Astroflight 109 HELP

it's finally nice out, so i put connectors on my 5s1p packs and my two 109 chargers..

i plugged both packs into each charger, and they started charging just fine.
while adjusting the amps to 4, i bumped it up to 6 for a second, and the charger instantly gave an error:
volts <10.5 (not sure if it was .5, but it was right around 10.5)
so I unpluged the battery and instantly the second charger gave an over voltage error.

i unplugged the psu, plugged it back in, and hooked one pack up again. started charging at 4amps. plug the second pack in, and get an over voltage error. everytime I plug that pack into that charger it gives an over voltage error.
so I left it unplugged, and watched the first pack that was still charging at 4amps.

the charger said:
5C2
3:11
.104ah
19.2volts

I watched it till the volts went up to 19.66v, then unplugged it and came on here. what voltage do these packs hold when charging? and i'm assuming the 19.66v is the battery's voltage?

the psu is an Elco 12v13a.
i'm guessing i need a psu that can do 20v and 8a at the minimum?
i'm still extremely cautious around lipo, having never used them before, so I'll await a reply.. hopefully the suns still out when this is resolved :(