I think that charger that you have charges to almost 100 % so be careful. What you could do, is buy two of these

http://hobbyking.com/hobbyking/store...itor_2-8S_Lipo

That'd be only about $35 total and that would solve your BMS problems. You could charge the batteries about 10 ft away from where ever you are in the house and then you could just listen for the alarm and if the alarm goes off then that means one of your cells is about to over charge. It has a low voltage alarm and an over voltage alarm and you can manually set it. So you could set it for like 3.8v and then if it hits that, run into the room and stop the charging and then if you wanted to top-off some of the other cells, use a single cell charger for the others. I don't know how loud the alarm is though.