Is your battery pack more than 3 years old (manufacture date, not install date)? Is it no longer able to power your panel for minimum of 24 hours in a power loss?
Then build a new one for $20.
You can make your own 7.2v 2300mah battery pack for around $20 using the existing wire leads/connector off an old battery pack and some electrical tape.
Just buy two 4-pack AA NIMH Energizer (each battery @ 2300mah or higher) rechargeables ($10 a pack), wire 6 of them in series for 7.2v, and attach the wire leads with the attached 2GIG plug. Tape the pack tight, and you are good to go.
Or you can spend $30 for a 7.2v 2600mah pack 2GIG-BATT2X
I would hazard a guess and say you will probably get more charge cycles (life) from the Energizer (or even Duracell) than from the generic pack used by the current pack supplier (Golden Power) used by 2GIG.