most automotive batteries are capable of running multiple chargers at once.....even 10 at once if you wanted.....

its just a matter of how many charges you can get out of it....

you'll have to purchase a 'deep cycle' battery if you want to use it for RC charging.....

i bought a 75Ah Bosch from supercheap for $150.............u can get about 15 charges of GP3300 packs

starting batteries are rated with CC and deep cycle are Ah.......