Product Manual

Document No. 6-0100 Rev. E
Page 32 of 41
APPENDIX B – FREQUENTLY ASKED QUESTIONS (FAQ’S)
What does AGM stand for?
It stands for Absorbed Glass Mat, the type of separator used in all Sun Xtender® AGM batteries.
What is the difference between AGM batteries and Gel batteries?
Both AGM and Gel batteries utilize oxygen recombination and pressure relief valves to minimize water loss and allow
maintenance-free operation. That is where the similarities end. AGM batteries have the advantage of being
mountable in any orientation without capacity loss, have lower internal impedance to support high load currents, and
have better capacity at low temperatures. Gel batteries must be mounted upright to prevent air pockets from forming
that will burn out the plates. They have inferior performance at high discharge rates and low temperatures. Refer to
Chapter 3 for further details.
Why should I choose Sun Xtender® AGM batteries?
Concorde has been supplying Sun Xtender® AGM batteries to the Renewable Energy Storage/ Solar Energy /
Photovoltaic (PV) Industries for over 20 years, providing excellent performance, reliability and life. Applications
include installations for telecommunications, village power, medical refrigeration, remote home, supervisory control &
data acquisition, cathodic protection, telemetry, residential homes, aids to navigation [sea & air], lighting, and many
more uses. With this long history and wide variety of successful applications, prospective customers are assured that
Sun Xtender® AGM batteries have proven themselves over and over again.
What depth of discharge should be used when sizing a battery?
To get the best cycle life, the average depth of discharge should be as low as possible. Concorde recommends the
average depth of discharge be no greater than 50% of the battery’s 24 hour rating.
What is the maximum number of batteries that can be connected in parallel?
There is no theoretical limit to the number of batteries that can be connected in parallel. As more batteries are
paralleled together, the risk of one faulty battery affecting the entire battery bank increases. Depending on the
criticality of the application, there may be a need to isolate each battery or battery string for fault protection or to allow
servicing of individual batteries. This can be accomplished by incorporating additional circuitry in the battery system
that includes fuses, circuit breakers, or diodes. For more details on this subject, contact Concorde Battery for
technical assistance.
Can Sun Xtender® AGM batteries be installed in sealed containers?
NO! Do not install Sun Xtender® AGM batteries in a sealed box or enclosure. During storage, charging, or
discharging hydrogen gas can be released and must be ventilated to prevent the possibility of ignition and/or
explosion.
What is the best way to charge my battery?
Charge with a 3 stage charger that compensates the voltage setting as the battery temperature changes. See
Chapter 5 for further information.
What is the best charge voltage setting for outdoor applications if temperature sensing is not available?
NONE! Charging voltage varies widely depending on the battery’s temperature and there is no single voltage that will
work over a wide temperature range. Batteries will fail prematurely if this is attempted.
How can I tell if my battery is fully charged?
For a battery at room temperature, it can be considered fully charged when the charging current falls below 0.5A per
100Ah of rated capacity. The open circuit voltage (after at least 4 hours of rest) will be 2.17 volts per cell or higher
(13.0 volts for a 12-volt battery), regardless of the battery temperature.
What causes some batteries to have convex or concave end walls?
Sun Xtender® AGM batteries contain a pressure relief valve (PRV) that prevents excessive pressure buildup
when the battery is being charged, and automatically reseals once the pressure is released. A slight
bulge in the battery container (convex end walls) can appear when the internal pressure is above the
surrounding atmospheric pressure but not enough to open the PRV. Alternatively, the end walls can flex
inward (concave end walls) when the internal pressure is less than surrounding atmospheric pressure.
Both of these conditions are normal and do not affect the battery’s operation.
How do I know when it is time to replace my battery?
Replace the battery when it no longer is capable of supporting the discharge load for the minimum required run time.