I have this charger for almost a year. I used it to charge all sort of 1s - 4s packs, and it has been working perfectly for me.

Until now, when I have to charge up some 6s packs. It will charge my 6s packs to about 24.5V then it beeps and displays "Output Circuit Problem" on the LCD. At this point, I can't charge or discharge the battery. However, I can use the charger to balance the pack. It doesn't matter what I set the charge current to, it won't charge or discharge a almost full pack. It just beeps at the beginning of the cycle and displays the message.

I'm using a 25V 10A bench power supply as input. Tried other power supply with no luck.

Anyone know if there's some kind of parameter that I need to set? I hope I don't have a bad unit.

Maybe it's faulty contact. You can try to clean all connectors, at output wires, battery and balance board.

Seems that your power supply has low voltage for 6s lipo. Try to find another with 27V output and try again.
Little math:
for fully charged 6s pack you need 6 x 4,2V = 25,2V
If I remember correctly 26V + 2V = 27V should be enough.

Hope, enlighted a little

I think it's not a problem. Any charger has DC-DC converter and increase voltage as needed. You can charge 6S LiPo from 12V power supply.

Hyperion charger manual says
"Output Circuit Problem - Non-Specific Circuit error. Check Battery condition"
Similar issue is described here, runryder heli site
Symptomes caused by faulty balancer cable and/or charger firmware.

thank for the suggestion.

I'm running the latest 5.52 already. After getting the error, I can balance the pack, so I think the balance harness should be fine.

If I can't get it to work, I'll have to try Hyperion's customer service.