Lifeline Technical Manual

Document No. 6-0101 Rev. D Page 21 of 38
5.6 Deep Discharge Recovery
Batteries that have been in storage for long periods of time without boost charging, or have
been kept deeply discharged for an extended time, may need to be charged at constant current
instead of constant voltage to restore capacity. The following procedure is effective if the
batteries are not too badly sulfated.
WARNING: This procedure should only be done in a well ventilated area because a
significant amount of hydrogen gases may be released from the battery.
1. Stabilize the battery at 68-86°F (20-30°C) for at least 24 hours prior to testing.
2. Charge at a constant current of 5% of rated (20 hour) capacity until the voltage reaches
15.6 volts (7.8 volts for a 6 volt battery), then continue charging at this rate for an
additional 4 hours. Note that the charging voltage may get as high as 18.0 volts (9.0
volts for a 6 volt battery), so the power supply must be capable of outputting this level to
maintain constant current. This constant current charge may take 16 to 20 hours.
CAUTION: If the battery becomes hot (above 130°F/55°C) during this charge, stop
the current and allow the battery to cool to room temperature before continuing
the charge.
3. Perform a capacity test as described in Section 5.7.
4. If the capacity is less than 80% of the battery’s rating, steps 2-3 may be repeated up to 2
times. Be sure to start the constant current charge with a fully discharged battery.
NOTE: The above procedure should be performed by an experienced battery maintenance facility
utilizing the proper charging and test equipment. For information regarding Concorde’s
recommended test equipment go to: www.concordebattery.com/accessories.php.
5.7 Capacity Testing
To determine the actual capacity of a Lifeline® AGM battery relative to its rated capacity, a full
discharge test should be performed. Although there are various battery testers available on the
market, such as carbon pile testers, impedance meters, conductance meters, and others, these
testers are not reliable in determining the battery’s actual capacity. To determine the battery’s
actual capacity relative to its rated capacity, use the following procedure:
1. Stabilize the battery at 68-86°F (20-30°C) for at least 24 hours.
2. Bring the battery to full charge as described in Sections 5.4, 5.5 or 5.6 as applicable.
3. Discharge the battery at a constant current of 25 amperes until the voltage falls to 10.5
volts (5.25 volts for a 6 Volt battery). Record the discharge time in minutes.
4. Compare the measured discharge time to the published 25A rating (reserve capacity
minutes) for the battery.
5. If the battery delivers less than 80% of the rated capacity the conditioning procedure
given in Section 5.5 should be attempted and the battery capacity should be retested.
6. If the battery delivers less than 50% of its rated capacity, it should be replaced.
However, the user should determine the amount of capacity needed for their particular
application and adjust the pass/fail threshold accordingly.
NOTE: The above procedure should be performed by an experienced battery maintenance facility
utilizing the proper charging and test equipment. For information regarding Concorde’s
recommended test equipment go to: www.concordebattery.com/accessories.php.