet,
and Hinckley Company to mention three, and quality coaches built
by such companies as Vision Coach, Royal Coach and Vantare Coach.
graphs and comparison charts are not necessary to compare the
three battery types. Consider:
Batteries can be dangerous. They store a tremendous amount of
energy, create explosive gas during charge and discharge, and
contain dangerous chemicals. Some designs and construction
techniques are safer than others are. Both Gel and Lifeline
Advanced AGM are sealed batteries that use recombinant gas
technology. Lifeline Advanced AGM is more efficient in the AGM
process and completes its gas recombination near the plates. In
fact, they are the only RV batteries to pass the rigid
MILITARY-SPECIFICATION for non-gassing even during severe
overcharge. A recent Coast Guard Advisory warned all users of Gel
recombinant gas batteries to install automatic temperature
compensated voltage regulators to prevent explosions associated
with their overcharging. Flooded batteries will spew acid, will
definitely spill and leak if tipped over, and they generate
dangerous and noxious explosive gases. "Lifeline"
Advanced AGM batteries are best at protecting both equipment and
All batteries die. The number of cycles it takes to kill them is a
function of the type and quality of the battery. When cycled at
between 25 to 40 percent depth of discharge (recommended deep
cycle use) "Lifeline "Advanced AGM batteries will
normally easily outlast the other two types.
Some battery designs are simply more durable than others are. They
are more forgiving in abusive conditions, i.e.; they are less
susceptible to vibration and shock damage, over charging, and
deeper discharge damage. Gel acid batteries are the most likely to
suffer irreversible damage from overcharging. Flooded acid
batteries are the most likely to suffer from internal shorting and
vibration damage. Lifeline Advanced AGM batteries are more durable
and can withstand severe vibration, shocks, and fast charging.
This comparison is critical. Internal resistance of a battery
denotes its overall charge/discharge efficiency, its ability to
deliver high cranking currents without significant drops in
voltage, and is a measure of how well it has been designed and
manufactured. Internal resistance in NiCad batteries is
approximately 40%, i.e., you need to charge a NiCad 140% of its
rated capacity to have it fully charged. For flooded wet
batteries, internal resistance can be as high as 26%, which is the
charging current lost to gassing, or breaking up of water. Gel
acid batteries are better at only approximately 16% internal
resistance and require only roughly 116% of rated capacity to be
fully charged. Lifeline Advanced AGM has the lowest internal
resistance of any battery manufactured only 2 percent. This allows
Lifelines to be charged much faster if needed and also to deliver
higher power when required. Owners using high output alternators,
operating inverter banks, or relying on solar panels can benefit
significantly when using Lifeline Advanced AGM batteries with
their equipment. "Lifelines" are more efficient!!
Measurements: Most buyers like to make comparisons by using
various specifications and measurements. A few common comparison
criteria are Cold Cranking Amps or CCA, which is a clear indicator
of a battery's ability to start an engine. Reserve Minutes depict
a battery's ability to deliver current at steady rates from a
fully charged condition down to 10.5 volts and are expressed in
minutes, i.e., reserve minutes at 25 amp discharge. Life Cycles
are used to measure longevity or how many times a battery can be
discharged in its life time at set levels. We compared one of each
battery type against various measurements and standards using data
published data, as it was available. In our comparison we selected
only top quality products; Advanced AGM Lifeline, Sea Gel and Sea
Volt. The Group 27 size comparison figures are printed below. An
independent comparison of GRP-27 batteries was completed by
Cruising World Magazine in June of 1997. Advanced AGM won this
||For more information see www.lifelinebatteries.com
If you look at any battery, you'll notice that it has two terminals. One
terminal is marked (+), or positive, while the other is marked (-), or negative.
In an AA, C or D cell (normal flashlight batteries), the ends of the battery are
the terminals. In a large car battery, there are two heavy lead posts that act
as the terminals.
Electrons collect on the negative terminal of the
battery. If you connect a wire between the negative and positive terminals, the
electrons will flow from the negative to the positive terminal as fast as they
can (and wear out the battery very quickly -- this also tends to be dangerous,
especially with large batteries, so it is not something you want to be doing).
