I have a 308 duo from Progressive RC with a 24v power supply that I have 2 Paraboards connected to. I can charge 12 6s batteries at once, at 5 amps per battery (30 amps total per paraboard). I've had it for two years and it has worked well. It can show the internal resistance of lipo packs as well. It has a servo tester feature also (I haven't used this feature yet) I have a Hitec X4 that I use for...well, I use that for anything from 2s up to 6s. It can supply up to 6 amps per pack. If you're charging flight packs, I'd recommend the 308 duo. The Hitec is great, I used it for a couple of years (until I bought the 308). I take a lot of packs with me to the field...the Hitec would take a long time to charge all of my packs for flying the next day. I have noticed that the Hitec tries really hard to perfectly balance lipo packs. sometimes it would "time out" (charging packs for 2 hours). They were fully charged after 45 minutes, but not balanced within the charger's parameters, so it kept trying to balance them perfectly. So, now I watch the cell readout and pull the packs when they get close. Sorry, I wrote an editorial here. I highly recommend Progressive RC. Nice folks.