Battery Types and Comparisons - VRLA vs GEL vs AGM
Flooded Valve Regulated Lead Acid Batteries (VRLA)
Gelled Electrolyte Lead Acid Battery (GEL)
Advanced Glass Mat Battery Construction (AGM)
Today, there 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 the
product design, processing, and manufacturing costs. This includes the amount of lead, purity of that 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.
Flooded Valve Regulated Lead Acid Batteries (VRLAB)
Flooded or vented lead acid battery The oldest types of lead acid batteries are flooded cell types. These have
been around for decades and evolved from wooden box models into the plastic valve regulated models on the
market today. The electrolyte in these batteries is liquid sulfuric acid solution. This stuff is pretty corrosive and
has destroyed more than a few sets of clothes and pieces of RV gear. VRLA flooded batteries generate and
vent dangerous explosive gases through their valve regulation and must be vented to the outside world. These
batteries also acid "mist" during charging and discharging. This leads to the corrosion of their terminals, and
often-acid damage to surrounding surfaces. (look at your car battery for an example) VRLA Flooded batteries
must be installed upright, can leak that acid, and require regular watering. Should they fail to be watered, they
will not perform to spec. That all being said, they are also the least expensive type and therefore are the choice
of many renewable and RV owners.
Gelled Electrolyte Lead Acid Battery (GEL)
The next types of batteries are gelled acid (Electrolyte) designs. They were introduced to American RVs and
Marine enthusiasts by Sonnenschein of Germany over 30 years ago. Their introduction and widespread
adoption was due to 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 due to this. Gelled
Electrolyte Battery 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 (pockets) or cracks when the amperage is increased. These pockets 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 battery explosions.
Advanced Glass Mat Valve Regulated Sealed Lead Acid Battery Construction (AGM or VRSLAB )
# The latest and most advanced battery technology is Advanced AGM VRSLAB batteries (Advanced Glass Mat,
Valve Regulated Sealed Lead Acid Batteries), which were 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 and held in place by capillary action. This construction technique, in coordination with double wall
design, and sealing has many advantages. Absorbed Glass Mat Battery There is never a way to make the acid
free to slosh around. This allows for installation at any angle, and has lead to DOT exemption for USPS, UPS,
and Fedex.(department of transportation)
# By keeping the "moist" with electrolyte, gas recombination is more efficient (99% AGM). This leads to fewer
incidents of exploding batteries than either of the 2 types above.
# Since the AGM material has an extremely low electrical resistance, the battery delivers much higher power
and efficiency than other battery types.
# Since the AGM material has an extremely low electrical resistance it can crank more amps in and out without
cost to life. AGM batteries are rated at 100% their capacity for charging and discharging amperage. (compared
with roughly 35% for gel and flooded models)
# Less acid means a lighter battery
# Advanced AGM batteries offer exceptional life cycles by far better than either gel or flooded batteries. This
leads to longer battery life and increases your ROI
A few more things to take into consideration - purity of the lead, and the construction of the battery.
Pure Lead: (99.999% pure or "triple 9") The manufacturers we choose to list only use this quality of materials in
their products. Quite simply, recylced lead in batteries is not as chemically able to absorb charge. The pure
lead can be as much as 20% more likely to chemically sustain a charge. *Please recycle your battereis.
Recycled lead is great for many other applications and is best for the environment.
Hand Soldered Cells: Lead is an extremely porous metal, and this leads to inconsistencies in the soldering of 2
lead parts. Hand soldering is by far the most effective, and time honored practice to join this metal. In the last
few years, several companies have pioneered machines for soldering designed to vary each and every weld to
meet spec. These systems are becoming increasingly more accurate and are becoming acceptable for low
vibration and stationary installations. Both Sun Xtender and Lifeline batteries are Hand Soldered here in the
United States and quality inspected prior to charging, and delivery.
Rolls - Surrette Batteries are soldered by machine, but are rigorously tested out as the highest quality flooded
batteries available.
Dual Wall Construction:
Oil Tankers are required to have two hulls to keep oil out of the ocean. Batteries should have 2 walls to keep
the acid out of living room. In addition, the space between the hulls should be used to recombine the gasses
produced during electrolysis to reduce the explosive nature of the installation. Sun Xtender and Lifeline
Batteries both employ this double wall design leading to a further margin of safety and durability.
Flooded Valve Regulated Lead Acid Batteries (VRLA)
Gelled Electrolyte Lead Acid Battery (GEL)
Advanced Glass Mat Battery Construction (AGM)
Today, there 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 the
product design, processing, and manufacturing costs. This includes the amount of lead, purity of that 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.
