SunXtender Technical Manual

Document No. 6-0100 Rev. G
Page 33 of 43
APPENDIX B – FREQUENTLY ASKED QUESTIONS (FAQ’S)
1. What does AGM stand for?
It stands for Absorbed Glass Mat, the type of separator used in all Sun Xtender® AGM batteries.
2. 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. AGM batteries have the advantage of lower internal
impedance to support high load currents and have better capacity at low temperatures. Gel batteries can
develop air pockets in the gelled electrolyte during operation which can cause local hot spots and burn
out the plates. They have inferior performance at high discharge rates and low temperatures. Refer to
Chapter 3 for further details.
3. 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.
4. 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.
5. 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.
6. May 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.
7. 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 Section 5.4 for further information.
8. 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.
9. 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.