I have a Life batterie for my 4PKS and it has been running fine for about a year or so. I decided to charge the batterie and noticed that half way threw the charge my charger stopped charging the battery and I got an error message
"Check Battery Open Cell"
what does that mean?

That means a break in one of the wires somewhere. I got that also when I use to charge LiFe packs. I use to mess with the wire or/and flip the battery a few times till it start charging. I switched to Lipo packs now though.