Flooded Valve Regulated Lead Acid Batteries (VRLAB)
Flooded or vented lead acid battery The oldest types of lead acid batteries are flooded cell types. These have
been around for decades and evolved from wooden box models into the plastic valve regulated models on the
market today. The electrolyte in these batteries is liquid sulfuric acid solution. This stuff is pretty corrosive and
has destroyed more than a few sets of clothes and pieces of RV gear. VRLA flooded batteries generate and
vent dangerous explosive gases through their valve regulation and must be vented to the outside world. These
batteries also acid "mist" during charging and discharging. This leads to the corrosion of their terminals, and
often-acid damage to surrounding surfaces. (look at your car battery for an example) VRLA Flooded batteries
must be installed upright, can leak that acid, and require regular watering. Should they fail to be watered, they
will not perform to spec. That all being said, they are also the least expensive type and therefore are the choice
of many renewable and RV owners.
Gelled Electrolyte Lead Acid Battery (GEL)
The next types of batteries are gelled acid (Electrolyte) designs. They were introduced to American RVs and
Marine enthusiasts by Sonnenschein of Germany over 30 years ago. Their introduction and widespread
adoption was due to 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 due to this. Gelled
Electrolyte Battery 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 (pockets) or cracks when the amperage is increased. These pockets 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 battery explosions.
Advanced Glass Mat Valve Regulated Sealed Lead Acid Battery Construction (AGM or VRSLAB )
# The latest and most advanced battery technology is Advanced AGM VRSLAB batteries (Advanced Glass Mat,
Valve Regulated Sealed Lead Acid Batteries), which were 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 and held in place by capillary action. This construction technique, in coordination with double wall
design, and sealing has many advantages. Absorbed Glass Mat Battery There is never a way to make the acid
free to slosh around. This allows for installation at any angle, and has lead to DOT exemption for USPS, UPS,
and Fedex.(department of transportation)
# By keeping the "moist" with electrolyte, gas recombination is more efficient (99% AGM). This leads to fewer
incidents of exploding batteries than either of the 2 types above.
# Since the AGM material has an extremely low electrical resistance, the battery delivers much higher power
and efficiency than other battery types.
# Since the AGM material has an extremely low electrical resistance it can crank more amps in and out without
cost to life. AGM batteries are rated at 100% their capacity for charging and discharging amperage. (compared
with roughly 35% for gel and flooded models)
# Less acid means a lighter battery
# Advanced AGM batteries offer exceptional life cycles by far better than either gel or flooded batteries. This
leads to longer battery life and increases your ROI
A few more things to take into consideration - purity of the lead, and the construction of the battery.
Pure Lead: (99.999% pure or "triple 9") The manufacturers we choose to list only use this quality of materials in
their products. Quite simply, recylced lead in batteries is not as chemically able to absorb charge. The pure
lead can be as much as 20% more likely to chemically sustain a charge. *Please recycle your battereis.
Recycled lead is great for many other applications and is best for the environment.
Hand Soldered Cells: Lead is an extremely porous metal, and this leads to inconsistencies in the soldering of 2
lead parts. Hand soldering is by far the most effective, and time honored practice to join this metal. In the last
few years, several companies have pioneered machines for soldering designed to vary each and every weld to
meet spec. These systems are becoming increasingly more accurate and are becoming acceptable for low
vibration and stationary installations. Both Sun Xtender and Lifeline batteries are Hand Soldered here in the
United States and quality inspected prior to charging, and delivery.
Rolls - Surrette Batteries are soldered by machine, but are rigorously tested out as the highest quality flooded
batteries available.
Dual Wall Construction:
Oil Tankers are required to have two hulls to keep oil out of the ocean. Batteries should have 2 walls to keep
the acid out of living room. In addition, the space between the hulls should be used to recombine the gasses
produced during electrolysis to reduce the explosive nature of the installation. Sun Xtender and Lifeline
Batteries both employ this double wall design leading to a further margin of safety and durability.
Battery Types
Parallel Connection
Batteries are connected in parallel when all the positive terminals of a
group of batteries are connected and, them all the negative terminals
are connected.
In Parallel, batteries have the voltage of a single battery and an
amp/hour rating equal to the sum of the individual batteries.
Batteries are connected in parallel when all the positive terminals of a
group of batteries are connected and, them all the negative terminals
are connected.
In Parallel, batteries have the voltage of a single battery and an
amp/hour rating equal to the sum of the individual batteries.
Solar Batteries Connections Information
Serial Connection
When Batteries are connected with the plus terminal of one to the
minus of the other one next, they are in series. A group of batteries in
series has the amp/hour rating of a single battery but a voltage equal
to the sum of individual batteries voltages.
When Batteries are connected with the plus terminal of one to the
minus of the other one next, they are in series. A group of batteries in
series has the amp/hour rating of a single battery but a voltage equal
to the sum of individual batteries voltages.
Battery Types