A critical factor in the proper use of a rechargeable battery is charging. Inadequate and/or improper charging is probably the single most dominant cause of premature failure of rechargeable lead acid batteries, and it is entirely appropriate that some time and space be devoted to this very important issue.

A good rule of thumb to remember is : for every ampere-hour discharged, one must replace 1.05 to 1.10 ampere-hours to fully recharge the battery. This rule is particularly critical when the battery is deep cycled repeatedly.

(A)Selecting a charger’s voltage output
The charger selection process is primarily determined by the battery system voltage, as illustrated in Table II. Using battery chargers that have output voltages outside these ranges may result in not achieving maximum battery cycle life.

IMPORTANT NOTE

The ODYSSEY® battery must not be left connected to a quick charge output voltage for more than 24 hours. Should this be a possibility, use a charger that automatically switches to a standby charge voltage after 24 hours.

(B) Selecting a charger’s current output
Maximum current

The pure lead technology of the ODYSSEY® battery does not require a limit on the maximum output current as long as the charger’s output voltage is within the limits described in Table II. Remember that when a fixed voltage is applied to the battery, the output (charge) current will automatically drop as the battery charges up. Even inrush currents as high as four times the battery capacity do not pose a danger to a healthy ODYSSEY® battery, provided constant voltage charging is used.

Minimum current

The minimum acceptable charger current depends on how the battery is used. For repeated deep discharges of the ODYSSEY® the minimum inrush current should not be less than the rated capacity of the batteries. For example, if a PC545 battery, rated at 13Ah, is being used, the inrush must not be less than about 13A.

Rapid charging of ODYSSEY® batteries

The pure lead-tin technology of ODYSSEY® batteries lends itself extremely well to rapid charging. The graph below shows the exceptional fast charge characteristics of the ODYSSEY® when it is charged at a constant 14.7V, at three levels of inrush current. This voltage level of 14.7V is very similar to the output of a modern automotive alternator. Table III following the graph illustrates the capacity returned as a function of the magnitude of the inrush current.

Rapid charging ODYSSEY® battery from 100% DOD

The table above shows that with a 0.8C₁₀ inrush current or an inrush current that is 80% of the battery capacity, a 100% discharged battery can have 80% of its capacity returned in 57 minutes; doubling the inrush to 1.6C₁₀ cuts the time taken to reach the same threshold capacity to only 28 minutes.

Sealed Rechargeable Drycell^TM - Deep Cycle Batteries