If the battery was stored without being maintained at a full charge, there is a pretty good chance that it is bad. A fully charged Emag battery pack should read at least 19.6V. It may read more than that when it first comes off the charger, but you should let it sit for an hour or two before measuring to get the true reading.
You can get new battery packs. There are new ones sold here on AO or you can get one directly from AGD. Most of the new ones are a higher capacity than the original 650mAh packs.
Except for the Automag in front, its usually the man behind the equipment that counts.