How about one battery powering both of these for 5:21 minutes! This was running phantom & keeping the Korg backlight on the entire time. I am really pleased & quite surprised. I made a simple cable to power both at the same time & taped my stereo on really high gain, even used the phone monitor a few times. Looks like it may be a little short for festi's but no problem getting a normal show done with one battery. I am very pleased with this battery, beats the hell out of lead.