Normally, you connect some type of load to the battery using the wire.
The load might be something like a light bulb, a motor or an electronic circuit
like a radio.
Inside the battery itself, a chemical reaction produces
the electrons. The speed of electron production by this chemical reaction (the
battery's internal resistance) controls how many electrons can flow
between the terminals. Electrons flow from the battery into a wire, and must
travel from the negative to the positive terminal for the chemical reaction to
take place. That is why a battery can sit on a shelf for a year and still have
plenty of power -- unless electrons are flowing from the negative to the
positive terminal, the chemical reaction does not take place. Once you connect a
wire, the reaction starts.
Probably the simplest battery you can create is called a zinc/carbon battery.
By understanding the chemical reaction going on inside this battery, you can
understand how batteries work in general.
Imagine that you have a jar of sulfuric acid (H2SO4).
Stick a zinc rod in it, and the acid will immediately start to eat away at the
zinc. You will see hydrogen gas bubbles forming on the zinc, and the rod and
acid will start to heat up. Here's what is happening:
If you now stick a carbon rod in the acid, the acid does
nothing to it. But if you connect a wire between the zinc rod and the carbon
rod, two things change:
- The acid molecules break up into three ions: two H+
ions and one SO4-- ion.
- The zinc atoms on the surface of the zinc rod lose two
electrons (2e-) to become Zn++
- The Zn++ ions combine
with the SO4-- ion to create ZnSO4,
which dissolves in the acid.
- The electrons from the zinc atoms combine with the
hydrogen ions in the acid to create H2 molecules
(hydrogen gas). We see the hydrogen gas as bubbles forming on the zinc rod.
The electrons go to the trouble to move to the carbon rod
because they find it easier to combine with hydrogen there. There is a
characteristic voltage in the cell of 0.76 volts. Eventually, the zinc rod
dissolves completely or the hydrogen ions in the acid get used up and the
- The electrons flow through the wire and combine with
hydrogen on the carbon rod, so hydrogen gas begins bubbling off the
- There is less heat. You can power a light bulb
or similar load using the electrons flowing through the wire, and you can
measure a voltage and current in the wire. Some of the heat energy is turned
into electron motion.
In any battery, the same sort of electrochemical reaction
occurs so that electrons move from one pole to the other. The actual metals and
electrolytes used control the voltage of the battery -- each different
reaction has a characteristic voltage. For example, here's what happens in one
cell of a car's lead-acid battery:
A lead-acid battery has a nice feature -- the reaction is
completely reversible. If you apply current to the battery at the right
voltage, lead and lead dioxide form again on the plates so you can reuse the
battery over and over. In a zinc-carbon battery, there is no easy way to reverse
the reaction because there is no easy way to get hydrogen gas back into the
- The cell has one plate made of lead and another plate
made of lead dioxide, with a strong sulfuric acid electrolyte that the
plates are immersed in.
- Lead combines with SO4 to create
PbSO4 plus one electron.
- Lead dioxide, hydrogen ions and SO4
ions, plus electrons from the lead plate, create PbSO4
and water on the lead dioxide plate.
- As the battery discharges, both plates build up PbSO4
(lead sulfate), and water builds up in the acid. The characteristic voltage
is about 2 volts per cell, so by combining six cells you get a 12-volt
Modern batteries use a variety of chemicals to power their
reactions. Typical battery chemistries include:
- Zinc-carbon battery - Also known as a standard
carbon battery, zinc-carbon chemistry is used in all inexpensive AA, C
and D dry-cell batteries. The electrodes are zinc and carbon, with an acidic
paste between them that serves as the electrolyte.
- Alkaline battery - Used in common Duracell and
Energizer batteries, the electrodes are zinc and manganese-oxide, with an
- Lithium photo battery - Lithium, lithium-iodide
and lead-iodide are used in cameras because of their ability to supply power
- Lead-acid battery - Used in automobiles, the
electrodes are made of lead and lead-oxide with a strong acidic electrolyte
- Nickel-cadmium battery - The electrodes are
nickel-hydroxide and cadmium, with potassium-hydroxide as the electrolyte
- Nickel-metal hydride battery - This battery is
rapidly replacing nickel-cadmium because it does not suffer from the memory
effect that nickel-cadmiums do (rechargeable).
