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9
TECH
tip
by BLUE SEA SYSTEMS
BATTERIES ARE THE HEART OF THE ELECTRICAL SYSTEM.
Batteries are often the largest single expense in the electrical system
and are sensitive to failure and shortened life if not charged properly.
Modern battery chemistries – Gel, AGM, TPPL, Lithium Ion, and Flooded
Lead Acid (FLA) – require adherence to manufacturer’s charging
recommendations. Following these recommendations requires a battery
charger which is both rugged and sophisticated.
All battery manufacturers agree precise control of these
variables is critical:
· Voltage
· Time
· Temperature
Batteries may perform poorly and fail prematurely due to a charger's
failure to properly manage voltage, time, and temperature. A well
designed battery charger will allow these variables to be correctly set
for the requirements of each battery type and will manage them
properly in the charging process.
Five critical features that enable batteries to be charged
according to manufacturers' recommendations:
1. User Defined Charge Profiles (Voltages)
For setting the charger’s voltages to match the battery
manufacturer’s recommendations.
2. User Defined Absorption Stage Values
For determining when the charger should exit the Absorption Stage
in order to prevent overcharging.
3. Charge Coordination
To ensure Charging Relays (ACR) are not operating in conflict with
the charger. On shore power with a three bank charger, ACRs are
not required as they are when away from the dock and one alternator
must charge 3 battery banks.
4. PreFloat
™
– a Blue Sea Systems P12 exclusive (Patent Pending)
Allows each battery on a P12 Battery Charger to exit the Absorption
Stage when it is ready. Conventional chargers hold all three batteries
in Absorption Stage until all three are ready to exit. This subjects 1
or 2 batteries to higher voltages than necessary while waiting for the
3rd battery to complete the Absorption Stage.
5. Battery Temperature Compensation
For adjusting charging voltage up (for colder batteries) or down
(for warmer batteries) as recommended by almost all battery
manufacturers for proper battery performance. Temperature must be
determined by a sensor on the battery . Sensing the temperature
of the charger itself, as is done on some models, is useless for
battery voltage compensation.
These 5 critical functions, are important features of a battery charger
and rely on voltage, time, and temperature control to achieve Battery
Manufacturers' recommendations.
P
O W E R
C
O N V E R S I O N
ELECTRICAL PRESSURE
AIR PRESSURE
BULK
Increasing air
pressure
Steady
electrical
pressure
High air volume
Steady amperage volume
Steady air
pressure
Increasing
electrical
pressure
Decreasing air volume
High amperage volume
Low
electrical
pressure
Small volume
(to offset leakage)
Small amperage volume
(to offset self discharge)
ABSORPTION
FLOAT
Battery Charging Explained
While not a perfect analogy, it is useful to think of voltage as
pressure. Just as applying too much pressure to a balloon
for too much time can ruin a balloon, applying too much
electrical pressure (voltage) ruins batteries.
Batteries are charged by applying a higher voltage
(electrical pressure) than a battery normally has. That forces
a chemical reaction in the battery that stores energy in
chemical form that is later turned into electrical energy
when power is required.
For this process to occur effectively, charging voltage must
be applied for the appropriate time and must be adjusted
up (for cold batteries) or down (for warm batteries).
A charger’s failure to properly manage these three variables
- VOLTAGE, TIME, and TEMPERATURE, results in batteries that
are chronically undercharged or overcharged. This delivers
less energy for the boater’s safety and comfort and results
in expensive premature failure of batteries.