Over the period of their organization, 2/1/62 to 4/26/65, a total of some 200-300 men served in the battery at one time or another.

The NPS Soldiers and Sailors System record 288 names in their roster of FERRELL'S BATTERY, GEORGIA LIGHT ARTILLERY
http://www.itd.nps.gov/cwss/regiments.cfm

The American CW Research Database contains 202 names in their roster

Unable to count those in the Compiled Service Records as they are commingled with Capt. Fraser's Battery.

Remember, men died, were discharged, deserted, captured, missing, etc., replacements occurred as necessary. I'm not sure, but I believe about
100 men would be the normal complement.