just curious, what are you using as the powersource for the charger? I haven't had any problems like you have mentioned with stopping mid charge with my accucel 6.
WE may be talking about accucels, but IMO Hyperions are still top of the line, the 610I Duo that I use gets 2 of my zippys at 4.2 per cell for all 3 cells on all 4 packs takes it 90min's with a 90% charge parallel them to a stock revo and get 35min runtime b4 the LVC cutsd it off.
I have a Accucel-6 and a pr of 0610i chargers, can't compare a $170 charger to a $38 charger. Can't beat the Accucell for a pit bag charger and taking it with you though, its been amazing for a $38 charger.
The Accucel-6 is only a 50watt charger and thats some of what you're running into, so its just going to take a while to charge and balance. You need to factor that into resetting the safety timer.