How to pick a
Car Battery Charger.
Here are some simple steps to aide you in
selecting the correct charger for your needs.
Step 1
Determine what type of battery or batteries you will be
charging. Maintenance Free, Wet Cell (flooded), AGM (absorbed
glass mat), Gel Cell or VRLA (valve regulated lead acid). In
most cases one charger will work for all except for Gel Cell.
However, some of our Gel Cell chargers will work well with the
other battery types.
Step 2
What size is your battery? What that means is not physical size,
but how many Amp hours does your battery store. As an example, a
typical full size auto battery is about 50 amp hours, and it
would take a 10 amp charger approximately 6 hours to recharge it
if the battery were completely dead. Another example, a Marine
Deep Cycle Battery may be rated at 100 amp hours, so it would
take a 10 amp charger about 11 hours to recharge a dead battery
to near 100% full charge, from a completely dead condition. As a
rule of thumb take the amp hour rating of the battery and divide
by the charger rating (amps) and then add about 10% for the
extra time to totally top off the battery, This will give you
total charge time.
Some folks need to size the charge for quick recharge, therefore
requiring more amps from their charger. Others are not in a
hurry and may select a smaller charger. The most important thing
here is to make sure you have enough charger power to do the job
you require in the time you allocate.
Step 3
Know your desired outcome. Some folks require a charger to keep
their motorcycle, classic car, or aircraft battery charged
during the off season. In such a case a simple low current
charger will work fine. Others require a fast and powerful
charger to quickly restore a trolling motor battery or a wheel
chair battery set.
There are certainly other factors in selecting a battery
charger, and it would be difficult to cover them all, but here a
few. Input voltage, generally for use foreign countries.
Exposure to elements, i.e. would you benefit from a waterproof
charger? Perhaps you will need a charger that doubles as a power
supply for a RV or some other application. Often people will
need to charge multiple batteries simultaneously, so multiple
bank chargers may be needed.
Following is a list of definitions of different types of
batteries and their uses.
Flooded: This is the traditional engine start
and traction style battery. The liquid electrolyte is free to
move in the cell compartment. The user has access to the
individual cells and can add distilled water as the battery
dries out. Popular uses are engine starting and deep cycle
designs.
Typical absorption voltage range 14.2 to 14.5 volts, typical
float voltage range 13.2 to 13.5 volts.
Sealed: This term can refer to a number of different
constructions, including only a slight modification to the
flooded style. In that case, even though the user does not
have access to the cell compartments, the internal structure
is still basically the same as a flooded battery. The only
difference is that the manufacturer has ensured that a
sufficient amount of acid is the battery to sustain the
chemical reaction under normal use throughout the battery
warranty period. Other types of lead acid batteries are also
sealed, as explained below. Very popular uses are engine start
and limited starting/deep cycle applications.
Typical absorption voltage range 14.2 to 14.5 volts, typical
float voltage range 13.2 to 13.5 volts.
VRLA: This stands for Valve Regulated Lead Acid battery. This
is also a sealed battery. The valve regulating mechanism
allows for a safe escape of hydrogen and oxygen gasses during
charging.
Typical absorption voltage range 14.2 to 14.5 volts, typical
float voltage range 13.2 to 13.5 volts.
AGM: The Absorbed Glass Matt construction allows the
electrolyte to be suspended in close proximity with the plate
s active material. In theory, this enhances both the discharge
and recharge efficiency. Actually, the AGM batteries are a
variant of Sealed VRLA batteries. Popular usage high
performance engine starting, power sports, deep cycle, solar
and storage battery.
Typical absorption voltage range 14.4 to 15.0 volts, typical
float voltage range 13.2 to 13.8 volts.
GEL: The gel cell is similar to the AGM style because the
electrolyte is suspended, but different because technically
the AGM battery is still considered to be a wet cell. The
electrolyte in a GEL cell has a silica additive that causes it
to set up or stiffen. The recharge voltages on this type of
cell are lower than the other styles of lead acid battery.
This is probably the most sensitive cell in terms of adverse
reactions to over-voltage charging. Gel Batteries are best
used in VERY DEEP cycle application and may last a bit longer
in hot weather applications. If the incorrect battery charger
is used on a Gel Cell battery poor performance and premature
failure is certain.
Typical absorption voltage range 14.0 to 14.2 volts, typical
float voltage range 13.5 to 13.8 volts.
Note about Gel Batteries: It is very common for individuals to
use the term GEL Cell when referring to sealed, maintenance
free batteries, much like one would use Kleenex when referring
to facial tissue or "Xerox machine" when referring to a copy
machine. Be very careful when specifying a charger. More often
than not, what someone thinks to be a Gel Cell is really a
sealed, maintenance free, GRT, probably AGM style battery.
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