- Lithium-ion battery - With a very good
power-to-weight ratio, this is often found in high-end laptop computers and
cell phones (rechargeable).
- Zinc-air battery - This battery is lightweight
- Zinc-mercury oxide battery - This is often used
- Silver-zinc battery - This is used in
aeronautical applications because the power-to-weight ratio is good.
- Metal-chloride battery - This is used in
Also see the following on howstuffworks.com
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There is a ritual debate on this topic each year. The
concensus seems to be that (1) It's OK to store a battery on a cement floor, but
if you stick it on an old piece of plywood, any drips or spills will be easier
to clean up, so perhaps the old wives' tale has some value, (2) storing a
battery cold in the winter, provided it is fully charged, is an OK thing to do.
The rate of discharge is reduced by the cold environment, so less frequent
recharging is called for.
Here is an article from Finn Stafsnes, which seems to have
some hard data (fs):
The content is taken from a booklet provided by norwegian
battery manufacturer (Anker-Sonnak).
I have done some linear interpolation between tabulated
values. Therefore minor errors due to non-linear effects may be present. I can
only hope that I have not done big errors in my calculations.
of...............@ 25 C, 77 F........point.........@ freez.temp
charge..........kilograms/litre.....deg C, F....kilograms/litre
Full (100.75 .50 .25
weak.................1.160..........-17, + 1..........1.189 0 0 If
it is impractical to measure the spec. gravity an approximate formula is given
based upon voltage measurment:
Spec.gravity (@ 25 C) = ((Voltage of battery)/(no of
cells)) - 0.84 (kilogr./lit.)
The voltage should be measured after the battery has been
disconnected (left to rest) for at least 6 hours.
A discharged battery will gradually be distroyed if stored
in a low state of charge condition due to crystal growth of PbSO4, even if it
Self discharge rate is halved for every 10 deg C (18 F)
the storage temperature is reduced.
Conclusion: Keep the battery well charged all the time. If
you don't want to recharge during the winter, store the battery cold.
And here is a mini-FAQ written by Alan Yelvington:
The efficiency of batteries varies with time, temperature,
and state of charge.
Batteries self-discarge over time. Lead-calcium (die-hard)
discharge faster that straight lead-acid. Their advantage is that they typically
do not need to have the water replaced.
Temperature will kill a battery over time. If a battery
gets too hot, its self-discharge rate goes up. If the battery gets to cold, the
reaction that produces electricity gets slowed down and the full capacity cannot
The state of charge limits efficiency because of the
reactions in the battery. If a battery is left dead for too long (this means
you), the internal plates will start to accumulate lead-sulphate on them. This
insulates that portion of the plate so that in can no longer contribue to the
output of the battery. It takes extra power in to remove the sulphation that
cannot be recouped. (EDTA will chemically remove the sulphate....)
A typical battery in good condition will return 90 to
95put into it under these conditions:
DO NOT recharge at a rate of more that one tenth its
capacity. eg. A 220 amp-hour battery should not be recharged at more than 22
amps. The excess current will generate waste heat and form lead-sulphite. The
lead-sulphite is worse than the sulphate because it cannot be removed.
DO NOT discharge a battery beyond 50 DO NOT over charge
the battery. (Lead Sulphite problem again.)
DO NOT discharge the battery faster than one tenth of its
capacity. That is, don't draw more than 22 amps from a 220 amp-hour battery.
You'll just make waste heat that cannot do work.
DO use the battery and not just leave it dormant all the
time. If you must have a battery for infrequent use, NiCd or gelcells are much
better and are another story altogether. (ay)
Another reader pointed me towards a nice solar panel
charge controller the November, 1993 issue of ``73'' magazine. It's used by a
guy with 200 WATTS of solar panels on his roof.
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