SunXtender Technical Manual

Document No. 6-0100 Rev. H
Page 21 of 43
In systems with limited charging output or long time periods between full charge, a routine
conditioning charge may helpful in preventing capacity loss due to sulfation. If a routine
conditioning charge is used, the time duration should be less than the 8 hours specified above.
As a starting point, a routine conditioning charge may be applied every 3 weeks for 4 hours at
the voltage levels given above. The frequency should be fine-tuned to assure the batteries are
not being undercharged or over-charged. In most cases, the optimum frequency will be between
2 and 4 weeks.
5.6 Deep Discharge Recovery
Batteries having an OCV less than 1.93 volts/cell (11.6 volts for a 12V battery) are considered
deeply discharged. This condition may occur when batteries are stored for long periods of time
without boost charging, or when discharged below 100% and not recharged. Batteries in this
condition may sometimes be recovered using a constant current charge instead of a constant
voltage charge. The deep discharge recovery procedure is given below.
WARNING: This procedure should only be done by a trained technician. Refer to Chapter
7 for safety precautions.
WARNING: This procedure should only be done in a well ventilated area because a
significant amount of hydrogen gases and fumes may be released from the battery.
CAUTION: If the battery becomes hot (above 55°C/130°F) during this charge, stop the
current and allow the battery to cool to room temperature before continuing.
1. Stabilize the battery at 20-30°C (68-86°F) for at least 24 hours.
2. Charge at a constant current of 5% of rated (24 hour) capacity until the voltage reaches 2.58
VPC (15.5 volts for a 12volt battery), then continue charging at this rate for an additional 4
hours. Note that the charging voltage may get as high as 3.0 volts/cell, 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.
NOTE (1): If the battery voltage exceeds 2.58 volts/cell at the beginning of charge and
then drops below 2.58 volts/cell within 2 hours, continue charging at constant current
until the voltage reaches 2.58 volts/cell a second time. Then continue charging for an
additional 4 hours as specified above.
NOTE (2): If the battery voltage does not reach 2.58 volts/cell within 24 hours, the
charge should be terminated.
5.7 Servicing
SunXtender® AGM batteries do not need electrolyte adjustment as do flooded lead-acid
batteries, but periodic servicing is essential to assure continued integrity of the battery system.
Servicing should include good record keeping to document the life history of the battery system
and to identify whether corrective action needs to be taken. The following servicing schedule is
recommended: