The 3010B has a 30A output if you have a strong enough power supply to feed it. With a parallel board you could charge (4) 5S packs at 1.5C which I have done many times. It runs nice and cold but has a very aggressive balance charge algorithum that annoys my generator. Parallel charging is convenient but not perfect as others have pointed out. I only do it with well known packs that are fairly new and reasonably matched. Mainly charge with my Cellpro 10S (250W version) or with Cellpro 10XP (600W) only 15A output and a lot noisier. Decent chargers but I blew up one 10S by connecting it to 24v power supply and the other one is getting a little flaky after many years of use. Replaced the cheap fans in the 10XP and have lots of time on them. Prefer to wire my stuff as 10S much simpler and reduce over an ounce of wire.